Australian Halichondriidae (Porifera: Demospongiae): I. Species from the Beagle Gulf.

John N . A . Hooper

Twenty species of sponge in seven genera of the family Halichondriidae (order Halichondrida) are described from the Beagle Gulf, Darwin region, Northern Territory, including eight new species and five new records for Australia. A resume is provided of generic characters and a survey of the known Indo-west Pacific species in these genera.

AUSTRALIAN HALICHONDRIIDAE (PORIFERA: DEMOSPONGIAE): I. SPECIES FROM THE BEAGLE GULF. JOHN N.A. HOOPER, STEPHEN D. COOK, LISA J. HOBBS AND JOHN A. KENNEDY Queensland Museum, PO Box 3300, South Brisbane, Qld 4101, Australia. ABSTRACT Twenty species of sponge in seven genera of the family Halichondriidae (order Halichondrida) are described from the Beagle Gulf, Darwin region, Northern Territory, including eight new species and five new records for Australia. A resume is provided of generic characters and a survey of the known Indo-west Pacific species in these genera. Porifera, Demospongiae, Halichondriidae, Axinyssa, Myrmekioderma, Topsentia, Ciocalypta, Amorphinopsis, Halichondria, Hymeniacidon, taxonomy, new KEYWORDS: species, northwest Australia. subsequently included in the order (Halichondriidae, Axinellidae, Dictyonellidae and Desmoxyidae), although there is not yet complete agreement about the generic composition of each of these (see Hooper and Levi 1993b). In its initial conception, Halichondriidae contained 27 very disparate genera allegedly related to each other by their possession of "fusiform or pin-shaped spicules variously fasciculated together" (Gray 1867: 503). Apart from Halichondria and Ciocalypta, all the other genera included here by Gray (1867) were subsequently assigned by contemporary authors to Poecilosclerida, Hadromerida or Haplosclerida. Nevertheless, the family name remains valid for the current assemblage of genera containing the genus Halichondria (Article 40 ICZN; Anon. 1985). Few subsequent authors used the family name Halichondriidae until it was redefined by de Laubenfels (1936) in a contemporary classification, after which time it came into general acceptance (e.g. Levi 1973; Berquist 1978; Hartman 1982). De Laubenfels' (1936: 133) interpretation of the family included eight genera, of which several were clear synonyms, all with "exceedingly simple spiculation ... of ... only oxeas ... smooth ... without microscleres ... [with] special dermal skeletons, although these are not conspicuous" (i.e. it specifically excluded sponges like Hymeniacidon with principal styles rath- INTRODUCTION Of the 114 families of extant Porifera only two (Raspailiidae and Microcionidae, order Poecilosclerida) can so far be considered well known in the Australian fauna (Hooper 1991, 1996). In this present work we deal with a third family, Halichondriidae, in the order Halichondrida. Traditional definitions of Halichondrida were based on the possession of diactinal megascleres, a relatively homogenous skeletal structure described as `halichondroid' (criss-cross reticulate), viviparous reproduction and completely ciliated larvae (Bergquist 1978; Hartman 1982). Under this interpretation two families were differentiated, Halichondriidae Vosmaer, 1887 (principal megascleres oxeas sometimes also with accessory styles), and Hymenacidonidae de Laubenfels, 1934 (principal megascleres styles sometimes with accessory oxeas), (Bergquist 1978). A recent revision of the order by Van Soest et al. (1990) allowed for the inclusion of species with compressed axial skeletons, differentiated axial and extra-axial skeletons (i.e. traditional Axinellidae), an indiscriminate occurrence of styles and oxeas within the skeletons, as well as 'typical' halichondrids with skeletal arrangements of styles or oxeas in plumose to ill-defined, confused tracts. Four families were In: Hanley, J.R., Caswell, G., Megirian, D. and Larson, H.K. (eds) Proceedings of the Sixth International Marine Biological Workshop. The marine flora and fauna of Darwin Harbour, Northern Territory, Australia. Museums and Art Galleries of the Northern Territory and the Australian Marine Sciences Association: Darwin, Australia, 1997: 1-65. 1 J.N.A. Hooperei al. collected from this region (extending from Northwest Cape, WA, to the Wessel Islands, NT; Hooper unpublished data), but so far less than 300 of these have been named in the literature (Hooper and Wiedenmayer 1994). Many species are unique to this region, with levels of endemism in some families thought to be about 70% (Hooper and Levi 1994), although for most sponge families this fauna is still poorly known. Habitats within this region are also incredibly diverse, most with at least some sponge species represented (ranging from ephemeral pockets of freshwater, large rivers, euryhaline estuaries and extensive mangroves, mud flats, fringing intertidal and subtidal rock and coral reefs, seagrass and Halimeda beds, artificial substrates, sand, coral rubble and shell-grit bottoms, deeper offshore rock reefs, submerged 'active' coral reefs, as well as pristine emergent platform and fringing coral reefs). There have been several major publications on sponges within the Beagle Gulf but prior to the present work only 71 species have been described. The earliest authenticated record of this fauna comes from material collected between 1875 and 1877 by T.J. Sturt, which was sent to Melbourne and initially described as a 'curiosity' (Barnard 1879), but subsequently identified by Carter (1879) as an endemic genus and species, Axos flabelliformis Carter (Hooper 1986a). In 1881 the British survey ship HMS Alert made extensive collections of the fauna, mostly dredging shallow waters within Darwin Harbour, Van Diemen Gulf, Dundas Strait and the Timor Sea. The sponges from this collection were described by Ridley (1884), and included 24 species, 21 named and three left uncertain, of which only 17 are currently recognisable as valid species. Nine of these species have not since been recorded elsewhere (i.e. apparent endemics). In the early 1960's a team from the Australian Museum, Sydney, led by Elizabeth Pope, travelled to Darwin, Cape Don and Port Essington to survey the intertidal marine biology of this region. This collection is the earliest comprehensive attempt to document the marine invertebrates of the northwest Australian coast (Pope 1967), from which the sponge fauna was described separately (Bergquist and Tizard 1967). These authors described 19 species of the larger, more prevalent intertidal sponges found in this region, belonging to 17 genera and with three new species. Since 1967, there have been 37 additional species in 16 genera described from the Beagle er than oxeas and a fleshy, gelatinous consistency). De Laubenfels (1936) further characterised the family in having "subdermal cavities ... so very enormous that the dermis is merely a roof supported on slender columns ... above ... the endosome". Since its creation, 54 genera have been associated with the Halichondriidae, although the most recent revision by Van Soest et al. (1990) (with subsequent refinements by Diaz et al. (1991, 1993) and Pomponi et al. (1991)), now recognises only 12 of these (the remainder being junior synonyms or incorrect assignments): Amoyhinopsis Carter, Axinyssa Lendenfeld, Ciocalvta Bowerbank, Collocalypta Dendy, Didiscus Dendy,Epipolasi.s de Laubenfels,Halichondria Fleming, Hymeniacidon Bowerbank, Myrmekioderma Ehlers, Petromica Topsent, Spongosorites Topsent and Topsentia Berg. All these genera have a highly dense choanosomal spicule skeleton arranged in vague, directionless (halichondroid) tracts composed of spicules in confusion (Van Soest et al. 1990), with spicules being either principal oxeas or styles, sometimes also with smaller accessory styles or oxeas (i.e. including Hymeniacidonidae and some Axinellidae). The Halichondriidae now represents one of the few spicule-bearing (`nonkeratose) families of Porifera 'accessible' to contemporary systematics. So far only 28 species in eight of the 12 halichondriid genera have previous published records from Australian territorial waters (including Antarctica) (Hooper and Wiedenmayer 1994), and surprisingly only two of these came from the northwest Australian region. In the present work we describe 20 species in seven genera from the Beagle Gulf, of which five are new records for Australia and eight are new species. A second contribution describing halichondriids from other tropical Australian provinces is currently in progress (Hooper et al. in prep.). DARWIN SPONGE FAUNA In this forum (i.e. The International Workshop on the Flora and Fauna of Darwin Harbour) it is appropriate to summarise existing knowledge on the Darwin sponge fauna of the greater region, namely the Beagle Gulf. The sponge fauna of northwest Australia is possibly the most diverse of all Australian marine provinces, with about 800 species already 2 Beagle Gulf halichondriid sponges Gulf region (Darwin Harbour in particular), as well as from other parts of the NT and northern WA coasts, including notes on the ecology, biochemistry and/or biogeographical relationships of several species (Hooper 1984, I986a, 1986b, 1987, 1991, 1994; Hooper and Bergquist 1992; Hooper and Levi 1993a, 1993b, 1994; Hooper et al. 1990, 1991, 1992; Capon et al. 1986; Capon and MacLeod 1988; Cambie et al. 1988a, 1988b; Van Soest et al. 1991). Significantly, Darwin Harbour is the type locality for 22 of these species, most discovered originally from the East Point Aquatic Reserve. Nevertheless, this described fauna represents less than 10% of the species known to live in the Beagle Gulf, and it is anticipated that this list of published species will increase substantially over the next decade. ate spicules not functionally localised to any particular region of skeleton. Spicules widely diverging in size in some taxa, sometimes with size differences between ectosomal and choanosomal skeletons. Skeletal structures ranging from disorganised plumoreticulate, crisscrossed "halichondroid skeleton", to distinctly compressed axis (or basal) skeleton and differentiated extra-axial (radial, plumose or plumoreticulate) skeleton. Spongin fibres usually poorly developed or absent. Ectosomal skeleton organised into tangential layer of spicules or erect spicule bundles, with minimal collagen, and large subectosomal spaces in many taxa. Microscleres raphides, microxeas, or spined microxeas with central bend in some species. Family Halichondriidae Gray METHODS Halichondriadae Gray, 1867: 503. Halichondriidae; Vosmaer, 1887: 336. - de Laubenfels 1936: 133; - Van Soest et al. 1990: 20. Ciocalyptidae Hentschel, 1923: 408. Spongosoritidae Topsent, 1928: 35,157. Petromicidae Topsent, 1928: 34,105. Hymeniacidonidae de Laubenfels, 1934: 13. Diagnosis. Halichondrida with choanosomal skeleton consisting of high density of spicules arranged in vague, ill-defined, directionless tracts and spicules in confusion. Ectosomal skeletons frequently detachable, often composed of spicules of different size than those in choanosome. Spicules are relatively large oxeas and/or styles, sometimes strongyloxeas or intermediate spicules Methods of collection, preservation, histological preparation, and techniques for light microscopy and scanning electron microscopy are given elsewhere (e.g. Hooper 1991). Spicule measurements are based on 25 measurements of each category of spicule, and represented as range (and mean). Abbreviations used in the text are: AM, Australian Museum, Sydney; BMNH, The Natural History Museum, London; CCNT, Conservation Commission of the Northern Territory, Darwin; MNHN, Museum National d'Histoire Naturelle, Paris; NCI AIMS, Australian Institute of Marine Science (US National Cancer Institute collection contract, 19851991); NCI CRRF, Coral Reef Research Foundation, Chuuk State, Federated States of Micronesia (US National Cancer Institute collection contract, 1992); NT, Northern Territory; NTM, Northern Territory Museum, Darwin; QM, Queensland Museum, Brisbane; SMF, NaturMuseum and Forschungsinstitut Senckenberg, Frankfurt; WA, Western Australia; ZMB, Museum fur Naturkunde an der HumboldtUniversitat zu Berlin. Genus Axinyssa Lendenfeld Axinyssa Lendenfeld, 1897: 116. Pseudaxinyssa Burton, 1931: 350. Axinomimus de Laubenfels, 1936: 163. Type species. Axinyssa topsenti Lendenfeld, 1897, by monotypy. Diagnosis. Massive, subspherical, lobate or lobate-digitate growth forms, often with apical cloacal cavity and fistulose surface processes. Choanosomal skeleton collagenous (although spongin fibres poorly developed), with widely spaced spicule tracts cored by larger oxeas, largely strewn in confusion or slightly plumose, dendritic or vaguely radiating. Subectosomal skeleton more organised than choanosomal region, plumose or plumo-reticulate, with regular tracts of larger choanosomal oxeote megascleres SYSTEMATICS Order Halichondrida Vosmaer Halichondrida Vosmaer, 1887: 335. Diagnosis. Demospongiae with plumoreticulate skeletal architecture composed of relatively large oxeas, styles, strongyloxeas or intermedi3 J.N.A. Hooper et al. Habitat. Sponge bed, soft mud and shell-grit substrate; subtidal 18-200 m depth. Description. Massive, lobate, with lumpy appearance, approximately 55 mm diameter. Oscules large, up to 4 mm in diameter, discrete, scattered over entire surface (i.e. not confined to apex of sponge), flush with surface (i.e. without raised membraneous lip). Colour. Pale pinkish alive in air (Mansell 5RP 8/2); ectosome purple-grey in ethanol, with lighter choanosome. Texture. Firm, resilient, barely compressible; not easily broken. Surface. Irregular surface with incorporated detritus; minutely hispid, with series of small raised ridges running over surface forming minute reticulation. Cavernous subectosomal skeleton visible through transparent surface membrane. Ectosomal skeleton. Plumose bundles of larger spicules from subectosomal region protrude through collagenous layer at surface, forming brushes or singly, with sparse tangential layer of both smaller and larger spicules, lying singly or in paucispicular tracts, overlaying ascending subectosomal skeleton. Choanosomal skeleton. Confused halichondroid reticulation of multispicular tracts in deeper choanosomal region of skeleton, becoming slightly more organised towards periphery; multispicular choanosomal skeletal tracts composed 20-50 spicules wide, ascending towards surface, becoming more plumose in subectosomal region, tracts separated by large subectosomal cavities of approximately same width as tracts themselves. Spongin fibres not evident. Collagen abundant in choanosomal mesohyl, associated predominantly with spicule tracts. Generally all spicule sizes dispersed throughout ectosomal and choanosomal skeletons, without clearly differentiated ectosomal and choanosomal size classes, although smaller spicules mainly found scattered between tracts whereas larger spicules mainly aligned in tracts. Spicules. Oxeas in two size classes, or more probably one class with large size range: larger oxeas slightly curved at centre, hastate relatively abruptly pointed (length 550-(622.4)-744 pm, width 13-(16.8)-21 pm); smaller oxeas straight or slightly curved, hastate abruptly pointed, occasionally styloid (length 188(241.4)-290 pm, width 4-(6.7)-11 pm). Remarks. This species has not previously been recorded having two size classes of oxeas, although Dendy (1922) notes that the main ascending to surface; without fibre component but with heavy collagenous mesohyl. Ectosomal skeleton highly collagenous, with mineral skeleton composed of smaller oxeote spicules forming discrete, sparse, regularly distributed surface brushes eventually producing surface conules; or of larger choanosomal oxeotes protruding through surface and producing regularly spaced surface conules. Megascleres are one or two size categories of oxeas or modified (styloid, strongyloid) oxeotes. Remarks. Axinyssa and the related genus Collocalypta differ from other halichondriids in having choanosomal spicule tracts protruding slightly through a largely organic ectosome (i.e. lacking a continuous ectosomal skeletal crust), producing a finely conulose surface (Van Soest et al. 1990). Axinyssa differs from the latter genus by its plumose or vaguely plumoreticulate skeletal structure (particularly near the surface), and growth form (the latter being exclusively fistulose). The emended diagnoses and discussions given by Van Soest et al. (1990) and Hooper and Bergquist (1992) clearly differentiate the two genera, whereas the diagnosis provided by Diaz et al. (1991) did not, mainly because they did not encounter Collocalypta in the central Atlantic fauna. Worldwide there are so far 13 described species of Axinyssa, distributed throughout the tropical oceans in shallow reefs to deeper coastal waters, but only one of these have been previously described from IndoAustralian waters: A. aplysinoides (Dendy) described from the Great Barrier Reef (Burton 1934). Axinyssa aplysinoides (Dendy) (Figs 1-2) Halichondria aplysinoides Dendy, 1922: 3940, pl. 3, figs 3-5, p1.12, fig. 9. Trachyopsis aplysinoides - Burton, 1926: 78; - Burton 1934: 564. Axinyssa aplysinoides - Van Soest et al., 1990, fig. 20; - Hooper and Bergquist 1992: 101. Type material. HOLOTYPE - BMNH 1921.11.7.31: Cargados Carajos, Indian Ocean, 30 August 1905, 58m depth, coll. HMS Sealark. Material. QM G303561: Outer region of Shoal Bay, NT, 12°06.9'S, 130°49.9'E, 18 m depth, 12 October 1993, coll. CCNT stn. 136 (ref. 2176), dredge. Distribution. Cargados Carajos, Amirante, Coetivy, Egmont Reef, Seychelles Is, Indian Ocean; southeast Indonesia; Satellite Reef, Great Barrier Reef; Shoal Bay, Timor Sea, NT. 4 Beagle Gulf halichondriid sponges I 111 Fig. 1. Axinyssa aplysinoides (Dendy). A, larger oxeas; B, smaller oxea. C, peripheral skeletal structure; B, preserved specimen QM G303561; E, live specimen (on deck). 