Shallow-water holothuroids (Echinodermata) of Yap, Federated States of Micronesia

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1 Shallow-water holothuroids (Echinodermata) of Yap, Federated States of Micronesia By Sun W. Kim*, Allison K. Miller, Catherine Brunson, Kristin Netchy, Ronald M. Clouse, Daniel Janies, Emmanuel Tardy, and Alexander M. Kerr Abstract In December 2002, July 2007 and December 2009, we surveyed the sea cucumber fauna of the western Caroline Island of Yap (Federated States of Micronesia). We collected 37 species of holothuroids, including 32 species of aspidochirotes and five species of apodans. We found all 13 of the previously reported species and 24 new records for the islands 19 aspidochirotes and five apodans. At least two of the new records appear to be previously undescribed species. Types of microhabitats and reef zonation were closely correlated with the species distributions of Yapese holothuroids.. *Corresponding Author Pacific Science, vol. 68, no. 3 February, 10, 2014 (Early view)

2 Introduction Coral reefs are among the most biologically diverse marine ecosystems, yet they are threatened by climate change, overexploitation, eutrophication and ocean acidification (Hughes 1994, Reaka-Kudla 1997, Bruno et al. 2009). The currently known 93,000 coral reef associated species are estimated to only represent a small portion of the actual diversity (Reaka- Kudla 1997). In addition, many species have not been seen since their original descriptions, often over a century ago, causing ongoing taxonomic confusion. This taxonomic confusion is not limited to rare species; statuses of even some common species remain in flux. We clearly have much to learn about the alpha diversity of coral reefs (Reaka-Kudla 1997, Bouchet et al. 2002, Michonneau et al. 2013). Holothuroids are one of the more poorly studied, yet abundant animals on shallow reefs of Micronesia. Only a handful of reports describe the holothuroid fauna of this region, and there are no published accounts of the holothuroids from the islands of Yap, Federated States of Micronesia. The earliest reports of Yapese echinoderms (Hayashi 1938, Clark 1954) do not include holothuroids. The more recent reports (Amesbury et al. 1976, 1977, Grosenbaugh 1978, Grosenbaugh 1981) record a total of 15 species, but many of the identifications remain uncertain because of a lack of voucher material. In December 2002, July 2007 and December 2009, we surveyed the reefs and adjacent habitats around the main islands of Yap and collected 37 species of holothuroids, 24 of which are new records for the island, including 2 potentially new species. Material and Methods Study sites Yap state comprises the main island group and fourteen outer atolls. The main island group (9 32 N E, 100km 2 ) consists of four closely lying volcanic islands 2

3 surrounded by fringing and barrier reefs, with a variety of shallow-water marine habitats (Figure 1). The inner reef flats are silty and support beds of the seagrass Thalassia hemprichii, Enhalus acoroides and Zostera spp. The middle reef flats are inhabited by large colonies of the corals Acropora spp., Pocillopora spp. and Porites spp. Outer reef flats and crests are covered by a large amount of coral rubble and loose rocks, but far fewer and smaller living corals. The reef flats are often interrupted by deep "blue holes," areas to 20 m depth with high coral cover. Few sites differ from the described common reef flat topography. The southernmost site, Rull, is a wide sand flat with several massive Porites spp. colonies and rubble. Balabat, further north, is also sandy but the bottom is covered with the seagrass, T. hemprichii and Enhalus acoroides, and outer reef flat has abundant Porites and Acropora spp. colonies. The two sites located between the islands, Fanif and O Keefe s island, both have soft substrate with copious beds of T. hemprichii and a few massive Porites spp. colonies. The fore-reef near Colonia is a gradual slope with high coral cover. <<Figure 1 near here>> Sampling methods Specimens were collected over five days in December 2002, nine days in July 2007 and eight days in December 2009 from a total of 12 different sites (Figure 1). Specimens were captured by hand while snorkeling or on SCUBA at depths up to 20 m. Specimens were often collected at night because many holothuroids are exclusively nocturnal. Depth, time of day, GPS coordinates, and microhabitat were noted for each specimen. Most collected specimens were also measured for length and photographed in situ. In laboratory, all specimens were first relaxed in a solution of MgCl 2, MgSO 4 or chloretone. Relaxed specimens were then photographed, and a 3

4 small portion of tissue was sampled and stored in 95% ethanol for molecular analyses. In addition, further subsamples of the dorsal and ventral body-walls were excised for ossicle preparations. These were initially dissolved in household bleach, and then rinsed in water and with an increasing concentration gradient of ethanol (60%, 80%, and 100%). The ossicles were spread onto a microscope slide for morphological examination. Whole specimens were initially fixed in 70% ethanol and are now deposited in the Florida Museum of Natural History (FLMNH). Results Annotated Species List A total of 37 holothuroid species were recorded including 32 species of aspidochirotes and 5 species of apodans. Ossicle micrographs are shown in Figures 2, 4, 6 and 8. Abbreviations used throughout are as follows: FSM, Federated States of Micronesia; NSF, U.S. National Science Foundation; UF, Florida Museum of Natural History; YAPCAP, Yap Community Action Program. Field numbers of the form YAP-SK-000 indicate material which is curated at UF, but for which museum accession numbers are presently pending. Class Holothuroidea Order Aspidochirotida Family Holothuriidae Genus Actinopyga Bronn, 1860 Actinopyga mauritiana (Quoy and Gaimard, 1833) Figures 2A, 2B Holothuria guamensis Quoy and Gaimard 1833:

5 Holothuria mauritiana Quoy and Gaimard 1833: 138. Mülleria mauritiana; Selenka 1867: 315; Semper 1868: 76. Microthele guamensis; Cherbonnier 1952: 40, Pl. II, fig. 1. Actinopyga mauritiana; Panning 1929: 128, fig. 11; Panning 1944: 55, fig. 24; Cherbonnier 1952: 41, figs. 16a-o; Domantay 1953: 349; Rowe 1969: 131; Clark A.M. and Rowe 1971: , pl. 27 fig. 3; Rowe and Doty 1977: 228, 247, figs. 3f, 6d, 9; Cherbonnier 1988: 16 17, fig. 2; Kerr 1994: 166; Hopper et al Material: UF5881, Colonia, Woneeday Channel, 5 m depth during the day at outer reef near crest, August 2, UF11392, Balabat, < 1 m depth during the day on reef crest, December 14, Remarks: This species is a new record for Yap. This species was common at the eastern sites, and much less common on western reefs. Specimens were found in higher energy zones, from the outer reef flat to the shallow reef front. <<Figure 2 near here>> Actinopyga?palauensis (Panning, 1944) Figure 3A Actinopyga obesa palauensis Panning 1944: 57 58, fig. 26. Actinopyga palauensis; Clark A.M. and Rowe 1971: ; Kerr et al. 1992: , fig. 3a, non A. obesa (Panning). Material: No voucher specimen, Gagil-Tamil, < 1 m depth in seagrass during the day, inner reef flat, September 21, Photo record (Figure 3A), Maap, < 1 m depth in seagrass during the day, inner reef flat, September 16,

