AMERICAN MUSEUM Novitates PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, N.Y. 10024 Number 2865, pp. 1-50, figs. 1-98, 1 table December 18, 1986 The Interstitial Bryozoan Fauna from Capron Shoal, Florida JUDITH E. WINSTON1 AND ECKART HAKANSSON2 ABSTRACT A unique fauna ofinterstitial bryozoans has been found encrusting sand substrata on a high-energy shoal off the Atlantic coast of Florida. This fauna includes juveniles of two species of free-living cupuladriids, as well as nine new species (one new genus) apparently adapted to interstitial conditions and characterized by small size, simplified colony structure, and very early reproduction. Other species known from larger substrata were also found encrusting interstitial sand and shell grains at Capron Shoal. The "interstitial refuge" may be important in explaining the broad species distributions of encrusting bryozoans along mostly sandy continental shelves. INTRODUCTION Large expanses of the continental shelves as substrata, in an interstitial habitat on a of the world's oceans are composed of sandy high-energy shoal located on the Atlantic coast sediments. These areas are known to sup- of Florida (HAkansson and Winston, 1986). In this paper we describe the 33 encrusting port abundant faunas of rooted and free-living bryozoans (Maturo, 1968; Cook and Chi- species found thus far, including nine new monides, 1978, 1981), but the unstable na- species and one new genus. We also discuss ture and extremely small size of sand substrata morphological variation occurring in interhave been assumed to prevent colonization stitial colonies of species which are also found by encrusting bryozoans. Recently, however, on larger substrata. The species found at Capduring a study of the population biology of ron Shoal are characterized by the small sizes two species of free-living bryozoans, Cupuof zooids and colonies, precocious sexual reladria doma and Discoporella umbellata de- production, presence of spines and tubercles, pressa, we discovered a number ofencrusting and lack of avicularia. The study clearly demspecies, utilizing sand and shell-gravel grains onstrates the importance of these characterI 2 Associate Curator, Department of Invertebrates, American Museum of Natural History. Institute of Historical Geology and Paleontology, University of Copenhagen. Copyright © American Museum of Natural History 1986 ISSN 0003-0082 / Price $4.85 2 AMERICAN MUSEUM NOVITATES istics and of morphological plasticity in the exploitation of stressed environments previously thought to be depauperate. STUDY AREA Capron Shoal is located on the Atlantic coast of Florida, off South Hutchinson Island, about 7 km south of Fort Pierce Inlet. It is one of a series of linear sand shoals distributed along this section ofthe Florida coast (Duane et al., 1972; Gallagher, 1977). The shoal trends roughly north-south and extends for approximately 6 km, with a minimum depth along its crest of 6 m, falling off to 17 m toward the coast and eventually to 40 m offshore. Capron Shoal was probably built up as a consequence of the northeast storm-generated hydraulic regime (Gallagher, 1977), which causes southward trending storm currents. In summer months, wind and current conditions may be mild, but during the rest of the year they are often severe, with breaking waves marking the shoal crest. Sedimentological conditions change with each storm, and even in fine weather some sediment shifting occurs on the shoal crest. The shoal sediment is a well-sorted, medium coarse biogenic sand, with a 15-30 percent quartz fraction. The biogenic portion is composed chiefly of mollusk shell fragments and barnacle plates. The finest sand is found at the shoal crest, with a tendency toward downslope coarsening; sediments of the trough lying between the shoal and the beach include shell-gravel and shell-hash in places (Gallagher, 1977). At some times of the year pockets of shell-gravel and shell fragments are common on the landward side ofthe shoal. Salinities in the area are generally between 34 and 38%oo, but surface salinities, at least, may be diluted by freshwater outflow through Fort Pierce Inlet. Water temperatures range between 15 and 30°C, with occasional rapid warming and cooling during summer months caused by upwelling (Smith, 1981). The macrofauna on these shoals is less diverse than in the trough shell-hash substrata. At nearby offshore stations studied during ecological monitoring for the Florida Power and Light Company's St. Lucie Plant (Applied Biology, 1976), 431 macrofaunal in- NO. 2865 vertebrate taxa were identified. Of these, 50 percent were annelids, 20 percent mollusks, and 5 percent echinoderms and minor phyla. At Capron Shoal the most noticeable macroinvertebrates are the sand dollars Encope michelini and Mellita quinquesperforata. Also common are starfish (especially Luidia clathrata), sea pansies, crabs, mantis shrimp, brittle stars (Ophiolepis elegans), gastropods (e.g., Oliva sayana, Murex fulvascens, Phalium granulatum), bivalves (especially Dinocardium robustum), and the lancelet, Branchiostoma virginiae. Bottom-dwelling fishes include lizard fish, a flatfish, and a sea-robin. Meiofauna have not been surveyed at Capron Shoal, but surveys at Pierce Shoal, 9 km further south, found nematodes, gastrotrichs, kinorhynchs, halocarids, and harpacticoid copepods to dominate (Applied Biology, 1976). METHODS At each census (April 1983, August 1983, January 1984, July-August 1984, November 1984, and January 1985) samples of sand (250-600 ml) were sorted under the dissecting microscope. The species described here were all found encrusting sand and shell grains in these samples. Photographs of living specimens were taken in the laboratory and observations were made whenever possible on morphology of living colonies with regard to color, size, surface condition, presence of embryos, etc. Ctenostome and entoproct species were preserved in formalin. Some of the cheilostomes were fixed in formalin and preserved in 70 percent alcohol, but most cheilostome colonies were rinsed in fresh water and allowed to dry. Measurements were made on one to five colonies of each species. Measurements (in mm) given following species descriptions include standard characters: Lz, Wz (zooid length and width); Lo, Wo (orifice length and width); Lop, Wop (opesia length and width); Lov, Wov (ovicell length and width); Lav, Wav (avicularium length and width); plus other measurements relevant to particular species. At least one specimen ofeach species was examined by SEM. Specimens were prepared for scanning by treatment with bleach 1986 WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS to remove tissue and chitinous parts, ultrasonic cleaning, and sputter coating with gold. In a few cases air-dried specimens were coated without bleaching to illustrate characterisics of opercula or avicularian mandibles. Illustrated specimens and type material are deposited in the Department of Invertebrates, American Museum of Natural History, New York (AMNH). Synonymies have been restricted to publications of major importance for recognition of the species and those that deal with western Atlantic and Caribbean records for the species. They include only papers having illustrations and descriptions, not checklists, with the exception of Maturo's (1968) checklist of species from the S.E. Atlantic continental shelf which was used in compiling species ranges. The classification used follows Brood (1972) for Stenolaemata and Gordon (1984) for Gymnolaemata. In individual species descriptions the characteristics described in the "description" section refer to Capron Shoal specimens. Any morphological differences between our specimens and those from other areas are noted in the "discussion" section. SPECIES LIST ECTOPROCTA STENOLAEMATA TUBULIPORATA Family Lichenoporidae Disporella plumosa, new species GYMNOLAEMATA CTENOSTOMATA Suborder Stolonifera Superfamily Terebriporoidea Family Spathiporidae cf Spathipora brevicauda Suborder Carnosa Superfamily Alcyonidioidea Family Alcyonidiidae Alcyonidium capronae, new species CHEILOSTOMATA Suborder Anasca Superfamily Membraniporoidea Family Membraniporidae Membranipora triangularis, new species Membranipora arborescens Membranipora savartii 3 Family Calloporidae Antropora leucocypha Alderina smitti Retevirgula caribbea Vibracellina laxibasis Family Cupuladriidae Cupuladria doma Discoporella umbellata subspecies depressa -Superfamily Microporoidea Family Microporidae Cymulopora uniserialis, new genus, new species Family Onychocellidae Floridina parvicella Superfamily Buguloidea Family Beaniidae Beania klugei Suborder Ascophora Superfamily Cribrilinoidea Family Cribrilinidae Cribrilaria innominata Cribrilaria parva, new species Bellulopora bellula Reginella repangulata, new species Superfamily Hippothooidea Family Hippothoidae Hippothoa balanophila, new species Trypostega venusta Superfamily Schizoporelloidea Family Schizoporellidae Schizoporella rugosa Escharina pesanseris Family Smittinidae Parasmittina nitida Parasmittina signata Family Microporellidae Microporella umbracula Family Phylactellidae Phylactella ais, new species Superfamily Celleporoidea Family Celleporidae Trematooecia psammophila, new species Family Cleidochasmatidae Cleidochasma porcellanum Cleidochasma angustum, new species Aimulosia pusilla Aimulosia uvulifera Family Sertellidae Drepanophora torquata, new species 4 AMERICAN MUSEUM NOVITATES ENTOPROCTA Family Pedicellinidae Barentsia minuta, new species Capron Shoal in all seasons. Live specimens were found in August 1984. CLASS GYMNOLAEMATA SUBORDER STOLONIFERA EHLERS, 1876 SUPERFAMILY TEREBRIPOROIDEA D'ORBIGNY, 1847 FAMILY SPATHIPORIDAE POHOWSKY, 1978 GENUS SPATHIPORA FISCHER, 1866 PHYLUM ECTOPROCTA CLASS STENOLAEMATA BORG, 1926 ORDER TUBULIPORATA JOHNSTON, 1847 FAMILY LICHENOPORIDAE SMITT, 1866 GENUS DISPORELLA GRAY, 1848 Disporella plumosa, new species Figures 1, 2 DIAGNOSIS: Neotenous Disporella in which colonies become sexually mature while still fan shaped and never become circular in shape. HOLOTYPE: AMNH 628. PARATYPES: AMNH 629, 630, 631. ETYMOLOGY: The species name, taken from the Latin plumosa = feathery, refers to the tufted appearance of the colonies. DESCRIPTION: Colonies are white and encrusting, forming a spiny tuft or fan. A colony is initiated by a hemispherical ancestrula which develops into the first tubular encrusting zooid. Unlike other members of the genus, which rapidly become discoidal, colonies of Disporella plumosa become sexually mature while still fan shaped. At the edge of the colony is a peripheral growing zone or common bud; as the colony grows outward it expands, increasing the number of partitions to form new zooid tubes. The white upper surface of the zooid tubes is roughened by a series of spiny projections; the tubes end in pointed spines. The entire colony surface, including the common bud and brood chamber, is speckled by small calcareous pustules and pseudopores. The brood chamber is a flask-shaped bulge between two central zooids, opening in the flared lip of the ooeciostome. Lz Wz Lo Wo OCCURRENCE: The species MEAN 0.208 0.113 0.076 0.058 was Spathipora brevicauda Pohowsky, 1978 Figures 3, 4 Spathipora brevicauda Pohowsky, 1978, p. 104. DESCRIPTION: Colonies make shallow borings in shells, most frequently with zooids opening on the concave side. Usually all that remains are traces of the narrow branched or unbranched stolon from which zooids have budded off laterally, leaving elongate seedshaped autozooidal scars. Globular, pedunculate polymorphs, "sac zooids," may also occur. Lz Wz MEASUREMENTS RANGE MEAN 0.180-0.378 0.311 0.036-0.072 0.059 0.018 0.018 N 15 15 W stolon 5 OCCURRENCE: No living colonies of this species were found, but bored shells were collected at each census. DISTRIBUTION: The species was described by Pohowsky (1978) from the Miocene of France. SUBORDER CARNOSA GRAY, 1841 SUPERFAMILY ALCYONIDIOIDEA JOHNSTON, 1838 FAMILY ALCYONIDIIDAE JOHNSTON, 1838 GENUS ALCYONIDIUM LAMOUROUX, 1813 Alcyonidium capronae, new species MEASUREMENTS RANGE 0.144-0.252 0.090-0.144 0.054-0.108 0.054-0.072 NO. 2865 N 15 15 15 15 found at Figures 5-7 DIAGNOSIS: Alcyonidium with baggy erect zooids, forming small clusters on colonies of Cupuladria doma. Polypides with 1 1-15 tentacles. HOLOTYPE: AMNH 633. PARATYPES: AMNH 634, 635. WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS 1986 $f ~p 11_ oll 5 4 .Oil. . , '-. .'.'. II, . Figs. 1-4. 