Sea Stars of Families Ophidiasteridae and Goniasteridae (Echinodermata: Asteroidea) from the Mesophotic Zone of the Ogasawara Islands, Including Two New Species

Home , Aquilonastra, Culcita (echinoderm), Fromia, Fromia indica, Goniasteridae, Mithrodia

Species Diversity 26: 7–21 Published online 1 January 2021 DOI: 10.12782/specdiv.26.7

Mikihito Arai1,2,3 and Toshihiko Fujita1,2 1 Department of Biological Sciences, Graduate School of Science, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan E-mail: [email protected] 2 National Museum of Nature and Science, 4-1-1 Amakubo, Tsukuba, Ibaraki 305-0005, Japan 3 Corresponding author (Received 23 October 2018; Accepted 3 November 2020)

http://zoobank.org/368822BA-78A5-44BC-9C15-2DCB77047D7E

Five species of sea stars of the families Ophidiasteridae and Goniasteridae including two new species, Bathyferdina caelator sp. nov. and Fromia labeosa sp. nov., were collected by dredging from the mesophotic zone of the Ogasawara Islands, Japan. Bathyferdina caelator is distinguished from B. aireyae Mah, 2017 by the presence of glassy bosses (crystal bodies) on actinal and adambulacral plates and the absence of them on marginal plates. Fromia labeosa has large, elliptical pedicellariae on the actinal plate and is further distinguished from its congeners based on characters of the abactinal and superomarginal plates, granules, actinal papulae, furrow spines, and the subambulacral spines. We also provide descriptions for three mesophotic species, Fromia eusticha Fisher, 1913, Ogmaster capella (Müller and Troschel, 1842), and Tama- ria tenella (Fisher, 1906), which are poorly studied in Japanese waters. Key Words: Bonin Islands, Valvatida, starfish, marine invertebrates, new species, Japan.

(Baldwin et al. 2018). The mesophotic zone is known to Introduction harbor characteristic fauna differentiated from neighboring communities in shallower reef or deep water for fish, scler- The Ogasawara Islands are oceanic islands located ap- actinian corals, and other invertebrate taxa including echi- proximately 1000 km south of Japan’s mainland. The islands noderms (Laverick et al. 2017; Semmler et al. 2017; Baldwin are in the subtropics and inhabited by tropical/subtropical et al. 2018). Although there has been no study explicitly marine animals (Imajima 1970). The sea star fauna of the mentioning the significance of sea stars in the mesophotic Ogasawara Islands was first reported by Hayashi (1938), who zone, Mah (2003) suggested high possibility of finding new described six shallow-water species. Subsequent reports on sea star species from the depth range of 60–200 m, which the marine diversity further recorded shallow-water sea stars is difficult to explore because of the depth limit of conven- from this region (Imajima 1969; Shigei 1970; Amemiya and tional SCUBA diving and steep, rocky substrate to prevent Yanagisawa 1991). However, these reports provide no mor- dredging. Several new or rarely found taxa of sea stars phological description, pictures, or information on preserved have been reported thereafter from the subtropical/tropical specimens of each species. Pope and Rowe (1977) described mesophotic zone with various sampling methods such as a single individual of Thromidia catalai Pope and Rowe, 1977 mixed-gas diving, manned and unmanned submersibles, from Chichi-jima Island of the Ogasawara Islands. Saba or dredging (Mah 2003; Pawson 2007; Kogure and Fujita (2011) listed ten species occurring in the islands with pho- 2012). Here we describe five species of sea stars of the fami- tographs and short notes on their morphological characters. lies Ophidiasteridae and Goniasteridae, expanding knowl- Fujita et al. (2015) recorded fourteen species from the islands edge of the sea stars occurring in the mesophotic zone of the with images of live individuals and vouchered specimens. All Ogasawara Islands. studies of asteroids from this region were conducted primar- ily in shallow water (<45 m), with only a single deep sea re- cord (550 m) in this region by Kogure and Tachikawa (2009), Materials and Methods who described Astroceramus boninensis Kogure and Tachi kawa, 2009 from east of Haha-jima Island. The examined specimens were collected from the Ogasa In this study, we sampled sea stars from a previously un- wara Islands, Japan, using biological dredges lined with 5 mm studied depth ranging 50–160 m with biological dredges. mesh operated by three vessels: R/V Koyo of Tokyo Metropol- This depth range corresponds to the mesophotic zone, itan Ogasawara Fisheries Center, TR/V Shin’yo-maru of the which is often recognized as depth range from 30 to 150 m Tokyo University of Marine Science and Technology, and R/V