6 Remarks: This species is a new record for Yap. We found several deep brown to nearly black Actinopyga sp(p)., which we were not permitted to collect. Six of the specimens appear closest to A. miliaris (Quoy and Gaimard 1833). These were smaller, averaging 15 cm in length, rounder and with an arched dorsum and occurring in seagrass on the inner reef flat, often quite near the mangrove fringe of the islands. Two specimens that resembled A. palauensis were found further seaward on the reef flat in deeper water on a silty sand bottom; they were larger, up to 28 cm in length, and more oblong. <<Figure 3 near here>> Actinopyga sp. Figures 2C, 2D, 3B, 3C Actinopyga echinites; Grosenbaugh 1981: Unidentified species (Holothuriidae?); Allen and Steene 1996: unnumb. fig Material: UF5848, 5868, 5870, 5884, 5887, Fanif, < 1 m depth during the day in seagrass, inner reef flat, July 30, UF11290, 11310, Gagil, September 25, YAP-SK-047, 048, 049, 050, O Keefe s Island, Fanif, < 1 m depth during the day in seagrass on inner reef flat, December 12, Remarks: This form of Actinopyga sp. seems to be restricted to the tropical western Pacific Ocean, only reported from New Guinea and Palau (G. Paulay, pers. comm.). Its distribution in Yap was quite patchy, with a high abundance at only a couple of sites, Tomil and Fanif, where the inner reef flat was silty and the bottom was covered with seagrass. Animals were striped, or uniformly tan to dark brown (Figures 3B, C). Amesbury et al. (1976, 1977) and Grosenbaugh (1981) reported an "A. echinites" as very common and occurring in small groups from several 6

7 shallow seagrass beds in Yap. Given their abundance, restricted microhabitat and density, the animals they mention are almost certainly the species considered here, Actinopyga sp. Recently, Borrero-Perez et al. (2012) reported two black Actinopyga species from Guam based on genetic data, and identified one of them as A. miliaris? Given the morphological similarity, A. sp. recorded here could be the same form that Borrero-Perez et al. (2012) reported from Guam. Genus Bohadschia Jaeger, 1833 Bohadschia argus Jaeger, 1833 Figures 2E, 2F Bohadschia argus Jaeger 1833: 19, pl. A figs. 1 1b; Panning 1944: 36, figs. 7-8; Rowe 1969: 130; Clark A.M. and Rowe 1971: , pl. 27 fig. 6; Rowe and Doty 1977: 233, 229, figs. 2h, 6f; Grosenbaugh 1981: 51; Cherbonnier 1988: 34 35, fig. 10; Kerr 1994: ; Kim et al. 2013: 86, figs. 3A-B. Holothuria (Bohadschia) argus; Panning 1929: 121, figs. 50a-c. Material: UF5873, Maap, < 1 m depth during the day on sand on inner reef flat, July 29, UF11417, Kaday, < 1 m depth during the day on sand on inner reef flat, December 11, Remarks: This species was found at all but two sites located between the volcanic islands, Fanif and O Keefe s island, where the bottom consisted of soft mud and seagrass. The most common color pattern observed in Yap was a grey background with dark ocellations, while others were dark brown or, rarely, pure white with only faint gray ocellations. Bohadschia marmorata Jaeger, 1833 Figures 2G, 2H 7

8 Bohadschia marmorata Jaeger 1833: 18, pl. 3 fig. 9; Brandt 1835: 256; Clark A.M. and Rowe 1971: , 209, pl. 27 fig. 8; Rowe and Doty 1977: , figs. 3a, 6g h; Cherbonnier 1988: 36, fig. 11a 1002E; Kim et al. 2013: 88-89, fig. 3K. Sporadipus ualanensis Brandt, 1835: 246. Holothuria ualensis Selenka, 1867: 341. Holothuria marmorata; Semper 1868: 79, pl. 80, fig. 10, pl. 35, fig. 3, pl. 36, fig. 8, pl. 37, figs. 1-4; Clark H.L. 1938: 523; Lampert 1885: 86-87; Théel 1886: Holothuria (Bohadschia) marmorata; Panning 1929: 120, fig. 1. Material: UF5856, 5859, 11401, Kaday, < 1 m depth at night in seagrass near mangroves, and on sand on middle reef flat, August 5-6, 2007, December 11, Remarks: This species is a new record for Yap. This species was most frequently observed at night in seagrass and sand flats of the inner and middle reef flats. Bohadschia marmorata has frequently referred to other members within the genus in the literature. However, a recent study by Kim et al. (2013) revealed that B. marmorata sensu Jaeger was genetically distinct from other forms frequently misidentified species as B. marmorata. In addition, B. marmorata can be easily distinguished by its dorsolateral markings and relatively small size (Kim et al. 2013). Bohadschia koellikeri (Semper, 1868) Figures 2I, 2J, 3D, 3F Holothuria koellikeri Semper 1868: 86, pl. 30, fig. 25, pl. 35, fig. 7; Lampert 1885: 36, 87; Théel, 1886: 204; Rowe and Gates 1995: 351. Bohadschia koellikeri; Rowe 1969: 130; Clark A.M. and Rowe 1971: 194, 209; Kim et al. 2013: 86-88, figs. 3E-F. Material: UF11420, Kaday, < 1 m depth at night on sand on inner reef flat, December 10,

9 Remarks: This species was nocturnal and only found in Kaday. Bohadschia koellikeri has been frequently misidentified as Bohadschia vitiensis, a morphologically similar but genetically distinct species (Kim 2010, Kim et al. 2013). Fine lineation and light brown blotches on the dorsal body-wall clearly contrast B. koellikeri from B. vitiensis, which possesses a smooth dorsum, often with solid transverse bands (Figure 3D, E, F, G). The overall color pattern of B. koellikeri observed in Yap was creamy-beige with light brown blotches on the dorsum (Figure 3D). Bohadschia vitiensis (Semper, 1868) Figures 2K, 2L, 3E, 3G Holothuria vitiensis Semper 1867: 80, pl. 30, fig. 12; Lampert 1885: 89; Théel 1886: ; Pearson 1914: 57-60, pl. VII, fig. 6; Domantay 1933: 76, pl. 1, fig. 2; Domantay 1953: 119. Holothuria similis Semper 1868: 85-86, pl. 25, 30. Holohuria clemens Ludwig 1875: 107, fig. 49. Holothuria bivittata Mitsukuri 1912: 68 71, pl. 3, fig. 75. Bohadschia marmorata vitiensis; Panning 1944: 40, figs. 11a-y. Bohadschia vitiensis; Pearson 1914: 170; Rowe 1969: 130; Clark A.M. and Rowe 1971: 194; Rowe and Doty 1977: ; Cherbonnier 1988: 42-44, fig. 14a-i; Kerr 1994: ; Rowe and Richmond 2004: 3300; Kim et al. 2013: 89, figs. 3G-J. Material: UF5852, 5853, 5914, Colonia, 1 m depth in seagrass at edge of mangroves, August 5, UF5891, 5915, Tamil, 2 m depth on sand on middle reef flat, July 31, UF11394, Kaday, < 1 m depth at night on sand on inner reef flat, December 10, Remarks: This species was found in Kaday and Tamil at night. The specimens were buried in sand during the day and emerged during the late afternoon. They were mostly found on inner 9