1. Disporella plumosa (AMNH 628), young colony. Scale bar = 200 ,m. 2. Disporella plumosa (AMNH 629), mature colony with brood chamber. Scale bar = 400 gm. 3. Spathipora brevicauda (AMNH 632), zooid and stolon borings on bivalve shell. Scale bar = 1 mm. 4. Spathipora brevicauda, close-up of borings. Scale bar = 200 ,um. ETYMOLOGY: Named after Capron Shoal where the species was discovered. In the 19th century the military trail called the Capron Trail, linking Fort Brooke (now Tampa) with Fort Capron, north of the present Fort Pierce, was the only road between the east and west coasts of Florida. DESCRIPTION: Colonies are encrusting on those of Cupuladria doma. Zooids are baggy and semierect, the saclike basal portion adherent to the substratum, the erect, tubular, and wrinkled distal portion ending in a squared tip. These zooids occur either in clusters on the upper surfaces of the Cupuladria colony, or spaced in the crevices between the zooids of its lower edge. Zooid color ranges from transparent (in newly formed zooids) to a mottled reddish brown in old zooids (due to adherent diatoms). Partially expanded zooids show the fringe of the setigerous collar. Polypides are transparent, with 11-15 tentacles and a straight to slightly belled lophophore. An intertentacular organ is present in breeding zooids. Retracted Lz Wz Expanded Lz Wz Wo Lophophore diameter Tentacle length Mouth diameter MEASUREMENTS MEAN RANGE 0.324-0.396 0.360 0.126-0.180 0.153 0.396-0.486 0.444 0.144-0.180 0.168 0.090-0.108 0.094 N 4 4 3 3 0.288-0.342 0.180-0.306 0.036 5 5 1 0.317 0.234 0.036 5 6 AMERICAN MUSEUM NOVITATES NO. 2865 Figs. 5-7. 5. Alcyonidium capronae (AMNH 633) (only lophophores visible) on surface of Cupuladria doma. Scale bar = 1 mm. 6. Alcyonidium capronae, retracted zooids on Cupuladria doma. Scale bar = 500 Am. 7. Alcyonidium capronae, close-up of zooids (speckled with diatoms) and actively scanning lophophores. Scale bar = 500 m. DISCUSSION: This species was found only on living colonies of Cupuladria doma. Zooids were attached directly to the cuticle of the Cupuladria zooids. In a Cupuladria colony bearing a ctenostome colony, vibraculae protruded between ctenostome zooid tips, but WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS 1986 their movement did not dislodge the Alcyonidium colony, or even cause its lophophores to retract. OCCURRENCE: The species occurred yearround. Specimens with intertentacular organs on lophophores and 3-4 white eggs in coeloms were found in August 1983 and November 1984. ORDER CHEILOSTOMATA BUSK, 1852 SUBORDER ANASCA LEVINSEN, 1909 SUPERFAMILY MEMBRANIPOROIDEA BUSK, 1854 FAMILY MEMBRANIPORIDAE BUSK, 1854 GENUS MEMBRANIPORA BLAINVILLE, 1830 Membranipora triangularis, new species Figures 8-10 DIAGNOSIS: Biserial, sand-encrusting Membranipora zooids with a triangular cross section due to low outer wall, a proximally beaded cryptocyst, and a large proximal tubercle. HOLOTYPE: AMNH 636. PARATYPES: AMNH 637, 638, 639. ETYMOLOGY: The species name is from the Latin triangularis, forming three angles. DESCRIPTION: Colonies are biserial, encrusting sand grains, typically forming bidirectional chains capable of "jumping" from grain to grain via a noncalcified tubular connection. Zooids are elongate, rounded distally, and somewhat narrowed proximally alternating or in pairs. The distal part of the frontal surface is membranous, the proximal part is underlain by a beaded cryptocyst with a slightly denticulated edge. Inner lateral walls are high and outer walls are minimal; thus zooids are triangular in cross section. They typically have a large tubercle on the inner proximal edge. Polypides are transparent, with 12 tentacles. There are no ovicells or avicularia. Lz Wz Lo Wo Lop Wop MEASUREMIENTS MEAN RANGE 0.422 0.360-0.504 0.246 0.198-0.288 0.087 0.072-0.090 0.096 0.090-0.108 0.211 0.108-0.270 0.163 0.144-0.180 ^ .- N 15 15 6 6 15 15 7 DISCUSSION: This species is referred to Membranipora on the basis of its cryptocystal calcification. What appear to be ancestral zooids are double (the proximal two zooids of a chain are side by side as in fig. 9), a diagnostic character for Membranipora, but because of the tendency of this species to form tubular uncalcified connections between grains, detaching portions of colonies from each other, many of these may be pseudoancestrulae rather than ancestrulae. The species is listed as membraniporid n. sp. A in HAkansson and Winston (1985). OCCURRENCE: Capron Shoal. Specimens collected at each census. Living colonies were present in August 1984. Membranipora arborescens (Canu and Bassler), 1928 Figures 11, 12 Biflustra savartii Smitt, 1873, p. 20. Not Flustra savartii Audouin. Acanthodesia arborescens Canu and Bassler, 1928a, p. 15. Conopeum commensale Marcus, 1937, p. 35; 1938a, p. 16; 1939, p. 126; 1941, p. 16; 1955, p. 30. Maturo, 1957, p. 37. Lagaaij, 1963, p. 166. Shier, 1964, p. 610. Not Conopeum commensale Kirkpatrick and Metzelaar. Membranipora arborescens Cook, 1968a, p. 138; 1968b, p. 121. Winston, 1982, p. 117. DESCRIPTION: Colonies are white, multiserial, and encrusting. Zooids are rectangular, with an oval membranous frontal area and two stout, smooth tubercles at the distal end and commonly a similar tubercle at the proximal end. There is a narrow raised mural rim and a narrow shelf of beaded cryptocyst in the proximal portion of the zooid. No avicularia or ovicells occur. Eggs are broadcast into the sea where they are fertilized and develop into feeding larvae. MEASUREMENTS MEAN N RANGE 15 0.325 Lz 0.252-0.450 Wz 0.223 15 0.180-0.306 15 0.053 0.036-0.054 Lo 15 0.092 0.072-0.108 Wo Lop 15 0.209 0.144-0.288 Wop 15 0.166 0.108-0.216 DISCUSSION: Colonies settled on Capron Shoal sand grains, like those of M. savartii, grow multiserially, encrusting the entire grain. 8 AMERICAN MUSEUM NOVITATES NO. 2865 IL Figs. 8-10. 8. Membranipora triangularis, living colony on barnacle plate grain; note uncalcified bud extending from grain surface. Scale bar = 500 ,um. 9. Membranipora triangularis (AMNH 636), two colonies on barnacle plate grain. Scale bar = 500,um. 10. Membranipora triangularis, colony on small grain. Scale bar = 200 ,m. OCCURRENCE: Colonies were collected at Capron Shoal in April 1983, August 1983, April 1984, August 1984, November 1984, and January 1985. None of the colonies collected were living. DISTRIBUTION: Cape Hatteras to Brazil. Gulf of Mexico. West Africa. Eastern Pacific: Mexico to Ecuador. Membranipora savartii (Audouin), 1826 Figure 13 Flustra savartii Audouin, 1826, p. 240. Biflustra denticulata Smitt, 1873, p. 18. Ancanthodesia savartii Canu and Bassler, 1928b, p. 14. Marcus, 1-937, p. 40. Osburn, 1940, p. 352. Membranipora savartii Osburn, 1950, p. 27. Ma- 1986 WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS99 1986 turo, 1957, p. 35. Shier, 1964, p. 670. Long and Rucker, 1970, p. 19. Winston, 1982, p. 119. DESCRIPTION: Colonies ar e multiserial, white, and are encrusting ons;and and shell fragments. Zooids are rectanLgular, with a beaded and variably denticulalted cryptocyst extending under the proximaLl part of the frontal membrane. There is a raised mural rim (broad and worn in these sjpecimens) and a distinct groove between zooi(ds. There may be a single raised proximal tub)ercle. No ovicells or avicularia occur. MEASUREM[ENTS RANGE MEAN 0.450-0.630 0.520 0.234-0.450 0.305 0.144-0.270 0.224 0.144-0.306 0.200 LZ Wz Lop Wop N 15 15 15 15 saarti was was DISCUSSION: Membranipor6 isavartl one of the most common spe,,cies found on large shell fragments at Capro:n Shoal (Winston, 1982) and was collected Ion shell and beach rock substrata at coasttal stations as well. In sand grain collectio: ns multiserial sneetilKe coionles were iouna on suostrata less than 2 square mm in size, which they almost completely covered. Thus, although the species is somewhat similar in zooid morphology to M. triangularis, there is a clear distinction in colony morphology. OCCURRENCE: Colonies were found at Capron Shoal in April and August 19 83, January, April, August, and November 19 84, and January 1985. None were alive at the time of collections. DISTRIBUTION: Cosmopolitan in subtropical and tropical waters. Western Atlantic: Beaufort to Brazil. Caribbean. Gulf of Mexico. FAMILY CALLOPORIDAE NORMAN, 1903 GENUS ANTROPORA NORMAN, 1903 Antropora leucocypha (Marcus), 1937 Figures 14-16 Crassimarginatella leucocypha Marcus, 1937, p. 46; 193 8a, p. 20. Cheetham and Sandberg, 1964, p. 10 17. Conopeum reticulum (in part) Osburn, 1940, p. 351. Antropora leucocypha Shier, 1964, p. 613. Winston', 1982, p. 123 DESCRIPTION: Colonies are encrusting on the bases of live Cupuladria doma colonies. Zooids are irregularly oval, somewhat narrowed distally, with a smooth-textured gymnocyst, a beaded crenulated cryptocyst that broadens proximally, and an irregularly oval to subtriangular opesia. The species is characterized by polygonal kenozooids which develop between zooids. When open they have an inner rim of beaded cryptocyst, but many are solid tubercles of relatively smooth gymnocyst. Also striking are the thick-walled pore chambers that can be seen in zooids at the growing edge (fig. 14), and the thick, roughtextured interior calcification which results in the interior sides of the communication pore being sunken in deep cavities. Ovicells are endozooidal, marked by a solid crescentshaped pillow of calcification at the distal end of the fertile zooid (fig. 15). Capron Shoal colonies had polypides with 10 transparent tentacles and a yellow-orange gut. In larger colonies from other substrata in the area the mean tentacle number is 12. MEASUREMENTS RANGE MEAN LZ Wz Lo Wo Lov Wov Lop Wop Lkz Wkz 0.252-0.306 0.180-0.234 0.036-0.054 0.054-0.090 0.036 0.108 0.162-0.216 0.126-0.180 0.036-0.108 0.036-0.090 0.27 1 0.199 0.046 0.078 0.036 0.108 0.192 0.142 0.077 0.050 N 12 12 12 12 2 2 12 12 10 10 DiscussioN: Though colonies ofthis species can become large and multilaminar, comparison of our specimens with young (fig. 36, Winston, 1982) and old (fig. 37, Winston, 1982) colonies from the Indian River area indicated that ovicelled zooids are found in the younger colonies. In the colony from Capron Shoal illustrated here, reproduction was initiated 7-8 generations from the ancestrula. OCCURRENCE: Capron Shoal, collected live in November 1984 and January 1985. Also common year-round at Indian River coastal 10 AMERICAN MUSEUM NOVITATES NO. 2865 Figs. 11-16. 11. Membranipora arborescens (AMNH 640), showing multiserial growth pattern. Scale bar = 400 ,um. 12. Membranipora arborescens, close-up of zooids. Scale bar = 200,m. 13. Membranipora savartii (AMNH 641), worn colony. Scale bar = 400 ,um. 14. Antropora leucocypha (AMNH 642), encrusting underside of C. doma colony. Scale bar = 1 mm. 15. Antropora leucocypha, zooids and kenozooids. Scale bar = 200,Am. 16. Antropora leucocypha, close-up of ovicelled zooid. Scale bar = 100 JAm. stations (Winston, 1982), chiefly shells of Thais haemostoma floridana. zone on DISTRIBUTION: Cape Hatteras to Brazil. Caribbean. Gulf of Mexico. 1986 WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS I1I Figs. 17-20. 17. Alderina smitti (AMNH 643) colony on shell grain. Scale bar = 400 sAm. 18. Alderina smitti (AMNH 644), close-up of ovicelled colony. Scale bar = 400,um. 19. Retevirgula caribbea (AMNH 645), colony in crevice of barnacle plate. Scale bar = 200 Am. 20. Retevirgula caribbea, close-up of ovicelled zooid. Scale bar = 100,m. GENUS ALDERINA NORMAN, 1903 Alderina smitti Osburn, 1950 Figures 17, 18 Membranipora irregularis Smitt, 1873, p. 8. Osburn, 1914, p. 194. Alderina irregularis Canu and Bassler, 1920, p. 142; 1928b, p. 27. Hastings, 1930, p. 708. Osburn, 1940, p. 363. Alderina smitti Osbum, 1950, p. 59. DESCRIPTION: Colonies are encrusting, single-layered, and glass-white. Zooids are very small, oval to pyriform, with an oval or pyriform opesia bordered by one to three rows of finely beaded cryptocyst, edged by a smooth textured gymnocyst on which small raised tubercles may be scattered. Large pore chambers (diatellae) are visible on the outer zooids of the colony. There are no avicularia and no lateral spines, although small distal spines have been noted on a few zooids. Ovicells are thick transversely elongated cushions of calcification. Polypides have 11 tentacles. Lz Wz Lo Wo Lov Wov Lop Wop MEASUREMENTS RANGE MEAN 0.234-0.306 0.276 0.180-0.306 0.226 0.054-0.072 0.059 0.072-0.126 0.092 0.090-0.126 0.108 0.144-0.180 0.169 0.180-0.216 0.203 0.126-0.198 0.155 N 15 15 4 15 5 5 15 15 DISCUSSION: Sexually mature colonies on sand grain substrata are very small, often consisting of the ancestrula, one or two au- 12 AMERICAN MUSEUM NOVITATES NO. 2865 Figs. 21-24. 21. Vibracellina laxibasis (AMNH 646), showing ancestrula and early growth pattern. Scale bar = 200 ,um. 22. Vibracellina laxibasis (AMNH 647), showing growth pattern. Scale bar = 400 ,um. 23. Vibracellina laxibasis (AMNH 648), colony completely encrusting sand grain. Scale bar = 400 ,um. 24. Vibracellina laxibasis, close-up showing ovicelled zooid (upper left). Scale bar = 100 ,um. tozooids, and a single ovicelled zooid (e.g., fig. 18). OCCURRENCE: Found in collections from each census. Living colonies were found in August 1984 and January 1985. DISTRIBUTION: Western Atlantic: Cape Hatteras to Florida. Gulf of Mexico. Caribbean. Eastern Pacific: Southern California to the Galapagos. GENUS RETEVIRGULA BROWN, 1948 Retevirgula caribbea (Osburn), 1947 Figures 19, 20 Pyrulella caribbea Osburn, 1947, p. 15. Retevirgulaflectospinata Shier, 1964, p. 64. DESCRIPTION: Colonies are encrusting, multiserial, and single layered, with zooids separated from each other by a series of tubes. Zooids are oval with a membranous frontal wall protected by 16-17 spines. The distal three pairs of spines are long and thick and curve upward, while the remaining lateral and proximal spines are more delicate and curve inward over the frontal membrane. From each zooid a series of tubules extends outward. These connect to an irregular tube of calcification which produces other tubules that in turn bud new zooids. These elongated intrazooidal tubes also produce occasional, vertically projecting, thornlike spines; the short tubules connecting to the zooids do not have spines. Polypides are transparent white and have 10 tentacles. The ovicell is helmet shaped and imperforate, with a shallow longitudinal groove. Ovicelled zooids occurred within two generations of the ancestrula. 