5 J.N.A. Hooperet al. Fig. 2. Axinyssa aplysinoides (Dendy). Specimen QM G303561. A, Perpendicular section through skeleton showing large multispicular tracts in choanosomal skeleton, becoming more plumose in periphery; B, transverse section of ectosomal skeleton showing outer surface of sponge with tangential uni- and paucispicular tracts of both larger and smaller oxeas; C, light micrograph of section through peripheral skeleton showing plumo-reticulate subectosomal skeletal tracts and protruding larger spicules; D, hastate pointed spicule terminations on both larger oxeas (left) and smaller oxeas (right). megascleres "vary considerably in size", with the upper size limit of 1000 x 30 pm. In the Darwin specimen, spicules are indiscriminantly scattered throughout the skeleton, without any marked localisation of spicule sizes to either ectosomal or choanosomal regions (unlike those of Topsentia or Epipolasis which have their ectosomal skeletons composed of a distinctly smaller category of spicules), and it is possible that smaller megascleres seen here (mostly scattered between the major spicule tracts) are juvenile forms of the main structural spicules. Dendy (1905) suggests that the most distinctive feature of this species is its resemblance to an Aplysina (Verongida) in external morphology, in particular to the series of minute, raised ridges forming a reticulation on the surface. These surface features, together with the ascending multispicular tracts of oxeas cemented together by granular collagen, and the spicule geometry (lacking telescoped points, occasion- ally styloid ends), differentiate this species from other Axinyssa. We do not know whether material from the Great Barrier Reef recorded by Burton (1934) is similar to the Darwin specimen, described above, as Burton did not describe his specimen, but it is assumed that conspecificity of his specimen was checked against type material given that he had easy access to the holotype in the BMNH collection. Genus Myrmekioderma Ehlers Myrmekioderma Ehlers, 1870: 28. Acanthoxifera Dendy, 1905: 156. Anacanthaea Row, 1911: 329. Neoprosypa de Laubenfels, 1954:189. Type species. Alcyonium granulatum Esper, 1830: 71. Diagnosis. Massive or encrusting growth forms. Surface hispid, with characteristic excavating meandering, sinuous or straight canals 6 Beagle Gulf halichondriid sponges and grooves (forming polygonal tuberculate plates in type species). Choanosomal skeleton collagenous, with compressed central portion composed of confused mass of larger spicules forming irregular, ascending, multispicular tracts bound together with collagen (spongin fibres present in some species but not all). Subectosomal skeleton composed of ascending tracts running radially or obliquely to surface. Ectosomal skeleton dense paratangential layer of smaller spicules forming closely adjacent brushes perpendicular to surface, with larger choanosomal spicules also protruding. Megascleres at least two distinct categories of choanosomal oxeas, strongyles, or more rarely styles, sometimes sinuous and centrally flexed, and smaller ectosomal oxeas or acanthoxeas of similar morphology. Microscleres raphides in trichodragmata, in one or more categories, larger usually sinuous or curved. Remarks. Recent revisions of this genus are provided by Bergquist (1965: 177), Van Soest et al. (1990: 31), Diaz et al. (1991) and Hooper and Levi (1993b: 1448). Myrmekioderma and Didiscus are apparently related (and both easily recognisable in the field) by their deeply sculptured sinuous and plate-like grooves on the surface, having an ectosome composed of smaller spicules forming an erect palisade over tangential larger spicules, and a similar basic choanosomal skeletal organisation (Van Soest et al. 1990; Diaz et al. 1991). Myrmekioderma lacks discorhabd microscleres, characteristic of Didiscus, but has instead bundles of sinuous raphides (trichodragmata). The genus has been traditionally defined with lightly acanthose ectosomal oxeas (e.g. Bergquist 1965; Hooper and Levi 1993b), but Diaz et al. (1991) correctly note that these ectosomal spicules are as frequently smooth as they are acanthose, and they emend the definition accordingly. Hooper and Levi (1993b) retained this genus in the family Desmoxyidae, supporting their decision with chemotaxonomic evidence based on an inferred close relationship between Higginsia and Myrmekioderma (Hooper et al. 1992). However, there is no strong morphological support for homology between the occasionally acanthose ectosomal oxeas in Myrmekioderma and the true ectosomal acanthoxeas in Higginsia. The overall similarity between the ectosomal structure, choansomal organisation and spicule composition (apart from the possession of microxeas or discorhabds, respectively) largely supports the inferred close relationship between Myrmekioderma and Didiscus and their inclusion in Halichondriidae, as proposed by Van Soest et al. (1990). However, it must be acknowledged that structural similarities in the erect palisade of ectosomal spicules is remarkable between Myrmekioderma and Higginsia (see illustrations in Hooper and Levi 1993b), for which genetic data might provide a more informed opinion. Myrmekioderma is widespread in shallow tropical and subtropical oceans, found predominantly on hard substrates, sand and rubble substrates. One species, M granulata, has been recorded previously from northwest Australian and southern Indonesian waters (Van Soest et al. 1990; Hooper and Levi 1993b), and is thought to be one of the truly widespread coral reef sponges throughout the Indo-west Pacific (Hooper 1994). Myrmekioderma granulata (Figs 3-4) (Esper, 1830) Alcyonium granulatum Esper, 1830: 71, pl. 24. Myrmekioderma granulata; - Ehlers, 1870:28; - Burton 1938: 39, p1.7, fig. 42; - de Laubenfels 1954: 121, fig. 75; - Levi 1961: 14, fig. 17; - Bergquist 1965: 177, fig.27a-b; - Van Soest et al. 1990: 29, fig. 28; - Hooper et al. 1992: 265; - Hooper and Levi 1993b: 1449, figs 35-36. Acanthoxifer ceylonensis Dendy, 1905: 157, pl. 9, fig. 5; - Dendy, 1922: 129. Myrmekioderma tylota de Laubenfels, 1954: 119, fig. 74. Neoprosypa atina de Laubenfels, 1954: 190, fig. 127. Acanthoxtfer fourmanoiri Levi, 1956: 5. Material. NTM Z196: Dudley Point reef flat, East Point, Darwin Harbour, NT, 12°25.0'S, 130°49.01'E, 0-0.5 m depth, 13 September 1981, coll. J.N.A. Hooper and P.N. Alderslade, by hand. NTM Z2053: Dudley Point reef slope, Darwin Harbour, 12°25.0'S, 130°48.40'E, 6-10 m depth, 10 May 1984, coll. J.N.A. Hooper and P.N. Alderslade, SCUBA. QM G303349: East Point `bommies', 12°24.5'S, 130°48.8'E, 10 m depth, 23 September 1993, coll. J.N.A. Hooper, L.J. Hobbs and B. Alvarez, SCUBA. NTM Z430: Lee Point, Darwin, 12°19.02'S, 130°53.01'E, 0-0.2 m depth, 13 December 1981, coll. J.N.A. Hooper, by hand. Comparative material (Refer to Hooper and Levi 1993b: 1449 for additional material examined). QMG300819: W of Port Musgrave, 7 J.N.A. Hooper et al. Gulf of Carpentaria, Qld 12°04.6'S, 139°21.5'E, 54 m depth, 25 November 1991, coll. S. Cook, RV Southern Surveyor, dredge. QMG303505: W of Duyfken Point, 12°28.4'S, 141°00.8'E, 53 m depth, 6 November 1993, coll. S.D. Cook and J.A. Kennedy, RV Southern Surveyor, trawl. QMG303172: NE side Flinders Reef, N. of Moreton I., SE Qld, 26°58.6'S, 153°29.2'E, 9 m depth, 31 May 1993, coll. J.N.A. Hooper, SCUBA. QMG303135: Lagoon, Truk Atoll, Caroline Is, 7°24.9'N, 151°44.4'E, 31 m depth, 24 March 1992, coll. NCI (CRRF). Distribution. Dudley Point, East Point, Lee Point, Darwin Harbour, NT; Port Essington, Cobourg Peninsula; Cumberland Strait, Wessel Is, NT; Parry Shoals, Arafura Sea, NT; Enderbry I., Direction I., Dampier Archipelago, WA; Hibernia Reef, Sahul Shelf, Territory of Ashmore and Cartier; Moreton Bay region, Qld; western Gulf of Carpentaria, Qld; Madagascar, Aldabra, Seychelles, Gulf of Manaar, SE Indonesia, Ponape, Truk (Chuuk), Ebon Atolls, Palau, Ifaluk, Chesterfield Is (refer to references in Hooper and Levi 1993b). Habitat. Shallow-water rock and coral platforms, coral pools, coral rubble, usually heavily sedimented, or in spur-and-grooves of fringing reefs; in deeper water found on exposed reef heads in gravel and mud substrates; intertidal to subtidal depths of 60 m. Description. Massive, subspherical or elongate bulbous, up to 1 m long, 1 m wide, 0.5 m thick; partially burrowing in soft sediment or excavating coralline substrate. Oscules large, discrete, conspicuous, usually situated in excavated grooves on apical surface, and each oscule with raised lip. Colour. Bright orange to dark orange-brown exterior (Munsell 7.5YR 7/10-5YR 6/10), often silt-covered in life; paler orange-yellow interior; orange-brown in ethanol. Texture. Firm but compressible, harsh with hispid surface; interior soft, producing mucus. Surface. Opaque and membranous, covered by rounded, raised polygonal plates separated by grooves and canals, producing pineapplelike external surface. Ectosomal skeleton. Detachable; distinct crust of smaller ectosomal spicules forming continuous paratangential palisade, associated with and protruding through heavy collagenous ectosomal layer, and dispersed amongst larger choanosomal oxeas and styles, the latter moreor-less erect and ascending to surface. Subecto- somal region dense, collagenous, cavernous in places, with tracts of larger choanosomal oxeas supporting ectosomal crust. Choanosomal skeleton. Skeletal structure vaguely halichondroid reticulate, with compressed central portion, oblique subectosomal skeletal tracts supporting paratangential ectosomal layer. Choanosomal spicule tracts composed of up to 50 choanosomal spicules abreast, ascending to surface, becoming both sparser and more confused in peripheral skeleton. Thick fibres visible only in some specimens (being fully cored by spicules in others), with differentiated primary, multispicular, ascending fibres and transverse paucispicular fibres. Fibre meshes up to 300 pm diameter. Collagen abundant, very granular and pigmented in choanosome. Choanocyte chambers small, oval, 40-70 pm diameter. Spicules. Two size classes of megascleres recognised: choanosomal and ectosomal; variable megasclere geometry, ranging from fusiform oxeas, strongyloxeas, strongyles or styles; spicule terminations range from pointed to telescoped, styloid or sometimes with terminal deformities; and spicules may be completely smooth or lightly and evenly acanthose (Berguist 1965). In Beagle Gulf populations choanosomal megascleres predominantly oxeas, less often strongyloxeas or styloid, usually larger than ectosomal spicules, often with microspination (length 495-(615.7)-950 pm, width 8-(18.2)-22 pm). Smaller ectosomal megascleres invariably oxeote, predominantly smooth but occasionally evenly microspined (length 305-(502.4)-580 pm, width 3-(7.5)-10 pm). Microscleres raphides in bundles (trichodragmata) (110-155 x 10-15 pm). Remarks. Live specimens of M. granulata are distinctive in their characteristic dark orange colouration, mango-like texture, massive growth form and plate-like surface ornamentation. The species is now relatively well documented and known to be widely distributed within the Indo-west Pacific region, extending from Madagascar to NW Australia, Indonesia and the central west-Pacific islands and atolls (Esper 1830; Ehlers 1870; Dendy 1905, 1922; Burton 1938; Levi 1956, 1961; de Laubenfels 1954; Bergquist 1965; Van Soest et al. 1990). In the southwest Pacific the species is rare, so far known only from isolated records (Flinders Reef off Moreton Bay (27°S) and Chesterfield Islands (21.5°S latitude; Hooper and Levi 1993b and unpublished data). Surprisingly, the spe8 6 0^!1 paTnclson!w 'D .0£17Z WIN uowpads 617ZEZ FUN uowpads ponnsaid !om ptuls imams Tungdpad 'a :alapson!ul ,a taxo imuosolDa ruwosoueotio gioows :01011011S IBUIOSOUCOlp pou!dsonlw‘v . (iadsa) vivinuty 8 vuLopopputakv y O so'g uods ppiptimpHINitno oif eat{ J.N.A. Hooper et al. Fig. 4. Myrmekioderma granulata (Esper). Specimen NTM Z3249. A, perpendicular section through skeleton, showing compressed central portion of skeleton, oblique subectosomal spicule tracts and cavities, and paratangential ectosomal skeleton; B, transverse section of ectosomal skeleton showing outer surface of sponge with palisade of smaller ectosomal oxeas dispersed amongst larger choanosomal oxeas and styles; C, terminations of choanosomal strongyloxeas; D, termination of ectosomal oxen and raphide microsclere. cies has not yet been discovered from the Great Barrier Reef, despite some intensive recent collections from many reefs, and it is possible that M. granulata is merely an incursive into the south Pacific region. Populations of M. granulata in the central west-Pacific region have been frequently recorded (refer to records in de Laubenfels (1954) and Bergquist (1965)), whereas Australian and southern Pacific populations were only recently published (Hooper and Levi 1993b; Hooper 1994). Nevertheless, its distribution within Australia is now relatively well understood, extending as far south as 27°S latitude on the eastern coast (restricted to inshore waters), and to 21.5°S latitude on the western coast of the continent, living in both coastal and offshore waters. Within the Beagle Gulf Marine Park this species has been seen on many shallow inshore fringing coral reefs and coral platforms, especially in the Darwin and Cobourg Peninsula regions (Hooper and Levi 1993b), and it is also abundant on the more pristine oceanic coral reefs off the coast of northwest Australia (Hooper 1994) where it grows to a much larger size and ranges to greater depths than do the inshore populations. Bergquist (1965) provided a detailed analysis of morphometric variability in M. granulata, which she correlated to some extent with regional populations of the species. Characters found to vary between populations included surface sculpturing, live colouration, geometry, spination and size of megascleres. These features are also shown to vary between the inshore northwest Australian populations and those from other localities. Specimens from the oceanic coral reefs of the Sahul Shelf and those from New Caledonia have meandering ridges excavating the apical surface (rather than discrete polygonal plates) (compare Hooper and Levi 1993b: fig. 36A and the present work, Figure 3F-G); spicules are virtually entirely oxeote and 10 Beagle Gulf halichondriid sponges well as raphide microscleres overlaying larger choanosomal oxeas, typically showing a strict localisation of spicule sizes, whereas in Topsentia there there may or may not be size difference between the ectosomal and choanosomal spicules, and if present it is usually not consistent (i.e. spicule size may not be exclusive to any particular region) (Diaz et al. 1991, 1993). Van Soest et al. (1990) include Trachyopsis in synonymy with Topsentia, but this only applies to the type species (others subsequently distributed amongst Axinyssa and Spongosorites). The genus is found in all tropical and subtropical oceans, extending from shallow waters to moderate depths. Within the Indo-Australian region eight species of Topsentia has been previously recorded: T. solicla (Ridley and Dendy) with several junior synonyms (Hooper and Wiedenmayer 1994) from Tahiti, New Hebrides (Vanuatu), Christmas Island (Indian Ocean), Great Barrier Reef, and Ternate, Indonesia (Ridley and Dendy 1887; Keller 1891; Kirkpatrick 1900; Burton 1934), T. glabrata (Keller) from Ternate, Indonesia (Keller 1891), T. indica Hentschel from Am Island, Indonesia (Hentschel 1912), T. dura (Lindgren) from Gaspar Straits, Java Sea, Indonesia (Lindgren 1897, 1898), T. variabilis (Lindgren) and T. armata (Lindgren) from Java, South China, southern Philippines and Arafura Seas (Lindgren 1897, 1898; Hentschel 1912; Wilson 1925); T. cavernosa (Topsent) from the Moluccas, Indonesia (Topsent 1897; Desqueyroux-Faundez 1981), and T. halichondrioides (Dendy) from the Gulf of Manaar, southern Philippines, northern Great Barrier Reef, New Zealand (Dendy 1905; Wilson 1925; Burton 1934; Bergquist 1970). smooth (whereas some inshore specimens have acanthose ectosomal oxeas and styloid modifications to choanosomal oxeas); and skeletal structure may be more cavernous (whereas most inshore samples appear to be more compact) (Hooper and Levi 1993b and present study). It is possible that these differences are indicative of a sibling species relationship (rather than conspecificity), but this is not detectable solely on the basis of morphological data. Genus Topsentia Berg [Anisoxya] Topsent, 1898: 225 (junior homonym of Anisoxya Mulsant, (Coleoptera)). Topsentia Berg, 1899: 77. Trachyopsis Dendy, 1905: 147. Oxeostilon Ferrer-Hernandez, 1922: 10. Alloscleria Topsent, 1927: 6. Coelocalypta Topsent, 1928: 167. Laminospongia Pulitzer-Finali, 1983: 546. Type species. Anisoxya glabra Topsent, 1898, by monotypy. Diagnosis. Massive, amorphous or lobate growth forms, with brittle texture. Choanosomal skeleton completely lacking spongin, with mineral skeleton composed of oxeas in confused, directionless arrangement closely packed around aquiferous system, lacking any multispicular tracts. Subectosomal skeleton sometimes with subdermal cavities, but never large. Ectosomal skeleton with compact paratangential or erect layer of oxeas producing microhispid surface, typically without definite organisation but often closely compacted producing radial palisade. Megascleres oxeas in two or more size classes, including twisted, sinuous and contort modifications, usually without consistent size differences between ectosomal or choanosomal spicules. Remarks. The genera Topsentia, Epipolasis and Petromica have completely confused halichondroid choanosomal skeletal structure, with spicules criss-crossing in deeper parts of the skeleton, they lack spongin within the choanosomal skeleton, and the only recognisable organisation is found at the surface in the form of spicule brushes. Species of Topsentia are most distinctive in the disorganisation of the choanosomal skeleton and lack of spongin (hence the brittle consistency), and they are typically drab in colour (Van Soest et al. 1990; Diaz et al. 1991). Epipolasis has a tangential felt-like ectosomal crust of smaller oxeas as Topsentia halichondrioides (Dendy) (Figs 5-6) Trachyopsis halichondrioides Dendy, 1905: 147, p1.10, fig.I0. - Burton 1926: 75, figs 6-7; Burton 1934: 564; - Bergquist 1961: 185, fig.9; - Bergquist 1970: 34. Type material. HOLOTYPE - BMNH 1907.2.1.44: Galle, Periya Paar, Gulf of Manaar, Ceylon (Sri Lanka). Other Material. NTM Z3262: SW side of cliff face, Table Head, Port Essington, Cobourg Peninsula, NT, 11°13.5'S, 132°10.5'E, 5 m depth, 11 September 1986, coll. J.N.A. Hooper and C. Johnson, SCUBA. QM G303442: W 11 J.N.A. Hooper et al. Fig. 6. Topsentia halichondrioides (Dendy). Specimen QM G303442. A, perpendicular section through skeleton showing disorganised ascending halichondroid choanosomal skeleton supporting the plumose subectosomal skeleton of larger oxeas, with a thin tangential ectosomal layer of smaller oxeas just below surface; B, transverse section of ectosomal skeleton showing outer surface of sponge with erect palisade of larger oxeas, with smaller oxeas lying below and tangential to this layer; C, light micrograph of section through peripheral skeleton showing distinct demarkation between the halichondroid reticulate choanosomal skeleton and the nearly plumose subectosomal skeleton; D, larger oxea (left) with faintly telescoped point, and