10 reef flats in seagrass or sand flats in large numbers. Bohadschia vitiensis showed a wide variation in shading. The background coloration varied from creamy white to brown, while the two dorsal transverse bands could be absent or quite distinct (Figure 3E). Bohadschia vitiensis has been frequently misidentified as B. marmorata; however, a study by Clouse et al. (2005) revealed that specimens referable to B. bivittata Mitsukuri, 1912 were genetically distinct and deserved a species status. A recent study by Kim et al. (2013) added that color forms matching the description of B. bivittata fell within the B. vitiensis clade, in which the members show variable color and banding patterns. Genus Holothuria Linnaeus, 1766 Holothuria (Acanthotrapezia) coluber Semper, 1868 Figure 2M Holothuria coluber Semper 1868: 90, pl. 28, pl. 30 fig. 28a b, pl. 34 fig. 5; Panning 1944: 62, fig. 30a-i. Holothuria (Holothuria) coluber; Panning 1935: 35, fig. 30a-b. Holothuria (Acanthotrapezia) coluber; Rowe 1969: ; Levin 1979: 20; Cherbonnier 1980: 636, fig. 11A-H; Tan Tiu 1981: 74, pl. 16, figs. 1-3; Clark A.M. and Rowe 1971: , fig. 85c, pl. 27 fig. 13; Cannon and Silver 1986: 21, fig. 6c; Féral and Cherbonnier 1986: 80 81, fig. 40f; Kerr 1994: 168, fig.4; Rowe and Gates 1995: 290. Material: UF5888, 11419, O Keefe s island, < 1 m depth during the day under a massive Porites sp. on inner reef flat, July 30, 2007, December 13, Remarks: This species was only found near O Keefe s island. During the day, the observed specimens were less active, often hiding under rocks or coral heads. The specimens extended their anterior end to feed at night. This may be the "Holothuria leucospilota" of Amesbury et al. 10

11 (1977) and Grosenbaugh (1981), who note a species in identical habitat also extending its anterior to feed, especially in the evening. Holothuria (Cystipus) inhabilis Selenka, 1867 Figures 2N, 2O, 3H Holothuria inhabilis Selenka 1867: 333, pl. 19 figs Jaegerothuria inhabilis; Deichmann 1958: , pl. 8 figs Holothuria (Cystipus) inhabilis; Rowe 1969: ; Clark A.M. and Rowe 1971: , 194, 209, pl. 28; Borrero-Perez et al Material: UF5861, Fanif blue hole, 10 m depth at night in blue hole, August 3, Remarks: This species is a new record for Yap. The sole specimen encountered had a white dorsum and ventrum with two rows of dorsolateral brown papillae and was exposed on coralline rubble at night (Figure 3H). Holothuria (Halodeima) atra Jaeger, 1833 Figures 4A, 4B Holothuria atra Jaeger 1833: 22. Holothuria (Holothuria) atra; Panning 1935: 30, fig. 22a-f Holothuria (Halodeima) atra; Rowe 1969: 137, fig. 7; Clark A.M. and Rowe 1971: , pl. 27 fig. 11; Clark A.M. and Taylor 1971: 91; Liao 1975: 210, fig. 10; Rowe and Doty 1977: , 247, figs. 3d, 7a; Grosenbaugh 1981: 51-53; Tan Tiu 1981: 73, pl. 15, figs. 1-3, pl. 29, figs. 1-2e; Cherbonnier 1988: 73, fig. 28a j; Kerr 1994:

12 Material: UF5875, 5897, Colonia, < 1 m depth in seagrass near mangroves, August 5, UF11402, Kaday, < 1 m depth during the day in seagrass bed on inner reef flat, December 11, Remarks: This species was ubiquitous at all reef flat sites, occurring in practically all types of microhabitats from inner to outer reef flats. Holothuria atra was the most common species observed during the surveys. <<Figure 4 near here>> Holothuria (Halodeima) edulis Lesson, 1830 Figures 4C, 4D Holothuria edulis Lesson 1830: 125, pl. 46 fig. 2. Holothuria (Holothuria) edulis; Panning 1935: fig. 36a-d. Holothuria (Halodeima) edulis; Levin 1979: 20; Rowe 1969: 138; Clark A.M. and Rowe 1971: , pl. 27 fig. 14; Rowe and Doty 1977: 231, figs. 3e, 7b; Cherbonnier 1980: 632, fig. 9A- L; Liao 1980: 115; Grosenbaugh 1981: 51-53; Liao 1984: 222; Cannon and Silver 1986: 22, fig. 6f, text fig.; Cherbonnier 1988: 75, fig. 29A-I; Kerr 1994: 168; Rowe and Gates 1995: 291. Material: UF5889, 5912, Colonia, < 1 m depth in seagrass with patch reefs nearby, July 30, UF11404, Kaday, < 1 m depth at night on sand near a massive Porites sp. on middle reef flat, December 11, Remarks: This species was commonly found in Kaday. This species displays geographic variation in its color (O. Loughlin et al. 2007). In Yap, the specimens possessed a black to dark gray dorsum and a pink ventrum. 12

13 Holothuria aff. (Lessonothuria) cavans Figure 3I Material: Photo record (Figure 3I), site unrecorded, < 1 m depth in seagrass collected by E. Tardy, September 22, Remarks: This species is a new record for Yap. The uncollected, photographed specimen showed a dark green background with dark brown blotches and white spots (Figure 3I). This species is frequently misidentified as a darker form of the closely-related, H. (L.) lineata; however, H. (L.) lineata is dark brown to grey in background, and does not display the greenish hue. This species has also been observed in Okinawa and Palau (G. Paulay and F. Michonneau, pers. comm.). Holothuria (Mertensiothuria) hilla Lesson, 1830 Figures 4E, 4F Holothuria hilla Lesson 1830: 226, pl. 79. Holothuria (Thymiosycia) hilla; Clark A.M. and Rowe 1971: ; Rowe and Doty 1977: , 247, figs. 4b, 8b; Grosenbaugh 1981: 51-53; Cherbonnier 1988: 85 87, fig. 343a 1; Kerr 1994: ; Rowe and Gates 1995: 372. Holothuria (Mertensiothuria) hilla; Samyn and Massin 2003: 2500; Rowe and Richmond 2004: Material: UF5871, Colonia, < 1 m depth in seagrass with patch reefs nearby, July 30, UF11426, Rull, 2 m depth during the day on sand under a rock on inner reef flat, December 12, Remarks: Specimens recorded in this survey were only found during the day hiding under rocks on inner and middle reef flats. Holothuria hilla is a nocturnal species, commonly found exposed on reef flats at night. 13

14 Holothuria (Mertensiothuria) leucospilota Lesson, 1830 Figure 5A Holothuria (Gymnochirota) leucospilota Brandt 1835: 51. Holothuria leucospilota; Ludwig 1881: 595; Clark H.L. 1921: 179. Holothuria (Mertensiothuria) leucospilota; Rowe 1969: 149; Clark A.M. and Rowe 1971: ; Amesbury et al. 1977: 13-16; Rowe and Doty 1977: 234, figs. 4g, 8c; Grosenbaugh 1981: 51-53; Cherbonnier 1988: , fig. 45a p; Kerr 1994: 168; Rowe and Gates 1995: 358; Rowe and Richmond: Material: Photo record (Figure 5A), Wanyan, < 1 m depth under exposed coral rubble on the outer reef flat at low tide, November 28, Remarks: While often abundant on other islands of Micronesia (e.g. Kerr et al. 1993, Kerr 1994), this species in Yap was only seen as a few small individuals under exposed coral rubble on the outer reef flat at low tide at Wanyan. <<Figure 5 near here>> Holothuria (Metriatyla)?lessoni Massin, Uthicke, Purcell, Rowe, Samyn, 2009 Figures 4G, 4H, 5B Holothuria timama Lesson 1830: 118, pl. 43; Lampert 1885: 94; Théel 1886: 240; Clark A.M. 1963: 388; Opinion : 15; Melville and Smith 1987: 301. Holothuria (Metriatyla) timana; Rowe and Gates 1995: 295; Marsh and Morrison 2004: 339. Holothuria (Metriatyla) scabra; VandenSpiegel et al. 1992: 168, figs. 2, 3A-E, 4A-G non H. (M.) scabra Jaeger,