Table 1. Locality, coordinates, depth, date, and substrate of sampling stations. Prefix of the stations represents the vessel as follows. KY: R/V Koyo, SY: R/V Shin’yo-maru, KT: R/V Tansei-maru.

Station Locality Latitude Longitude Depth (m) Date Substrate KY-08-21 East of Chichi-jima 27°3.84′N 142°15.44′E 95–98 29 October 2008 Sand KY-08-25 West of Nishi-jima 27°7.31′N 142°7.70′E 127–129 30 October 2008 Sand, coral, shell KY-09-21 Northwest of Ototo-jima 27°13.09′N 142°9.19′E 135.5–135.8 15 July 2009 Mytilid shell KY-10-31 West of Hutami Port, Chichi-jima 27°5.18′N 142°8.48′E 96.5–96.8 9 July 2010 unknown KY-16-06 Northwest of Ototo-jima 27°13.104′N 142°9.091′E 135–137 11 July 2016 unknown KY-16-09 East of Chichi-jima 27°3.836′N 142°15.353′E 90.5–94.6 11 July 2016 Pebble, Sand KY-16-14 East of Ototo-jima 27°9.407′N 142°12.163′E 56.6–62.9 12 July 2016 Boulder KY-17-24 West of Minami-jima 27°1.182′N 142°7.269′E 147–149 20 July 2017 Pebble SY-09-21 West of Ototo-jima 27°12.80′N 142°5.13'E 159–161 18 November 2009 Sand KT-09-2-TW1-1 West of Chichi-jima 27°1.40′N 142°7.41′E 138.6–145.2 19 March 2009 unknown

Tansei-maru of the Japan Agency for Marine-Earth Science and Technology. Locality of the sampling stations is shown in Table 1. The collected specimens were on most occasions anesthetized by immersion in MgCl2 solution (34.2 g/L), photographed, and then preserved in 99% ethanol. Otherwise they were just preserved in 99% ethanol. Specimens were photographed using a digital camera with a macro lens or mounted on a stereoscopic microscope. Some of the images were generated by focus stacking per- formed by StackReg plug-in and Extended Depth of Field plug-in (http://bigwww.epfl.ch/) on ImageJ 1.48v (https:// imagej.nih.gov/ij/). Observation by scanning electron microscope (SEM) was also conducted on some specimens. Total DNA was extracted from tubefeet using DNeasy Blood & Tissue Kit (QIAGEN). We amplified partial sequences (655 bp) of mitochondrial cytochrome c oxidase subunit I (COI) by polymerase chain reaction (PCR) using Ex Taq (Takara Bio). PCR was carried out with the primers COIceF and COIceR (Hoareau and Boissin 2010) following the cycle condition they provide. Amplified DNA was purified by ExoSAP-IT (Affymetrix) and sequenced using BigDye Terminator v3.1 Cycle Sequencing Kit and 3500xL genetic analyzer (Applied Biosystems). We obtained partial Fig. 1. Sampling stations. See Table 1 for the detailed informa- COI sequences from each species to facilitate future iden- tion on each station. tification. The sequence data were deposited in DNA Data Bank of Japan (DDBJ). with five short arms. Abactinal plates homogenous in size. The specimens examined in this study are deposited in Marginal plates significantly larger than abactinal plates, the Department of Zoology, National Museum of Nature and gradually decrease in size toward the arm tip. Abactinal, and Science, Tsukuba, Japan (NSMT). marginal, actinal and adambulacral plates covered with skin We generally followed the morphological terminology containing granules. Skin absent on circular or quadrate bare in A. M. Clark and Downey (1992). R and r represent the areas on marginal plates. Either or both abactinal, marginal, length from the center of disc to the arm tip and the inter- actinal and adambulacral plates have glassy bosses (crystal radial edge, respectively. bodies) on their surface. Furrow spines arranged in a single longitudinal series. Actinal surface of adambulacral plates covered with skin and granules, but devoid of spinelets, en- Taxonomic Accounts larged granules or other accessories. Remarks. This diagnosis is emended from Mah (2017) to Family Goniasteridae Forbes, 1841 include presence of glassy bosses on actinal and adambula- Subfamily Ferdininae Mah, 2017 cral plates. For details see remarks under B. caelator sp. nov. Genus Bathyferdina Mah, 2017 Type species. Bathyferdina aireyae Mah, 2017 [New Japanese name: Koyo-akamon-hitode-zoku] Species included. Bathyferdina aireyae; B. caelator sp. nov. Diagnosis (emended). Body flat on both sides, disc broad Sea Stars from Ogasawara Islands 9