sharply smaller oxea (right). in dimensions; T. dura is greenish alive, olivebrown when preserved, stony consistency, small sunken oscules, two sizes of oxeas up to 600 x 20 pm and 260 x 6 pm, respectively, and an erect, continuous ectosomal palisade; T. armata is tuberculate, fibrous consistency, minute oscules, very large oxeas up to 1700 x 48 pm, and a sparse ectosomal skeleton; T. variahilis is massive flattened, grey-brown preserved, fibrous consistency, with prominent surface microconules, minute oscules, two sizes of oxeas, up to 770-1160 x 16-30 pm and 520-650 x 10-24 pm respectively, with an oblique, plumose ectosomal skeleton composed of discrete (not continuous) brushes, and multispicular tracts in the choanosomal skeleton; T indica is gray preserved, fibrous consistency, small oscules with slightly raised margins, oxeas in two sizes, up to 800 x 23-55 pm and 380 x 18 pm, respectively, ectosomal skeleton radial, well devel- oped; T. cavernosa is massive, has a hard texture, moderately well developed erect ectosomal skeleton composed of only marginally smaller oxeas than in the choanosomal skeleton, and oxeas are 600-1000 x 17-20 pm. Topsentia dura (Lindgren) (Figs 7-8) Halichondria dura Lindgren, 1897: 480. Lindgren 1898: 286-287, pl. 17, fig. 2, pl. 19, fig. 3. Type material. Fragment of holotype BMNH 1929.11.26.41: Selat Kelasa (Gaspar Straits), Java Sea, Indonesia, coll. C. Aurivillius, 1891. Other Material. NTM Z3195: East Point `bommies', Darwin, NT, 12°24.5'S, 130°48.8'E, 9 m depth, 16 September 1987, coll. N. Smit, 14 Beagle Gulf halichondriid sponges ■ I MOW Fig. 7. Topsentia dura (Lindgren). A, larger (predominantly) choanosomal oxea; B, smaller (predominantly) ectosomal oxea; C, peripheral skeletal structure; D, preserved specimen NTM Z3I95; E, specimen NTM ZI442. Colour. Yellow-green to dark green in life (Munsell 5Y 8/4 - 2.5GY 5/4), white in ethanol. Texture. Very firm, incompressible, brittle, easily broken. Surface. Optically smooth but uneven, lumpy; encrusted in places with detritus; hispid. Ectosomal skeleton. Continuous erect palisade of protruding single spicules or paucispicular brushes, composed mainly of larger oxeas, standing erect on ascending peripheral choanosomal tracts and protruding through surface only slightly beyond collagenous membrane; sparse tangential layer of smaller oxeas at base of protruding larger spicules, presumably lying on ectosomal membrane. Choanosomal skeleton. Dense halichondroid disorganised mass of single spicules, mostly larger oxeas, organised only around lacunae SCUBA. NTM Z3178: Dudley Point Reef, East Point, Darwin, NT, 12°25.0'S, 130°49.1'E, 0.5 m depth, 10 September 1987, coll. N. Smit, by hand. NTM Z1442: Blue Hole, Gunn Point, NT, 12°09.0'S, 131°00.5'E, 25 m depth, 19 August 1983, coll. J.N.A. Hooper and P.N. Alderslade, SCUBA. Distribution. Java Sea, Indonesia; East Point Aquatic Reserve and Gunn Point, Darwin Harbour, NT. Habitat. Laterite rock and fringing coral reef, sandy substrate; intertidal-subtidal depths. Description. Massive to lobate, irregularly anastamosing lobes, up to 110 mm long, 40 mm diameter. Oscules small, less than 2 mm diameter, discrete, scattered over surface of lobes, sunken in slight depressions on surface, without visible oscular rim. 15 J.N.A. Hooperet al. Fig. 8. Topsentia dura (Lindgren). Specimen NTM Z3195. A, perpendicular section through skeleton of branch showing halichondroid reticulate choanosome and plumose subectosomal skeletons; B, transverse section of ectosomal skeleton showing outer surface of sponge with a plumose ectosomal skeleton composed of protruding larger oxeas and a sparse tangential skeleton of smaller oxeas at their base; C, light micrograph of section through peripheral skeleton showing faint demarkation between the halichondroid reticulate choanosomal skeleton and the nearly plumose subectosomal skeleton; D, sharply pointed fusiform larger oxea (left) and smaller oxea (right). and in peripheral skeleton, becoming plumose in periphery. Choanosomal and subectosomal regions equally cavernous, with occasionally large lacunae (>500 pm diameter) but mostly smaller oval meshes (<230 pm diameter). Only faint demarkation visible between choanosomal and subectosomal regions. Collagen in choanosome present but lightly pigmented. Spicules. Oxeas in two sizes; larger predominantly choanosomal oxeas moderately or slightly curved at centre, fusiform, sharply pointed (length 344-(447.0)-585 pm, width 10-(12.3)16 pm); smaller predominantly ectosomal oxeas straight or slightly curved, fusiform, sharply pointed (length 190-(211.5)-262 pm, width 1(3.8)-6 pm) Remarks. Topsentia dura is also characteristically stony in texture, has a massive lobate growth form, and has a well developed continuous palisade of erect ectosomal oxeas on the surface, similar to T. halichondrioides. It differs from T. halichondrioides in its live colouration (greenish), oscule morphology (small, sunken in slight depressions, without an oscular rim), spicule dimensions (mean of 447 x 12 pm and 211 x 4 pm for larger and smaller oxeas, respectively) (although only one size class of oxeas was originally recorded by Lindgren 1897, 1898), sharply pointed spicule terminations, and a less extensive ectosomal palisade. By comparison, T. halichondrioides has a distinctive purple-mauve live colouration, its oscules are large, discrete, lying on the apex of bulbous projections, with a membraneous lip, and oxeas differ in both dimensions (562 x 23 pm and 185 x 8 pm, respectively) and geometry (the larger ones commonly with telescoped points). Refer to Remarks for T. halichondrioides for further comparisons between species. As in T. halichondrioides, his species has some 16 Beagle Gulf halichondriid sponges degree of localisation between spicule sizes forming various portions of the skeleton, with smaller oxeas predominantly found in the ectosome and larger oxeas predominantly in the choanosomal skeleton, reminiscent of Epipolasis. But this localisation is not completely strict, with both sizes also found throughout the skeleton, and the value of this character in Topsentia is questionable. Genus Ciocalypta these differences will eventually be considered artificial, especially considering that echinating ectosomal styles in Amorphinopsis can only be detected reliably using SEM techniques (i.e. a character of limited value to field biology), but any proposed merger between these genera requires more rigorous evaluation of a greater suite of species than presented here. Species of Ciocalypta are widely distributed in temperate, subtropical and tropical oceans, mostly confined to shallow waters on muddy or sandy bottoms, frequently burrowing, at least partially, into the soft sediments. Within the Indo-Australian region eight species are known: C. massalis (Carter) from Bass Strait, Vic., and Fremantle, WA (Carter 1883); C. polymastia (Lendenfeld) from an unspecified locality, east coast of Australia (Lendenfeld 1888; Hallmann 1914); C. occulata (Kieschnick) and C. simplex Thiele from Ternate, Moluccas, Indonesia (Kieschnick 1896; Thiele 1900), and C. subaceratus (Ridley and Dendy) from southern Mindanao, Philippines, and Ternate, Indonesia (Ridley and Dendy 1886; Thiele 1900); C. fenestrata (Ridley) from the Arafura Sea, Great Barrier Reef, and South China Sea (Ridley 1884; Lindgren 1897, 1898; Burton 1934); C. gracilis (Hentschel) and C. heterostyla Hentschel from the Arafura Sea (Hentschel 1912), both synonymised in Halichondria ryleri (Bowerbank) by Burton (1959; see Hooper and Wiedenmayer 1994), but this synonymy is rejected. Bowerbank Ciocalypta Bowerbank, 1863: 1105. Leucophloeus Carter, 1883: 323. Apatospongia Marshall, 1892: 16. Type species. Ciocalypta penicillus Bowerbank, 1864, by monotypy. Diagnosis. Growth form exclusively fistulose, with base burrowing into substrate. Surface usually semi-transparent, detachable, parchmentlike. Choanosomal skeleton composed of styles in confused, directionless arrangement, spicule tracts unispicular, and spongin virtually absent in massive portion of sponge, whereas fistules supported by multispicular columns of styles confined to central portion of fistules. Ectosomal skeleton tangential layer of smaller styles, usually in bundles, supported by widely spaced multispicular tracts of styles, perpendicular to central choanosomal tracts, producing large subclermal cavities (lacunae) in peripheral region. Megascleres predominantly styles, sometimes accompanied by fewer oxeas. Remarks. The revised concept of Ciocalypta is now restricted to fistulose species (Van Soest et al. 1990) which have exclusively stylote megascleres including a second, smaller category of ectosomal styles. Although fistulose growth forms seen in Ciocalypta are also known for some species of Topsentia, Halichondria and Petromica (i.e. this is likely to be an independently acquired ecological adaptation to living in sand substrates whereby fistules prevent smothering), these other genera differ from Ciocalypta substantially in their spicule geometry (oxeas instead of styles) and ectosomal characteristics (with erect bundles of spicules). Ciocalypta is most similar to Amorphinopsis, both having smaller ectosomal styles and larger stylote or oxeote choanosomal megascleres, whereas in Ciocalypta these ectosomal spicules are simply styles overlaying the choanosomal skeleton, in Amorphinopsis the ectosomal skeleton is composed of bundles of oxeas which are echinated by smaller styles. It is possible that Ciocalypta fenestrata (Ridley) (Figs 9-10) Leucophloeus fenestratus Ridley, 1884: 464, pl. 42, fig. s. - Burton, 1934: 564. Leucophloeus fenestratus var. [unnamed] Ridley, 1884: 464, pl. 43, fig. g. Not Leucophloeus fenestratus - Dendy, 1922: 124. Hymeniacidon fenestratus - Lindgren, 1897: 483; - Lindgren, 1898: 312-313. Axinyssa fenestratus - Van Soest et al., 1990: 27; - Hooper and Bergquist, 1992: 102. Type material. HOLOTYPE - BMNH 1882.2.23.255: Port Darwin, NT, 16-24 m depth, October 1881, HMS Alert, bottom mud and sand. Holotype of variety - BMNH 1882.2.23.195: Arafura Sea, NT, 64-72 m depth, 18 October 1881, coll. HMS Alert, bottom mud, sand, shells. Other Material. NTM Z2018: West side Weed Reef, Darwin, NT, 12°29.2'S, 130°47.1'E, 17 J.N.A. Hooper et al. C C Fig. 9. Ciocalypta fenestrata (Ridley). A, larger choanosomal styles; B, smaller ectosomal styles; C, peripheral skeletal structure (surface at right); D, preserved specimen NTM Z2018. 18 Beagle Gulf halichondriid sponges 8 m depth, 11 May 1984, coll. J.N.A. Hooper, P.J. Homer and P.N. Alderslade, SCUBA. Distribution. Darwin Harbour, Arafura Sea, Shoal Bay, NT; Low Isles, Mangrove Park, Great Barrier Reef, Qid.; Providence Reef, Amirante, Indian Ocean; Java and Lesser Sunda Islands, Indonesia (Ridley 1884; Lindgren 1897, 1898; Dendy 1922). Habitat. Burrowing in sand, mud, coral rubble, shell grit substrates; 4-72 m depth range. Description. Partially burrowing; subspherical, massive, buttressed base (50mm diameter, 100 mm high), with small tapering fistules on apex (up to 30 mm long, 10 mm basal diameter) with basal portion buried beneath sediment and fistules protruding through sand. Oscules large, up to 8mm diameter, on apex of fistules. Colour. Yellow-brown in life (Mansell 7.5YR 7/8), pale brown in ethanol. Texture. Compressible, harsh, easily torn; sand and coral rubble embedded on under surface and outer surface of base. Surface. Irregular, transparent and hispid. Ectosomal skeleton. Multispicular tracts of larger choanosomal styles, up to three spicules abreast, lying tangential to surface, and irregular bundles of smaller ectosomal styles arranged mostly paratangentially to surface as plumose brushes. Collagen present but light in ectosomal region. Choanosomal skeleton. In deeper regions of sponge, skeleton disorganised halichondroid criss-cross of both unispicular and multispicular tracts, containing 5-10 spicules abreast, composed of larger choanosomal styles; in subectosomal region tracts becoming more wide-meshed, paratangential, producing cavernous subectosomal region; in fistules choanosomal tracts more compressed in central region, cavernous towards Fig. 10. Ciocalypta fenestrata (Ridley). Specimen NTM Z2018. A, perpendicular section through skeleton of fistule, showing multispicular halichondroid reticulate skeleton, large subectosomal lacunae, and paratangential subectosomal skeleton; B, transverse section of ectosomal skeleton showing outer surface of sponge with a tangential multispicular bundles of larger styles and paratangential bundles of smaller styles; C, terminations on choanosomal styles; D, terminations on ectosomal styles. 19 J.N.A. Hooperet al. also substantially larger (670-920 x 20-30 pm, 200-400 x 7-10 pm, respectively), and growth form consists of a thinner crust, but apparently not burrowing, with fairly large fistules up to 30 mm long and 15 mm diameter. Similarly, C. massalis is massive and buttressed, with a prominently rugose surface but apparently lacking fistules (probably destroyed in the unregistered BMNH dry type material, re-examined by the senior author in the BMNH `Bowerbank Collection'). Ciocalypta massalis also has a relatively distinctive skeletal structure (consisting of a clearly differentiated compressed central region and radiating peripheral tracts of styles which become plumose closer to the surface, supporting a paratangential ectosomal crust composed of smaller styles), and spicule dimensions differ from those of C. fenestrata with only marginal size differences between the choanosomal and ectosomal styles (475 x 15 pm, 225 x 8 pm, respectively). It is possible that these four species are conspecific, representing substantial morphometric variability across a large latitudinal gradient, but this explanation is unacceptable under current interpretations of sponge morphometrics, and it is suggested that these species are at most close siblings. periphery; cavities at least as wide as spicule bundles, up to 400 pm in basal region, 1.5 mm in fistular region. Choanosomal spicule tracts predominantly composed of larger styles, whereas smaller (ectosomal) styles scattered throughout mesohyl. Collagen moderately abundant in central region of choanosome, sparse in peripheral skeleton; no spongin fibres observed. Spicules. Larger choanosomal styles variable in size, straight or slightly curved at centre, fusiform with sharp points or very slightly telescoped points, tapering to hastate rounded base smaller in diameter than centre of spicule (length 355-(521.6)-775 pm, width 8-(19.2)-32 pm). Smaller ectosomal styles fusiform, sharply pointed with evenly rounded bases (length 153(246.5)-330 pm, width 6-(9.1)-12 pm). Remarks. Comparison between the known specimens of this species, including type material, confirm their conspecificity, and the species is referred here to Ciocalypta based on the possession of a specialised tangential-paratangential ectosomal skeleton. In re-evaluating the genera Pseudaxinyssa and Axinyssa, both Van Soest et al. (1990) and Hooper and Bergquist (1992) considered that this species might be included in Axinyssa, (based on its published skeletal structure and surface characters; the ectosomal skeleton of type material was in relatively poor condition). However, examination of fresh material described above discovered that smaller styles are mostly confined to a specialised ectosomal layer, not scattered within the choanosomal skeleton as presumed previously, indicating that Ciocalypta is a more appropriate generic assignment. Ciocalypta fenestrata belongs to a species group of Ciocalypta characterised in having `subacerate' larger choanosomal styles, whereby the thickest part of the spicule occurs in the apical third and the basal end is substantially narrower than the centre of the spicule. Included in this group are C. oculata (Kieschnick, 1896) from Temate, Indonesia, C. oculata var. maxima Hentschel, 1912, from Aru Is, Indonesia, C. subacerata (Ridley and Dendy, 1886) from the Mindinao, Philippines, and Ternate, Indonesia, and C. massalis (Carter, 1883) from southwest Australia. The growth form of C. subacerata consists of massive anastomosing branches (`trabeculae') forming a cavernous construction, and megascleres are substantially larger than in C. fenestrata (1200 x 31 pm, 200 x 6 pm for both categories of styles). Spicule dimensions in C. oculata and its subspecies are Ciocalypta oscitans sp. nov. (Figs 11-12) Type material. HOLOTYPE - QM G303560: 4 km E of Fish Reef, Bynoe Harbour, NT, 12°24.8'S, 130°28.9'E, 17 m depth, 6 October 1993, coll. CCNT stn. 92 (ref. 1128), dredge. Distribution. Bynoe Harbour, NT. Habitat. Coarse sand and gravel sediment; subtidal. Description. Massive, subspherical, 110 mm diameter, excavated, partially hollow interior, buttressed exterior, partially burrowing into soft sediments. Oscules very large (10-15 mm diameter) on upper surface, with vestigial fistules up to 10 mm long. Colour. Pale mauve alive on deck (Munsell 5RP 8/2), white in ethanol. Texture. Firm, compressible, harsh and easily torn. Surface. Optically smooth, unornamented, with subectosomal cavities visible through translucent ectosomal membrane. Ectosomal skeleton. Detachable, dense tangential layer, composed of both smaller and larger styles arranged mostly tangential to surface, in thick multispicular tracts, supported by 20 Beagle Gulf halichondri id sponges O O Fig. 11. Ciocalypta oscitans sp. nov. A, larger choanosomal style; B, smaller ectosomal styles; C, peripheral skeletal structure (surface at right); D, preserved holotype QM G303560; E, live holotype (on deck). 