15 Holothuria scabra var. versicolor Conand 1986: 19; Conand 1991: 170; Conand and Byrne 1993: 3ss; Forbes et al. 1999: 38; Hamel et al. 2001: 146, fig. 4B; Uthicke et al. 2005: 261ss, fig. 1B-D. Holothuria aculeata; Cherbonnier 1951: 298 non H. aculeata Semper, 1868; Catala 1979: 245, fig. 91 non H. aculeata Semper, 1868; Rowe and Gates 1995: 295 (cited as a synonym of H. timana) Holothuria (Metriatyla) aculeata; Rowe 1969:160; Clark A.M. and Rowe 1971: 176. Holothuria (Metriatyla) lessoni Massin, Uthicke, Purcell, Rowe, Samyn, 2009: 41 47, figs. 1, 3, 4, 5, Table 1, 2. Material: UF5880, Gagil, < 1 m depth during the day in mangrove habitat near corals and seagrass, August 6, Remarks: This species is a new record for Yap. One specimen was found in shallow water at the boundary between mangrove forest and seagrass bed with small, scattered Porites sp. The color pattern was grey with several small, black blotches (Figure 5B). This species has been frequently misidentified as H. scabra (see below); however, the recent description of H. lessoni (Massin et al. 2009) clarified the diagnostic morphological characters, such as size, color and ossicles, to eliminate frequent confusion between the two species. When describing, the authors were not able to use the name H. timama because it has been suppressed by ICZN Opinion 762 (1966). We are unable to confidently identify the collected specimen because it showed mixed characters of H. lessoni and H. scabra. The collected specimen showed the diagnostic morphology of H. scabra including transverse grooves, lack of blotches and general color pattern; however, the specimen also showed the characteristic, spiny table ossicles of H. lessoni (Figures 4G, 5B). Holothuria (Metriatyla) scabra Jaeger,

16 Figures 4I, 4J Holothuria scabra Jaeger 1833: 23. Holothuria (Holothuria) scabra; Panning 1935: 80, fig. 66a-f. Holothuria (Metriatyla) scabra; Rowe 1969: , figs. 20a c; Clark A.M. and Rowe 1971: , fig. 871, pl. 15 fig. 15; Cherbonnier 1980: 647, fig. 16A-L; Liao 1980: 116; Tan Tiu 1981: 83, pl. 25, figs. 1-3; Féral and Cherbonnier 1986: 86 87; Cherbonnier 1988: , fig. 55a o.; Kerr 1994: 168, fig. 4c; Rowe and Gates 1995: 294. Material: UF5851, O Keefe s island, < 1 m depth during the day in seagrass at the edge of mangroves, August 5, Remarks: This species is a new record for Yap. Several specimens were observed during this survey at a depth of about one meter during the daytime. They all occurred on the inner reef flat, adjacent to mangroves, and in seagrass and on silty sand. Holothuria (Microthele) fuscogilva Cherbonnier, 1980 Figures 4K, 4L, 5C Holothuria (Microthele) fuscogilva Cherbonnier 1980: 628, fig. 7, pl. C; Féral and Cherbonnier 1986: 88 89; Kerr et al. 1992: 208, fig. 4d, pl. 1h; Uthicke et al Material: UF11163, 11414, Kaday, < 1 m depth, one specimen collected during the day and one collected at night, both were in seagrass beds on the middle reef flat, December 11, Remarks: This species is a new record for Yap. Holothuria fuscogilva is usually found at depths below 10 m; however, most of the specimens in Yap were observed at depths of less than 2 m in seagrass. Holothuria fuscogilva specimens in the western Pacific frequently display color patterns that are mixtures of black and white, hence the common name, white teatfish. Specimens seen in Yap showed a rather uniform beige background with dark brown mottling 16

17 (Figure 5C). This color form has also been observed in other localities, such as Moorea (G. Paulay, pers. comm.), Guam (Kerr et al. 1992), Australia and the southwest Pacific (Uthicke et al. 2004). Holothuria (Microthele) fuscopunctata Jaeger, 1833 Figure 4M Holothuria fuscopunctata Jaeger 1833: 23; Semper 1868: 86, 277, pl. 30 fig. 29; Théel 1886: 235; Lampert 1885: 79; Ludwig 1883: 136. Holothuria axiologa Clark H.L., 1921: 175, pl. 38; Grosenbaugh 1981: 51. Holothuria (Microthele) fuscopunctata; Cherbonnier 1980: 623, fig. 5; Rowe and Gates 1995: 361. Material: UF11390, Balabat, 3 m depth during the day on sand on middle reef flat, December 14, Remarks: This large and distinctive species was observed occasionally on sandy middle reef flats at depths between one and three meters. Holothuria (Microthele) whitmaei Bell, 1887 Figures 4N, 4O Holothuria (Bohadschia) whitmaei Bell 1887: , pl. 45, fig. 4. Holothuria mammifera Saville-Kent 1890: 4, pl. 1, fig. 3. Holothuria (Microthele) nobilis Selenka 1867: 313, pl. 17, fig. 16; Rowe 1969: 162, 164, fig. 21; Clark A.M. and Rowe 1971: , fig. 87m, pl. 27 fig. 10, pl. 28 fig. 20; Rowe and Doty 1977: 231, figs. 3f, 7d; Grosenbaugh 1981: 51-53; Cherbonnier 1988: , fig. 58a 1. Holothuria (Microthele) whitmaei; Rowe and Gates 1995: 362; Uthicke et al. 2004: fig. 1H-J. 17

18 Material: UF5866, Tamil, 1 m depth on rubble on middle reef flat, July 31, UF11389, Gilifith, 3 m depth during the day on rubble on middle reef flat, December 13, Remarks: This species was commonly found on the eastern outer reef flats and the western reef edges. This species tends to inhabit high-energy habitats with strong wave action. Adults of this species resemble H. fuscogilva in shape and size, but have a uniformly black dorsum. Holothuria (Platyperona) excellens (Ludwig, 1875) Figure 5D Mülleria excellens Ludwig 1875: 98, fig. 32a c; Lampert 1885: 97. Holothuria (Microthele) excellens; Panning 1929: 132, fig. 16. Holothuria (Platyperona) excellens; Théel 1886: 199; Cherbonnier 1988: 94 95, fig. 37a n; Kerr et al. 1992: , pls. 1e-f, figs. 3g-h, 4a-c, 5a-e. Material: UF5879, Tamil blue hole, 15 m depth at night, July 30, Remarks: This species is a new record for Yap. One specimen was seen at night in an area with high coral cover. This species is uniformly brown with purplish tinge, has a smooth bodywall, and ejects numerous fine Cuvierian tubules when handled (Figure 5D). Holothuria (Semperothuria) roseomaculata Kerr, 2013 Figures 5E, 6A, 6B Holothuria flavomaculata; Yamanouti 1939: ; Yamanouti 1956: 361; Amesbury et al. 1977: 14 16; Grosenbaugh 1981: 51 53; Colin and Arneson 1995: 260, fig Holothuria (Semperothuria) flavomaculata; Féral and Cherbonnier 1986: 90 91, fig. 40 D, unnumbered fig. (p. 90); Conand 1989: 27 et non seq., figs ; Purcell et al. 2013: 50-51, unnumbered figs. 18