1986 WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS MEASUREM:DENTS RANGE MEAN N 0.252 15 Lz 0.216-0.288 15 0.187 Wz 0.162-0.234 LO 15 0.050 0.036-0.054 Wo 0.054-0.090 15 0.067 Lov 7 0.090-0.108 0.100 Wov 7 0.108-0.162 0.139 DISCUSSION: Several species of Retevirgula have been described from the Caribbean. Lagaaij (1963) discussed the characteristics of R. tubulata and R. periporosa. The Capron Shoal species best fits the description of R. caribbea described by Osburn (1947) from 13 curved vibracular setae which hinge upon the condyles marking the waist ofthe figure eight. Ovicells are endozooidal, visible only as a thickened gymnocystal cap at the distal end of the zooid, covering the narrow distal cryptocyst and giving a hooded appearance to the fertile zooid. MEASUREMENTS Lz Wz Lo Wo Lop RANGE 0.198-0.342 0.162-0.234 0.036-0.072 0.072-0.090 0.162-0.216 0.108-0.144 0.036 0.072-0.108 0.108-0.180 0.090-0.144 0.054-0.126 0.054-0.090 MEAN 0.319 0.204 0.047 0.089 0.191 0.136 0.036 0.086 0.139 0.124 0.095 0.060 N 15 15 13 15 15 15 15 15 15 15 15 15 Aruba. Retevirgula flectospinata, described by Shier (1964) from northwest Florida, appears to be synonymous with R. caribbea, sharing with it the three pairs of enlarged and curved distal spines. His specimens also had "small round punctations surrounded by a low rim," apparently corresponding to the bases of the interzooecial spines described above, as they are visible in this condition in worn Capron Shoal specimens. Our specimens differ from Osburn and Shier's specimens in lacking interzooecial avicularia and are somewhat smaller. OCCURRENCE: Colonies found April 1983 (live), August 1983, April 1984, August 1984, November 1984, and January 1985. DISTRIBUTION: Florida (Atlantic and Gulf coasts). Caribbean. OTHER SPECIMENS EXAMINED: (NMNH), USNM 70868, Vibracellina laxibasis, Pliocene, Minnitimmi Creek, Bocas Is., Almirante Bay, Panama, cotypes. Vibracellina caribbea USNM 208837, 2 slides, cotype and GENUS VIBRACELLINA CANU AND BASSLER, 1917 of sediment samples maintained in the lab- Vibracellina laxibasis Canu and Bassler, 1928 Figures 21-24 Vibracellina laxibasis Canu and Bassler, 1 928b, p. 23. Vibracellina caribbea Osburn, 1947, p. 1 1. DESCRIPTION: Colonies are encrusting and single layered, forming a lacy meshwork that may completely enclose, but does not project outward from, a grain. Zooids are oval, with a membranous frontal wall underlain by a narrow lateral cryptocyst. Interzooecial vibracula are budded distolaterally from zooids, and are round with a raised tubercle at the end nearest the budding point, a figure-eight shaped opening, and long Wop Lov Wov Lavz Wavz Lav-op Wav-op paratype. as DISCUSSION: Note: this species was listed Setosellina ?goesi in Hakansson and Win- ston (1986). Living Vibracellina colonies can use vibracular motion to rock sand grains but apparently are not able to unbury themselves from sediment as cupuladriids can (HAkansson and Winston, 1986). Unlike cupuladriid colonies, they never appeared on the surface oratory. OCCURRENCE: Living colonies were found at Capron Shoal in August 1983 and August 1984. Colonies were collected at all times of the year. DISTRIBUTION: Cape Hatteras to Florida. Gulf of Mexico. Caribbean. FAMILY CUPULADRIIDAE LAGAAU, 1952 GENUS CUPULADRIA CANU AND BASSLER, 1919 Cupuladria doma (d'Orbigny), 1851 Figures 25, 27, 29 Discoflustrellaria doma d'Orbigny, 1851, p. 561. Cupularia doma Smitt, 1873, p. 15. Canu and Bassler, 1923, p. 77; 1928a, p. 64. 14 AMERICAN MUSEUM NOVITATES Discoporella doma Osburn, 1940, p. 374. Maturo, 1957, p. 41. Cheetham and Sandberg, 1964, p. 1022. Shier, 1964, p. 621. Cupuladria doma Gautier, 1962, p. 54. Cook, 1965, p. 216; 1968a, p. 145. Prenant and Bobin, 1966, p. 314. Winston, 1982, p. 122. DESCRIPTION: Living colonies are pink to brownish red, conical, subtriangular or shaped like drumlins, their basal surfaces flat to convex, glistening white, with radial grooves and tubercles. They may reach 6 mm in length. Larvae settle on a sand grain, metamorphosing into an ancestrular triad of zooids (fig. 26). The colony grows around the sand grain completely and becomes free living on and between sand grains. Zooids are rhomboidal, small in size, and regularly arranged. The opesia is subtrifoliate, the opercular area spade shaped to semicircular; the proximal portion has a lacy cut-out shape due to inward denticulate projections of the granular cryptocyst. In older colonies central and peripheral zooids are closed by continuous granular calcification. A vibraculum with a strong, slightly curved mandible occurs distal to each zooid. Those around the colony periphery are largest; their zooids give a scalloped edge to still-growing colonies. In completely mature colonies there is a double row of those vibracula, and the interstices between them are filled in by colonial basal calcification, making the basal rim smooth rather than scalloped. Polypides have 11-13 tentacles and are a pale translucent pink. Embryos are brooded internally. Larvae are pinkish orange, becoming rapidly geopositive after release from adult colonies. MEASUREMENTS MEAN N RANGE Lz 0.346 15 0.270-0.432 15 Wz 0.196 0.180-0.252 0.092 15 0.072-0.108 Lo 15 0.104 0.090-0.126 Wo 0.080 15 0.054-0.108 Lav 0.074 15 0.054-0.090 Wav OCCURRENCE: Living colonies were found year-round at Capron Shoal. Live recently settled juveniles were found in April 1983, August 1983 and 1984, and November 1984. This is the most abundant lunulitiform species occurring on the continental shelf of the NO. 2865 southeastern United States (Maturo, 1968; Knowles, personal commun.), where it is an important component of sand-bottom communities. DISTRIBUTION: Subtropical and tropical Atlantic. Western Atlantic: Cape Hatteras to Florida. Gulf of Mexico. Caribbean. GENUS DISCOPORELLA D'ORBIGNY, 1851 Discoporella umbellata subspecies depressa (Conrad), 1841 Figures 26, 28, 30 Lunulites depressa Conrad, 1841, p. 348. Cupularia umbellata Smitt, 1873, p. 14. Canu and Bassler, 1928a, p. 64. Hastings, 1930, p. 718. Cupularia lowei Osburn, 1914, p. 194. Discoporella umbellata Osburn, 1940, p. 374; 1950, p. l 13. Maturo, 1957, p. 41. Shier, 1964, p. 621. Cheetham and Sandberg, 1964, p. 1022. Soule and Soule, 1964, p. 10. Discoporella umbellata subspecies depressa Cook, 1965, p. 180. Winston, 1982, p. 122. DESCRIPrION: Living colonies are pink to brownish red, shaped like flattened cones or bowls, with concave (rather than flat) basal surfaces, and reach 9.5 mm. Like those of C. doma, larvae settle and metamorphose on sand grains; adults are free living among the sand grains. Zooids are rhomboidal and regularly arranged. The frontal surface consists of a distal semicircular opesia and a proximal granular calcified area, made up of fused cryptocystal processes, pierced by six to eight opesiules. Vibracula with long curved mandibles occur at the distal end of each zooid. Polypides have an average of 13 tentacles, a mean lophophore diameter of 0.45 3 mm, and are rose pink. Embryos are brooded in zooids. Lz Wz Lo Wo Lav Wav MEASUREMENTS MEAN RANGE 0.400 0.342-0.468 0.258 0.198-0.324 0.096 0.072-0.126 0.110 0.090-0.162 0.100 0.072-0.126 0.09 1 0.072-0.108 N 15 15 15 15 15 15 DISCUSSION: The larger and flatter colonies of this species undergo more fragmentation by physical and biological agents than those of Cupuladria doma, and regenerated asexually produced colonies are more common than those developed from settled larvae. 1 986 WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS -Awt-'j 15 _!_b;',-sn'_ Figs. 25-30. 25. Cupuladria doma (AMNH 649), young colony. Scale bar = 1 mm. 26. Discoporella umbellata depressa (AMNH 652), young colony. Scale bar = 1 mm. 27. Cupuladria doma (AMNH 650), ancestral triad produced by metamorphosis of settled larva. Scale bar = 900 ,um. 28. Discoporella umbellata depressa (AMNH 653), large asexually produced colony with lophophores expanded. Scale bar = 1 mm. 29. Cupuladria doma (AMNH 651), zooids and vibracula. Scale bar = 200 ,um. 30. Discoporella umbellata depressa (AMNH 654), zooids and vibracula. Scale bar = 200 ,um. 16 AMERICAN MUSEUM NOVITATES OCCURRENCE: Living colonies were collected year-round at Capron Shoal. Recently settled juveniles were collected in April and August 1983 and April 1984. This species is less abundant than Cupuladria doma in the Capron Shoal area and apparently over the entire southeastern continental shelf (Maturo, 1968; Knowles, personal commun.). DISTRIBUTION: Western Atlantic: Cape Hatteras to Florida. Gulf of Mexico. Caribbean. Also found in the eastern Pacific from Point Concepcion, California, to Ecuador. SUPERFAMILY MICROPOROIDEA GRAY, 1848 FAMILY MICROPORIDAE GRAY, 1848 slightly concave and covered by a faintly roughened calcification showing concentric growth rings. The opesia is bell shaped, with shallow opesiular indentations and a smooth, slightly bowed proximal margin. The ancestrular zooid, which is morphologically similar to other zooids, but lacks the elongated proximal portion, produces first a distal and then a proximal bud from large pore chambers. The ovicell is a very small gymnocystal tubercle consisting of an ovoid cap of calcification interrupting the mural rim at its distal end. Polypides have eight transparent white tentacles. CYMULOPORA, NEW GENUS TYPE SPECIES: Cymulopora uniserialis. DIAGNOSIS: Zooids pyriform, with proximally elongate gymnocyst, a smooth to radially striated cryptocyst, and triangular to bell-shaped opesia. Ovicell endozooidal, inconspicuous. Avicularia absent. ETYMOLoGY: The genus name is taken from the Latin cymula, diminutive of cyma, young shoot or sprout. DISCUSSION: We have placed the genus in the Microporidae because of similarities with other genera in that family, particularly Mollia, which resembles Cymulopora in the bellshaped opesia and the small immersed, pillow-shaped ovicell. Yet, in Mollia species and in species of the other microporid genera, the cryptocyst is rough, granular, or beaded in texture, never showing the concentric striations found in Cymulopora. Cymulopora uniserialis, new species Figures 31-36 DIAGNOSIS: As for genus. HOLOTYPE: AMNH 655. PARATYPES: AMNH 656, 657, 658. ETYMOLOGY: The species name is from the Latin unus (one) and series (row)-because zooids are arranged in a single series. DESCRIPTION: Colonies are encrusting, made up of short and bidirectional chains of zooids. Avicularia are lacking. Zooids are elongate, pyriform, the lateral walls with smooth transversely wrinkled calcification raised high centrally around the ovoid frontal surface and tapering proximally. The frontal wall, surrounded by the raised mural rim, is NO. 2865 LZ Wz Lo Wo MEASUREMENTS MEAN RANGE 0.211 0.180-0.270 0.126-0.180 0.167 0.089 0.072-0.108 0.084 0.072-0.090 N 15 15 15 15 DIScuSSION: The taxonomic affinities of this unique species are not certain. The raised lateral walls and straggling uniserial growth of C. uniserialis are reminiscent ofthe shootlike early stages of some erect forms (hence the genus name) and suggest that this species may be neotenously derived from an erect ancestor. Perhaps it is significant that the only other species we have observed with a similar concentrically striated cryptocyst is Nellia tenella, a primitive erect species of anascan (Winston and Cheetham, 1984). OCCURRENCE: Colonies were collected at Capron Shoal in April 1983 (live), August 1983 (live), January 1984, August 1984, and January 1985 (live). FAMILY ONYCHOCELLIDAE JULLIEN, 1882 GENUS FLORIDINA JULLIEN, 1882 Floridina parvicella Canu and Bassler, 1923 Figures 37, 38 Floridina parvicella Canu and Bassler, 1923, p. 57. Lagaaij, 1963, p. 177. DESCRIPTION: Colonies are single layered and encrusting on shell grains. Color of living colonies is a shining white, invisible against white shell background except for the golden trefoils of opesiae and opercula. Zooids are 1986 WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS 17 Figs. 31-36. 