21 J.N.A. Hooper et al. Fig. 12. Ciocalypta oscitans sp. nov. Holotype QM G303560. A, perpendicular section through skeleton showing disorganised halichondroid reticulation and cavernous meshes in central choanosomal region, more organised towards periphery; B, transverse section of ectosomal skeleton showing outer surface of sponge with a thin tangential layer of intermixed smaller and larger styles; C, hastate point (left) and rounded base of smaller ectosomal style (right); D, slightly telescoped point (left) and evenly rounded base of larger choanosomal style (right). paratangential spicule tracts from subectosomal skeleton. Choanosomal skeleton. Disorganised halichondroid reticulation of distinct multispicular tracts in centre of choanosome, composed mainly of larger choanosomal styles, with only slightly cavernous meshes throughout choanosomal and subectosomal regions, up to 500 pm diameter in choanosomal region but much smaller in peripheral skeleton; subectosomal tracts of larger styles ascending perpendicular to surface, producing nearly regular, open reticulate (crisscross) arrangement of multispicular tracts, with large subdermal cavities visible close to surface; smaller styles also scattered throughout skeleton, mostly paratangential to major spicule tracts, these largely confined to ectosomal skeleton. Fibres absent; collagen poorly developed in mesohyl. Spicules. Styles in two size classes: larger choanosomal styles straight or slightly curved near basal end, fusiform, sharply pointed or slightly telescoped points, with evenly rounded or slightly tapering hastate bases (length 515(776.1)-944 pm, width 11-(16.7)-20 pm); smaller ectosomal styles hastate pointed, with evenly rounded bases (122-(175.4)-216 pm, width 5-(6.3)-8 pm). Etymology. Named for the large oscules, from oscitans (L.), yawning. Remarks. This species has a choanosomal skeleton notably more compact (less cavernous) than other known species of Ciocalypta. It also has a more dense tangential ectosomal skeleton, distinctly detachable from the subectosomal region, whereas in most other species the tangential layer of smaller ectosomal styles is relatively sparse and forms mainly uni- or paucispicular tracts. These characters are perhaps better developed than in most other species examined, but this is a subjective interpretation which is difficult to substantiate amongst the relatively homo22 Beagle Gulf halichondriid sponges geneous skeletal structures seen in this group of halichondriids (i.e. they are not particularly discriminatory between species). Ciocalypta oscitans is a typically 'amorphous' burrowing sponge, similar in growth form to many other halichondriids, such as C. confossa sp. nov., but it has distinctive, very large oscules raised on small (vestigial) fistules. Certainly in comparison with C. confossa the present species differs substantially in all skeletal structures, whereas spicule dimensions are comparable between the species (although spicule geometries are not). Spicule dimensions in both these burrowing species, C. oscitans and C. confossa, are also equivalent to those seen in C. heterostyla Hentschel, from Aru Island, Indonesia, although growth form is substantially different (the latter compris- ing erect fistulose ridges, distinct ectosomal `skin' and oscules on the apex of ridges), and skeletal structures are markedly more cavernous in the Indonesian species. Ciocalypta confossa sp. nov. (Figs 13-14) Type material. HOLOTYPE - NTM Z3106 (fragment NCI Q66C-0559-W): Parry Shoals, Arafura Sea, NT, 11°12.53'S, 129°42.08'E, 20 m depth, 15 August 1987, coll. A.M. Mussig and NCI AIMS, SCUBA. Other Material. QM G303287: S of South Shell I., East Arm, Darwin, NT, 12°29.8'S, 130°53.5'E, intertidal, 19 September 1993, coll. J.N.A. Hooper and L.J. Hobbs, by hand. QM ■ IN e • ■ III 1 Fig. 13. Ciocalypta confossa sp. nov. A, larger choanosomal style; B, smaller ectosomal styles; C, peripheral skeletal structure; D, preserved specimen QM G303287; E, live intertidal specimen QM G303287, burrowing under substrate. 23 J.N.A. Hooper et al. G303541: W of South West Vernon I., NT, 12°06.9'S, 131°04.8'E, 13 m depth, 10 October 1993, coll. CCNT stn. 140 (ref. 1664), dredge. QM G303558: NW of Cape Hotham, NT, 12°01.3'S, 131°13.9'E, 34 m depth, 9 October 1993, coll. CCNT stn. 159 (ref. 1498), dredge. Distribution. East Arm, Darwin Harbour; Vernon Islands, Cape Hotham, Parry Shoals, Arafura Sea. Habitat. Coral reef, rubble, coarse sand and shell grit; intertidal-subtidal depths. Description. Completely burrowed into soft muddy substrate, with small fistules and small apical oscules barely visible above sediment; massive, up to 120 mm diameter, subspherical or tubulo-digitate, cavernous insubstantial construction (excavated throughout); fistules rudimentary, up to 18 mm long, 12 mm diameter, with moderately small oscules up to 5 mm diameter conspicuous on upper surface. Colour. Yellow or yellow-brown in life (Munseli 2.5Y 8/8 - 7/10), pale brown in ethanol. Texture. Firm, compressible, stringy, friable, easily torn. Surface. Opaque, membranous, roughened, fibrous, usually with some detritus, often mudcovered in situ. Ectosomal skeleton. Thin, detachable, tangential layer of small styles, scattered in uni- or paucispicular directionless tracts over surface, usually associated with granular collagen. Choanosomal skeleton. Disorganised halichondroid reticulation of both multispicular directionless tracts and single spicules; multispicular tracts consisting of spicule bundles composed mainly of larger styles, 5-20 spicules abreast, without apparent organisation but forming vaguely halichondroid-reticulate skeleton; single spicules scattered throughout mesohyl in between major tracts; meshes large, oval, cavernous, up to 700 pm diameter, found throughout skeleton (not necessarily confined to subectosomal region). Fibres absent; poorly developed collagen in choanosomal mesohyl. Fig. 14. Ciocalypta confossa sp. nov. Specimen QM G303287. A, perpendicular section through skeleton showing cavernous halichondroid reticulate skeleton supporting a thin ectosomal peel; B, transverse section of ectosomal skeleton showing outer surface of sponge with a thin tangential layer of smaller styles; C, smaller ectosomal style with fusiform point (left) and slightly subtylote base (right); D, larger choanosomal style with fusiform point (left) and evenly rounded base (right). 24 Beagle Gulf halichondriid sponges Spicules. Styles in two size classes; larger choanosomal styles straight or slightly curved near pointed end, fusiform, sharply pointed with evenly rounded bases or sometimes anisotylote (length 4254661.6)-940 pm, width 8-(13.4)-20 pm); smaller ectosomal styles slightly curved at centre or near basal end, fusiform, sharply pointed, with evenly rounded or slightly subtylote bases, occasionally anisotylote or centrotylote (length 1304183.3)-275 pm, width 3-(5.1)-7 pm). Etymology. Named for the burrowing, excavated habit, from confossus (L.), perforated, full of holes. Remarks. Although both are burrowing species, with vestigial fistules and similar ranges of spicule sizes, C. confossa differs from C. oscitans substantially in both its field characteristics and skeletal stuctures. It is nearly completely submerged below the substrate, with rudimentary fistules barely protruding above the surface, having much smaller oscules placed on top of these fistules, its ectosomal skeleton is sparse, with poorly developed paratangential single ectosomal styles scattered over the surface, overlaying a relatively cavernous subectosomal skeleton, spicule geometry of the smaller ectosomal styles in particular differs, and choanosomal skeletal structure is much less compact than in C. oscitans. Genus Amorphinopsis Carter Amorphinopsis Carter, 1887: 77. Migas Sollas, 1908: 395 (junior homonym of Migas Koch (Arachnida)). Prostylissa Topsent, 1925: 208. Tumata de Laubenfels, 1936: 77. Milne de Laubenfels, 1954: 116. Type species. Amorphinopsis excavans Carter, 1887, by monotypy. Diagnosis. Growth forms encrusting, excavating or ramose. Choanosomal skeleton with widely spaced halichondroid criss-cross of larger spicules, producing relatively large meshes bounded by mostly multispicular tracts. Ectosomal skeleton composed of thick bundles of larger oxeas lying tangential to surface echinated by smaller styles or oxeotes. Megascleres include smaller styles and/or oxeas, and larger choanosomal spicules predominantly oxeas or strongyloxeas, occasionally stylote. Remarks. The possession of smaller styles forming the ectosomal skeleton, overlaying larger choanosomal megascleres, is shared with 25 the sister genus Ciocalypta. In Amorphinopsis, however, these smaller styles echinate the tracts of larger choanosomal oxeas that lie tangential to the ectosome (which is unique amongst the Halichondriidae). The few known species appear to be restricted to the Indo-west Pacific region, confined to shallow waters (Van Soest et al. 1990). Four species of Amorphinopsis have been previously described in the Indo-west Pacific: A. excavans (Carter) from Torres Strait, Java Sea and Arafura Sea (Lindgren 1897; Burton 1934), A. megarrhaphea (Lendenfeld) from the south coast of NSW (Lendenfeld 1888), A. foetida (Dendy) and A. sacctformis (Thiele) from the Moluccas, Indonesia, and Papua New Guinea (Topsent 1897; Thiele 1900; Kelly-Borges and Bergquist 1988). Amorphinopsis excavans Carter (Figs 15-16) Amorphinopsis excavans Carter, 1887: 77, p1.5, figs 12-15. - Annandale 1915: 467, fig. 4A; - Burton 1959: 257; - Van Soest et al. 1990: 45, fig. 61. Amorphinopsis excavans digitifera Annandale, 1915: 469, figs 4B, 5. Halichondria armata Lindgren, 1897: 480. Lindgren 1898: 285-286, pl. 17, fig. 1, pl. 19, fig. 2. Halichondria panicea hemisphaerica Dendy, 1905: 146-147. Amorphinopsis kempi Kumar, 1925: 226, fig. 7. Prostylissa siamensis Topsent, 1925: 208, figs 1-2. - Van Soest et al. 1990: 45, fig. 64. Type material. HOLOTYPE - IM 6597/7 ZEV: Mergui Archipelago, Burma, Andaman Sea. holotype fragment of H. armata - BMNH 1929.11.26.31 (slide): Batan Island, Philippines. Syntype of H. panicea hemisphaerica - BMNH 1907.2.1.43: N. of Galle, Gulf of Manaar, Sri Lanka. Holotype of A. excavans digitifera - IM 501/7 ZEV: Fisher Bay, Tavoy Island, off Tenasserim, Burma, Andaman Sea. Holotype of A. kempi - IM P199/1: Waltair, Bay of Bengal, India. Other Material. QM G303658: Vernon Islands, South of Marsh Shoals, NT, 12°07.0'S, 130°56.1'E, 16 m depth, 11 October 1993, coll. CCNT stn. 138, dredge (ref. CCNT 1997). Distribution. Widespread in coral reefs of the Indo-west Pacific - Gulf of Manaar, Sri Lanka; Bay of Bengal, India; Andaman Sea, J.N.A. Hooper et al. B 00 Fig. 15. Amorphinopsis excavans Carter. A, larger choanosomal oxea; B, smaller ectosomal style; C, peripheral skeletal structure (surface at right); D, preserved specimen QM G303658; E, live specimen (on deck) encrusting coral. 26 Beagle Gulf halichondri id sponges Burma; South China Sea, Vietnam; Sulu Sea, Philippines; Gaspar Strait, Java Sea, Banda Sea and Arafura Sea, Indonesia; Vernon Islands, NT; Torres Strait, Old. Habitat. Gravel substrate; intertidal to 54 m depth. Description. Thickly encrusting over Pocillopora coral fronds and large fragments of siliceous detritus, up to 15 mm thick, with convoluted surface profile. Oscules small, discrete, 1-2 mm diameter, scattered over surface, with slighlty raised membraneous lip. Colour. Yellow-brown in life (Mansell 7.5YR 7/10), beige-white in ethanol. Texture. Firm but compressible, easily torn. Surface. Opaque, optically smooth, porous convoluted surface. Ectosomal skeleton. Ectosome a thin peel, detachable, composed of tangential layer of larger oxeas, mostly in bundles lying on surface, with small styles oriented paratangential to ("echinating") and protruding through surface. Ectosome with sparse collagen and detritus. Choanosomal skeleton. Tightly packed confused halichondroid reticulate skeleton of larger oxeote spicules, mostly formed by multispicular bundles bound together with very little collagenous material, producing small elongate cavities (lacunae) and oval meshes throughout skeleton. Towards periphery, spicule tracts becoming more paratangential, subplumose, producing larger lacunae free of spicules. Sparse collagen dispersed throughout mesohyl. Spicules. Larger choanosomal oxeas fusiform, slightly curved at centre, tapering to sharp points (length 175-(506.6)-642 pm, width 8-(12.8)-18 pm). Smaller ectosomal styles slightly curved at Fig. 16. Amorphinopsis excavans Carter. Specimen QM G303658. A, perpendicular section through skeleton, showing halichondroid reticulate skeleton of mostly multispicular tracts and spaces (lacunae) within choansomal skeleton, paratangential subplumose subectosomal tracts and thin ectosomal peel; B, transverse section of ectosomal skeleton showing outer surface of sponge with a tangential layer of larger oxeas, in bundles, echinated by small styles; C, closer view of tangential ectosomal skeleton; D, sharply pointed terminations on choanosomal oxeas (left) and ectosomal styles (right). 27 J.N.A. Hooperet al. Amorphinopsis foetida - Topsent, 1897: 445, p1. 18, fig. 8; - Desqueyroux-Faundez 1981: 757. Ciocalypta foetida - Lindgren, 1897: 483; Lindgren 1898: 313-314; - Thiele 1900: 75, pl. 3 fig. 26; - Hentschel 1912: 427-428. Leucophloeus foetida - Dendy, 1905: 197, 234. Material. QMG303677: Shoal Bay, middle of bay, NT, 12°13.1'S, 130°56.0'E, 17 m depth, 12 October 1993, coll. CCNT stn. 122, dredge (ref. CCNT 2104). Distribution. Tuticorin, Gulf of Manaar, Sri Lanka; S. coast of Vietnam, South China Sea; Ambon and Ternate, Moluccas, Indonesia; Arafura Sea, Indonesia; Shoal Bay, Darwin region, NT. Habitat. Sandy mud substrate with sparse seagrass cover. Description. Enlarged base burrowing into substrate with two subconical, low volcanoshaped fistules protruding above sediment. Larger oscules, up to 8 mm diameter, grouped on a terminal sieve-plate at the apex of each fistule. Colour. Yellow-beige on deck (Munsell 7.5YR 8/2), white in ethanol. Texture. Soft, compressible and easily torn. Surface. Transparent, membranous, irregular, wrinkled and hispid. Ectosomal skeleton. Dense layer of larger choanosomal styles lying tangential to the surface, mostly in irregular multispicular bundles of 2-10 spicules, with smaller ectosomal styles producing tufts (`echinating') around spicule bundles. Spicule bundles bound together with small amounts of collagen. Choanosomal skeleton. Architecture cavernous, reticulate, with distinct structural differences between central and peripheral skeletons. Deeper choanosomal skeleton with large multispicular tracts composed of larger choanosomal styles, 20-50 spicules wide, mainly confined to central region of sponge (particularly in fistules). Peripheral skeleton with widely spaced multispicular radial tracts of styles arising perpendicular to central skeleton, becoming plumose in near surface, supporting tangential ectosomal skeleton; spicule tracts forming widemeshed reticulate skeleton with very large cavernous meshes up to 2 mm diameter, particularly in fistular region; some collagenous material associated with spicule tracts but true fibres absent. centre, with rounded bases and tapering fusiform points (length 164-(190.3)-244 pm, width 2-(4.1)-8 pm). Remarks. Amorphinopsis excavans is a widely distributed Indo-west Pacific species commonly associated with coral reefs and coral rubble. Burton (1959) included it under the name A. megalorhaphis (Carter), but this synonymy cannot be corroborated (the type material being lost; Hooper and Wiedenmayer 1994) and the name excavans' has seniority. Similarly, many of the synonyms given by Burton (1959) are questionable, and we include only those species for which conspecificity has been established through comparison of relevant type material (listed above). In particular, two species mentioned in synonymy with A. excavans, Halichondria dura Lindgren and H. variabilis Lindgren (both from Indonesia and both belonging to Topsentia), are specifically excluded from comparison of fragments of type material (BMNFI 1929.11.26.41 and BMNH 1929.11.26.1, respectively). Significant differences in spicule sizes, geometries and skeletal structures justify their separation contrary to the opinion of Burton (1959), and followed subsequently by Hooper and Wiedenmayer (1994). Amorphinopsis excavans is most closely related to A. foetida in skeletal structure (both species having relatively cavernous choanosomal skeletons), differing from the latter species in spicule geometry and spicule dimensions. The specimen described above from the Vernon Islands is a typical example of this widely dispersed species, showing close similarities to the type material in its excavating growth form, and ectosomal and choanosomal skeletal structure (tangential `echinating' smaller styles; relatively wide-meshed choanosomal halichondroid reticulation, respectively). Conversely, it is atypical in having relatively consistent spicule geometry (most recorded populations of A. excavans have interchangeable smaller oxeas and styles composing the tangential ectosomal skeleton) and in the specific dimensions of spicules (these are relatively smaller than most described specimens). Nevertheless, present material clearly belongs to this species. Amorphinopsis foetida (Dendy) (Figs 17-18) Hymeniacidon (?) foetida Dendy, 1889: 8788, pl . 4 fig. 5. 28 Beagle Gulf halichondriid sponges Fig. 17. Amorphinopsis foelida (Dendy). A, larger choanosomal style; B, smaller ectosomal style; C, peripheral skeletal structure (surface at left and top); D, preserved specimen QM G303677; E, live specimen (on deck). 