19 Holothuria (Semperothuria) sp.; Kerr et al. 2007: 15, 31, fig. 3b. Holothuria (Semperothuria) non flavomaculata; Friedman et al. 2008: 8, 12; Tardy and Pakoa 2009: 10, Holothuria (Semperothuria) roseomaculata Kerr Material: UF5849, 5850, 5872, 5890, 5911, O Keefe s island, < 1 m depth in seagrass near patchy massive Porites sp., July 30, UF11397, 11403, Fanif, < 1 m depth during the day under a massive Porites sp. on inner reef flat, December 12, Remarks: This species was locally abundant near O Keefe s island and Fanif in seagrass. This species has been misidentified as H. flavomaculata, of which the color and form are consistently different from this species. Holothuria flavomaculata possesses yellow papillae, whereas H. (S.) roseomaculata has larger, rose-colored papillae (Figure 5E). We found this species on silty sand, under massive Porites spp. colonies near O Keefe s island, at Fanif and in the Colonia harbor. Based on the similarity in abundance and habitat, it appears to be the "Holothuria moebii" mentioned in Amesbury et al. (1976). <<Figure 6 near here>> Holothuria (Stauropora) pervicax Selenka, 1867 Figures 6C, 6D Holothuria pervicax Selenka 1867: 327, pl. 18 fig. 54; Clark A.M. 1952: 204. Holothuria depressa Ludwig 1875: 108, fig. 44. Holothuria (Mertensiothuria) pervicax; Rowe 1969: 149; Clark A.M. and Rowe 1971: ; Rowe and Doty 1977: 234, figs. 4g, 8c; Clark A.M. 1984: 99; Cherbonnier 1988: , fig. 43a k; Kerr 1994:

20 Holothuria (Stauropora) pervicax; Rowe and Gates 1995: 368; Rowe and Richmond 2004: Material: UF11425, Kaday, < 1 m depth at night on sand under a coral head on middle reef flat, December 11, Remarks: This species is a new record for Yap. Holothuria pervicax was an uncommon nocturnal species on Yap and only seen in Kaday. Specimens occurred under rocks and coral heads during the day and were seen exposed on sand and rubble at night. Holothuria (Theelothuria) sp. Figures 5F, 5G, 6E, 6F Material: UF5892, Tamil blue hole, 15 m depth at night in blue hole among dead coral rubble, July 31, UF5893, Gagil blue hole, 12 m depth at night in blue hole, August 6, UF5896, Fanif blue hole, 15 m depth at night in blue hole, August 3, Remarks: This species is a new record for Yap. A relatively common holothuroid at night in the blue holes on the western reefs (Figures 5F, G). Most specimens possessed a gray dorsum with many raised tubercles and a slightly lighter ventrum (Figure 5F). A less common color morph also seen had an olive green dorsum (Figure 5G), but was otherwise identical in form, habitat and behavior. Dorsal and ventral body-wall ossicles consist of tables and buttons. Tables have flattened, lace-like discs with spiny margins and a large central hole in which the four tiers form a distinctive cross. The buttons are variably developed and often knobby. When disturbed, specimens readily ejected many long translucent Cuvierian tubules, most resembling those of H. (Theelothuria) turriscelsa and H. (Stauropora) pervicax. Holothuria (Theelothuria) turriscelsa Cherbonnier, 1980 Figures 6G, 6H 20

21 Holothuria (Theelothuria) turriscelsa Cherbonnier, 1980: 644; pl. 1e, fig. 15a l; Féral and Cherbonnier 1986: 92-93; Kerr et al. 1992: 209. Material: UF5878, Tamil, 15 m depth at outer reef slope, August 2, UF11396, Kaday, < 1 m depth at night under a coral head on middle reef flat, December 11, Remarks: This species is a new record for Yap. This species was found under coral heads and rubble on middle reef flats in Kaday. At night, H. turriscelsa was often seen roaming on the reef flat. Specimens readily ejected thick, transparent Cuvierian tubules when disturbed. Holothuria (Thymiosycia) impatiens (Forsskål, 1775) Figures 5H, 6I, 6J, 7A Fistularia impatiens Forsskål, 1775: 121, pl. 39b. Holothuria impatiens; Haacke 1880: 46; Clark H.L. 1921: 178, pl. 19, figs. 3, 5; Panning 1935: 86, fig. 72; Panning 1941: 7, figs Holothuria impatiens concolor Clark H.L., 1921: 179. Holothuria impatiens lutea Clark H.L., 1921: 179. Holothuria impatiens pulchra Clark H.L., 1921: 179, pl. 19. Holothuria impatiens bicolor Clark H.L., 1938: 522. Holothuria (Thymiosycia) impatiens; Rowe 1969: , fig. 13a c; Clark A.M. and Rowe 1971: , fig. 85a a, pl. 26 fig. 2, pl. 28 fig. 8; Rowe and Doty 1977: 233, figs. 4c, 7e; Cherbonnier 1988: 88 89, fig. 35a k; Kerr 1994: 170; Rowe and Gates 1995: ; Rowe and Richmond 2004: Material: UF5877, Kaday, blue hole, August 4, UF11427, Kaday, < 1 m depth during the day on sand under a rock on middle reef flat, December 11,

22 Remarks: This species is a new record for Yap. This cryptic species was infrequently found under rocks at the western sites, Kaday and Gilfith. Like many other holothuroids, the taxonomic status of H. impatiens has been debated for years because of its color and morphological variation. Likely, it is a complex of several species (F. Michonneau, pers. comm.). We found at least three distinct color variants with morphology and ossicle variation currently assignable to H. impatiens (Figures 5H, 7A). One of the forms was nearly all white and inhabited the blue holes of the reef flat. It was nocturnally active and retracted into its shelter even at the slightest exposure to light, making it difficult to photograph in situ. Hence, we do not have a photo record of this variant. Holothuria (?Thymiosycia) sp. Figure 7B Material: Photo record (Figure 7B), site unrecorded, < 1 m depth in seagrass collected by E. Tardy, September 16, Remarks: This species is a new record for Yap. The uncollected, photographed specimen s mustard color, sparsely placed papillae and habitat resemble a form of H. (Thymiosycia) impatiens that has also been observed in Palau (A. M. Kerr, unpubl. obs.). <<Figure 7 near here>> Genus Pearsonothuria Levin, Kalinin and Stonik, 1984 Pearsonothuria graeffei (Semper, 1868) Figures 6K, 6L Holothuria graeffei Semper 1868: 78, pl. 30 fig. 9a-b. 22