31. Cymulopora uniserialis (AMNH 655), whole colony in crevice of barnacle plate. Scale bar = 1 mm. 32. Cymulopora uniserialis (AMNH 656), another colony showing high lateral walls. Scale bar = 200 ,um. 33. Cymulopora uniserialis, close-up of zooid. Scale bar = 100 0Am. 34. Cymulopora uniserialis, close-up of ovicelled zooid. Scale bar = 40 ,um. 35. Cymulopora uniserialis (AMNH 657), unbleached colony to show operculum and frontal membrane. Scale bar = 100 Am. 36. Cymulopora uniserialis, close-up to show attachment of frontal membrane; portion of an ovicell is visible at lower left. Scale bar = 20 ,um. ovoid to subhexagonal. The opesia is trifoliate, with two narrow opesiular indentations and a large rounded operculum filling in the center. The rest of the frontal surface is un- AMERICAN MUSEUM NOVITATES 18 derlain by a granular cryptocyst, which curves concavely inward from the mural rim and is raised convexly at the proximal edge of the opesia. Junctions between adjacent zooids are marked by the development of rounded tubercles (fig. 37). No ovicells. Vicarious avicularia occur occasionally between autozooids in some, but not all, Capron Shoal colonies. When present they are of elongated ovoid shape, with a figure-eight shaped opesia, a cryptocystal surface texture similar to that of autozooids, and a pair of condyles for the support of the avicularian mandible. Lz Wz Lo Wo Lavz Wavz Lav Wav MEASUREMENTS RANGE MEAN 0.270-0.378 0.301 0.180-0.288 0.230 0.110 0.090-0.126 0.229-0.144 0.121 0.216-0.324 0.262 0.162-0.180 0.172 0.108-0.162 0.121 0.054-0.072 0.064 DISCUSSION: This species was described by Canu and Bassler (1923) as a Pliocene fossil from South Carolina, but living specimens have since been found in the Gulf of Mexico (Lagaaij, 1963). OCCURRENCE: Specimens were present in all of the censuses. Living colonies were collected at Capron Shoal in January 1985. DISTRIBUTION: Cape Hatteras to Florida. Gulf of Mexico. SUPERFAMILY BUGULOIDEA GRAY, 1848 FAMILY BEANIIDAE CANU AND BASSLER, 1927 GENUS BEANIA JOHNSTON, 1840 Beania klugei Cook, 1968 frontal membrane, and a rounded, lightly calcified abfrontal surface. Zooids narrow proximally into the tubes by which they were budded from previous zooids. At the distal end of the zooid, above the operculum, there are two pointed distal projections. On either side of the operculum is a short-stalked bird's head avicularium. There are no lateral spines or ovicells. Lz Wz Lo Wo N 15 15 15 15 7 7 7 7 Figure 39 Beania intermedia Osburn, 1914, p. 189; 1940, p. 398. Hastings, 1930, p. 705. Shier, 1964, p. 624. Maturo, 1966, p. 579. Beania klugei Cook, 1968a, p. 164. Winston, 1982, p. 131. DESCRIPTION: Colonies are uniserial and straggling, attached to the substratum by radicles. Zooids are ovoid, with a flattened NO. 2865 Lov Wov MEASUREMENTS RANGE MEAN 0.270-0.360 0.316 0.144-0.270 0.220 0.036-0.054 0.052 0.054-0.090 0.074 0.126-0.144 0.138 0.144 0.144 N 15 15 15 15 3 3 OCCURRENCE: The one specimen collected at Capron Shoal (August 1983) was a living two-zooid colony attached to a vibraculum of a Cupuladria doma colony. DISTRIBUTION: Tropical and subtropical. Western Atlantic: Cape Hatteras to Florida. Gulf of Mexico. Caribbean. SUBORDER ASCOPHORA LEVINSEN, 1909 SUPERFAMILY CRIBRILINOIDEA HINCKS, 1879 FAMILY CRIBRILINIDAE HINCKS, 1879 GENUS CRIBRILARIA CANU AND BASSLER, 1928 Cribrilaria innominata (Couch), 1844 Figures 40, 42, 44 Lepralia innominata Couch, 1844, p. 114. Cribrilina innominata, Smitt, 1873, p. 22. Puellina innominata, Canu and Bassler, 1928b, p. 73. Colletosia radiata, Marcus, 1937, p. 73 (in part; fig. 39). Maturo, 1957, p. 48. Shier, 1964, p. 625. Colletosia innominata Prenant and Bobin, 1966, p. 589. Cribrilaria radiata, Long and Rucker, 1970, p. 19. Winston, 1982, p. 133. Cribrilaria innominata Harmelin, 1970, p. 84. Hayward and Ryland, 1979, p. 64. DESCRIPTION: Colonies are encrusting, biserial to multiserial. Zooids are small, ovoid to egg-shaped and separated from each other by deep grooves. The orifice is semicircular 1 986 WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS 19 39 Figs. 37-39. 37. Floridina parvicella (AMNH 659), portion of multiserial colony. Scale bar = 200 ,um. 38. Floridina parvicella, close-up of zooid and avicularium. Scale bar = 100 ,tm. 39. Beania klugei (AMNH 660), colony detached from Cupuladria doma vibraculum. Scale bar = 300 ,um. with five spines around its distal margin (four in ovicelled zooids). The frontal wall is formed by the fusion of pairs of ribs or costae (five or six pair in these specimens) with radiating rows of pores between them and a larger pore just below the orifice. In these specimens the outer ends of costae are noticeably thickened and rise into tubercles, while the two costae surrounding the suboral pore form a raised triangle. Pore chambers are clearly visible in lateral walls of outer zooids. Ovicells are imperforate, helmet shaped, and have a raised central keel. Ovicelled zooids may occur within five gen- 20 AMERICAN MUSEUM NOVITATES erations of the ancestrula. The;ancestrula has 9-10 spines. Polypides have elight tentacles and are transparent white in clolor. Lz Wz Lo Wo Lov Wov MEASUREM:ENTS MEAN RANGE 0.316 0.270-0.360 0.220 0.144-0.270 0.052 0.036-0.054 0.074 0.054-0.090 0.126-0.144 0.138 0.144 0.144 N 15 15 15 15 3 3 DISCUSSION: Colonies of Cribrilaria innominata encrusting small sand grains often have a runnerlike growth form with only two or three zooids in a row. Interzooecial avicularia with long pointed mandibles usually occur in this species, but were lacking in sandgrain encrusting colonies. Cribrilaria innominata was the more common of the two species of Cribrilaria found at Capron Shoal and is one of the few species that makes the transition from sand-size grains to larger shell substrata. According to Hayward and Ryland (1979) it is most abundant on shell banks in shallow continental shelf waters. For a long time the species was regarded as a variety of C. radiata, but is now recognized as distinct. Marcus (1937) synonymized the two species, and Osburn (1940) questioned their distinction, thus creating confusion in tropical western Atlantic records. Five or six species of Cribrilaria occur in this region, most of them apparently distinct from the European species described so far. Only a thorough study will resolve the taxonomic confusion that now exists, but we have attempted to include in the synonymy above the records that (either from illustrations or examination of specimens) appear to pertain to C. innominata. OCCURRENCE: Colonies were found at Capron Shoal at each census. Living colonies were found in August 1984 and January 1985. DISTRIBUTION: Cosmopolitan in temperate to tropical waters. Southwestern England to Mediterranean. Western Atlantic: Cape Hatteras to Brazil. Gulf of Mexico. Caribbean. Cribrilaria parva, new species Figures 41, 43, 45 DIAGNOSIS: Extremely small Cribrilaria with six oral spines and five to six rows of NO. 2865 costae, the second row raised and enlarged to form a curved or V-shaped ridge. Suboral lacuna not enlarged. No avicularia. HOLOTYPE: AMNH 662. PARATYPES: AMNH 663, 664, 665. ETYMOLOGY: The species name is taken from the Latin parvus, or little. DESCRIPTION: Colonies are encrusting on sand grains and small shells. Zooids are ovoid and even smaller than those of C. innominata from the same habitat. The frontal wall consists of a narrow border of gymnocyst and a frontal shelf made up to 5-6 pairs of costae. Tubercles at outer ends of costae, if they occur, are smaller and less prominent than those of the preceding species. The central suboral pore is not enlarged, but the second pair of costae is enlarged on most zooids, forming a curved bar or ridge across the frontal surface. The orifice is semicircular, its distolateral margin bearing six oral spines. Ovicells are imperforate, with laterally ridged calcification raised into a bump or keel centrally. Ovicells may occur within two generations of the ancestrula. Only four spines are visible on ovicelled zooids. There are no avicularia. The ancestrula is tatiform with 12 spines. Lz Wz Lo Wo Lov Wov MEASUREMENTS MEAN RANGE 0.180-0.270 0.232 0.185 0.144-0.216 0.037 0.036-0.054 0.061 0.054-0.072 0.102 0.090-0.126 0.123 0.108-0.144 N 15 15 15 15 6 6 OCCURRENCE: Colonies were found at Capron Shoal at each census. GENUS BELLULOPORA LAGAAIJ, 1963 Bellulopora bellula (Osburn), 1950 Figures 46, 47 Colletosia bellula Osburn, 1950, p. 188. Bellulopora bellula Lagaaij, 1963, p. 183. Winston, 1982, p. 134. DESCRIPTION: Colonies are encrusting and unilaminar. Zooids are ovoid, separated by deep grooves, the frontal surface composed of six or seven radiating pairs of costae with rows of slitlike lacunae between them and a variously developed proximal oval shield. 1986 WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS 21 Figs. 40-45. 40. Cribrilaria innominata (AMNH 661), whole colony on barnacle plate grain. Scale bar = 400 ,um. 41. Cribrilaria parva (AMNH 662), whole colony on shell at same magnification as previous figure. Scale bar = 400 um. 42. Cribrilaria innominata, zooids and ovicells. Scale bar = 100 ,um. 43. Cribrilaria parva, zooids and ovicells. Scale bar = 100 ,um. 44. Cribrilaria innominata, zooid orifice and oral spines. Scale bar = 100 ,um. 45. Cribrilaria parva, zooid orifice and oral spines. Scale bar= 100 Jim. The orifice is keyhole shaped. The ovicell is small relative to the size of the zooid, hemi- spherical, and carinate, with the same pattern of radiating rows of costae as the zooids. Ovi- 22 AMERICAN MUSEUM NOVITATES NO. 2865 '50 Figs. 46-51. 46. Bellulopora bellula (AMNH 666). Scale bar = 100 ,m. 47. Bellulopora bellula, closeup of zooids. Scale bar = 40 ,um. 48. Reginella repangulata (AMNH 667), whole colony, showing long oral spines. Scale bar = 200 ,um. 49. Reginella repangulata, ancestrula. Scale bar = 100 ,um. 50. Reginella repangulata. Scale bar = 100 ,um. 51. Reginella repangulata, same colony tilted to show ovicell and raised, barlike structure of first pair of costae. Scale bar = 200 ,m. cells occur in the third generation of zooids. The ancestrula has nine delicate spines, the second zooid has two distal spines above the large hollow spines. 1986 LZ Wz Lo Wo Lov Wov WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS MEASUREM::ENTS RANGE MEAN 0.288-0.378 0.342 0.162-0.306 0.211 0.054-0.090 0.082 0.054-0.108 0.074 0.126-0.198 0.173 0.162-0.234 0.198 N 15 15 15 15 15 5 of the orifice, forming a raised and centrally pointed bar. The orifice is subrectangular, edged distolaterally by a pair of spines. Ovicells are helmet shaped and heavily calcified, with a few scattered pores and often a flattended central keel. Embryos are shell pink. Polypides are glassy and transparent, with I 1 tentacles. DISCUSSION: Pedicellate avicularia adja- MEASUREMENTS cent to the orifice have been described in this species, but no avicularia occurred in Capron Shoal specimens. The two hollow spines which bear the avicularia do occur, but their ends are membranous. OCCURRENCE: Live colonies were collected at Capron Shoal in April and August 1983 and January 1985. The only time the species was not collected was January 1984. The species was also collected from offshore shell (60-90 m) in the Sebastian Pinnacle area (Winston, 1982). DISTRIBUTION: Western Atlantic: Cape Hatteras to Florida. Also reported from the Gulf of California and the Galapagos. GENUS REGINELLA JULLIEN, 1886 Reginella repangulata, new species Figures 48-51 DIAGNOSIS: Reginella with elongate unbranched distal spines and a frontal shield composed of 7-11 fused costae, the topmost pair raised to form a suborificial bar. No avicularia. Ovicell with scattered pores. HOLOTYPE: AMNH 667. PARATYPES: AMNH 668, 669, 670. ETYMOLOGY: The species name is taken from the Latin repangulata, meaning barred or bolted, in reference to the shape of the suborificial pair of costae. DESCRIPTION: Colonies are encrusting and single layered. The ancestrula is tatiform with narrow lateral spines and two stout distal spines. Zooids are ovoid to subhexagonal, convex, and set off from each other by deep grooves. The frontal wall is a raised frontal shield formed by the coalescence of 7 to 11 costae, with rounded lacunae marking their fusion. The topmost pair of costae is clasped like a pair of hands across the proximal border 23 Lz Wz LO Wo Lov Wov RANGE 0.252-0.396 0.198-0.324 0.054-0.108 0.090-0.108 0.126-0.162 0.162-0.216 MEAN 0.347 0.266 0.089 0.098 0.138 0.174 N 15 15 15 15 6 6 DISCUSSION: Costae are more smoothly fused than in Cribrilaria and concentric growth lines may make a stronger pattern than the radial lines between adjacent costae. This species appears to fit the description of Reginella (Jullien, 1886) as given by Osburn (1950). Examination of the superficially similar West Coast species described by Canu and Bassler (1923) as Metracolposa mucronata (USNM 68530) showed that species to have much larger zooids with more numerous costae and with less gymnocyst visible around the zooid edge. In R. mucronata the first pair of costae has fused into a flattened bifid mucro below the orifice, whereas in R. repangulata they have become enlarged, but remain rounded and one overlaps the other. Reginella mucronata also lacks the distolateral oral spines. Figularia contraria (Lagaaij, 1963) appears superficially similar from his illustration (pl. IV, fig. 1), but examination of his specimen (USNM 648027) showed it to be a true Figularia, with typical pores on the ovicells and with a larger number of costae. Reginella floridana has been collected from deeper water in the area (Winston, 1982), but differs from R. repangulata in having trifid distal spines and flattened lateral spines arching over the orifice, as well as a larger zooid size. OCCURRENCE: Living specimens were found at Capron Shoal in April 1983, November 198 4, and January 1985. Specimens were collected at each census except January 1984. AMERICAN MUSEUM NOVITATES 24 in H. flagellum colonies from Oculina sub- SUPERFAMILY HIPPOTHOOIDEA FISCHER, 1866 strata (see fig. 84 in Winston, 1982) are shortened or absent; the female zooids are