Fig. 2. Abactinal view of the live specimens (A–D) and ethanol-preserved specimen (E). A, Bathyferdina caelator sp. nov., NSMT E-8265, holotype; B, Fromia eusticha, NSMT E-10595; C, Fromia labeosa sp. nov., NSMT E-9297, holotype; D, Ogmaster capella, NSMT E-9312; E, Tamaria tenella, NSMT E-9277. Scale bars: 10 mm. 10 M. Arai and T. Fujita

Fig. 3. Bathyferdina caelator sp. nov., NSMT E-8265, holotype. A, actinal side; B, abactinal side, abactinal plates partly denuded. Arrows indicate pedicellariae on superomarginal plates; C, arm tip, lateral view. Arrow indicates terminal plate; D, SEM picture of a denuded abactinal plate at proximal portion of the arm; E, pedicellaria on actinal interradial plates; F, actinal, adambulacral and oral plates, partly denuded. Arrow indicates glassy boss on adambulacral plate. Scale bars: 10 mm (A), 1 mm (B, F), 5 mm (C), 0.5 mm (D, E). Abbreviations: ab, abactinal plates; sm, superomarginal plates; im, inferomarginal plates; ac, actinal plates; ad, adambulacral plates; op, oral plates.

Bathyferdina caelator sp. nov. radius to the tip of arms. Glassy boss/ridge present on abac- [New Japanese name: Koyo-akamon-hitode] tinal and actinal plates. One or two glassy bosses on the cen- (Figs 2A, 3) ter of each adambulacral plate. Three furrow spines on each adambulacral plate. Bathyferdina sp.: Arai et al. 2018: 194–196. Description of holotype. R=23.2 mm, r=9.9 mm, R/r= 2.3, width of arm is 11.1 mm at base, 6.6 mm at half of R, Material examined. Holotype: NSMT E-8265, KY-09-21, and 3.1 mm at 1/10 R from the tip. Body is flat on both Northwest of Ototo-jima Island, 135.5–135.8 m. Paratypes: abactinal and actinal sides. Arms are five and tapering more NSMT E-8266, 1 individual, KT-09-2-TW1-1, West of greatly near the disc than near the arm tip (Fig. 3A). Chichi-jima Island, 138.6–145.2 m; NSMT E-8267, 1 indi- Abactinal plates are polygonal to elliptical in shape, not vidual, dry, locality unknown. lobed, variable in size, and tessellated so that only small Diagnosis. A species of Bathyferdina with glassy bosses spaces are left for papulae around the corners of these plates on abactinal, actinal and adambulacral plates. Disc broad (Fig. 3B). Those on the disc are about 1.5–2.0 times larger with R/r 2.0–2.3. Abactinal plates are homogeneous in size than those on the arms. The arrangement of abactinal plates and shape. Superomarginal plates rectangular to barrel-like is regular, and median rows of plates are conspicuous. Be- in outline, and regularly decreasing in size from the inter- tween two upper interradial corners of first superomarginal Sea Stars from Ogasawara Islands 11 plates on a ray, there are seven to nine abactinal plates. The scription of B. aireyae. Bathyferdina caelator sp. nov. is de- entire abactinal surface of abactinal plates is rough with void of any subambulacral spines or enlarged granules while glassy bosses which are circular around the center of the it shows small R/r, a uniform granular skin covering abacti- plate and elongated around the periphery (Fig. 3D). Madre- nal and actinal surface, marginal plates continuous in size, porite is single, 1 mm in diameter, flat and pentagonal with large quadrate bare area on marginal plates, homogenous rounded corners; gyri extend radially from the central area abactinal plates completely covered with skin, and glassy where nine discontinuous, short gyri lie in parallel to one bosses on abactinal plates. These characters support place- another. Terminal plates are conical with a broad base and a ment of the present species in Bathyferdina. Mah (2017) narrow