29 J.N.A. Hooper et al. Fig. 18. Amorphinopsis foetida (Dendy). Specimen QM G303677. A, perpendicular section through skeleton in fistule region, showing cavernous reticulate construction; B, transverse section of ectosomal skeleton showing outer surface of sponge with a tangential layer of larger styles echinated by small styles; C, terminations on choanosomal styles; D, terminations on ectosomal styles. spicules predominantly supporting the central portion of fistules, producing a wide-meshed cavernous reticulation supports the close relationship between the two genera. This species is now relatively well known in the literature from several populations in the Indo-west Pacific (Sri Lanka, South China Sea, Moluccas and Arafura Sea), probably being a dominant sponge of the soft, shallow-water benthos. The specimen described above, the first record for Australia, agrees closely with Dendy's (1889) original description, including the characteristic low, volcano-like fistules on the upper surface, skeletal structure and spicule sizes, whereas spicule dimensions cited in the Indonesian records are larger than those reported in other populations. Dendy (1889) also records that the species has a strong fetid smell (hence the specific name) but this characteristic has not been subsequently recorded. Spicules. Choanosomal styles long, slender, straight or slightly curved at centre, nearly hastate (abruptly pointed), occasionally slightly telescoped points, with evenly rounded bases (length 448-(609.8)-794 pm, width 8-(16.4)-23 pm). Smaller ectosomal styles slender, straight, fusiform, with sharp points and evenly rounded bases (length 67-(106.8)-252 pm, width 3-(5.4)-8 pm). Remarks. The possession of fistules and styloid spicules in this species suggests it could be placed in Ciocalypta. However, the fistules in A. foetida (short, squat, volcano-like) are unlike those characteristic of Ciocalypta (long, slender, pointed). Moreover, this species has an ectosomal skeleton with `echinating' smaller styles over tangential tracts of larger choanosomal styles (whereas in Ciocalypta the smaller spicules are in bundles and also placed tangentially). Nevertheless, the possession of a core of 30 Beagle Gulf halichondriid sponges Fig. 19. Amorphinopsis sacciformis (Thiele). Specimen NTM Z22 I 5. A, perpendicular section through skeleton, showing halichondroid reticulate choanosomal skeleton, oblique tracts in peripheral skeleton and tangential ectosomal layer (bottom of photo); B, transverse section of ectosomal skeleton showing outer surface of sponge with a tangential layer of larger oxeas echinated by small styles; C, closer view of tangential ectosomal skeleton; D, sharply pointed terminations on choanosomal oxeas (left) and ectosomal styles (right). Amorphinopsis sacciformis (Thiele) Description. Thinly encrusting under laterite rock boulders and covering bivalve shell, up to 8 mm thick following contours of substrate. Oscules not visible. Colour. Yellow-brown in life (Munsell 7.5 YR 6/8), brown in ethanol. Texture. Firm, compressible, harsh. Surface. Hispid, not opaque. Ectosomal skeleton. Indistinct, very thin surface peel with larger choanosomal oxeas lying tangential to surface and pointed ends of smaller ectosomal styles arranged paratangentially (`echinating') over larger spicules. Choanosomal skeleton. Confused halichondroid reticulation of larger choanosomal oxeas, packed densely and bound together by small amount of collagen, in uni- and paucispicular bundles. Skeletal meshes oval, usually compressed, and only few larger spaces (lacunae) (Figs 19-20) Ciocalypta sacciformis Thiele, 1900: 76, pl. 3, fig. 28 - Hentschel 1912: 125-126; - KellyBorges and Bergquist 1988: 132, pl. 2a. Ciocalapata sacciformis - de Laubenfels, 1936: 134; - de Laubenfels 1954: 183-184, fig. 122. Material. NTM Z2215: Vestey's Beach, Bullocky Point, Darwin, NT, 12°26.2'S, 130°49.9'E, intertidal, 21 January 1985, coll. J.N.A. Hooper, by hand. Distribution. Moluccas, Arafura Sea; Palau Is., central west Pacific; Motupore Island, Papua New Guinea; and Darwin Harbour, 0-23 m depth. Habitat. Intertidal rock and dead coral reef, frequently mud covered. 31 J.N.A. Hooper et al. Fig. 20. Amorphinopsis saccifbrmis (Thiele). A, larger choanosomal oxea; B, smaller ectosomal styles; C, peripheral skeletal structure; D, live intertidal specimen (encrusting under coral boulder and bivalves); E, preserved specimen NTM Z22I5 on bivalve. 32 Beagle Gulf halichondriid sponges visible in choanosomal or subectosomal regions. Subectosomal skeleton with more obliquely directed tracts supporting tangential ectosomal skeleton. Spicules. Larger choanosomal oxeas straight or slightly curved at centre, with long tapering fusiform sharply pointed ends, in two size classes (length I 2254318.5)-420 pm, width 5-(7.9)-10 pm; length 11 540-(781.1)-1105 pm, width 11(20.3)-35 pm)). Styles short, slender, fusiform, sharply pointed, with rounded or occasionally slightly subtylote bases (length 118-(213.4)-264 pm, width 3-(5.3)-9 pm). Remarks. This species is atypical of Amorphinopsis in having a more compressed choanosomal skeleton than most other species, and only few small meshes between multispicular tracts, but this is considered here to be a function of its thinly encrusting (juvenile) growth form. The possession of smaller `echinating' styles in the ectosomal skeleton indicates its affinities with Amorphinopsis rather than with Ciocalypta as suggested by previous authors. Amorphinopsis sacciformis is readily differentiated from other species of the genus in having two size categories of choanosomal oxeas, and both spicule dimensions and skeletal structures agree with those originally described for the species, although architecture is more noticeably wide-meshed in the Indonesian material (Thiele 1900; Hentschel 1912). skeleton (or vice versa). Cavities (lacunae) often occuring in choanosomal and subectosomal regions, with ascending choanosomal spicule tracts supporting ectosomal crust. Ectosomal skeleton invariably tangential to surface, usually easily peeled, composed of thin detachable crust of single spicules or multispicular tracts forming halichondroid criss-cross reticulation. Megascleres include predominantly oxeas of wide size ranges, commonly sharply pointed, but sometimes strongylote, stylote or rarely true styloid. Remarks. There is a wide range of variation in the development of choanosomal spicule tracts amongst species of Halichondria, most having the major tracts obliquely directed or parallel to the surface. Similarly, development of the ectosomal skeleton varies from discrete tangential bundles to largely collagenous with fewer scattered tangential spicules (Van Soest et al. 1990). Halichondria, like Hymeniacidon, is characterised by the possession of a thin detachable ectosomal membrane bearing a unispicular, tangential, halichondroid criss-cross of oxeas, or sometimes vague bundles of spicule tracts lying tangential to the surface. The two genera are differentiated by their spicule geometry, having predominantly oxeas or exclusively styles, respectively. Many species of Halichondria have been described from all oceans, although the genus has diversified to a larger extent in colder seas, including polar regions, and found predominantly in shallower waters (Diaz et al. 1991). Within the Indo-Australian region, 15 species have been described so far: H. aciculata (Carter), H. arenacea Dendy, H. claviformis Carter, H. nigrocutis (Carter) and H. schmidti (Dendy) from Bass Strait, Vic. (Carter 1885, 1886; Dendy 1895; Ayling et al. 1982); H. latrunculioides Ridley and Dendy and H. prostata Thiele from the Australian Antarctic Territory (Ridley and Dendy 1887; Thiele 1905; Hentschel 1914; Koltun 1964, 1976); H. lycopodium (Esper) and H. cartilaginea (Esper) from unspecified localities in northern Australia and Southern Indonesia (Topsent 1933); H. mollissima (Lendenfeld) from central NSW (Lendenfeld 1888); H. phakellioides Dendy and Frederick from the Houtman Abrolhos and Perth regions, WA (Dendy and Frederick 1924); H. tyleri (Bowerbank) widely distributed in northern Australia and Indonesia (Marshall 1892; Hentschel 1912; Burton 1934); H. mertoni (Hentschel) and H. Genus Halichondria Fleming Halichondria Fleming, 1828: 520. Raspaigella Schmidt, 1868: 25. Eumastia Schmidt, 1870: 42. Spuma Miklucho-Maclay, 1870: 13. Menanetia Topsent, 1896: 115. Pyloderma Kirkpatrick, 1908: 51. Halichondriella Burton, 1931: 137. Trachyopsilla Burton, 1931: 138. Ciocalapata de Laubenfels, 1936: 134. Ciareamastia de Laubenfels, 1942: 265. Type species. Spongia panicea Pallas, 1766, by original designation. Diagnosis. Massive amorphous growth forms. Choanosomal skeleton composed of poorly defined directionless spicule tracts; often two components recognisable: vaguely reticulate multispicular tracts and halichondroid crisscrossed single spicules dispersed between the major tracts, but major tracts may be sustantially reduced in favour of unispicular halichondroid 33 J.N.A. Hooper et al. (Hentschel) from the Am Islands, Indonesia (Hentschel 1912); and H. melichlora (Sollas) from Straits of Malacca and Arafura Sea (Sollas 1902; Hentschel 1912) . Description. Flattened or massive burrowing base extending below substrate for up to 30 mm, with long, thick, tapering fistules protruding above substrate, up to 125 mm long, 15 mm thick at base. Oscules surmounted on apex of most fistules, although some fistules blind and merely sharply pointed. Colour. Live colouration mottled mauvebrown (Munsell 2.5R 5/6) and mauve-green (5Y 5/4) fistules and beige base (5Y 8/4); mauvebeige in ethanol. Texture. Compressible, flexible, relatively easily torn. Surface. Opaque and membranous with drainage channels running down sides of fistules, visible through ectosome. External surface even, slightly conulose and minutely hispid. Ectosomal skeleton. Thick, continuous, dense spiculous layer, easily peeled from sponge surface, with multispicular tangential skeletal tracts composed mainly of larger oxeas, overlayed by unispicular paratangential tracts or plumose tufts of smaller oxeas. Ectosomal skeleton associated with moderate quantities of pigmented collagen. Choanosomal skeleton. Interior of choanosome a confusion of single spicules, mostly large, becoming more organised into radial bundles of spicules towards surface. In some specimens, medium-sized spicules forming distinct tracts approximately 20-50 spicules in width, traversing subdermal lacunae perpendicular to surface. In fistules choanosomal skeleton compressed, confined to central portion of skeleton, with huge subectosomal spaces (up to 5 mm diameter) and only few large subectosomal multispicular tracts support ectosomal peel. Collagen present in interior of choanosome and closely associated with spicule tracts. Spicules. Two size classes of oxeas: larger choanosomal oxeas slightly or moderately curved at centre, tapering fusiform, sharply pointed, occasionally asymmetrical anisoxeote (length 423-(536.7)-665 pm, width 8-(14.4)-22 pm); smaller ectosomal oxeas straight or slightly curved at centre, sharply pointed fusiform (length 150-(205.4)-312 pm, width 3-(4.2)-5 pm). Remarks. Under the traditional definitions of halichondrids, this species would have been included in Ciocalypta, having a fistulose growth form, plumose ectosomal skeleton of smaller spicules overlaying a tangential skeleton of larger choanosomal megascleres, and with supporting spicules located mainly at the core of fistules (as stalagmites Halichondria tyleri (Bowerbank) (Figs 21-22) Ciocalypta tyleri Bowerbank, 1873: 21, pl. 4, figs 9-12. Ciocalypta penicillus - Burton 1934: 564; Ciocalypta penicillus Burton 1959: 264 (not Bowerbank, 1864: 180). Ciocalypta penicillus var. gracilis Topsent, 1897: 445, pl. 18, figs 6-7. Ciocalypta tyleri var. manaarensis Dendy, 1889: 91. Apatospongia fallax Marshall, 1892: 16, pl. 8, figs 1-5. Type material. SYNTYPE - BMNH 1930.7.3.32: Port Elizabeth, South Africa, coll. Capt. Charles Taylor. Other Material. - NTM Z592: Table Head, Port Essington, Cobourg Peninsula, NT, 11°13.5'S, 132°10.5'E, 3 m depth, 04 May 1982, coll. J.N.A. Hooper, SCUBA. NTM Z3286: SW side of cliff face, Table Head, Port Essington, 11°13.5'S, 132°10.5'E, 5 m depth, 11 September 1986, coll. J.N.A. Hooper and C. Johnson, SCUBA. NTM Z1358: Coral Bay, Port Essington, 11°11.3'S, 132°03.75'E, 6 m depth, 16 May 1983, coll. J.N.A. Hooper, SCUBA. NTM Z1395: same locality, 11°10.4'S, 132°02.8'E, 2m depth, 19 May 1983, coll. J.N.A. Hooper, SCUBA. NTM Z941: East Point `bommies', Darwin, NT 12°24.05'S, 130°48.0'E, 12 m depth, 13 September 1982, coll. J.N.A. Hooper, SCUBA. NTMZ3133: Parry Shoals, 11°11.41'S, 129°43.01'E, 18m depth, 13 August 1987, coll. A.M. Mussig and NCI AIMS, SCUBA. NTM Z3410: 500 m east of Hermite Island, Monte Bello Islands, WA, 20°27.6'S, 115°32.8'E, 8m depth, 29 August 1988, coll. D. Low Choy and NCI AIMS, SCUBA. Distribution. South Africa, Red Sea, Gulf of Manaar, Indo-Malayan region, northern Australia; Turtle Islands, North Direction Island, Great Barrier Reef, Q1d.; East Point, Darwin Harbour; Parry Shoals, Arafura Sea; Port Essington, Cobourg Peninsula, NT; Monte Bello Islands, WA. Habitat. Base of coral reefs, sandy substrate; intertidal to 81 m depth. 34 Beagle Gulf halichondri id sponges E O Fig. 21. Halichondria tyleri (Bowerbank). A, larger choanosomal oxeas; B, smaller ectosomal oxea; C, peripheral skeletal structure; D, preserved specimen NTM Z592; E, preserved specimen NTM Z1358. Topsentia, Ciocalypta, and Petromica, as well as many other sponge orders. Burton (1959) synonymised many quite different species, including Ciocalypta tyleri, under the name C. penicillus. Most of this synonymy is now rejected following examination of relevant type material. Of relevance to the Australian fauna, Hooper and Wiedenmayer (1994) listed several species in synonymy with H. tyleri, following Burton (1959), but these can now be opposed to peripheral supporting spicules found in Petromica). However, given that all spicules are oxeas (not styles), this species is referred to Halichondria under the revised criteria of Van Soest et al. (1990) and Diaz et al. (1991) which hypothesises that fistules are an ecological adaptation for colonising soft substrata, and consequently they have been independently developed throughout various genera of Halichondriidae, and are also found in some species of 35 J.N.A. Hooper et al. Fig. 22. Halichondria tyleri (Bowerbank). Specimen NTM Z94I. A, perpendicular section through skeleton of fistule, showing choanosomal skeleton restricted to central portion of fistules, extremely cavernous subectosomal skeleton and thick paratangential ectosomal skeleton; B, transverse section of ectosomal skeleton showing outer surface of sponge with a multispicular and unispicular tangential skeletons; C, light micrograph of section through choanosomal skeleton showing compressed halichondroid reticulation in central portion of skeleton and halichondroid plumose subectosomal region; D, sharply pointed spicule terminations on larger oxeas (left) and smaller oxeas (right). allocated more accurately now that we have had access to type material. Of Burton's (1959) synonymised species, Ciocalypta heterostyla Hentschel (1912) and C. rutila gracilisHentschel (1912) (which belong to Ciocalypta), and C. mertoni Hentschel (1912) (which belongs to Halichondria), are not fistulose, they do not have exclusively oxeote spicules, and are not closely related to H. tyleri. Ciocalypta penicillus aciculata Carter (1885) is fistulose, with tapering "sub-pinlike" spicules (which are subacerate styles, with the thickest part of the spicule near the point rather than the base), and lacks the specialised tangential ectosomal skeleton characteristic of Ciocalypta. It is probably most appropriately referred to Halichondria, although this needs to be established from recollection of fresh material. Stylotella polymastia Lendenfeld (1888) is also a Ciocalypta (Hamann, 1914), and not closely related to H. tyleri. Sigmaxinella papillata Brondsted (1923), Axinella colvilli Brondsted (1924) and Hymeniacidon novaezelandiae Brondsted (1924) have both large choanosomal styles and small ectosomal oxeas and a fistulose growth form. Bergquist (1970) subsequently included these three species from New Zealand into synonymy with the European species Ciocalypta penicillus Bowerbank, but this conspecificity is very unlikely. They probably represent a single, distinct New Zealand species, possibly best allocated toAmorphinopsis or Ciocalypta (depending on whether ectosomal spicules are merely tangential or echinating). The name C. papillata (Brondsted) is the oldest available name for this taxon. As a consequence of rejecting Burton's (1959) synonymy, Halichondria tyleri is restricted now to Indo-west Pacific populations, extending into the Pacific 36 Beagle Gulf halichondriid sponges Fig. 23. Halichondria vansoesti sp. nov. Holotype NTM Z2678. A, perpendicular section through skeleton showing distinctive cavernous, reticulate subectosomal skeleton and thin tangential ectosomal peel; B, transverse section of ectosomal skeleton showing outer surface of sponge with a mostly uni- or paucispicular tangential layer; C, light micrograph of section through deeper choanosomal skeleton showing halichondroid reticulation of multispicular tracts; D, faintly telescoped points of larger oxeas (left) and smaller oxeas (right). cific attributes distinguish it from other fistulose species including those mentioned above and H. vansoesti sp. nov. only as far as the northern Great Barrier Reef. Several other species with similar growth forms but differing in various aspects of their spiculation and skeletal structures have been recently collected from central, southern Queensland and New South Wales waters, and these represent distinct sibling species, some at least still undescribed. These will be dealt with in a second part to this present contribution (Hooper et al., in prep.). Halichondria tyleri is distinctive in its burrowing fistulose growth form, with sharply pointed fistules with small terminal oscules, mauve-brown live colouration, slightly conulose surface with clearly visible subectosomal drainage canals, cavernous skeletal construction in the peripheral skeleton (not in the central portion of the skeleton), exclusively oxeote spicules both of moderate size range (mean 540 x 14 pm and 205 x 4 pm), and sharply pointed spicule terminations (no telescoped endings). These spe- Halichondria vansoesti sp. nov. (Figs 23-24) Type material. HOLOTYPE - NTM Z2648: East Point, Darwin, NT, 12°24.5'S, 130°48.0'E, 12m depth, 3 April 1986, coll. J.N.A. Hooper and A.M. Mussig, SCUBA. PARATYPE - QM G303450: W. side Fish Reef, Bynoe Harbour, NT, 12°26.1'S, 130°26.5'E, 11 m depth, 26 September 1993, coll. J.N.A. Hooper and L.J. Hobbs, SCUBA. Material. NTM Z84: Coral Bay, Port Essington, Cobourg Peninsula, NT, 11°11.5'S, 132°02.0'E, 4 m depth, 18 October 1981, coll. J.N.A. Hooper and P.N. Alderslade, SCUBA. NTM Z2678: East Point, Darwin, NT, 12°24.50'S, 130°48.0'E, 12 m depth, 3 April 37 J.N.A. Hooper er al. O O Fig. 24. Halichondria vansoesti sp. nov. A, larger choanosomal oxeas; B, smaller ectosomal oxeas; C, peripheral skeletal structure; D, preserved specimen NTM Z84; E, live subtidal paratype QM G303450. 