Memoirs of Museum Victoria 66: 81–84 (2009) ISSN 1447-2546 (Print) 1447-2554 (On-line) http://museumvictoria.com.au/About/Books-and-Journals/Journals/Memoirs-of-Museum-Victoria Compoceration garyi, a new genus and species of Paramunnidae (Crustacea, Isopoda, Asellota), from south-eastern Australia. JEAN JUST Museum of Tropical Queensland, 70–100 Flinders Street, Townsville QLD 4810, Australia. (jean-just@mail.dk) (Hon. Associate, Museum Victoria). Abstract Just, J. 2009. Compoceration garyi, a new genus and species of Paramunnidae (Crustacea, Isopoda, Asellota), from southeastern Australia. Memoirs of Museum Victoria 66: 81–84. A new genus, Compoceration, in the asellote family Paramunnidae Vanhöffen, 1914 is diagnosed. The type species Compoceration garyi sp. nov. was collected from 220 m depth off southern New South Wales. The new species shares several characters with Pentaceration Just, 2009. It differs from the latter mainly in its unique head structures and a cylindrical, non-flared mandible molar. Keywords Crustacea, Isopoda, Paramunnidae, Compoceration garyi new genus and species, Australia. Introduction Asellote isopods of the family Paramunnidae from Australia and adjacent subantarctic islands have recently been the subject of major revisionary studies (Just & Wilson 2004, 2006, 2007, Just 2009). As a result, many new species of much morphological novelty have been described and new genera established, while several ‘old’ genera (primarily Paramunna Sars, 1866, Austrimunna Richardson, 1906, Austrosignum Hodgson, 1910, and Munnogonium George and Strömberg, 1968) have been redefined. Among the many paramunnids still to be studied from the area, a single female stands out immediately because of its unusual ornamentation on the cephalon. This new species is here made the type of a new genus as Compoceration garyi gen. et sp. nov. Terminology and measurements follow those used in the suite of papers by Just and Wilson (see above) with additions in Just (2009). The single specimen to hand lacks parts of the antennae and most pereopods. To avoid destroying the holotype, some mouthparts only were drawn in situ. present, stubby, molar long, cylindrical throughout, with transverse grinding surface. Pereopod I carpus oval, with two straight robust setae on posterior margin; propodus narrowing distally to insertion of dactylus. Female operculum ovoid. Uropods on dorsal surface of pleotelson. Remarks. It should be borne in mind that the diagnosis is based on the female of the species. Males should be identifiable on the shape and armature of the head, the eyestalks and the general shape of the body. Lateral pereonite 1 and spines on the remainder may be more strongly developed in males, though, and pereopod I may differ significantly, especially the shape of the carpus. Etymology. The new genus name is composed of the Greek κομπος (kompos = knot or lump) and κέρατο (kerato = horn) with the diminutive ending –ion, thus a little horn with a knot, alluding to the complex head spines. Compoceration garyi sp. nov. Figures 1–2 Compoceration gen. nov. Type species. Compoceration garyi sp. nov. Here designated. Diagnosis. Body generally tapering from pereonite 3. Eyestalks elongate, overreaching pereonite 1 lateral margins. Frontal margin of head with two lateral forward pointing spines and upright outgrowths at base of spines. Pereonites laterally extended into broad spines. Coxae hidden under extended tergites in dorsal view. Pleotelson lateral margins denticulate, posterior margin produced. Antennula article 1 length and width subequal to 2. Antenna article 3 tubular. Mandible palp Material examined. Holotype, ovigerous female, 0.9 mm, Australia, New South Wales, off Eden 36°57.40'S 150°18.80'E, 220 m, muddy shell, WHOI epibenthic sled, 20 July 1986, Poore et al., RV Franklin, stn SLOPE 21, Museum Victoria NMV J18982 (incl. 2 slides). Description. Body widest between pereonites 2 and 3, width 0.42 length. Head length 0.25 width (including eyestalks); length posterior to eyestalks 0.63 anterior length. Frontal margin with low convex bulge in middle; lateral spines approximately 0.7 length of eyestalks, pointing forward at about 50° to head midline, length/width at base approximately 82 J. Just Figure 1. Compoceration garyi gen. et sp. nov. Holotype, ovigerous female. a, antenna; au, antennula; c, enl, dorsal view of head enlarged; cv, ventral view of head; p1 and 2, pereopods I and II; up, uropod. Scale bar for habitus: 0.5 mm. 1.4: dorsal outgrowth at base of spine spherical, diameter approximately 1.5 spine width at base, with heavily calcified sculptured surface. Eyestalks overreaching anterior lateral corner of pereonite 1 by about 1/2 their length, pointing laterad at 90º to head midline, anterior and posterior margins parallel, apex rounded, ocelli not observed. Pereonite 1 length half midlength of pereonite 2, 3 1.5 length of pereonite 2, 4 length equalling pereonite 2, 5 length equals pereonite 1, 6 1.3 length of pereonite 5, 7 length equals pereonite 5. Pereonite 1 lateral margins irregularly rounded truncate, broadest at midpoint; pereonites 2–7 lateral margins extended into broad-based pointed spines with fine marginal denticles; Compoceration garyi, a new genus and species of Paramunnidae (Crustacea, Isopoda, Asellota), from south-eastern Australia. 