closely adherent to autozooids. This species is most FAMILY HIPPOTHOIDAE FISCHER, 1866 GENUS HIPPOTHOA LAMOUROUX, 1821 Hippothoa balanophila, new species Figures 52-5 5 DIAGNOSIS: Uniserial Hippothoa with very small keeled autozooids, no zooeciules, female zooids smaller than autozooids and closely attached to them. Distally sloping orifice with raised rim and moderately deep U-shaped sinus with a double set ofcondyles. HOLOTYPE: AMNH 671. PARATYPES: AMNH 672, 673, 674. ETYMOLOGY: The species name is taken from the Greek balanus = barnacle and philia = friendly love, because of the preference of the species for the grooved inner surfaces of barnacle plates. DESCRIPTION: Straggling uniserial colonies are found encrusting shell grains, particularly barnacle plates. They are usually oriented along grooves or concavities in the grain (fig. 51). Autozooids are pyriform, with a flat tubular proximal portion and an ovoid, raised, commonly keeled, distal portion. They are imperforate, with a smooth or slightly wrinkled texture to the calcification. Autozooid orifices are rounded distally and have a moderately deep U-shaped proximal sinus (figs. 53, 54). Female zooids are short, with a smoothly calcified helmet-shaped ovicell, often bearing a single central bump. Female zooid orifices are also rounded distally and convex proximally, with a very shallow sinus (fig. 53). Lz Wz Lo Wo Lov Wov ENTS MEASUREM]ENTS MEAN RANGE 0.221 0.144-0.288 0.114 0.090-0.144 0.040 0.018-0.054 0.040 0.036-0.054 0.090 0.090 0.099 0.090-0.108 DISCUSSION: Colonies on sa nd NO. 2865 N 15 15 15 15 2 2 grain sub- strata are more compact than those of Hip- pothoa flagellum from larger s hell and coral substrata; the tubular portioins of zooids, which may be a millimeter or rnore in length similar to H. flagellum Manzoni (reviewed in Ryland and Gordon, 1977) and H. peristomata Gordon (1984). Autozooids differ from those of H. flagellum in their smaller size, frontal keel, and relatively larger orificial sinus. They are also smaller than those of H. peristomata. That species also lacks a raised longitudinal keel and has an orifice with a shallower sinus. Female zooid orifices lack the proximal tubercles shown by H. peristomata. They are similar to those of H. flagellum, but the distal end of the ovicell is never pointed, as it sometimes is in H. flagellum; ovicells often have a large central bump. OCCURRENCE: Colonies were found at Capron Shoal in April 1983 (live), April 1984, August 1984, November 1984, and January 1985. GENUS TRYPOSTEGA LEVINSEN, 1909 Trypostega venusta (Norman), 1864 Figures 56, 57 Lepralia venusta Norman, 1864, p. 84. Gemellipora glabra forma striatula Smitt, 1873, p. 37. Trypostega venusta Osburn, 1914, p. 198; 1940, p. 409; 1952, p. 280. Canu and Bassler, 1928b, p. 77. Marcus, 1938a, p. 35. Shier, 1964, p. 627. Cook, 1968a, p. 177. Winston, 1982, p. 151; 1984, p. 18. DESCRIPTION: Colonies are encrusting and single layered, with a smooth, glassy, transparent surface, spangled by glittering pores. Small pores are scat~~Zooids are rhomboidal. tered evenly over the frontal surface. Transverse lines and faint longitudinal striations may also be present. Autozooids are interspersed with dwarf zooids or zooeciules, which ordinarily are found at the distal end of each autozooid. Autozooid orifices are keyhole shaped, circular distally, and have proximally directed condyles and a proximal V-shaped sinus. Sometimes there is a small umbo proximal to the orifice. Zooeciule orifices are simple, but also rounded distally, with a moderate sinus proximally. In living specimens the operculum is a very pale gold. Ovicells are 1986 WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS 25 Figs. 52-57. 52. Hippothoa balanophila (AMNH 671), colony in crevice of barnacle plate. Scale = 400 ,um. 53. Hippothoa balanophila, female zooids. Scale bar = 200 ,um. 54. Hippothoa balanophila (AMNH 672), showing orifices of female zooids. Scale bar = 40 ,um. 55. Hippothoa balanophila, closeup of autozooid orifice. Scale bar = 10 ,um. 56. Trypostega venusta (AMNH 675), whole colony on barnacle plate grain. Scale bar = 200 um. 57. Trypostega venusta, close-up of ovicell and associated zooeciule. Scale bar = 100 jum. embedded, covered with the same small evenly spaced pores, and cover the proximal portions of zooeciules. Polypides are transparent white. Embryos are pinkish red. 26 AMERICAN MUSEUM NOVITATES Lz Wz Lo Wo Lov Wov Zooeciules Lz Wz Lo Wo MEASUREM ENTS RANGE MEAN 0.329 0.234-0.378 0.126-0.324 0.228 0.054-0.090 0.071 0.054-0.072 0.065 0.108-0.198 0.138 0.180-0.234 0.195 0.144-0.234 0.126-0.216 0.018 0.018 0.185 0.171 0.018 0.018 N 15 15 15 15 6 6 4 4 4 4 DIscussIoN: Zooids of sand grain colonies are considerably smaller than those of colonies from large substrata from Florida, Jamaica, and Belize that we have examined and have fewer pores. They also reproduce at a very small size. (Figure 56 shows a colony with seven zooids, two of them ovicelled; maximum diameter of this colony is about 0.9 mm.) This is very unlike Jamaican cryptic reef colonies, for example, which did not reproduce until they were at least 2 cm maximum diameter (Winston, unpub. data). This species is given as Trypostega sp. in HAkansson and Winston (1985). OCCURRENCE: Living colonies occurred at Capron Shoal in August and November 1984. Colonies were found in each census. DISTRIBUTION: Cosmopolitan in warmer waters. Western Atlantic: Cape Hatteras to Brazil. Gulf of Mexico. Caribbean. SUPERFAMILY SCHIZOPORELLOIDEA JULLIEN, 1883 FAMILY SCHIZOPORELLIDAE JULLIEN, 1883 GENUS SCHIZOPORELLA HINCKS, 1887 Schizoporella rugosa (Osbum), 1940 Figures 58-60 Stephanosella rugosa Osbum, 1940, p. 423. DESCRIPTION: The colony is biserial, encrusting on a shell grain. Zooids are very small, ovoid to subhexagonal, and convex. The wall is perforated by numerous small pores, many of them not round, but irregularly shaped. As secondary calcification proceeds the frontal surface becomes covered by irregular ridges which more or less rim the orifice and come to cover most of the pores. NO. 2865 The orifice is semicircular to almost circular distally, with two small rounded condyles and a broad V-shaped sinus proximally. A small bluntly pointed avicularium is located on a raised umbo below and to one side of the orifice. Ovicells have an outer layer of imperforate calcification and a semicircular to band-shaped inner layer, with faint radiating ribs and a row of marginal pores. Lz Wz Lo Wo Lov Wov Lav Wav MEASUREMENTS RANGE MEAN 0.270-0.360 0.313 0.162-0.306 0.238 0.054-0.108 0.076 0.054-0.108 0.068 0.126 0.126 0.126-0.144 0.135 0.072 0.072 0.036 0.036 N 5 5 5 5 2 2 1 1 DISCUSSION: The species was described by Osbum from Puerto Rico and Bermuda. The present location of his specimens is unknown, but we were able to examine specimens from Venezuela (Jackson collection). The sand grain specimens are somewhat warped and irregular in comparison with these and with Osburn's illustration (pl. 8, fig. 57), but we have no doubt they belong to Osburn's species. Like other species which also occur on larger substrata, the Capron Shoal colony of S. rugosa is not multiserial and has reproduced at a very small size. In contrast to most other interstitial species, however, characteristic avicularia occur and appear to have been functional. OCCURRENCE: Found at Capron Shoal in April 1983 and April and August 1984. DISTRIBUTION: Bermuda. Cape Hatteras to Florida. Caribbean. GENUS ESCHARINA MILNE-EDWARDS, 1838 Escharina pesanseris (Smitt), 1873 Figure 61 Hippothoa pesanseris Smitt, 1873, p. 43. Escharina pesanseris Osburn, 1914, p. 207. Mastigophora pesanseris Osbum, 1927, p. 130; 1940, p. 452; 1952, p. 479. Canu and Bassler, 1928b, p. 133. Hastings, 1930, p. 722. Marcus, 1939, p. 142. Escharina pesanseris Cook, 1968a, p. 195. Long andRucker, 1970, p. 19. Winston, 1982, p. 145; 1984, p. 26. 1986 27 WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS W i t wP§tt- 4 ;- _ i.; Figs. 58-63. 58. Schizoporella rugosa (AMNH 676). Scale bar = 200 Atm. 59. Schizoporella rugosa, showing ovicelled zooids. Scale bar = 100 um. 60. Schizoporella rugosa, close-up of orifice and irregular pores. Scale bar = 40 um. 61. Escharina pesanseris (AMNH 677) and Hippothoa balanophila. Scale bar = 400 ,um. 62. Parasmittina nitida morphotype B, whole colony on shell grain (AMNH 678). Scale bar = 400 um. 63. Parasmittina nitida morphotype B, close-up of zooids. Scale bar = 100 Mtm. DESCRIPrION: Colonies are encrusting and very small. Zooids are polygonal, the frontal surface slightly convex and covered with fine pores, which may become occluded by secondary calcification. The orifice is semicircular, its proximal border straight, with a nar- 28 AMERICAN MUSEUM NOVITATES NO. 2865 Figs. 64-69. 64. Parasmittina signata (AMNH 679), colony on shell grain. Scale bar = 400 ,gm. 65. Parasmittina signata, showing high peristomes. Scale bar = 100 ,um. 66. Parasmittina signata, close-up of zooid. Scale bar = 100 jAm. 67. Parasmittina signata, close-up of orifice, showing oral spines. Scale bar = 40 ,um. 68. Microporella umbracula (AMNH 680), multiserial colony on large grain. Scale bar = 400 jAm. 69. Microporella umbracula, showing ovicelled zooids and avicularia. Scale bar = 400 um. row, deep sinus. The peristome forms a raised rim around the distal portion of the orifice. It bears six to eight thick spines. Distally directed avicularia occur on one or both sides 1 986 WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS of the orifice; they have a fin-s haped "duckfoot" mandible. Ovicells are snnall, globular, and imperforate. MEASUREM ENTS RANGE MEAN 0.378-0.504 0.438 0.180-0.360 02 Lz Wz Lo 0.090-0.126 0.072-0.108 Wo A J.UJ7 0.090 N 6 6 FAMILY SMITTINIDAE LEVINSEN, 1909 GENUS PARASMITTINA OSBURN, 1952 Parasmittina nitida morphotype B Maturo and Schopf, 1968 Figures 62, 63 DESCRIPTION: Colonies are encrusting and multiserial. Zooids are rectangular, with a coarsely granular frontal wall and a single row of marginal pores. The primary orifice is rounded distally, with short blunt condyles and a broad proximal lyrula. The orifice is surrounded by a short orificial collar, and there are two distal oral spines (often broken or overgrown). No ovicells were present in interstitial colonies. Ovicells in this species are prominent and rounded, the distal rim and sides covered with granular calcification, the center penetrated by two rows of large pores (Winston, 1982, fig. 71). Avicularia are variable in shape, one to three per zooid. Those of interstitial specimens lacked crossbars and appeared to be vestigial. Lz Wz Lo Wo Lav Wav MEASUREM ENTS MEAN RANGE 0.324-0.540 0.384 0.268 0.198-0.360 0.090-0.126 0.100 0.100 0.090-0.108 0.066 0.036-0.090 0.046 0.036-0.054 DISCUSSION: Parasmittina nitida morphotype B was one of the most common specimens on subtidal beach rock in the area. It has also been found on larger shell substrata at Capron Shoal (Winston, 1982). OCCURRENCE: Colonies were collected at Capron Shoal in April and August 1983, April 1984, November 1984, and January 1985. DISTRIBUTION: New England to Brazil. 6 OCCURRENCE: Living colonies found at Capron Shoal in January 1985. The species has also been collected from larger shell and coral substrata at Capron Shoal and on the offshore Oculina pinnacles (Winston, 1982). DISTRIBUTION: Circumtropical. Western Atlantic: Cape Hatteras to Brazil. Caribbean. Gulf of Mexico. N 15 15 15 15 9 9 29 Parasmittina signata (Waters), 1889 Figures 64-67 Smittina signata Waters, 1889, p. 17. Schizoporella horsti Osburn, 1927, p. 127. Rimulostoma ? signata Cheetham and Sandberg, 1964, p. 1038. Parasmittina signata Lagaaij, 1963, p. 197. DESCRIPTION: Colonies are encrusting, forming small irregular patches on sand grains. Zooids are ovoid to subhexagonal, with a wavy, rugose frontal wall, perforated only by marginal areolae. Distally the frontal surface rises to a thick and scalloped peristomial collar around the lateral and proximal sides of the orifice. The peristome dwindles at the distal end of the orifice where a smooth rim bears two or three oral spines. The orifice is semicircular distally, with two elongate condyles defining a small U-shaped proximal sinus. No ovicells or avicularia occurred on our specimens. Lz Wz Lo Wo Lov Wov MEASUREMENTS MEAN RANGE 0.270-0.468 0.376 0.231 0.198-0.306 0.095 0.072-0.144 0.093 0.072-0.126 0.189 0.180-0.198 0.198 0.180-0.216 N 12 12 12 12 2 2 OCCURRENCE: Collected at Capron Shoal in August 1983, August 1984, November 1984, and January 1985. DISTRIBUTION: Cosmopolitan in warm water. Western Atlantic: Cape Hatteras to Florida. Caribbean. Gulf of Mexico. FAMILY MICROPORELLIDAE HINCKS, 1880 GENUS MICROPORELLA HINCKS, 1877 Microporella umbracula (Audouin), 1826 Figures 68, 69 30 AMERICAN MUSEUM NOVITATES Flustra umbracula Audouin, 18246, p. 239. Microporella ciliata var. coronata Hastings, 1930, p. 727. Microporella coronata Osburn, 15)52, p. 386. Microporella umbracula Harmer , 1957, p. 964. Powell, 1971, p. 772. Banta an(d Carson, 1977, p. 395. Winston, 1982, p. 150. DESCRIPTION: Colonies encrnisting, unilaminar, pink to orange when aliNve, with short, dark green spines. Zooids are nAlvYnal and variable in size. The surface is inflated, wit roughened calcification