38 Beagle Gulf hahchondriid sponges 1986, coll. J.N.A. Hooper and A.M. Mussig, SCUBA. QM G300815: E of Gove Peninsula, Gulf of Carpentaria, Qld, 12°37.1'S, 136°49.3'E, 26 m depth, 23 November 1991, coll. S.J. Cook, RV Southern Surveyor, dredge. Distribution. East Point, Darwin Harbour; Fish Reef, Bynoe Harbour; Cobourg Peninsula, NT; eastern Gulf of Carpentaria. Habitat. Rocky reef, reef slope, sandy substrate; subtidal 4-26 m depth. Description. Flattened base burrowing only shallow distance into substrate; top of base with long, tapering, pointed fistules protruding up to 250 mm above substrate; base approximately 25 mm thick, fistules up to 200 mm long, 25 mm diameter at base. Oscules large, up to 3 mm diameter in preserved state, located on basal plate in between fistules. Colour. Completely unpigmented, white in life and in ethanol. Texture. Firm, compressible, fistules flexible but easily torn and detachable from basal plate. Surface. Transparent, parchment-like membrane with subectosomal cavities clearly visible beneath. Surface of fistules regularly conulose, minutely hispid, with longitudinal striations visible subectosomally (presumably peripheral skeletal tracts running longitudinally from base to tip of fistule). Ectosomal skeleton. Detachable relatively thick peel formed by halichondroid reticulation of mostly smaller ectosomal oxeas, in uni- or paucispicular tracts, lying tangential to surface. Ectosomal skeleton varying greatly in thickness, thicker in region of base than at apex of fistules. In addition to tangential skeleton, sparse plumose tufts of smaller spicules occurring at junction where choanosomal tracts meet ectosome, standing paratangential to and just protruding through surface, producing prominent surface conules. Choanosomal skeleton. Confused halichondroid skeleton of mostly directionless multispicular tracts, 20-50 spicules in width, with some single spicules also dispersed between tracts. Spicule tracts composed of both large and small oxeas, becoming more perpendicular closer to surface and forming distinctive cavernous subectosomal region. Moderate quantities of collagen present in mesohyl associated with spicule tracts. Spicules. Oxeas in two size classes. Larger choanosomal oxeas straight or slightly curved at centre, fusiform, with slightly telescoped points (length 470-(558.3)-615 pm, width 8- (11.5)-15 pm). Smaller ectosomal oxeas straight or very slightly curved at centre, fusiform, with slightly telescoped points (length 200-(265.7)425 pm, width 2-(3.8)-6 pm). Etymology. For Dr Rob Van Soest, Zoological Museum, University of Amsterdam, for extensive contributions to the systematics of sponges, particularly the contemporary classification of Halichondriidae. Remarks. Halichondria vansoesti and H. tyleri are sibling species sharing a burrowing, fistulose growth form and comparable spicule sizes (mean lengths and widths 560 x 11 pm and 265 x 4 pm, versus 540 x 14 pm and 205 x 4 pm, for choanosomal and ectosomal oxeas, respectively). They are clearly not conspecific, differing substantially in their field characteristics (the fistules of H. vansoesti being consistently white alive, whereas those of H. tyleri are mauve-brown), ectosomal skeletal structure (marginally thicker in H. vansoesti), choanosomal skeletal structure (whereby in H. vansoesti the most cavernous part of the fistulose skeleton is found near the periphery, and in this region spicule tracts become reticulate, whereas in H. tyleri the deeper, central choanosomal region is prominently cavernous whereas the peripheral, subectosomal skeleton is dense and radial in construction), and spicule geometry (with telescoped points on spicules as opposed to sharply pointed spicules). Halichondria phakellioides Dendy and Frederick (Figs 25-26) Halichondria phakellioides Dendy and Frederick, 1924: 498-499, pl. 26, fig. 10. - Burton 1934: 600, pl. 2, fig. 1. Type material. HOLOTYPE - BMNH 1925.11.1.185: Sandy Isle, Houtman-Abrolhos, WA, coll. W. Dakin. Other Material. NTM Z900: East Point Aquatic Reserve, off Dudley Point, Darwin, NT, 12°25.0'S, 130°48.04'E, 10 m depth, 31 August 1982, coll. J.N.A. Hooper, SCUBA. NTM Z2063: same locality, 12°25.0'S, 130°48.4'E, 610 m depth, 10 May 1984, coll. J.N.A. Hooper and P.N. Alderslade, SCUBA. NTM Z2255: same locality, 12°24.5'S, 130°48.0'E, 10 m depth, 12 April 1985, coll. J.N.A. Hooper and C. Johnson, SCUBA. NTM Z2610, 2623, 2643, 2652, 2674: same locality, 12°24.5'S, 130°48.0'E, 9-12 m depth, 03 April 1986, coll. J.N.A. Hooper and A.M. Mussig, SCUBA. NTM Z935: same 39 J.N.A. Hooper et al. Description. Erect, buttressed flattened ridges. Base fixed to substrate by basal plate, attached to fragments of coral or shell, usually burrowing into soft substrate; ridges ('fistules') thick, flat (up to 220 mm long, 50 mm wide, 30 mm thick) growing in several planes, anastomosing and becoming buttressed or digitate in some specimens. Oscules small (330-500 pm diameter) but conspicuous and scattered on lateral surfaces of ridges, each with slightly raised membraneous lip. Colour. Yellow-brown to pale orange alive (Munsell 2.5Y 8/10 - 5YR 7/10), beige to grey in ethanol. Texture. Harsh, firm but compressible, can be torn. Surface. Surface smooth, even between large di g itate projections (ridges); usually membraneous and clearly detachable (although in some material surface roughened and minutely conulose due to poor preservation). Surface membrane translucent, with subectosomal lacunae and drainage channels clearly visible below. Ectosomal skeleton. Ectosomal skeleton consisting of distinct tangential crust of both single spicules and bundles of mostly medium-sized spicules, forming prominent 'skin'. Paratangential tracts of subectosomal spicules meeting tangential surface layer at regular intervals, giving ectosome patchy or striated appearance in cross-section; ascending spicule tracts may protrude slightly through tangential layer. In transverse section, ectosome nearly regularly reticulate, with cross-hatched spicule tracts five to eight spicule widths (20-50 pm in diameter) forming oval meshes 80-15 pm in diameter, distinctly detachable and clearly offset from cavernous subectosomal skeleton. Small amounts of collagen present in ectosomal layer bonding tangential spicule tracts. Choanosomal skeleton. Skeletal structure halichondroid reticulate in deeper choanosomal skeleton and cavernous reticulate in subectosomal peripheral skeleton. Deeper choanosomal region more disorganised than peripheral skeleton, largely composed of single spicules forming directionless halichondroid reticulation (criss-cross), comprising both large and small oxeas, whereas only large and medium-sized spicules comprise tracts or bundles of approximately 20-50 spicules in width (150-250 pm in diameter). Multispicular tracts forming prominent ascending lines arising to surface, with tracts aligned perpendicular to surface, support- locality, 12°24.05'S, 130°48.0'E, 12 m depth, 13 September 1982, coil. J.N.A. Hooper, SCUBA. QM G303320: East Point `bommies', East Point Aquatic Life Reserve, 12°24.5'S, 130°48.8'E, 10m depth, 23 September 1993, coll. J.N.A. Hooper and L.J. Hobbs, SCUBA. QM G303261: S of South Shell I., East Arm, 12°29.8'S, 130°53.5'E, intertidal, 19 September 1993, coll. J.N.A. Hooper and L.J. Hobbs, by hand. NTM Z241: Indian I., 12°35.0'S, 130°33.0'E, 3 m depth, 18 November 1981, coll. Byers, P., FV Skelton, snorkel. QM G303448: Fish Reef, W side near wreck of HMAS Brisbane, Bynoe Harbour, NT 12°26.1'S, 130°26.5'E, 1 lm depth, 2 September 1993, coll. J.N.A. Hooper and L.J. Hobbs. NTM Z3929: Bay N side of Cumberland Strait, Wessel Is, NT 11°27.5'S, 131°28.8'E, 20 m depth, 14 November 1990, coll. J.N.A. Hooper, SCUBA. NTM Z621: Unnamed shoal, N of Melville I., NT, 11°38.23'S, 129°51.0'E, 24 m depth, 17.v.1982, coll. R. Lockyer and B. Thom, SCUBA. NTM Z3077: Parry Shoals, 11°11.41'S, 129°43.01'E, 18 m depth, 13 August 1987, coll. A.M. Mussig and NCI AIMS, SCUBA. NTM Z3139: same locality, 11°12.28'S, 129°42.71'E, 16m depth, 14 August 1987, coll. A.M. Mussig and NCI AIMS, SCUBA. NTM Z3075: same locality, 11°11.72'S, 129°43.26'E, 16 m depth, 12 August 1987, coll. Mussig, AM and NCI AIMS, SCUBA. NTM Z3349: 8 km from shore, NW corner of Herald Reef, Coolga Point, WA, 21°29.5'S, 115°17.1'E, 5 m depth, 25 August 1988, coll. D. Low Choy and NCI AIMS, SCUBA. NTM Z3395: 50 m from shore, 3 km west of Hermite Island, Monte Bello Islands, 20°27.1'S, 1 15°34.2'E, 6 m depth, 29 August 1988, coll. D. Low Choy and NCI AIMS, SCUBA. NTM Z3361: 5 km from shore, Flinders Shoals, N of Mary Anne Island, Mary Anne Passage, WA, 25°14.2'S, 115°28.2'E, 8 m depth, 25 August 1988, coll. D. Low Choy and NCI AIMS, SCUBA. Distribution. Swan River region and Houtman-Abrolhos, southern WA; Herald Reef, Mary Anne Island and Monte Bello Islands, northern WA; East Point, Dudley Point and East Arm, Darwin Harbour; Indian Island and Fish Reef; Bynoe Harbour; Wessel Islands, Gove Peninsula; Parry Shoals and Melville Island, Arafura Sea, NT; ? unspecified locality, Great Barrier Reef, Qld. Habitat. Coral rubble and soft substrates, usually between patches of reef; intertidal to 30 m depth. 40 Beagle Gulf halichondriid sponges Remarks. This species is probably widely distributed in tropical and subtropical waters of Australasia, although its recorded distribution so far is restricted to the southwest and northwest coasts, from the Perth region, WA, to the Wessel Islands, NT. The single Pacific record is based on a specimen collected by Saville Kent (Burton 1934), with no specific locality data given. This record remains unsubstantiated, although Burton (1934) states that the Queensland specimen agrees in all details to the holotype. One of the prominent features of H. phakellioides is the clearly detachable tangential ectosomal skeleton, which peels off the sur- ing ectosomal skeleton, and traversing large subdermal cavities; cavities (lacunae) varying greatly in size between specimens ranging from 200-2000 pm diameter. Spongin fibres not evident but sparse collagen present in mesohyl closely associated with spicule tracts. Spicules. Oxeas in three size classes, all fusiform, slightly curved at centre or straight; larger ones usually faintly telescoped, sometimes sharply pointed or rarely styloid; smaller ones include both prominently telescoped and sharply pointed forms (I: length 314-(444.6)-578 pm, width 10-(13.1)-20 pm; II: length 195-(230.6)275 pm, width 4-(6.9)-12 pm; III: length 58(196.8)-266 pm, width 1-(2.2)-3 pm). ABC Fig. 25. Halichondria phakellioides Dendy and Frederick. A, larger oxeas; B, medium sized oxeas; C, smaller oxeas; D, peripheral skeletal structure; E, preserved specimen NTM Z900; F, live subtidal specimen NTM Z2610. 41 J.N.A. Hooper et al. Fig. 26. Halichondria phakellioides Dendy and Frederick. Specimen NTM Z2255. A, perpendicular section through skeleton of erect ridge, showing distinctive cavernous and reticulate nature of subectosomal skeleton and spicule columns supporting thin tangential ectosomal skeleton; B, transverse section of ectosomal skeleton showing outer surface of sponge with a tangential layer of mostly multispicular tracts composed of both larger and smaller oxeas, forming cross-hatched reticulation; C, light micrograph of section through deeper choanosomal skeleton showing halichondroid reticulation of mostly single spicules; D, telescoped terminations on larger oxeas (left) and smaller oxeas (right). face relatively easily, exposing a cavernous reticulate skeleton beneath (often infested with shrimps and polychaete worms). Initially this species was subdivided into two morphs, one with and the other without a detachable ectosomal skeleton, but it was eventually recognised that this feature was largely dependent on the state of preservation of material (in badly preserved material the surface was minutely conulose, lacking the tangential ectosomal peel). Another important feature of this species, making it easily recognisable in the field, is the erect buttressed growth form and yellowish live colouration (although in deeper or murkier waters pigments may be absent entirely), and harsh texture of the ectosomal skeleton. In its erect, buttressed growth form this species is very similar to Leucophloeus massalis Carter from southern Australia (in particular to an unpublished variety alata of Carter's (1883) in the BMNH, with 'hypotypes' BMNH 1886.12.15.454 and 473 from Fremantle, WA). Leucophloeus massalis, however, has much thicker lamellae than H. phakellioides, and exclusively stylote megascleres which places it in Ciocalypta (Hooper and Wiedenmayer 1994). Other species referred to Halichondriidae at one time or another with similar erect buttressed growth forms include: L. compressus Carter (1883) from Westernport Bay, Victoria. (syntype BMNH 1886.12.15.9) and Axinella solida Carter, (1885) from Bass Strait, Vic. (lectotype BMNH 1887.7.11.24); L. compressus belongs to Pseudoclathria (family Crellidae) (Dendy 1897), and A. solida belongs to Rhaphoxya (family Axinellidae) (Hooper and Levi 1993b). Three spicule sizes are differentiated in the description of H. phakellioides, although realistically only two sizes are clearly distinguished (the smallest category probably being juvenile 42 Beagle Gulf halichondriid sponges Fig. 27. Halichondria stalagmites (Hentschel). Specimen NTM Z131. A, perpendicular section through skeleton of fistule, showing multispicular halichondroid reticulate skeleton, large lacunae near in the subectosomal region, and thin tangential ectosomal peel on convoluted part of surface (top of photo); B, transverse section of ectosomal skeleton showing outer surface of sponge with a thin tangential layer of both larger and smaller oxeas without apparent difference in their distribution; C, light micrograph of section through peripheral skeleton showing extensive canal system in subectosomal region; D, slightly telescoped terminations on larger oxeas (left) and smaller oxeas (right). representatives of the medium-sized oxeas). There is no clear size-class localisation of spicules (such as seen in Amorphinopsis and Ciocalypta), although smaller spicules are mostly found scattered between the multispicular tracts. NTM Z1097: East Point, Darwin, NT, 12°25.0'S, 130°48.4'E, 6-7 m depth, 22 December 1982, coll. J.N.A. Hooper, SCUBA. NTM Z2651: same locality, 12°24.5'S, 130°48.0'E, 9-12 m depth, 3 April 1986, coll. J.N.A. Hooper, A.M. Mussig, A. Howard and C. Hood, SCUBA. NTM Z1991: W side Weed Reef, Darwin, NT, 12°29.2'S, 130°47.1'E, 8 m depth, 11 May 1984, coll. J.N.A. Hooper, P.J. Homer and P.N. Alderslade, SCUBA. NTM Z3147: Parry Shoals, Arafura Sea, NT, 11°12.53'S, 129°42.08'E, 16 m depth, 15 August 1987, coll. A.M. Mussig and NCI, SCUBA. Distribution. Arafura Sea, Indonesia; Darwin Harbour, Cobourg Peninsula and Parry Shoals, Arafura and Timor Seas, NT. Habitat. Sand, mud, coral rubble, usually with base burrowing slightly into substrate; 616 m depth. Halichondria stalagmites (Hentschel) (Figs 27-28) Ciocalypta stalagmites Hentschel, 1912: 126, pl. 21, fig. 60. Type material. SYNTYPE - SMF 1595: Meriri and Leer Is., Aru Is, Arafura Sea, Indonesia, 31 March 1908, coll. H. Merton, 10 m depth, dredge. Other Material. NTM Z131: Sandy Island No. 2, Cobourg Peninsula, NT, 11°05.5'S, 132°17.0'E, 10 m depth, 21 October 1981, coll. J.N.A. Hooper and P.N. Alderslade, SCUBA. 43 J.N.A. Hooper et al. B Fig. 28. Halichondria stalagmites (Hentschel). A, larger oxeas; B, smaller oxeas; C, peripheral skeletal structure; D, preserved specimen NTM Z3I47; F, live subtidal specimen NTM Z1097. Description. Growth form generally cushion-shaped base with fistulose apex, but specifically ranging from elongate, flattened palmatebranching (up to 160 mm high), with slightly flattened, spreading, lobate-digitate branches (up to 30 mm wide, 10 mm thick), slightly convoluted digits on lateral sides of sponge (presumed older specimens), to subspherical massive habits (up to 70 mm diameter), with tapering, blind fistule-like digits on upper surface, base attached to hard object (coral, shells) burrowing slightly into substrate (presumed younger specimens). Oscules discrete, conspicuous, approximately 3 mm diameter, found at base of larger fistules, or on lateral surface in flattened, branching specimens. Colour. Orange-brown in life (Munsell 5YR 7/10-6/10), pale brown in ethanol. Texture. Soft, compressible, spongy, easily torn. Fistules easily collapsable upon collection. Surface. Fistules opaque, collagenous, slightly microconulose; surface even, unornamented be- 44 Beagle Gulf hatichondriid sponges nesian population). In all other respects, including the possession of telescoped points on spicules, northwest Australian and Indonesian populations are comparable. tween fistules; surface of burrowing mass generally membraneous and translucent through which cavernous choanosome visible. Ectosomal skeleton. Thin tangential layer of unispicular tracts or multispicular tracts (two to three spicules abreast) composed of both smaller and larger choanosomal oxeas, without apparent localisation, bound together with granular collagen; spicules becoming plumose bundles in places, with oxeas occasionally protruding through ectosome, but mostly lying tangential to surface. Choanosomal skeleton. All histological preparations contained cyanobacteria. Basal mass containing disorganised halichondroid unispicular reticulation of both larger and smaller oxeas, supported by occasional multispicular (`reticulate') tracts of larger oxeas; towards subectosomal region larger spicules producing more prominent multispicular bundles containing three to five spicules per tract; these becoming oriented perpendicular to surface near peripheral skeleton, occasionally protruding through it. Choanosomal region cavernous throughout, particularly in fistules, with lacunae between 100-300 pm in diameter in deeper choanosomal region of basal mass but larger (up to 500 pm) in subectosomal region of fistules. Collagen relatively abundant in mesohyl, in both basal mass and fistules, but no spongin fibres visible. Spicules. Oxeas, fusiform, slightly telescoped or less frequently sharply pointed, in two size classes although not restricted to any particular location within skeleton (length I 335-(478.3)675 pm, width 7-(11.4)-15 pm; length II 88(171.2)-325 pm, width 2-(3.7)-5 pm). Remarks. This species is apparently widely distributed throughout the Aru and Kai Islands of Indonesia, and is also relatively common throughout the Darwin region, although this is area appears to be its southernmost extent in distribution. The species is easily recognisable in the field by its orange-brown colouration and cushion-shaped fistulose growth form. The northwest Australian population differs slightly from type material and the description of Hentschel (1912) in the extent to which the ectosomal skeleton is developed (represented only by a thin tangential peel in material described above, but more prominent in Hentschel's specimens), and the upper range of length of choansomal oxeas (675 pm long in present material whereas up to 1040 pm long in the Indo- Halichondria bergquistae sp. nov. (Figs 29-30) Type material. HOLOTYPE - QM G303351: East Point `bommies', Darwin, NT, 12°24.5'S, 130°48.8'E, 10 m depth, 23 September 1993, coll. J.N.A. Hooper, L.G. Hobbs and B. Alvarez, SCUBA. Distribution. East Point Aquatic Reserve, Darwin Harbour. Habitat. Fringing coral reef, subtidal. Description. Massive-lobate, bulbous-digitate (resembling a Psetidaxinella, family Axinellidae), 70 mm long, 55 mm wide, up to 45 mm thick. Oscules small (up to 3 mm diameter), conspicuous, discrete, with slightly raised membranous lip, mainly on apical surface of sponge. Colour. Dark purple-mauve alive (Munsell 5RP 3/6); light brown in ethanol. Texture. Firm, compressible. Surface. Prominently hispid, conulose, shaggy in appearance, with an opaque, membranous, skin-like surface covering stretched between adjacent conules. Ectosomal skeleton. Membranous, hispid with brushes of larger spicules protruding through surface, paratangential to it, supporting a sparse thin, tangential layer of smaller oxeas on external surface. Choanosomal skeleton. Deeper parts of skeleton consisting of halichondroid reticulate architecture of single spicules or paucispicular tracts composed of larger oxeas. In subectosomal region spicule tracts more obvious, running predominantly longitudinally, ascending, becoming more radial, plumo-reticulate near periphery, with tracts composed mainly of larger oxeas and thinner oxeas also scattered throughout mesohyl. Spicule tracts uni- or paucispicular, loosely bound together with sparse collagen, without any obvious spongin fibres. Collagen in mesohyl light, nearly unpigmented. Choanocyte chambers ovoid, 40-50 pm diameter. Spicules. Oxeas in two size classes: larger (predominantly choansomal) oxeas slightly curved at centre, tapering to fusiform sharp points (length 610-(797.2)-855 pm, width 15(21.6)-32 pm); smaller (predominantly ectosomal) oxeas straight or slightly curved, fusiform 45 J.N.A. Hooperet al . O O Fig. 29. Halichondria bergguistae sp. nov. A, larger (predominantly) choanosomal oxea; B, smaller (predominantly) ectosomal oxeas; C, peripheral skeletal structure; D, preserved holotype QM G303351; E, live subtidal holotype. 