23 Bohadschia drachi Cherbonnier 1955: 134, pl. 24a-n. Bohadschia graeffei; Panning 1929: 124, fig. 5; Panning 1944: 44, fig. 13; Clark A.M. and Rowe 1971: , pl. 27 fig. 7; Rowe and Doty 1977: 229, figs. 2g, 6e. Pearsonothuria graeffei; Levin et al. 1984: 33 38, figs. 1 2; Cherbonnier 1988: 49 50, fig. 17a f; Kerr 1994: 170; Rowe and Gates 1995: 376. Material: UF5895, Kaday, 15 m depth at outer reef slope, August 2, UF11393, Colonia Outer Reef, 10 m depth on coral on reef slope, December 15, Remarks: This species is a new record for Yap. In this survey, this species was only found at the Colonia outer reef slope around 10 m in depth, but it is a conspicuous and abundant species in other locations in the western Pacific (Massin 1999). Family Stichopodidae Genus Stichopus Brandt, 1835 Stichopus chloronotus Brandt, 1835 Figures 6M, 6N Stichopus (Perideris) chloronotos Brandt 1835: 50. Stichopus hirotai Mitsukuri 1912: 161, fig. 28. Stichopus chloronotus; Ludwig 1888: 812; Lampert 1885: 107; Théel 1886: 159, pl. 7, fig. 6; Sluiter 1887: 196; Clark H.L. 1946: 417; Clark A.M. and Rowe 1971: , pl. 27 fig. 18; Grosenbaugh 1981: 51-53; Cherbonnier 1988: , fig. 60a o; Kerr 1994: 170; Rowe and Gates 1995: : Rowe and Richmond 2004: Material: UF5867, Colonia, 1 m depth on sand and rubble, July 31, UF11407, Kaday, < 1 m depth during the day on rubble on middle reef flat, December 11,

24 Remarks: This species was common in almost all types of habitats from seagrass to inner and middle reef flats with high coral cover. It was also encountered on reef slopes at deeper depths, where individuals were often larger. Stichopus cf. monotuberculatus (Quoy and Gaimard, 1833) Figures 6O, 6P, 6Q Holothuria monotuberculata Quoy and Gaimard 1833: 131, pl. 432, fig. I. Stichopus monotuberculatus; Cherbonnier, 1952: 23, pl. 3, fig. 4, text fig. 8a-t; Rowe and Gates 1995: 325; Samyn 2000: 15. Stichopus cf. monotuberculatus; Samyn and Vanden Berghe 2000: 31, pl. 2F-H. Material: UF11415, Kaday, < 1 m depth during the day under rubble on middle reef flat, December 11, Remarks: This species is a new record for Yap. This nocturnal species displayed an array of color patterns, also seen in other locations in the Indo-Pacific (Byrne et al. 2010, Michonneau et al. 2013). The background varies from beige to camel with green and dark brown mottling. This species was commonly observed under rocks and coral heads during the day and exposed on sand or coralline rock at night. Recent genetic work by Byrne et al. (2010) revealed that S. horrens and S. monotuberculatus share similar sets of variable color patterns. The two species are distinguished by ossicle morphology; S. horrens possesses tack-like bodywall ossicles whereas S. monotuberculatus does not (Byrne et al. 2010). The collected specimen was devoid of tack-like ossicles (Figures 6O, P, Q); however, ubiquity of the shared color forms in Yap suggests that S. horrens may also inhabit Yapese reefs. Stichopus vastus Sluiter,

25 Stichopus vastus Sluiter 1887: , pl. 2, figs ; Sluiter 1895: 79; Clark H.L. 1946; Massin 1999: 71-77, figs. 57a-l, 58a-m, 59a-g, 60a-d, 61, 112d-e; Forbes et al. 1999: 14; Rowe and Gates 1995: Stichopus sp.; Allen and Steene 1996: 246: Gosliner et al. 1996: 282, fig Material: UF5367, 5869, 5913, O Keefe s island, < 1 m depth during the day in seagrass bed near patchy reef, July 30, Remarks: This species is a new record for Yap. This species was uncommon and seen during the day and night on silty sand near mangroves and in the inner harbor. Genus Thelenota H.L. Clark, 1921 Thelenota ananas (Jaeger, 1833) Trepang ananas Jaeger, 1833: 24, pl. 3 fig. 1; Clark H.L. 1922: 48. Holothuria ananas Quoy and Gaimard, 1833: 110, pl. 6, figs Holothuria (Thelenota) ananas Brandt, 1835: 253. Stichopus ananas; Ludwig 1882: 133; Sluiter 1901: 30, pl.2, fig. 1; Semper, 1868: 75; Mitsukuri, 1912: , pl. 1, figs. 6-8, textfig. 25. Thelenota ananas; Clark A.M. and Rowe, 1971: , fig. 87a; Rowe and Doty, 1977: 227, figs. 2b, 5e; Grosenbaugh 1981: 51-53; Cherbonnier, 1988: , fig. 63a k; Rowe and Gates 1995: 382. Material: UF5857, Balabat, 5 m depth during the day on pavement, August 2, Remarks: This survey suggests that T. ananas is uncommon in Yap, relative to other locations in the western Pacific. It was occasionally seen exposed during the day and night on the outer reef slope on coralline rock or sand to at least 20 m deep. 25

26 Thelenota rubralineata Massin and Lane, 1991 Figure 7C Thelenota rubralineata Massin and Lane, 1991: 57 64, figs. 1-8; Kerr et al. 2007: 21-22, fig. 4. Material: Photo record (Figure 7C), Ulithi Atoll, 25 m depth. Picture from Vanessa Fread, July 27, Remarks: This species is a new record for Yap. Several specimens of this unmistakable and striking species have been seen by Brian Greene (Univ. Hawaii, Manoa, pers. comm. 2007) around Yap and other islands in Yap State, on the deep outer reef slopes to at least 60 m depth. Order Apodida Family Chridotidae Genus Chiridota Eschscholtz, 1829 Chiridota sp. Figure 7D Material: Photo record (Figure 7D), site unrecorded, exposed near coral rubble on mid reef flat, November 28, Remarks: This species is a new record for Yap. This species usually takes shelter under rubble, often near sandy areas. Chiridota sp. often cleaves its body transversely when disturbed as shown in Figure 7D. This is likely either C. rigida Semper 1868 or C. hawaiiensis Fisher, 1907, two widespread and poorly characterized species in the Pacific Ocean (Clark and Rowe 1971). Family Synaptidae Genus Euapta Oestergren, 1898 Euapta godeffroyi (Semper, 1868) 26

27 Figures 8A, 8B, 8C Synapta godeffroyi Semper, 1868: 231, pl. 39 fig. 13. Euapta godeffroyi; Oestergren 1898: 113; Clark H.L. 1907: 72; Clark H.L. 1921: 158; Cherbonnier 1955: 172, pl. 48, figs. a-j; Clark A.M. and Rowe, 1971: , pl. 30 fig. 8; Rowe and Doty, 1977: , figs. 5c, 8h; Cherbonnier, 1988: , fig. 111a j; Kerr, 1994: 171; Rowe and Gates 1995: 338; Rowe and Richmond 2004: Material: UF11413, Gilifith, < 1 m depth at night on rubble on middle reef flat, December 14, Remarks: This species is a new record for Yap. The few other specimens of Euapta seen in this survey also all appear to be this species, rather than the closely related E. tahitiensis Cherbonnier, 1955, which also occurs in Micronesia (Michonneau et al. 2013). This species was active at night on rubble and sand. Specimens seen during the day were hidden under rocks and rubble. <<Figure 8 near here>> Genus Opheodesoma Fisher, 1907 Opheodesoma grisea (Semper, 1868) Figures 7F, 7G, 7H, 8D, 8E, 8F Synapta grisea Semper, 1868: 11, pl. 4. figs Opheodesoma grisea; Fisher, 1907: 723; Heding, 1928: 129, figs. 4.7, 7.3, 9; Cherbonnier 1955: 171, pl. 49, fig. k-t; Clark A.M. and Rowe, 1971: 186, pl. 30. fig. 11; Rowe and Doty 1977: 235, fig. 5a, 8g; Cherbonnier 1988: , fig. 109a-f; Rowe and Gates 1995: 340; Rowe and Richmond 2004:

28 Material: UF5862, 5876, Fanif, 10 m in blue hole, August 3, UF5885, 5886, O Keefe s island, 1 m depth in seagrass near massive Porites sp. colonies, July 30, UF5855, 5900, O Keefe s island, 1 m depth in seagrass near mangroves, August 5, UF11406, Kaday, < 1 m depth during the day in seagrass bed on inner reef flat, December 11, Remarks: This species is a new record for Yap. We found diverse color patterns among specimens referable to O. grisea (Figures 7F, G, H). This species was frequently observed in seagrass on inner reef flats, as well as at night in areas with high coral cover in the blue holes. Genus Polyplectana Clark, 1907 Polyplectana sp. (Selenka, 1867) Figures 8G, 8H Material: UF5874, Maap, 2 m depth during the day in seagrass bed on inner reef flat, July 29, Remarks: This species is a new record for Yap. A small species found in large numbers in seagrass, bordering a patch reef of Acropora spp. Absence of miliary granules and branched ossicles suggest that this species is P. kerfersteini. Genus Synapta Eschscholtz, 1829 Synapta maculata (Chamisso and Eysenhardt, 1821) Figure 7E Holothuria maculata Chamisso and Eysenhardt, 1821: 352, pl. 25; Clark H.L. 1907: 78, pls. 1, 4, figs , 26; Clark H.L. 1921: 160; Clark A.M. 1952: 204; Cherbonnier 1955: 170, pl. 47, figs. a-d; Clark A.M. and Rowe 1971: , pl. 30, fig. 9. Synapta maculata andreae; Heding 1928: 115, textfig. 3, fig

29 Synapta maculata sundaensis; Heding 1928: 116, textfig. 3, figs Synapta maculata; Heding 1928: 113, fig. 2; Rowe and Doty, 1977: , figs. 5a, 8e; Cherbonnier, 1988: , fig. 43a k; Kerr, 1994: 171; Rowe and Gates 1995: ; Rowe and Richmond 2004: Material: Photo record (Figure 7E), Wanyan, 1.5 m depth in grassflats mixed with corals, November 26, UF5894, Balabat, 15 m on sandy bottom of channel, August 2, UF11424, Kaday, < 1 m depth during the day in seagrass bed on inner reef flat, December 10, Remarks: This species is a new record for Yap. This large, diurnally active species was commonly found in seagrass. Specimens were also rarely found in silty sites, scattered with occasional coral colonies. Discussion Despite the rich fauna, only a handful of accounts report the holothuroids of Micronesia. The most recent and comprehensive account from Guam (Borrero-Perez et al. 2012) enumerated 64 species of sea cucumbers, including 18 new records. The 37 species recorded in this study is comparable to the diversity known from Guam before the recent update (46 species) and makes Yap the best documented Micronesian island after Guam. The known species composition of Yap is similar to that of Guam; the aspidochirotes dominate the reefs and adjacent habitats in Yap (86%) and Guam (81%), and the dendrochirotes are the most poorly reported group in Yap (0%) and Guam (5%). Of the 37 holothuroid species recorded in this study, 24 (19 aspidochirotes and 5 apodans) are new records. At least two species, Actinopyga sp. and Holothuria (Theelothuria) sp., appear to be undescribed. One of the species we collected, H. (Semperothuria) 29

30 roseomaculata, was also undescribed at the time during the surveys, yet was recently described (Kerr 2013). A few of the species were only reported as photo records because we lacked permission to collect during one visit. Two of these species, H. aff. (Lessonothuria) cavans and H. (?Thymiosycia) sp., may represent rare species; however, we cannot make confident identifications because we are lacking voucher specimens. The small-scale distribution patterns of holothuroids are closely related to microhabitat and reef zonation (Levin 1979, Sloan 1979, 1982, Kerr et al. 1993, Kerr 1994). The distribution of Yapese holothuroids also varied considerably between reef zonations (Table 1). Seagrass beds on the inner reef flats were inhabited by the largest diversity of apodans, Opheodesoma grisea, Polyplectana sp., and Synapta maculata, as well as small cryptic aspidochirotes, H. aff. (Lessonothuria) cavans and H. (?Thymiosycia) sp., and the commercially valuable aspidochirotes, Holothuria (Metriatyla)?lessoni and H. (Metriatyla) scabra. The diurnally burrowing Bohadschia species, B. marmorata, B. vitiensis and B. koellikeri were also frequently observed in seagrass beds and near mangroves during the late afternoon and at night. Diurnally cryptic species, H. coluber, H. hilla, H. impatiens, H. pervicax, H. turriscelsa, Chiridota sp., Euapta godeffroyi and Stichopus cf. monotuberculatus, were recorded on middle reef flats, where numerous coral colonies and rubble covered the bottom. Blue holes hosted an interesting set of less common species, such as H. (Cystipus) inhabilis, H. (Theelothuria) sp., and H. (Platyperona) excellens. The most common species encountered on the surveys, H. atra, was found at nearly all sites on inner and middle reef flats and its large biomass was unrivaled by other species. Another common species, B. argus, was widespread at the western sites, but was found less frequently at the more wave-exposed eastern sites. On the other hand, species that withstand higher wave energies, such as H. whitmaei and A. mauritiana, were mostly found on outer reef flats and edges at the eastern sites. In particular, A. mauritiana was absent at the 30

31 relatively calm western sites. Table 1 summarizes the distribution pattern of Yapese holothuroids. <<Table 1 near here>> The sites of O Keefe s island and Fanif were unique in having large seagrass beds and lacking middle and outer reef flats. The silty bottom of both sites was inhabited by Actinopyga sp. and Holothuria (Semperothuria) roseomaculata. O Keefe s island was also home to other cryptic species, such as H. coluber, B. vitiensis and B. koellikeri. When these sites were visited in the late afternoon, nocturnal species, B. vitiensis and B. koellikeri, started to emerge from the sand. Holothuroid taxonomy is being revised frequently with the publication of molecular analyses (Uthicke et al. 2004, Byrne et al. 2010, Uthicke et al. 2010, Honey-Escandón et al. 2012). Several taxa in this survey are also in need of review. For example, H. impatiens is certainly a species complex including several forms, all distinct in color or morphology (F. Michonneau, pers.comm.). In contrast, the color variation of Opheodesoma grisea has been suspected to indicate an unrecognized complex; however, color morphs appear mixed within a single clade in molecular analyses, suggesting extensive color polymorphism (G. Paulay, pers. comm.). Time constraints and limited microhabitat coverage often hamper comprehensive biodiversity documentation. For example, a recent study by Borrero-Perez et al. (2012) showed a consistent increase in species diversity even after nearly 200 years of surveys. Similarly, the short time spent collecting on Yap suggests that the 37 species listed here are undoubtedly an under-representation of the Yapese holothuroid fauna. For example, among specimens housed at 31