perforrated pores. Zooids are separated fr4 om each other by a depression. The orifice is semicircular, vvith four to six spines occurring around its (distal margin usually becoming broken ofiE. A crescentshaped ascopore, edged with a row of fine In sand grain teeth, is found under the orifice In specimens the area below th sascooreain greatly thickened and raised into an umbo.i Distolaterally directed aviculiaria with very pointed mandibles occur on on e or both sides ofthe ascopore. The ovicell is Ilarge globular, porous, and closed by the zooi lal operculum. bywsmall Lz Wz Lo Wo Lov Wov Lav Wav Lasc Wasc MEASUREM[ENTS RANGE MEAN 0.521 0.432-0.630 0.372 0.306-0.504 0.094 0.072-0.108 0.090-0.126 0.243 0.234-0.252 0.270 0.270 0.173 0.036-0.090 0.032 0.036-0.054 0.021 0.018-0.036 0.031 0.018-0.036 N 15 15 15 15 2 15 15 14 14 DISCUSSION: This species (wIiich was found onlv on larc-er -rains) is alwa2 vs multiserial. Ovicells appear to form earlier than in colonies from larger substrata; in the colony illustrated in figure 68 they are developing on zooids in the third generation from the ancestrula. OCCURRENCE: Living colonies were found at Capron Shoal in August 1983 and January 1985. Colonies were found at each census. Microporella umbracula is also found on larger shell substrata at Capron Shoal, Walton Rocks, and further offshore on the Ocu- lina pinnacles (Winston, 1982). NO. 2865 DISTRIBUTION: Circumtropical. Western Atlantic: Florida. Caribbean. FAMILY PHYLACTELLIDAE CANU AND BASSLER, 1917 GENUS PHYLACTELLA HINCKS, 1879 Phylactella ais, new species Figures 70-75 DIAGNOSIS: Uniserial Phylactella, with condyles but no lyrula, and with a prominent flared peristome which comes to blunt a point proximally. No avicularia. Prominent ovicell with scattered pores. HOLOTYPE: AMNH 681. PARATYPES: AMNH 682, 683, 684, 685. ETYMOLOGY: The species is named for the Indian tribe that once inhabited the shores of South Hutchinson Island. DEScRIPrIoN: Colonies are white, encrusting, sometimes branching in uniserial rows. Zooids are rectangular in shape; the frontal wall convex, rough textured and punctured by large round, evenly spaced, sunken pores. The primary orifice is semicircular anteriorly, with blunt lateral condyles and a shallowly curved proximal margin. The orifice is surrounded laterally and proximally by a broad raised peristomial collar which comes to a central point proximally. The ancestrula is not tatiform. Its frontal wall is heavily calcified with a few pores; it lacks the orificial collar of other zooids and possesses two distolateral spines. Ovicells are helmet shaped, with scattered pores (smaller and fewer than those of zooids) and can be found in the first generation from the ancestrula. Embryos are orange-yellow. Polypide has 12 pale-orange tentacles and displays Schizoporella-type writhing behavior. Lz Wz Lo Wo Lov Wov MEASUREMENTS MEAN RANGE 0.278 0.216-0.324 0.228 0.144-0.306 0.082 0.072-0.090 0.089 0.072-0.108 0.114 0.108-0.126 0.198 0.180-0.216 N 12 14 14 14 3 3 OCCURRENCE: Colonies were found at Capron Shoal in April 1983 (live), August 1983, 1986 WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS . i.: 31 $ 75' 4k*rs;t ,,. Figs. 70-75. 70. Phylactella ais (AMNH 681), colony on barnacle plate grain. Scale bar= 1 mm. 71. Phylactella ais (AMNH 682), showing ancestrula (also visible is a zooid of Membranipora triangularis). Scale bar = 200 ,um. 72. Phylactella ais (AMNH 682), colony with ovicelled zooid. Scale bar = 200 ,um. 73. Phylactella ais, close-up of ovicelled zooid. Scale bar = 40 ,um. 74. Phylactella ais, showing flared peristome. Scale bar = 100 ,m. 75. Phylactella ais, close-up of orifice. Scale bar = 40 ,m. August 1984, November 1984, and January 1985. DISTRIBUTION: Capron Shoal, Atlantic coast of Florida. 32 AMERICAN MUSEUM NOVITATES s~ !'.t -W NO. 2865 ..61 WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS 1 986 DISCUSSION: The ancestrula of this species SUPERFAMILY CELLEPOROIDEA LAMOUROUX, 1821 most frequently occurs in a hollow or crevice FAMILY CELLEPORIDAE BUSK, 1852 GENUS TREMATOOECIA OSBURN, 1940 Trematooecia psammophila, new species Figures 76-80 DIAGNOSIS: Trematooecia with colony encrusting sand grains. Zooids with 4-5 marginal spines and with marginal pores only. Ovicell frontal area with about 8-12 pores. No avicularia. HOLOTYPE: AMNH 686. PARATYPES: AMNH 687, 688, 689. ETYMOLOGY: The species name, psammophila, is taken from the Greek psammos (sand) and philia (love) in recognition of its preference for small grains as substrata. DESCRIPTION: Colonies are encrusting, unilaminar, and pale pink when alive. Zooids are erect, covered by a thick tubercular calcification that is penetrated only by a few marginal pores. The primary orifice is centrally located, circular anteriorly with a short pointed condyle, convex posteriorly, and surrounded by four or five (usually four) thick, solid, tapering spines, also covered by the same minute tubercles. There are no avicularia. The ovicells, which may be initiated in colonies with only three to five zooids, are buried in the surface calcification between the two distal spines. The ovicell has a lacy, porous central area and an arched opening above the zooidal operculum. Embryos are red. Lophophores have a translucent peach coloration. Lz Wz Lo Wo Lov Wov MEASUREMENTS MEAN RANGE 0.413 0.270-0.486 0.336 0.252-0.450 0.143 0.126-0.162 0.132 0.090-0.162 0.216 0.216 0.180 0.180 33 of a grain, but unlike most sand grain species, T. psammophila colonies are most commonly found encrusting convex surfaces of grains or protruding from them (HAkansson and Winston, 1985). They are found most often on very small grains (fig. 76), but they have also been observed to cement two grains together (fig. 77). This species is very similar to Trematooecia turrita (Smitt), which is found on larger substrata in the area. It differs from T. turrita in its smaller colony and zooid size (zooids of Florida specimens average about 0.50 mm in length and width; zooids of Belize specimens about 0.54 in length and 0.52 in width). T. turrita zooids also have pores scattered over the frontal surface, rather than limited to zooid margins and have ovoid adventitious avicularia of two size classes, smaller ones with a serrated frontal rostrum, and larger ones with a smooth, scoop-shaped rostrum. In addition, the ovicells of T. turrita have fewer (4-8), and larger pores than those of T. psammophila. (The species is listed as Cigclisula cf. turrita in HAkansson and Winston, 1985.) OCCURRENCE: Colonies were collected at Capron Shoal during each census and found alive in the following censuses: April 1983, August 1984, and January 1985. FAMILY CLEIDOCHASMATIDAE CHEETHAM AND SANDBERG, 1964 GENUS CLEIDOCHASMA HARMER, 1957 N Cleidochasma porcellanum (Busk), 1860 15 15 Figures 81, 82 15 15 1 1 Lepralia porcellana Busk, 1860, p. 283. Lepralia cleidostoma Smitt, 1873, p. 63. Hippoporina cleidostoma Canu and Bassler, 1928b, p. 104. Figs. 76-80. 76. Trematooecia psammophila, live colony on quartz grain. Scale bar = 300 ,um. 77. Trematooecia psammophila (AMNH 685), colony welding two sand grains together. Scale bar = 400 ,um. 78. Trematooecia psammophila (AMNH 687), colony on edge of grain, showing developing ovicell. Scale bar = 400 ,um. 79. Trematooecia psammophila (AMNH 688). Scale bar = 200 ,um. 80. Trematooecia psammophila, close-up of ovicell and orifice. Scale bar = 100 ,um. 34 AMERICAN MUSEUM NOVITATES NO. 2865 '4' ' Figs. 81-86. 81. Cleidochasma porcellanum (AMNH 690), whole colony on shell grain. Scale bar = 400 ,um. 82. Cleidochasma porcellanum, close-up of zooids. Scale bar = 200 ,um. 83. Cleidochasma angustum (AMNH 691), colony on barnacle plate grain. Scale bar = 200 ,um. 84. Cleidochasma angustum, close-up of orifice. Scale bar = 40,um. 85. Cleidochasma angustum, close-up of orifice. Scale bar = 40 ,im. 86. Aimulosia pusilla (AMNH 695), whole colony on shell grain. Scale bar = 1 mm. Hippoporina porcellana Hastings, 1930, p. 721. Marcus, 1937, p. 96. Osburn, 1940, p. 428; 1952, p. 344. Shier, 1964, p. 633. Cleidochasma porcellanum Cheetham and Sandberg, 1964, p. 1032. Cook, 1964, p. 11; 1968a, p. 198. Long and Rucker, 1970, p. 19. Powell, 1986 WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS 1971, p. 771. Winston, 1982, p). 148; 1984, p. 28. DESCRIPTION: Colonies ar e encrusting, multiserial, unilaminar, and porcellanous white, distinguishable from the white oftheir shell grain substrata only by the6ir golden-colored opercula. The ancestrula iss tatiform with eight spines. Subsequent zooidIs are hexagonal, the frontal surface granula:r, often with a large suboral and two lateral unnbos, and several marginal pores. The orifice is keyhole shaped its distal portion circular, with proximally directed cardelles and with a posterior sinu.s which varies from narrow to broad. There a rC iour to nvC spines around the orifice. In tiis species avicularia are triangular, with tr openings; their size and position cain vary considerably. No avicularia were pr*esent in sand grain specimens. Ovicells are Ihyperostomial and imperforate, prominent onI young zooids (as in the developing ovicell of fig. 82). Away from the growing edge they m ay be increasingly embedded in calcificatioin. MEASUREM:ENTS RANGE MEAN N LZ 0.216-0.306 0.257 15 Wz 0.126-0.234 0.185 15 Lo 0.072-0.108 0.097 15 Wo 0.054-0.090 0.070 15 rifoliate Developing ovicells Lov Wov 0.126-0.162 0.126-0.198 0.149 0.162 4 4 DISCUSSION: Though not as precocious as other sand grain species, these colonies reproduced early in comparison to Jamaican colonies of Cleidochasma porcellanum. Ovicells occurred in the fourth generation from the ancestrula (fig. 81). Morphological variation in C. porcellanum has been discussed by Cook (1964). Most zooids in our specimens have mamillated, rather than smoothtextured, frontal walls, the orifice surrounded distally by long spines and proximally by the lateral and suboral umbos. The proximal sinus of the orifice and the proximal portion of the operculum display the wide intercolony variation described by Cook (1964). Capron Shoal specimens differ from other specimens from Florida and the Caribbean 35 in lacking avicularia and having four or five rather than the three spines described by Cook (1964). OCCURRENCE: Living colonies were found at Capron Shoal in April 1984. Dead colonies were found in November 1984 and January 1985. DISTRIBUTION: Circumtropical. Western Atlantic: Cape Hatteras to Brazil. Gulf of Mexico. Caribbean. Cleidochasma angustum, new species Figures 83-85 DIAGNOSIS: Cleidochasma with uniserial encrusting colony. Zooid orifice surrounded by four thick spinous processes. Ovicell imperforate, with a granular semicircular frontal area. No avicularia. HOLOTYPE: AMNH 691. PARATYPES: AMNH 692, 693, 694. ETYMOLOGY: The species is named from the Latin angustus, narrow, because of its uniserial growth habit. DESCRIPTION: The colony is uniserial, encrusting sand grains. Zooids are ovoid, the entire frontal surface imperforate and smooth textured. The orifice is keyhole shaped, circular anteriorly, with a U-shaped proximal sinus. It is surrounded by a thick peristome ending in four tubby tapering spines. The ovicell also is smooth walled and imperforate, but has a semicircular frontal area with more granular calcification. There are no avicular- ia. Lz Wz Lo Wo Lov Wov MEASUREMENTS MEAN RANGE 0.289 0.252-0.360 0.216 0.144-0.270 0.061 0.054-0.072 0.061 0.054-0.072 0.117 0.108-0.126 0.153 0.144-0.162 N 12 12 12 12 2 2 DISCUSSION: Members of the genus Cleidochasma show a tendency to produce minute "sand fauna" colonies or species (see Cook, 1966; Harmelin, 1977; Hayward and Cook, 1979). OCCURRENCE: Living colonies were found at Capron Shoal in April 1983. Dead colonies were found in August 1984 and January 1985. 