46 Beagle Gulf halichondriid sponges Fig. 30. Halichondria bergquistae sp. nov. Holotype QM G303351. A, perpendicular section through skeleton showing halichondroid reticulation of directionless pauci- and unispicular tracts, becoming more plumo-reticulate in subectosomal region, protruding through and supporting the thin tangential ectosomal crust; B, transverse section of ectosomal skeleton showing outer surface of sponge with protruding larger oxeas and sparse tangential smaller oxeas (with an ostium, upper right); C, light micrograph of section through peripheral skeleton showing plumo-reticulate subectosomal skeletal tracts; D, sharply pointed spicule terminations on both larger oxeas (left) and smaller oxeas (right). sharply pointed (length 382-(509.5)-675 pm, width 5-(7.4)-12 pm). Etymology. For Professor Patricia Bergquist, University of Auckland, for her unparalleled contributions to contemporary debate on sponge biology and systematics, and specific contributions to the taxonomic knowledge of Australasian sponges, including material from Darwin Harbour (Bergquist and Tizard 1967). Remarks. This species was initially thought to belong to H. melichlora (Sollas) (from the Straits of Malacca (Sollas 1902) and Am Island, Indonesia (Hentschel 1912)) based on descriptions of growth form, spicule geometry, possession of a slightly radial peripheral skeleton, and range of spicule sizes. But for several reasons this is not now accepted. Unfortunately, the holotype of H. melichlora has not yet been located, and both Sollas' (1902) and Hentschel's (1912) descriptions are fairly brief. However, from both these authors we know that H. melichlora has a massive growth form with flattened surface processes, a smooth unsculptured surface, a longitudinal central skeleton, a plumose subectosomal skeleton and a cavernous peripheral skeleton, and published spicule dimensions ranging from 350-960 x 30-42 pm for larger oxeas and 168-208 x — pm for smaller oxeas. By comparison, the growth form of H. bergquistae is lobate, bulbous-digitate, its surface is prominently conulose, shaggy (very reminiscent of Pseudaxinella), the choanosomal skeleton is halichondroid reticulate, becoming more radial towards the periphery, but without cavernous construction, and spicule dimensions are 610-855 x 15-32 pm for larger oxeas and 382-675 x 5-12 pm for smaller oxeas. On the basis of these differences it is warranted to recognise H. bergquistae and H. melichlora as distinct taxa. 47 J.N.A. Hooper et al. O O Fig. 31. Halichondria darwinensis sp. nov. A, larger choanosomal oxea; B, smaller ectosomal oxea; C, peripheral skeletal structure; ll, preserved paratype QM G303252; E, live intertidal paratype. 48 Beagle Gulf halichondriid sponges Halichondria darwinensis sp. nov. (Figs 31-32) Type material. HOLOTYPE - NTMZ3205: Dudley Point Reef, East Point, Darwin, NT, 12°24.5'5, 130°48.0'E, intertidal, 25 September 1987, coll. N. Smit, by hand. PARATYPE QM G303252: S of South Shell Island, East Arm, Darwin Harbour, NT, 12°29.8'S, 130°53.5'E, intertidal, 19 September 1993, coll. J.N.A. Hooper, L.J. Hobbs and B. Alvarez, by hand. Distribution. South Shell Island and East Point Aquatic Reserve, Darwin Harbour, NT. Habitat. Fringing coral reef, binding coral nibble substrate, growing on algae and dead coral; intertidal. Description. Encrusting base, up to 15 mm thick, with stoloniferous, arborescent and bushy, fibrous, insubstantial digits on upper surface, with digits standing erect or meandering across substrate; digits up to 85 mm long, 6 mm diameter. Oscules small, discrete and conspicuous, up to 2 mm diameter, scattered on upper surface between upright surface processes. Colour. Live colouration blue-grey on branch tips (Munsell 2.5B 8/2) and pale grey on base (5G 8/2); beige in ethanol. Texture. Very soft, friable, easily torn. Surface. Translucent, even, with fibrous and porous surface and underlying spicule tracts visible through ectosomal skeleton. Ectosomal skeleton. Poorly developed, not detachable, thin tangential layer two to three spicules wide, composed mainly of smaller oxeas, overlaying larger choanosomal oxeas in paratangential subectosomal skeleton. Choanosomal skeleton. Halichondroid reticulate skeleton of mainly longitudinal, multispicular tracts, with bundles of 5-10 oxeas ar- Fig. 32. Halichondria darwinensis sp. nov. Paratype QM G303252. A, perpendicular section through skeleton showing halichondroid unispicular reticulation and directionless multispicular tracts of the choanosomal skeleton; B, transverse section of ectosomal skeleton showing outer surface of sponge with a thin tangential unispicular layer of predominantly smaller spicules; C, light micrograph of section through choanosomal skeleton showing disorganised halichondroid multispicular tracts of larger spicules and thin, vestigial ectosomal skeleton (at right); D, sharply pointed spicule terminations on larger choanosomal oxeas (left) and abruptly telescoped (mucronate) points of smaller ectosomal oxeas (right). 49 J.N.A . Hooper et al. moreso than their length, the shorter found mainly in the ectosomal skeleton, the larger found mainly in choanosomal tracts), spicule geometry (with sharply pointed choanosomal oxeas and prominently telescoped, mucronate points on ectosomal oxeas), skeletal structure (mainly longitudinal multispicular tracts of choanosomal oxeas, with single spicules dispersed between tracts producing a disorganised halichondroid-reticulate skeleton). In addition to these features seen in preserved material, the species also has distinctive field characteristics including a meandering stoloniferous growth form suited to growing on coral rubble, binding the substrate, a soft, easily torn consistency and a blue-grey live colouration. Relationships between H. darwinensis and other Halichondria are presently uncertain given that most of the field characters of this species have not been ranged paratangentially in subdermal region supporting surface skeleton, and unispicular tracts dispersed between, both composed mainly of larger oxeas. Spongin fibres not evident. Collagen light to moderate in mesohyl, associated predominantly with spicule tracts. Spicules. Oxeas in two sizes: thicker choanosomal oxeas straight or slightly curved at centre, with sharply pointed, tapering fusiform points (length 5254622.0)-808 pm, width 6-(8.4)12 pm); thinner ectosomal oxeas straight or rarely slightly curved, tapering fusiform, with prominently telescoped points (mucronate) (length 320(392.2)-485 pm, width 1.5-(2.2)-3 pm). Etymology. Named for the type locality, Darwin Harbour. Remarks. Halichondria darwinensis is distinctive in its spicule size (having two categories of oxeas differentiated by their thickness C C I 5- Fig. 33. Halichondria ridleyi sp. nov. A, larger choanosomal oxea; B, smaller ectosomal oxea; C, peripheral skeletal structure; D, live intertidal holotype QM G303309; E, preserved holotype. 50 Beagle Gulf halichondriid sponges well documented in other publications on Indowest Pacific halichondriids. mm diameter at base. Oscules small, less than 2 mm diameter, scattered between surface processes. Colour. Slightly mottled khaki dark yellowbrown exterior (Munsell 2.5Y 7/8-6/6) and beige interior alive; uniform beige-white in ethanol. Texture. Firm, friable. Surface. Opaque, hispid, even, unornamented. Ectosomal skeleton. Thin, hispid, collagenous, non-detachable layer, with larger choanosomal spicules protruding through ectosome, erect or paratangential to surface, overlayed by smaller spicules lying tangential to surface, forming sparse tracts or occurring individually. Choanosomal skeleton. Disorganised halichondroid, directionless tracts of single spicules throughout skeleton, composed mainly of larger oxeas, with tracts becoming only vaguely plumo- Halichondria ridleyi sp. nov. (Figs 33-34) Type material. HOLOTYPE - QM G303309: Dudley Point Reef, East Point, Darwin, NT, 12°25.3'S, 130°49.0'E, intertidal, 20 September 1993, coll. J.N.A. Hooper and L.J. Hobbs, by hand. Distribution. East Point Aquatic Reserve, Darwin Harbour. Habitat. Dead coral and laterite rock reef; intertidal. Description. Partly burrowing, excavating base, boring into dead coral, with massive erect, irregular surface processes, buttressed and fistulose, with fistules up to 54 mm long, 35 Fig. 34. Halichondria ridleyi sp. nov. Holotype QM G303309. A, Perpendicular section through skeleton showing halichondroid unispicular reticulation of directionless tracts throughout the choanosomal skeleton. B, Transverse section of ectosomal skeleton showing outer surface of sponge with protruding larger oxeas and tangential smaller oxeas. C, Light micrograph of section through peripheral skeleton showing directionless halichondroid uni- or paucispicular reticulation in choanosome, and vaguely plumo-reticulate subectosomal skeleton. D, Sharply pointed spicule tenninations on both larger choanosomal oxeas (left) and smaller ectosomal oxeas (right). 51 J.N.A. Hooper et al. Genus Hymeniacidon Bowerbank reticulate in subectosomal region, forming erect or paratangential tracts ascending to (and protruding through) surface. Few multispicular tracts observed, meshes produced by skeletal reticulation small, ovoid, up to 200 pm diameter. Mesohyl collagen abundant, lightly pigmented and dispersed evenly throughout choanosome. Choanocyte chambers small, ovoid, up to 50 pm diameter. Spicules. Oxeas in two size classes: larger choanosomal oxeas moderately or slightly curved at centre, with tapering fusiform, sharply pointed ends, occasionally stylote (length 305-(448.5)565 pm, width 9-(16.3)-21 pm); smaller ectosomal oxeas straight or slightly curved, tapering fusiform, sharply pointed or blunt terminations (length 112-(164.2)-188 pm, width 4(5.9)-8 pm). Etymology. Named for Stuart 0. Ridley, a pioneer of sponge taxonomy and author of the first comprehensive scientific treatise on Australian sponges, including material from Darwin Harbour (Ridley 1884). Remarks. This species is similar to H. mertoni (Hentschel) from Aru Island (Hentschel 1912) in its burrowing, excavating base with robust, irregularly fistulose digits on the upper surface (unlike other fistulose species such as H. tyleri which have pencil-like digits). It differs from H. mertoni and other Indo-west Pacific Halichondria in having a khaki-brown live colouration, an even, unsculptured surface, a firm texture, a non-detachable tangential ectosomal skeleton, a choanosomal skeleton that is nearly completely disorganised halichondroid-reticulate throughout, including the peripheral skeleton (whereas many species of Halichondria have at least some skeletal organisation near the surface), and two size classes of oxeas (305-565 x 9-21 pm and 112-188 x 4-8 pm), the smaller distributed in the ectosomal skeleton. In H. mertoni the colouration is white, the fistules are prominently conulose and the outer surface is shaggy, the choanosomal skeleton has differentiated halichondroid central choanosomal skeleton and radial subectosomal skeleton, and there is only a single size class of (choanosomal) oxea (640785 x 18-22 pm). Hentschel (1912) reported that there was no ectosomal skeleton in H. mertoni (in which case it would not belong to Halichondria at all), but one of the syntypes (SMF1608) does have a tangential ectosome although spicule sizes are undifferentiated. Hymeniacidon Bowerbank, 1863: 1112. Amorphilla Thiele, 1898: 44. Stylohalina Kirk, 1909: 539. Thieleia Burton, 1932a: 329. Uritaia Burton, 1932b: 198. Rhaphoxiella Burton, 1934: 554. Rhaphidostyla Burton, 1935: 651. Nailondra de Laubenfels, 1954: 182. Type species. Hymeniacidon caruncula Bowerbank, 1864, by original designation (junior synonym of Spongia perlevis Montagu, 1818). Diagnosis. Massive, encrusting or fistulose growth forms. Choanosomal skeleton poorly defined directionless spicule tracts with vaguely reticulate multispicular bundles and halichondroid criss-cross of single spicules between major tracts. Cavities (lacunae) often occurring in choanosomal and subetosomal regions, with vaguely ascending or oblique spicule tracts supporting ectosomal crust. Ectosomal skeleton thin tangential crust of single spicules or spicule bundles, usually detachable from surface. Megascleres exclusively styles and stylotes, usually of a single category. Remarks. According to recent revisions (Van Soest et al. 1990; Diaz et al. 1991), Hynzeniacidon is very similar to (and a sister taxon of) Halichondria. The two genera differ only substantially in having styles instead of oxeas, respectively (i.e. with the assumption that oxeas have been secondarily lost in Hymeniacidon). Hymeniacidon also has a characteristically more fleshy choanosomal structure, and its tangential ectosomal crust may be more poorly developed than in Halichondria, but there are few other significant differences between these genera. There is some doubt about the proposed inclusion of Stylotella into synonymy with Hymeniacidon (Van Soest et al. 1990: 51). This doubt was implied by Hooper and Wiedenmayer (1994) in their recognition of Stylotella as a distinct genus from Hymeniacidon. This interpretation was based on characters taken from a single syntype of the type species, Stylotella digitata Lendenfeld, 1888 (AM G9152) from Port Jackson, NSW, which has a predominantly plumose subectosomal skeleton (best developed towards the periphery of the skeleton), a more disorganised halichondroid reticulate skeleton in the central portion of the choanosome, and lacks a tangential skeleton completely (having 52 Beagle Gulf halichondriid sponges instead plumose bundles of styles protruding through the surface), unlike typical Hymeniacidon. These characters essentially agree with the redescription of S. digitata by Hallmann (1914: 349), although it is unclear which material his description was based. However, a redescription of a syntype of Hymeniacidon agminata Ridley, 1884 (BMNH 1881.10.21.347) also from Port Jackson, NSW, by Van Soest et al. (1990) (allegedly a senior synonym of S. digitata; Hallmann 1914), conflicts with this diagnosis, particularly in the fact that it does have "horizontally disposed spicules" in the ectosomal skeleton (Van Soest's et al. 1990: 55) and thus belongs to Hymeniacidon. (Van Soest et al.'s (1990) use of the term `holotype' for this specimen is implicitly a lectotype designation). It is possible that H. agminata is not a synonym of S. digitata, contrary to the opinion of Hallmann (1914), but this must be ascertained by careful re-examination of the 25 or so type specimens of S. digitata and its alleged synonyms (see Hooper and Wiedenmayer 1994: 212). Species of Hymeniacidon are widely distributed in both tropical and temperate waters of all oceans, including polar seas (see Diaz et al. 1991), recorded from shallow subtidal waters to depths exceeding 3500 m. Within the IndoAustralian region nine species have been recorded so far: H. agminata Ridley from eastern Australia (discussed above), H. centrotyla Hentschel,H. fernandezi Thiele, H. kerguelensis Hentschel and H. torquata Topsent from Macquarie Island, Subantarctic and Antarctic waters (Thiele 1905; Hentschel 1914; Koltun 1964, 1976), H. halichondroides (Thiele) from the south coast of NSW and Tasmania (Carpay 1986), H. rigida Dendy from Bass Strait, Vic. (Dendy 1897; Hallmann 1914), H. gracilis (Hentschel) and H. suberitoides (Brondsted) from the Java and Arafura Seas (Hentschel 1912; Brondsted 1934). Fig. 35. Hymeniacidon vernonensis sp. nov. Holotype NTM Z4085. A, perpendicular section through skeleton showing disorganised unispicular halichondroid reticulation and cavernous, highly collagenous skeleton; B, transverse section of ectosomal skeleton showing the thin layer of collagen with scattered single spicules in halichondroid arrangement tangential to the surface; C, slightly telescoped points (left) and hastate base of smaller style (right); D, prominently telescoped point (left) and evenly rounded base of larger style (right). 53 J.N.A. Hooper et al. NI III EV 11111 Fig. 36. Hymeniacidon vernonensis sp. nov. A, thicker style (predominantly in choanosomal skeleton); B, thinner style (predominantly in ectosomal skeleton); C, peripheral skeletal structure; D, preserved paratype QM G303570; E, live specimen (on deck) QM G303565. Hymeniacidon vernonensis sp. nov. Other Material. QM G303565: SSE of Lyne Reef, Vernon Islands, NT, 12°07'S, 130°59'E, 30m depth, 11 October 1993, coll. CCNT stn. 139 (1959), dredge. Distribution. Known only from the Vernon Islands, Van Diemen Gulf, NT. Habitat. Shell and rock substrate; subtidal, 6-30 m depth. Description. Flat, plate-like, fan-shaped growth form, encrusting, following contours of substrate, with prominently shaggy and conulose (Figs 35-36) Type material. HOLOTYPE - NTM Z4085 (fragment QM G303617): S of Northwest Vernon Island, NT, 12°03.9'S, 131°01.9'E, 25 m depth, 10 October 1993, coll. CCNT stn. 148 (1716). PARATYPE - QM G303570: SSE of Lyne Reef, Vernon Islands, NT, 12°07'S, 130°59'E, 30 m depth, 11 October 1993, coll. CCNT stn. 139 (1976), dredge. 