83 Figure 2. Compoceration garyi gen. et sp. nov. Holotype, ovigerous female. mdr, right mandible, with enlargement; mdl, left mandible; mxp, maxilliped; op, female operculum (pleopod II); pl3 and 4, pleopods III and IV; pt vv, pleotelson, ventral view. pereonites 2 and 3 spines similar, approximately 0.3 length of pereonite width, spine on 4 reduced compared to 3 and 5, spine on 5 and 6 similar to 2 and 3, on 7 slightly shorter than 6; spines on 6 and 7 pointing backward at approximately 45 degrees. Pleon length 1.4 width. Pleonite 1 width 0.85 distance between uropods, length 0.2 width. Pleotelson without noticeable neck or shoulders, lateral margins evenly convex to level of uropods, with 9 denticles on left side (partly broken on right); posterior margin 0.33 length of entire pleotelson, broad, merging straight into lateral margin except for distal denticle of the latter, triangular at 85°, apex a tiny square knob. Antennula articles 1 and 2 combined reaching apex of eyestalk; 3 and 4 of equal length, both 0.6 length of subequal 5 and 6. Antenna article 1 in ventral view approximately 0.4 length of article 2 along lateral margin; article 3 width 0.3 length, with small denticle in distal half of lateral margin, narrowing in distal 1/3. Pereopod I basis length 3.6 times width; ischium 0.5 length of basis, anterior margin with single acute spine in proximal half; merus with single acute spine on anterior margin; carpus margin distal to robust setae straight; propodus with single 84 robust seta on posterior margin. Pereopod II propodus with 2 slender robust setae on posterior margin. Pleopod II (female operculum) distolateral margins nearly straight, width 0.72 length. Uropods recessed into simple non-protruding cuticle pockets, with single ramus (endopod), length 3 times width. Etymology. The species is named for Dr Gary Poore, Museum Victoria, Melbourne, Australia, in recognition of his contributions to many aspects of isopodology, and in gratitude for much help over decades. Discussion. Among the paramunnids with dorsally covered coxae, especially on pereonites 5–7, the new genus Compoceration share several characteristics with Pentaceration Just, 2009: spines on the frontal margin of the head; elongate eyestalks; article 2 of the antennal peduncle about 3 times longer than 1; pereopod I carpus oval; pereonites 2–7 laterally extended into spines; pereonite 4 width reduced (although not as strongly as in Pentaceration). Compoceration differs from Pentaceration (character in parentheses) as follows: front margin of head with 2 lateral spines with dorsal outgrowth at their base (3 spines, 1 mid-frontal, 2 lateral, no basal outgrowth); eyestalks 4 times longer than wide (2–3 times); mandible molar cylindrical, not distally expanded (strongly expanded distally, ‘flared’). By analogy with Pentaceration, it is possible that these differences are more strongly expressed in the as yet unknown males of Compoceration. Species in Paramunna also have head ornaments, but they are in the shape of 2 dorsomarginal broad, square or rounded lobes (small pointed lobes in one species) that do not appear to be homologous with the above mentioned frontal margin spines. Generally Paramunna species have ovoid bodies with rounded to truncate pereonite margins. Only in terminal males of Paramunna bilobata Sars, 1866 and the somewhat aberrant P. walvisensis Just and Wilson, 2004 are pereonites extended laterally into broad pointed laplets, especially on the last 3 pereonites. Paramunna species otherwise differ from J. Just Compoceration in most other diagnostic characters: peduncle article 2 of antenna short, about as long as 1; eyestalks about as long as wide, not overreaching pereonite 1; mandible molar expanded distally, ‘trumpet-shaped’; pereopod I carpus triangular; pereonite 4 similar to 3 and 5; uropods inserted in pleotelson margin, not on dorsal surface, bi-ramous. Acknowledgements I thank Dr. Jo Taylor, Museum Victoria, Melbourne, for the opportunity to contribute to this Festschrift in honour of Dr. Gary Poore, friend and colleague. References George, R.Y. and Strömberg, J.-O. 1968. Some new species and new records of marine isopods from San Juan Archipelago, Washington, U.S.A. Crustaceana 14(3): 225–254. Hodgson, T.V. 1910. Crustacea. IX. Isopoda. National Antarctic Expedition, Natural History 5: 1–77. Just, J. 2009. Pentaceration, an unusual new genus of Paramunnidae from Australia (Isopoda, Asellota). Zootaxa 2134: 36–48. Just, J. and Wilson, G.D.F. 2004: Revision of the Paramunna complex (Isopoda: Asellota: Paramunnidae). Invertebrate Systematics 18: 377–466. Just, J. and Wilson, G.D.F. 2006. Revision of Southern Hemisphere Austronanus Hodgson, 1910, with two new genera and five new species of Paramunnidae (Crustacea: Isopoda: Asellota). Zootaxa 1111: 21–58. Just, J. and Wilson, G.D.F. 2007. Revision of Austrosignum Hodgson and Munnogonium George & Strömberg (Paramunnidae) with descriptions of eight new genera and two new species, (Crustacea: Isopoda: Asellota). Zootaxa 1515: 1–29. Richardson, H. 1906. Isopodes (Premiere Memoire). Expédition Antarctique Française (1903–1905), Crustacés: 1–21. Sars, G.O. 1866. Beretning om en i sommeren foretagen zoologisk rejse ved kysterne af Christianias og Christiansands stifter. Nyt Magasin for Naturvidenskaberne 15: 84–128. Vanhöffen, E. 1914. Die Isopoden der Deutschen Südpolar Expedition 1901–1903. Deutschen Südpolar Expedition 15: 447–598.