36 AMERICAN MUSEUM NOVITATES GENUS AIMULOSIA JULLIEN, 1888 Aimulosia pusilla (Smitt), 1873 Figures 86-89 Discopora albirostris forma pusilla Smitt, 1873, p. 70. Holoporella pusilla Osburn, 1914, p. 215. Hippoporella pusilla Cook, 1964, p. 10; 1968a, p. 190. DESCRIPTION: Colonies are encrusting, multiserial, and unilaminar. Zooids are hexagonal, convex, and outlined by a single row of large marginal pores. The rest of the frontal surface is covered by thick roughened calcification, rising to a peak in the suboral umbo. The orifice is large relative to zooid size and hoof shaped, with a circular anterior portion and a broad shallow proximal portion. The anterior portion is bordered by four oral spines which may become broken and obscured with age. The ancestrula is tatiform, with a circular frontal membrane and eight oral spines. Ovicells have a concave lower rim, large marginal pores, and a roughened surface, sometimes with a projecting central tubercle. MEASUREM]ENTS MEAN N RANGE 15 0.268 0.180-0.360 Lz 15 0.217 Wz 0.162-0.270 15 0.074 0.054-0.108 Lo 15 0.084 0.072-0.126 Wo 4 0.126 0.090-0.162 Lov 4 0.176 0.162-0.180 Wov OCCURRENCE: This species was collected at Capron Shoal at each census. DISTRIBUTION: Florida. West Africa. Aimulosia uvulifera (Osburn), 1914 Figures 90-92 Lepralia uvulifera Osburn, 1914, p. 210; 1940, p. 427. Aimulosia uvulifera Osburn, 1947, p. 35; 1952, p. 352. Maturo, 1957, p. 52. Soule, 1961, p. 20. Shier, 1964, p. 634. Soule and Soule, 1964, p. 19. DESCRIPTION: Colonies are encrusting and very small. Zooids are small and subhexagonal. The frontal surface is heavily calcified except for a very few marginal pores and is smooth textured; it rises distally into a pro- NO. 2865 jecting pointed umbo, so that the primary orifice lies sunken within a peristome. The orifice is rounded distally, with straight sides, and arcuate proximally. Six marginal spines (four in ovicelled zooids) border the orifice. The ancestrula is tatiform with eight to nine oral spines. The ovicell is globose and imperforate and broader than long, with a scalloped proximal margin and a central projecting point. MEASUREMENTS Lz Wz Lo Wo Lov Wov RANGE 0.198-0.270 0.144-0.216 0.054-0.072 0.054-0.072 0.090-0.108 0.108-0.144 MEAN 0.240 0.190 0.062 0.065 0.099 0.126 N 15 15 15 15 4 4 DISCUSSION: A trifid end to the umbo has been described (Osburn, 1914), but umbos of sand grain specimens end in a single point. A small triangular avicularium may occur lateral to the orifice, but no avicularia were found in sand grain specimens. Soule and Soule (1964) have discussed the confusion of this species with Hippoporella gorgonensis. OCCURRENCE: The species was collected at Capron Shoal in April 1983 (live), August 1983, January 1984, and August 1984. DISTRIBUTION: Beaufort, N.C. to Florida. Gulf of Mexico. Caribbean. Gulf of California and tropical E. Pacific. FAMILY SERTELLIDAE JULLIEN, 1903 GENUS DREPANOPHORA HARMER, 1957 Drepanophora torquata, Figures 93-96 new species DIAGNOSIS: Uniserial Drepanophora, with tubular peristome and curved orificial process, but no peristomial avicularium. Ovicells globose, lateral pores large. HOLOTYPE: AMNH 699. PARATYPES: AMNH 700, 701, 702. ETYMOLOGY: From the Latin torquatus, meaning adorned with a necklace or collar. DESCRIPTION: Colonies are primarily uniserial, rarely loosely pluriserial, arising from an 8?-spined tatiform ancestrula, with a gymnocystal area as large as the opesia. Zooids 1986 WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS 37 Figs. 87-92. 87. Aimulosia pusilla. Scale bar = 200 ,um. 88. Aimulosia pusilla (AMNH 696), closeup of ovicells. Scale bar = 100 ,um. 89. Aimulosia pusilla, close-up of orifice. Scale bar = 40 ,um. 90. Aimulosia uvulifera (AMNH 697), close-up of orifice and oral spines. Scale bar = 40 ,um. 91. Aimulosia uvulifera (AMNH 698), whole colony. Scale bar = 400 ,um. 92. Aimulosia uvulifera, close-up of ovicells. Scale bar = 200 ,gm. are ovoid, the frontal surface convex proximally and rising distally into a thick-walled tubular peristome. The frontal wall is imperforate except for marginal pores, and rough 38 AMERICAN MUSEUM NOVITATES textured, with many small tulbercles. Some zooids may have an umbo devreloped below the peristome. The secondary orifice is irnregularly subtriangular, the distal part broad , the proximal part tapering. A thin curved pIrocess or denticle is located near the proxinial end of the secondary orifice and projects inito it, but there is no associated peristomial avicularium. Ovicells are globose, wider tha n long, with a thick outer covering and two large lateral pores. In some colonies the per]istome of ovicellate zooids becomes transve rsely elongated and fluted. Polypides have 12 tentacles and a pale orange coloration. Lz Wz Lo Wo Lov Wov MEASUREM ENTS MEAN RANGE 0.20.2788 0.198-0.360 0.162-0.270 u.1Z06Y 0.072-0.144 0.106 0.090-0.126 0.102 0.072-0.144 0.108 0.144-0.234 0.180 N 15 1 1.3 15 15 4 4 DISCUSSION: This species can be assigned to Drepanophora on the basis of the peristomial denticle and the two lateral pores in the ovicell. In zooidal characters it most closely resembles two of the species described by Thornely (1905) from Ceylon as Rhyncopora [sic] incisor and Rhyncopora corrugata. Harmer (1957) pointed out that the basal denticle is actually the tip of an acute triangular projection of the avicularium. From Harmer (1957) it is apparent that ofthe specimens of D. corrugata he examined many had "incomplete" or "undeveloped" avicularia, thus had only basal denticles. The species also resembles Drepanophora tuberculatum, but that species has a shorter peristome and the ovicell is completely calcified, with a thickened proximal rim, the lateral pores obvious only on young ovicells. OCCURRENCE: Living specimens were collected at Capron Shoal in August 1984 and January 1985. Dead colonies were collected at each census. DISTRIBUTION: Capron Shoal, Atlantic coast of Florida. PHYLUM ENTOPROCTA NITSCHE, 1869 FAMILY PEDICELLINIDAE JOHNSTON, 1847 NO. 2865 GENUS BARENTSIA HINCKS, 1880 Barentsia minuta, new species Figure 97 DIAGNOSIS: Very small Barentsia with colonies epizooic on those of Cupuladria doma. HOLOTYPE: AMNH 703. PARATYPE: AMNH 704. ETYMOLOGY: The species name is from the Latin minutus, meaning little. DESCRIPTION: Colonies consist of creeping stolons with clusters of cup-shaped individuals on upright stalks spaced along them. The stolon is flexible and thin-walled, with a septum perforated by a central pore just above its muscular barrel-shaped base. Septa also occur between the pedicel base and the stolon. The cuplike calyx holds the internal organs. It ends in 12-13 short tentacles. The size of individuals varies with age. Calyx L w Pedicel heights Diameter Basal enlargement L w MEASUREMENTS RANGE MEAN N 0.126-0.315 0.171 8 0.105-0.315 0.171 8 0.420-0.630 0.321 7 0.042-0.063 0.046 5 0.168-0.231 0.063-0.105 0.210 0.084 5 5 DISCUSSION: Entoproct species seem to be extremely plastic in their morphology, varying both in quantitative characters like size, and in qualitative characters such as presence or absence of spines, pores, joints, etc. The presence of the muscular basal enlargement of the pedicel establishes this species as Barentsia. Barentsia gracilis is probably the closest relative of this species, but the extremely small size range of our specimens, plus their commensal habit, resulted in a decision to describe them as a new species. OCCURRENCE: Found attached to Cupuladria doma colonies at Capron Shoal. Entoprocts were noted in all samples. In April samples many of the individuals consisted only of pedicels-the calyces had been lost or shed during the winter months. January 1985 samples showed white embryos in calyces of some individuals. DISTRIBUTION: Capron Shoal, Atlantic coast of Florida. 1 986 WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS 39 Figs. 93-96. 93. Drepanophora torquata (AMNH 699), colony inside Crepidula shell, partially overgrown by sponge. Scale bar = 1 mm. 94. Drepanophora torquata (AMNH 700), another colony. Ovicelled zooid with large hole bored on left side. Scale bar = 400 ,m. 95. Drepanophora torquata (AMNH 701), close-up of ovicelled zooid. Scale bar = 200 ,um. 96. Drepanophora torquata, close-up of peristomial denticle. Scale bar = 20 Am. DISCUSSION THE INTERSTITIAL EXISTENCE Almost every invertebrate phylum is represented in interstitial faunas, and some whole groups, such as the Gnathustomulida, Gastrotricha, Kinorhyncha, and the most recently described phylum, the Loricifera (Kristensen, 1983), are entirely interstitial. However, most studies on interstitial meiofauna have been carried out in intertidal sand or mud habitats. Much less work has taken place in subtidal habitats like that at Capron Shoal. The sediment in our study area was primarily a well-sorted, medium-coarse biogenic sand, with very little silt and a low organic content, grading in places to coarse sand and shell gravel. The internal surface area of such a sand, composed of the surfaces of all the grains, is vast in extent, providing an enormous habitat for microbial populations: bacteria and (near the surface) sessile diatoms (Jansson, 1971). Many sand dwellers utilize bacteria or diatoms as a food source. Thus, a rich fauna may be present even when the organic content is low. Detritus may also be a food source, but can be detrimental as well, because detritus particles may restrict pore space. In fact, pore space, rather than grain size, appears to be what limits distribution of at least the larger interstitial organisms (Jansson, 1971; Williams, 1971). Interstitial or- 40 AMERICAN MUSEUM NOVITATES NO. 2865 _i FiiI 9' Fig. 97. Barentsia minuta (AMNH 703), living colony on upper surface of a Cupuladria colony. Scale bar = 200 ,um. ganisms live in an array of channels formed by the spaces between sediment grains. Through these channels water flows in a viscous manner; in them the animals move or feed. As Vogel (1981) put it, for us to imagine the physical world of these animals is to imagine "slithering through moving glop between boulders while blindfolded." Other factors affecting meiofaunal distributions are temperature, salinity, oxygen, and water movement. Subtidal communities are buffered from the abrupt changes of temperature and salinity experienced in the intertidal zone. Coarse subtidal sand like that at Capron Shoal acts like a giant aquarium filter, the action of waves and currents causing a constant flow of oxygenated water to pass through the sediment; oxygen is not a problem due to the effects of this subtidal pump (Riedl et al., 1972). The reducing layer is situated well below the sediment-water interface, and, in comparison with the intertidal, meiofaunal organisms can live many centi- meters into the sand. Preliminary analyses of cores taken at Capron Shoal in August 1984, for example, showed live encrusting bryozoans occurring 16 cm into the substratum (HAkansson, unpub. data). Effects of wave and current action are more important in shallow areas like Capron Shoal than in deeper waters. Fifty meter SCUBA transects carried out at the Capron Shoal study site in August 1983 showed sediment patterns to consist of ripple marks, 3 crests per meter, about 20 cm in relief, arranged parallel to the long axis of the shoal. Such ripple marks were again observed during dives made the following August. No large-scale transition in grain size was observed over the transects; all the variation was microvariation on or between ripples. Thus, sediment grains of different sizes, weights, and shapes were not evenly distributed, but aggregated in patches due to their differential behavior with regard to wave surge (larger shell fragments seem to drift to the top of the sediment) and the action 1986 WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS of burrowing animals, chiefly the sand dollars, Encope and Mellita. This microvariation is obliterated in dredged samples subjected to sediment analysis, but may be important in regulating the distribution ofthe interstitial fauna. No quantitative meiofaunal surveys have been undertaken at Capron Shoal. In our samples, the most common motile organisms were ciliates, copepods, nematodes, ostracodes, flatworms, archiannelids, polychaetes, small gastropods, scaphopods, juvenile bivalves, and Amphioxus. The bryozoans, of cousre, are not part of this motile fauna. They are, instead, an important component of the encrusting meiofauna, a category which seems to have been almost totally neglected by meiofaunal ecologists. At Capron Shoal the encrusting meiofauna included the following groups: foraminiferans, serpulid and spirorbid tubeworms, hydroids, sponges, turbellarian and other egg cases, and fungi. Fungal and algal borings were also common, as were the borings produced by ctenostome bryozoans. The foraminiferans encrusted the largest percentage of grains, followed by the tubeworms and bryozoans; the other encrusting organisms were much rarer. This community is illustrated in figure 98. CHARACTERISTICS OF INTERSTITIAL BRYOZOANS Morphological and ecological characteristics of the noncupuladriid bryozoans are shown in table 1. All meiofaunal organisms share certain adaptations to the interstitial existence. These include small body size, elongate form, simplified body organization relative to noninterstitial relatives, development of adhesive organs, neoteny, small number of eggs or embryos, and brooding or nonplanktonic development. Eleven ofthe noncupuladriid species found at Capron Shoal are only known from sand or gravel-sized sediments. Our previous study (HAkansson and Winston, 1985) showed that several of these species have specific grain size preferences, indicating that they are adapted to the interstitial life. Preliminary studies of a series of grains 41 ranging from sand to whole shells (Winston, unpub.) showed also that species diversity is bimodal. Diversity is high on the sand and fine gravel fraction (those species described in this paper). It declines considerably on small whole shells (6-10 mm in length) to less than a dozen species with Cribrilaria innominata, Bellulopora bellula, Trypostega venusta, and Alderina smitti dominating. On larger shells the number of species climbs again, but in addition to the 17 species listed (table 1), includes an additional suite of species not found on smaller grains (Winston, unpub. data). Other characteristics also adapt Capron Shoal species to live in interstitial sand. TRANSPARENCYf: Most interstitial organisms are transparent. Their invisibility against the shiny grains on which they dwell may render them less susceptible to predation. The bryozoans in our sample showed few exceptions to this rule. As exemplified