54 Beagle Gulf halichondriid sponges surface, up to 90 mm long, 15 mm thick. Oscules small, up to 2 min diameter, conspicuous, discrete, scattered over upper surface, with thin membraneous lip. Colour. Yellow, yellow-brown, or orangebrown, alive in air) (Munsell 7.5YR 7/8 - 2.5Y 8/8))„ pale grey in ethanol. TOxture. Soft, compressible, easily torn. Surface. Transparent outer surface, hispid, uneven, shaggy, conulose, with fibrous-membraneous appearance. Ectosomal skeleton. Detachable, thin, membranous layer of granular pigmented collagen, with sparse layer of mostly thinner styles lying tangential to surface, usually in unispicular tracts and in disorganised halichondroid arrangement, and larger choanosomal styles protruding slightly through surface. Choanosomal skeleton. Deeper regions of skeleton disorganised halichondroid reticulate, with single spicules or occasionally bundles of two or three, usually not forming tracts, consisting of mostly larger styles but also with thinner spicules dispersed between unispicular tracts. Subectosomal skeleton marginally more organised towards periphery, with choanosomal spicules generally ascending to surface, producing slightly plumose paucispicular tracts corresponding to position of surface conules. Spongin fibres absent, but collagen abundant in choanosomal mesohyl, containing large pigment granules. Choanosomal region irregularly cavernous, with large lacunae up to 1 mm diameter. Spicules. Styles is two size classes: thicker styles (mostly found in choanosomal tracts) curved at centre, sinuous or rhabdose, fusiform, with evenly rounded bases,. occasionally anisoxeote or mucronate, and prominently tetescoped points or less often sharply pointed end (length 4954584.4)-6615 pm,. width 12416‘.6). 22 pm); thinner styles (mostly fbund in tangem-tial ectosomal skeleton) slightly curved at centre, with sharp pointed or slightly telescoped p6,ints, and tapering hastate rounded bases. (length 252-(422.0)-565 pm, width 546.4)-8' pm). Etymology. ;`lamed for the type locality, Vernon Islands. were initially Remarksmisidentified as Stylotella j1L-Ll.)elliformis Hentschel, 19 111?-sitite both taxa have a cr9 mi -netlyshagWik,fbterowhm essentially styloterriegascleres forming disorganised, halichondroid reticulate skeletal struc- tures only slightly more organised near the surface forming vaguely ascending spicule tracts, than in the centre of the skeleton. However, H. cernonensis has a tangential ectosomal skeleton composed of generally thinner styles than those inside the choanosomal skeleton (whereas the ectosome in S. flabellifOrmis is simply fleshy, membraneous, without tangential spicules but with protruding, vaguely erect choanosomal spicules piercing the surface). Its megascleres are also exclusively styles, many with telescoped points (whereas spicules of S. flabellifOrmis are either sharply pointed or modified to strongylote forms, never telescoped); the choanosome is fleshy, halichondroid-reticulate, with distinct horizontal and vertical spicule tracts throughout the skeleton (whereas in S. fiabelliformis spicule tracts are essentially plumo-reticulate, vaguely ascending to the surface); and growth form is flattened fan-shaped, appearing to grow flat on the substrate (as opposed to erect, flabellate typical for S. fiabellifortids). Hooper and Levi (1993b) recently redescribed S. flabelliformis from its Indonesian holotype as well as many other specimens from a number of localities throughout the Indo-west Pacific. They included it in the genus Stylissa, within the family Axinellidae, although both its generic and family assignments are still debatable, whereas the present species clearly belongs to Hymeniacidon in its spicule and skeletal characters. Hymeniacidon gracilis (Hentschel) (Figs 37-38) Stylotella digitata var. gracilis Hentschel, 1912: 356-357, pl. 19, fig. 27. Type material. HOLOTYPE - SMF 970: Between Meriri. L and Leer I., Aru Is, Arafura Sea, 6- ha mi depth,. 31 March 1908. Other Material. NTM Z945: East Point `bommies% Darwin, NT, 12°24.05'5, 130°48.0'E, m depth, 13 September 1982, coll. J.N.A. Hooper, SCUBA. NTM Z987: same locality, 8 in depth, 26 October 1982. NTM, Z8'83:. Dudley Point Reef, East Point, Darwin, NT,. 12°25.0'S, 30°48.04'E, 10 m depth, 31 Alugust.1982, coll. J.N.A. Hooper, SCUBA. Distribution. Aru Islands, Arafura Sea; Darwin Harbour. Habitat. Rocky reef, sandy substrate; intertidal-subtidal depths. 1;e5cription. Thickly encrusting with erect, conulose iamellae forming thickly branching, 55 J.N.A. Hooper et al. I= imm ma I= Ell II Fig. 37. Hymeniacidon gracilis (Hentschel). A, choanosomal styles; B ,. peripheral skeletal structure; C, specimen NTM Z945. irregularly anastomosing, subspherical mass, up to 95 mm long, 55 mm diameter. Oscules small, less than 2 mm diameter, scattered over surface of lamellae. Colour. Pale orange-red in life, (Munsell lOR 7/8), pink-beige in ethanol. Texture. Soft, compressible, slimy. Surface. Opaque, collagenous; uneven and papiliose-conulose. Ectosomal skeleton. Dense collagenous ectosomal skeleton, with single spicules or tracts of styles, 5-10 spicules abreast, aligned tangen56 Beagle Gulf halichondriid sponges Fig. 38. Hyrneniacielon gracilis (Hentschel). Specimen NTM Z945. A, perpendicular section through skeleton showing halichondroid reticulate choanosomal structure; B, transverse section of ectosomal skeleton showing outer surface of sponge with paratangential-plurnose bundles of styles from the subectosomal skeleton and irregularly dispersed single or paucispicular tracts of styles lying tangential to the surface; C, light micrograph of section through peripheral skeleton showing plumo-reticulate development of the outer portion of subectosomal region; D, fusiform point (left) and evenly rounded base of style (right). tial to surface; erect paucispicular plumose bundles of styles protruding through tangential layer, arising from deeper choanosomal skeleton. Choanosomal skeleton. Interior of choanosome consists of single spicules or paucispicular bundles of two or three spicules abreast, forming partially organised, mostly halichondroid reticulate structure; spicule tracts becoming more organised towards surface, with distinct ascending multispicular plumose tracts in peripheral skeleton; paucispicular bundles protruding slightly through surface but only partially beyond collagenous layer. Collagen in choanosome less dense than ectosomal region and mostly associated with spicule bundles. In some specimens collagen appearing granular. Spicules. Styles of single size class, straight or slightly curved, fusiform, sharply pointed, with evenly rounded bases (length 218-(251.2)285 pm, width 2-(5.1)-8 pm). Remarks. This species was originally described by Hentschel (1912) as a new variety (subspecies) of Stylotella digitata Lendenfeld, but there is very little resemblance in skeletal structure or growth form between these taxa and the Arafura Sea population is elevated here to full species rank. Spicule geometry, spicule dimensions and skeletal structure are comparable between southeast Indonesian and northwest Australian populations, whereas the holotype is substantially thinner than present material, with a concomitant reduction in the extent of development in the (organised portion) of the peripheral skeleton. The possession of a tangential ectosomal skeleton and a halichondroid-reticulate choanosomal skeleton, the latter only showing significant organisation near 57 J.N.A. Hooper et al. tember 1981, coll. J.N.A. Hooper and P.N. Alderslade, by hand. PARATYPE - QM G303414: N of South Shell I., Darwin Harbour, NT, 12°29.8'S, 130°52.9'E, 14 m depth, 25 September 1993, coll. J.N.A. Hooper and L.J. Hobbs, SCUBA. Other Material. NTM Z272: Dudley Point Reef, East Point, Darwin, NT, 12°25.0'S, 130°49.01'E, 17 September 1981, coll. J.N.A. the periphery, indicates that the species belongs in Hymeniacidon. Hymeniacidon hapalia sp. nov. (Figs 39-40) Type material. HOLOTYPE - NTM Z184: Dudley Point Reef, East Point, Darwin, NT, 12"25.0'S, 130°49.01'E, 0.5 m depth, 13 Sep- a Fig. 39. Hymeniacidon hapalia sp. nov. A, larger styles; B, smaller strongylote styles; C, peripheral skeletal structure; D, paratype QM G303414; E, live intertidal specimen QM G303280; F, live subtidal holotype NTM Z 184. 58 Beagle Gulf halichonclri id sponges Hooper, by hand. NTM Z286, Z291: same locality, lm depth, 18 September 1981, coll. J.N.A. Hooper, by hand. NTM Z2146: same locality, 27 September 1984, coll. J.N.A. Hooper, by hand. NTM Z2560: Fannie Bay reef, Darwin, NT, 12°24.50'S, 130°48.0'E, intertidal, 12 December 1985, coll. A.M. Mussig and C. Hood, by hand. NTM Z775: Channel Island, Darwin Harbour, NT, 12°33.0'S, 130°52.03'E, intertidal, 24 May 1982, coll. P.N. Alderslade, by hand. QM G303280: S of South Shell Island, East Arm, Darwin Harbour, NT, 12°29.8'S, 130°53.5'E, intertidal, 19 September 1993. coll. J.N.A. Hooper, L.J. Hobbs and B. Alvarez, by hand. Distribution. East Point Aquatic Reserve, Fannie Bay Reef, Lee Point, Channel Island and South Shell Island, Darwin Harbour. Habitat. Rocky reef, mudflats, fringing coral reef and coral pinnacles; intertidal-subtidal depths. Description. Thickly encrusting, massive-bulbous, stoloniferous or elongate ridges, up to 30 mm thick, closely following contours of substrate. Oscules relatively large, conspicuous, discrete or multiple (sieve-plate), up to 5 mm diameter, usually on apex of surface ridges, between conules, surrounded by slightly raised membraneous lip. Colour. Bright orange to dark orange alive (Munsell IOR 6/10 - 5YR 7/8), pale orangebrown in ethanol. Texture. Soft, insubstantial, membraneous, easily torn, fragile (often disintegrating upon collection), producing clear mucus. Surface. Long, sharply pointed or bifurcated, bushy, digitate and conulose surface processes scattered over surface, interconnected by fibrous ridges; surface opaque, prominently membranous, collagenous. Ectosomal skeleton. Collagenous, membraneous, detachable ectosomal peel composed of granular, heavily pigmented collagen together with sparse, tangential or paratangential tracts or individual spicules, composed of both larger Fig. 40. Hymeniacidon hapalia sp. nov. Holotype NTM Z184. A, perpendicular section through skeleton showing irregular paucispicular reticulate fibres in subectosomal skeleton supporting collagenous ectosome; B, transverse section of ectosomal skeleton showing the aspicular collagenous outer surface; C, rounded, slightly asymmetrical ends of smaller strongylote styles; D, slightly telescoped point (left) and evenly rounded base of larger style (right). 59 J.N.A. Hooperet al. ertheless detachable, thus conforming to the strict definition of the genus Hymeniacidon. It was absent in some specimens, such as poorly fixed frozen samples, where the ectosome had presumably become detached from the remainder of the sponge prior to histology. Hymeniacidon hapalia is also clearly unusual amongst other species of the genus in having smaller spicules of different morphology than the main structural megascleres. These strongylote spicules are clearly derived from styles as they have asymmetrical strongylote ends. They are not localised to any particular region of the sponge but are dispersed throughout the ectosomal and choanosomal regions, albiet sparsely. Hymeniacidon hapalia should be compared to Batzella corticata (Thiele) and Nailondra maza de Laubenfels, both of which have styles together with modified strongylote styles (see brief redescriptions in Van Soest et al. 1990), but in both these species all spicules are approximately of equivalent length. It is possible that one of the genera synonymised under Hymeniacidon by Van Soest et al. (1990) should be resurrected for H. hapalia, such as Rhaphoxiella Burton (i.e. based on possession of modified stylote spicules as well as styles), or Uritaia Burton (with differentiated larger and smaller styles), or Thieleia Burton (with a predominantly collagenous ectosomal peel) - differences which Van Soest et al. (1980) considers to differ from Hymeniacidon s.s. only by degree - but such action is not warranted without a more in-depth study of the family, and for the present H. hapalia fits with a broad definition of Hymeniacidon. The present species is also similar to Stongylacidon intermedia Burton, 1934, from the Great Barrier Reef (which de Laubenfels (1954) suggested belonged to Ulosa, Hooper and Wiedenmayer (1994) subsequently referred to Batzella, but is still poorly known). Stongylacidon intermedia is so far known only from the holotype, and has not yet been described from the living population. Nevertheless, its distinctive external appearance (massive, subspherical, with prominent, short digitate processes), skeletal structure (irregularly reticulate, branching, anastomosing tracts of megascleres surrounded by heavy collagen) and spicule geometry (strongyles and styles) are similar to those in H. hapalia, although spicule sizes are considerably different between the two spe- styles and smaller strongylote styles; choanosomal fibres and spicules also protruding through surface only at surface conules. Choanosomal skeleton. Deeper regions of choanosome predominantly collagenous, very granular; larger styles scattered individually throughout mesohyl and also forming paucispicular, irregular, directionless, halichondroid tracts, with both horizontal and vertically reticulate elements, bound together with abundant collagen. Subectosomal skeleton more obviously reticulate than central skeleton with pauciand multispicular tracts easily visible. Collagen dominant over spicules throughout skeleton, particularly in periphery. Smaller strongylote styles also scattered within mesohyl, not confined to any particular region of skeleton, but generally not forming spicule tracts. Spicule meshes cavernous, up to 600 pm diameter in places. Spicules. Spicules in two categories: larger styles straight or slightly curved at centre, fusiform, sharply pointed or with slightly telescoped points, with evenly rounded bases, some slightly rhabdose (length 375-(583.5)-1130 pm, width 3-(8.1)-15 pm); smaller strongylote styles straight, usually asymmetrical, with evenly rounded ends (length 182-(231.9)-275 pm, width 1-(2.1)-2.5 pm). Etymology. Named for the soft, delicate, collagenous consistency, from hapalus (L.), soft to touch. Remarks. This species is distinctive in the field, with dark orange colouration, prominently conulose fleshy surface, and very soft, relatively fragile, collagenous texture. It is predominantly intertidal, being a prominent member of the coral rubble community fringing the shores of Darwin Harbour, and when it is exposed to air during spring low tides it literally drips mucus (like many other tropical intertidal sponges and soft corals in this region), presumably with a function to protect the species from dessication during prolonged exposure to air. Although the species appears to be fragile to touch and collect, individuals exposed to air for many hours do not appear to undergo tissue necrosis or any other visible effects, unlike the widespread necrosis seen in many other subtidal species. Hymeniacidon hapalia is unusual to the genus in having a predominantly collagenous ectosomal peel with only sparse tangential spicules or spicule tracts supporting the ectosomal peel. This paper-like ectosomal skeleton is nev- 60 Beagle Gulf halichondriid sponges Berg, C. 1899. Substitution de nombres genericos. III. Communicationes de Museo Nacional Buenos Aires 1: 77-80. Bergquist, P.R. 1961. Demospongiae (Porifera) of the Chatham Islands and Chatham Rise, collected by the Chatham Islands 1954 Expedition. New Zealand Department of Scientific and Industrial Research Bulletin 139. Biological Results of the Chatham Islands 1954 Expedition (5): 169-206. Bergquist, P.R. 1965. The sponges of Micronesia, Part I. The Palau Archipelago. Pacific Science 19: 123-204. Bergquist, P.R. 1970. The Marine fauna of New Zealand: Porifera, Demospongiae, Part 2. (Axinellida and Halichondrida). New Zealand Department of Scientific and Industrial Research Bulletin. New Zealand Oceanographic Institute Memoir 197:1-85, pls. 1-20. Bergquist, P.R. 1978. Sponges. Hutchinson: London. Bergquist, P.R. and Tizard, C.A. 1967. Australian intertidal sponges from the Darwin area. Micronesica 3: 175-202. Bowerbank, J.S. 1863. On the anatomy and physiology of the Spongiaidae. Part III. One the generic characters, the specific characters, and on the method of examination. Philosophical Transactions of the Royal Society 152 (1862): 1087-1135, pls 72-74. Bowerbank, J.S. 1864. A Monograph of the British Spongiadae. Ray Society: London. Volume 1. Pp 1-290, pls 1-37. Bowerbank, J.S. 1873. Contributions to a general history of the Spongiadae. part IV. Proceedings of the Zoological Society of London 1873: 325, pls 1-4. Brondsted, H.V. 1923. Sponges from New Zealand. Part I. In: Mortensen, T. (ed.) Papers Dr. Th. Mortensen's Pacific Expedition 1914-16. XV Videnskabelige Meddelelser fra Dansk Naturhistorisk Forening 77: 435-483. Brondsted, H.V. 1924. Sponges from the Auckland and Cambell Islands. In: Mortensen, T. (ed.) Papers from Dr. Th. Mortensen's Pacific Expedition 1914-16. XV Videnskabelige Meddelelser fra Dansk Naturhistorisk Forening 75: 117167. Brondsted, H.V. 1934. Resultats Scientifiques du voyage aux Indies Orientales Neerlandaises. Sponges. Memoires de Brusseles Institut Royal des Sciences Naturelles de Belgique 2(15): 326. Burton, M. 1926. Observations on some British species of sponges belonging to the genus Reniera. Annals and Magazine of Natural History 22: 71-83. Burton, M. 1927. III. Report on the sponges. In: Zoological results of the Suez Canal Expedi- cies, 375-1130 x 3-15 pm and 182-275 x 1-2.5 pm for styles and strongyles, respectively, in H. hapalia; versus 140 x 3 pm for both strongyles and styles in S. intermedia. This latter species is incertae sedis until living populations are rediscovered. ACKNOWLEDGEMENTS We thank Sandy Bruce and Phil Alderslade (Northern Territory Museum of Arts and Sciences) for facilitating our access to the NT Museum sponge collections, and various technical staff who have assisted the senior author during ten years of research on the sponge fauna in northwest Australia; Ron Billyard (Parks and Wildlife Commission of the Northern Territory, Ocean Rescue 2000 Program) for trawled specimens from the Beagle Gulf Marine Park; Neil Smit (Northern Territory University) for assisting in various field surveys; Daryl Grey, Dave Ramm and Anne Coleman (Northern Territory Fisheries) for collection permits, logistic field support and generous access to the fisheries research vessel over the years; Peter Murphy and colleagues (NCI AIMS) for providing samples from Parry Shoals; and Penny Barents (AM, Sydney), Shirley Stone (BMNH, London), Claude Levi (MNHN, Paris), Manfred Grasshoff (SMF, Frankfurt) and Dieter KOhlmann (ZMB, Berlin) for providing access to extensive type collections. 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