32 the USNM and collected during the Fourth Pacific Atoll Survey (unpubl.) from nearby Ifalik Atoll, Yap State, FSM, E. Deichmann and C. Ahearn have identified several often widespread species that likely also occur in the main islands of Yap: Afrocucumis africana (Semper 1868), Holothuria (Semperothuria) cinerascens (Brandt 1835) and H. (Platyperona) difficilis (Semper 1868). They also identified from Ifalik two species not previously reported in Micronesia, Polycheira rufescens, and an unidentified Synaptula sp. We were also unable to explore several habitat types on Yap, such as the wider sand flats and steep slopes to the south; these areas may host additional species. Acknowledgements We thank A. Tafiliechig, D. Mailing (Marine Resource Management Division, Yap State Government, FSM), the late C. Chieng (Yap Community Action Program, YAPCAP), C. Mugunbey and S. Savage for facilitating this trip and help in the field. We are also grateful for valuable comments by two anonymous reviewers. This study was funded by NSF PEET grant (DEB ) to G. Paulay and A. M. Kerr, NSF AToL grant (DEB ) to A. M. Kerr, and a Lerner-Gray grant from the American Museum of Natural History to S. Kim. Korea Institute of Ocean Science and Technology research fund (PE99161, 98962) and Ministry of Land, Transport and Maritime Affairs, Republic of Korea (PM57122) supported S. Kim when writing. The NASA Fundamental Biology Program funded travel in

33 Table 1. List of shallow-water holothuroids of Yap and their reef zone distributions. The last column records the combined past data from technical reports by Amesbury et al. (1967), Amesbury et al. (1977), Grosenbaugh (1978), and Grosenbaugh (1981). 33

34 Table 1, cont d 34

35 Table 1, cont d 35

36 Table 1, cont d 36

37 Figure 1. Map of Yap proper and sampling sites. Scale indicates 5 km. 37

38 Figure 2. Ossicle micrographs of collected specimens. A: Actinopyga mauritiana (UF11392): rosettes from dorsal bodywall, B: A. mauritiana (UF11392): rods from dorsal bodywall, C: A. sp. (YAP-SK-049): rosettes from dorsal bodywall, D: A. sp. (YAP-SK-049): rod from ventral bodywall, E: Bohadschia argus (UF11417): rosettes from dorsal bodywall, F: B. argus (UF11417): grain-rosettes from ventral bodywall, G: B. marmorata (UF11401): rosettes from dorsal bodywall, H: B. marmorata (UF11401): grain-rosettes from ventral bodywall, I: B. koellikeri (UF11420): rosettes from dorsal bodywall, J: B. koellikeri (UF11420): grain-rosettes from ventral bodywall, K: B. vitiensis (UF11394): rosettes from dorsal bodywall, L: B. vitiensis (UF11394): grain-rosettes from ventral bodywall, M: Holothuria (Acanthotrapezia) coluber (UF11419): tables from dorsal bodywall, N: H. (Cystipus) inhabilis (UF5861): tables from dorsal bodywall, O: H. (Cystipus) inhabilis (UF5861): irregular buttons from dorsal bodywall. Scale indicates 50 μm. 38

39 Figure 3. Conspicuous color patterns of selected new records including potential new species. A: Actinopyga?palauensis, B: Actinopyga sp., C: A. sp., D: Bohadschia koellikeri, E: B. vitiensis, F: Close-up of B. koellikeri body-wall, G: Close-up of B. vitiensis body-wall, H: Holothuria (Cystipus) inhabilis, I: H. aff. (Lessonothuria) cavans. 39

40 Figure 4. Ossicle micrographs of collected specimens. A: Holothuria (Halodeima) atra (UF11402): tables from dorsal bodywall, B: H. (Halodeima) atra (UF11402): rosettes from bodywall, C: H. (Halodeima) edulis (UF11404): tables from bodywall, D: H. (Halodeima) edulis (UF11404): rosettes from bodywall, E: H. (Mertensiothuria) hilla (UF11426): tables from dorsal bodywall, F: H. (Mertensiothuria) hilla (UF11426): buttons from bodywall, G: H. (Metriatyla)?lessoni (UF5880): spiny and irregular tables from bodywall, H: H. (Metriatyla)?lessoni (UF5880): buttons from bodywall, I: H. (Metriatyla) scabra (UF5851): tables from bodywall, J: H. (Metriatyla) scabra (UF5851): buttons from bodywall, K: H. (Microthele) fuscogilva (UF11414): tables from bodywall, L: H. (Microthele) fuscogilva (UF11414): irregular buttons from bodywall, M: H. (Microthele) fuscopunctata (UF11390): irregular buttons from bodywall, N: H. (Microthele) whitmaei (UF11389): tables from bodywall, O: H. (Microthele) whitmaei (UF11389): irregular buttons from bodywall. Scale indicates 50 μm. 40

41 Figure 5. Conspicuous color patterns of selected new records including potential new species. A: Holothuria (Mertensiothuria) leucospilota, B: H. (Metriatyla)?lessoni, C: H. (Microthele) fuscogilva, D: H. (Platyperona) excellens, E: H. (Semperothuria) roseomaculata, F: H. (Theelothuria) sp., G: H. (Theelothuria) sp., H: H. (Thymiosycia) impatiens. 41

42 Figure 6. Ossicle micrographs of collected specimens. A: Holothuria (Semperothuria) roseomaculata (UF11403): tables from bodywall, B: H. (Semperothuria) roseomaculata (UF11403): spiny rods from bodywall, C: H. (Stauropora) pervicax (UF11425): tables from bodywall, D: H. (Stauropora) pervicax (UF11425): buttons from bodywall, E: H. (Theelothuria) sp. (UF5896): tables from bodywall, F: H. (Theelothuria) sp. (UF5896): buttons from bodywall, G: H. (Theelothuria) turriscelsa (UF11396): tables from bodywall, H: H. (Theelothuria) turriscelsa (UF11396): buttons from bodywall, I: H. (Thymiosycia) impatiens (UF11427): smooth tables from bodywall, J: H. (Thymiosycia) impatiens (UF11427): buttons from bodywall, K: Pearsonothuria graeffei (UF11393): pin-shaped irregular tables, L: P. graeffei (UF11393): complex rosettes from bodywall, M: Stichopus chloronotus (UF11407): tables from bodywall, N: S. chloronotus (UF11407): C-shaped ossicles from bodywall, O: S. cf. monotuberculatus (UF11415): tables from dorsal bodywall, P: S. cf. monotuberculatus (UF11415): rosettes from ventral bodywall, Q: S. cf. monotuberculatus (UF11415): C-shaped ossicles from bodywall. Scale indicates 50 μm. 42

43 Figure 7. Conspicuous color patterns of selected new records including potential new species. A: Holothuria (Thymiosycia) impatiens, B: Holothuria (?Thymiosycia) sp., C: Thelenota rubralineata, D: Chiridota sp., E: Synapta maculata, F: Opheodesoma grisea, G: O. grisea, H: O. grisea. 43