by the colony of Membranipora triangularis shown in figure 8, living colonies are almost impossible to photograph -only the guts ofthe polypides (which had been fed with dark-colored flagellates) can be seen against the light-colored barnacle plate grain. Transparency may, in fact, be common among most shell-dwelling bryozoans, as all but two of the other encrusting cheilostomes were unpigmented. SMALL SIZE: Interstitial species are also characterized by the small size of zooids and colonies. Such colonies exhibit paedomorphosis, becoming sexually mature at a juvenile stage. Zooids of the entire colony remain neanic (in the sense of Ryland, 1970), the colony never reaching the zone of astogenic repetition found in most encrusting species. Colony structure is simplified in that there is little or no investment in nonfeeding polymorphs like avicularia. All the nonlunulitiform species that were restricted to small grains lacked avicularia. Moreover, colonies of five of the species also found on larger substrata either lacked avicularia entirely or had nonfunctional avicularia, lacking mandibles. This parallels the situation in social insects, in which colonies are initiated by nanitic workers, small in size and timid in behavior, and larger workers and defensive castes appear later, once the colony has achieved a certain population size (Oster and 42 1986 WINSTON AND HiKANSSON: INTERSTITIAL BRYOZOANS 43 TABLE 1 Characteristics of Sand Fauna Species ci ~~ c~~ 0 Species * 8 | = Q ;C cd Q Disporella plumosa Membranipora triangularis Phylactella ais X X X X X X X X X X Trematooecia psammophila X X Cleidochasma angustum Drepanophora torquata Membranipora arborescens Membranipora savartii Alderina smitti Antropora leucocypha Retevirgula caribbea Beania klugei Floridina parvicella Cribrilaria inominata X X X X Vibracellina laxibasis Cymulopora uniserialis Cribrilaria parva Reginella repangulata Hippothoa balanophila X X X X X X X X X X X X X X X X X X X X X X X X X Cleidochasma porcellanum Aimulosia pusilla Aimulosia uvulicera Parasmittina signata X X X X a NB bW X X X X X Belluloporla X Xh X Trypostegaia psa X X Schizoporella rugosa Escharina pesanseris X X Microporella umbracula X X X X X X X X (X) X X X X X X X X X (X) (X) X (X) (X) X X W/T W/T W/T X 4-5Z X X X 3Z 3Z NB X (X) X 15-20 3Z NB 3Z X X X 12 3Z 6Z 3Z X X X 20 6Z X ? X X 20 6c12 X X _c 5Z 4Z X X X 3Z X ? X X 15-20 X X X Nc10 24 X X 2c3z X X -c 1 X Color of X X X X X X Size at W/Tb X X X fl 6Z NBa X X X X X i ? W/T W/T W/T W/pale orange pale pink/ peach pink W/? W/T W/T W/T W/T W/T W/T tan/tan W/T W/T W/T W/T W/T W/? pink-orange/ pink W/T W/? W/? W/? nonbrooding. = = white; T c Nonfunctional. = transparent. Wilson, 1978). As in the social insects, a newly founded colony should attempt to maximize number of workers (autozooids) and their initial survival rate, on the basis of the limited energy available to the founder (queen or metamorphosed larva). And, as in the shorter-lived social insects, in the interstitial bryozoans, only two castes are produced, workers and reproductives. REPRODUCTIVE PRECOCITY: Sexual repro- duction takes place very early. It is not pos- sible to indirectly assess reproductive state in nonbrooding species (four species in this study), but the presence of ovicells in brooding species shows the reproductive status reached even by colonies dead when collected. Ovicelled zooids occurred in the first three zooids of five of the species limited to small substrata and three of the species also found on larger substrata. Six more species were capable of initiating reproduction with colonies six zooids in size. Of the species re- 44 AMERICAN MUSEUM NOVITATES stricted by substratum size, Cribrilaria parva and Vibracellina laxibasis produced the greatest number of zooids before reproducing, 12 zooids and 15-20 zooids, respective- ly. But perhaps more interesting is the flexi- bility shown by species which also occur on larger substrata. Of the 14 species which produce ovicells, 12 had colonies with ovicells in our sample; all of these had reproduced with colonies of 24 or fewer zooids. Colonies of the same species from other habitats (e.g., Cleidochasma porcellanum and Trypostega venusta are both common in cryptic reef communities in Jamaica) reproduce at a much larger colony size. If colonies from other environments really are conspecific (and it must be stressed that we can only judge this on morphological criteria) then it appears that at least some bryozoans show a remarkable plasticity in the onset of sexual reproduction, and that onset seems to be triggered by environmental cues rather than a threshold colony size. PROJECTIONS AND SPINES: One of the most striking features of most of these species is the presence of numerous projecting umbos, tubercles, and spines (e.g., Membranipora triangularis, fig. 9; Reginella repangulata, fig. 50; Phylactella ais, fig. 71). These may be important in the interstitial environment, where physical damage may be a greater problem than predation. Nevertheless, predation does occur in the interstitial fauna. A large percentage of motile forms are predators. A number of these, such as flatworms and gastropods (e.g., see drilled hole in the Drepanophora ovicells, fig. 94) may prey on bryozoans. Colonies are also damaged by boring organisms (e.g., holes in Phylactella ais, figs. 74, 75). But the effects of abrasion are more noticeable (e.g., figs. 13, 37, 41, 48, 56-5 8, 64, 88). Skeletal abrasion is very common in dead colonies, but many living colonies also showed evidence of regeneration and repair of abraded zooids, indicating that much damage takes place during life. Although flow of water through undisturbed sediment occurs in a viscous manner, and this viscosity may protect grains, preventing them from touching and abrading their encrusting fauna, physical processes in shallow water environments such as Capron Shoal NO. 2865 may become violent. The polished, rounded surfaces of many grains indicate that much grinding of grain against grain does occur; this grinding may be enhanced by the intermixture of the small, hard, sharper-edged quartz grains which make up 15-30 percent of the sediment. The abrasion probably takes place primarily during the periods of heavy seas or storm conditions that are more common during winter months. SHORT LIVES: We have no data on the lifespan of the interstitial encrusting species, but their early reproduction, the presence of a large number of skeletons for every living colony (averaging about 20 to 1), and the large amount of partial mortality and repair noted, suggest that colonies of these species are ephemeral. Population data on cupula- driids indicate that colonies of Cupuladria doma, whose juveniles are among the most common interstitial bryozoans, were primarily annual, with the greatest mortality taking place between January and April when weather conditions are most severe. Colonies ofthe larger Discoporella umbellata depressa, which reproduced primarily by fragmentation, appeared to be longer lived (Winston and HAkansson, unpub. data). MORPHOLOGICAL PLASTICITY The degree to which a species can exhibit changes in zooid or colony morphology under varied environmental conditions has long been a subject of speculation among bryozoan workers because of its taxonomic implications. If morphological plasticity is high, then we run the risk of splitting morphotypes that belong within the same species. If it is low, we may be lumping several similar species together. Growth form seems more plastic than zooid form. We know that some species can vary their growth from encrusting, to erect, to tubular or bilaminate and platy, depending on substratum and environmental conditions (e.g., Cook, 1968a; Ryland, 1970). But can a species vary its growth pattern from uniserial to multiserial according to its substratum? Sixteen of the species we collected are known also from larger substrata. On such substrata they grow as multiserial sheets. Six species retain this growth pattern even on 1986 WINSTON AND HAKANSSON: INTERSTITIAL BRYOZOANS small grains, which they generally cover almost completely (e.g., Membranipora arborescens, fig. 1 1; Microporella umbracula, fig. 68). Other species show a biserial-triserial fanlike growth pattern on sand grains (e.g., Cribrilaria innominata, fig. 40; Aimulosia uvulifera, fig. 91). Young colonies of these species often exhibit similar growth on large substrata; they may also be multiserial. No species we studied varied from uniserial to multiserial. Plasticity in growth form appears real, but moderate. Plasticity in zooid form is more restricted. The chief differences between sand grain specimens and those from larger substrata appear to be the strong development of skeletal projections in sand grain species and a slightly smaller, overall zooid size. As pointed out in the previous section, onset of reproduction shows great plasticity. The situation with regard to other types of polymorphism-the development of avicularia, kenozooids or zooeciules-is more ambiguous. It does appear that at least half the species which have avicularia on larger substrata lack them in sand grain specimens. In interstitial colonies of Trypostega venusta, which normally have zooeciules between zooids, they are present only on ovicells (fig. 56). BIOGEOGRAPHIC SIGNIFICANCE OF INTERSTITIAL HABITAT The fact that two-thirds of the species found interstitially also occur on larger substrata has important implications for bryozoan biogeography. Fourteen of these species have relatively broad distributions, occurring in at least two tropical or subtropical regions. Ecologists and biogeographers have struggled to explain such distributions in animals like bryozoans, with nonfeeding larvae which spend a very short period of time (less than 24 hours) in the plankton. The idea of vicariance, the distribution of animals via drift of the continental plates themselves, has great appeal for such animals. The idea of dispersal by rafting has also recently been revived (Jokiel, 1984; Jackson, in press). Unlike these two hypotheses, the interstitial refuge cannot explain dispersal across deep water, but it can help explain distributions along shallow shelves. On continental shelves 45 like that off the southeastern United States, encrusting bryozoans have been assumed to be limited to the scattered occurrences of hard substrata: fossil reef, shell debris, ballast deposits, etc. (Maturo, 1968). The fact that a number of encrusting species can grow and reproduce on very small grains indicates that distributions may not be that patchy. It is true that living colonies are sparsely distributed. In Capron Shoal samples the average abundance of living encrusting (nonlunulitiform) species was 0.75 per cm3 of sediment. Thus, one square meter of sediment 1 cm in depth would contain 7500 living colonies. For the inner continental shelf off Florida alone this would yield a population of about 1.3 x 1012 colonies, and this estimate is conservative, as living colonies are known to occur much deeper than 1 cm into the sediment. In fact, the interstitial refuge may be an important factor in maintaining distributions of encrusting species, acting almost like the seed bank for populations of plants, by buffering the effects of physical and biological perturbations and lowering the chances of local extinction. ACKNOWLEDGMENTS We would like to thank the many people who helped us with this long and labor-intensive project. Dr. Mary E. Rice and the Smithsonian Marine Laboratory, Fort Pierce, Florida, provided us with laboratory and logistical support. Woodie Lee, Hugh Reichardt, Sherry Petry, and Julie Piraino, Smithsonian Marine Laboratory; Bob Starcher, Rutgers University; and Beverly Heimberg and Jeff Teitelbaum, American Museum of Natural History, provided field or diving assistance. Beverly Heimberg (AMNH) measured specimens and sorted many of the samples. Additional sorting was carried out by Barbara Worcester, Robin Otton, and Louisa Gralla (AMNH volunteers) and Peter Harries (AMNH), as well as by the authors. Financial support was provided by the National Geographic Society, the American Museum of Natural History, and the National Science Foundation of Denmark. We also thank Miss Patricia Cook, British Museum (Natural History), Dr. Scott Lidgard, Field Museum, and Dr. Alan Cheet- 46 AMERICAN MUSEUM NOVITATES ham, Smithsonian Institution, for their critical review ofthe entire manuscript; Dr. John Bishop, British Museum (Natural History), for comments on cribimorph species; and Dr. Robert P. Higgins, Smithsonian Institution, for review of sections dealing with the interstitial habitat. LITERATURE CITED Applied Biology, Inc. 1976. Ecological monitoring at the Florida Light and Power Co. St. Lucie Plant. Annual Report, 1976, vol. 1. Applied Biology, Inc., Atlanta. Audouin, J. V. 1826. Explication sommaire des planches de polypes de 1'Egypte, histoire naturelle, vol. 28. Paris, C. L. F. Panckouche, pp. 225-249. Banta, W. C., and R. J. M. Carson 1977. Bryozoa from Costa Rica. Pacific Sci., vol. 31, pp. 1-424. Blainville, H. de 1830. Dictionnaire des sciences naturelles, vol. 60, 546 pp. Art. Zoophytes, p. 411. Brood, K. 1972. 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