rounded apex, smaller than the distalmost marginal mentioned that Bathyferdina has no glassy bosses on mar- plates, smooth and bare without skin or granules (Fig. 3C). ginal plates in his key of Ferdininae but he also stated that Superomarginal and inferomarginal plates correspond in it has glassy bosses on both abactinal and marginal plates. number and size. There are six (seven on one arm) plates to According to Mah (personal communication), B. aireyae in each side of an arm. Superomarginal plates are rectangular fact has glassy bosses on the abactinal and marginal surfaces in outline, longer than width, rounded at corners, and con- but not on the actinal surface. We have emended the diag- spicuous on the abactinal side; first superomarginal plates nosis of Bathyferdina accordingly. are about 3 mm in length and 2 mm in width on the abacti- Bathyferdina caelator is distinguished from the single nal surface. They gradually decrease in size toward the arm congeneric species, B. aireyae, in having glassy bosses on tip where the distalmost superomarginal plates are more not only abactinal but actinal and adambulacral plates while squarish, measuring about 1–1.5 mm in both length and lacking them on marginal plates. Bathyferdina caelator lacks width. No glassy boss was observed on any marginal plates. granules or tubercles on the inferomarginal plates, while Actinal plates are quadrangular, regularly arranged, and they are occasionally present in B. aireyae. Mah (2017) de- normally flat except several small plates slightly convex be- scribed B. aireyae as lacking any pedicellariae but one of the tween larger actinal plates (Fig. 3F) and inferomarginal paratypes reexamined in this study (CASIZ 219696) pos- plates are slightly convex. The surface of actinal plates is sesses a large number of pedicellariae on marginal and ac- rough with glassy bosses when denuded of granular skin. tinal plates. Although these pedicellariae varied in number Adambulacral armature is composed of three (distally of valves from one to five, the shape of the valves closely re- two) furrow spines on each adambulacral plate (Fig. 3F). sembled those in B. caelator. Furrow spines are truncated at the tip, prismatic, and quad- Distribution. Ogasawara Islands, 135.5–145.2 m (this rangular or triangular in a cross section. The adambulacral study). plates are rectangular with slightly rounded corners. On the Etymology. The specific epithet, caelator, is a Latin mas- proximal first to tenth adambulacral plates, there are one or culine noun in apposition meaning sculptor, and alluding to two glassy bosses at the center of the plates. the complex patterns of glassy bosses on abactinal, actinal Abactinal, actinal and adambulacral plates are covered and adambulacral plates. with a thin skin concealed by fine granules. On the mar- Japanese name. Koyo is taken from R/V Koyo, the ves- ginal plates, the skin and granules are limited at the periph- sel which collected the holotype, and akamon-hitode comes ery, leaving the rest of the plate surface exposed (Fig. 3B). from the Japanese name of Neoferdina cumingi (Gray, 1840), Papulae are isolated, confined around the abactinal plates another species of Ferdininae which occurs commonly in except in the abactinal interradial areas where they are ab- Japanese waters. sent. There are no papulae on the actinal surface. Most papulae occur in spaces where corners of three abactinal plates Fromia eusticha Fisher, 1913 meet. There are pedicellariae on some of the first or second [Japanese name: Nameraka-juzuberi-hitode] superomarginal plate and actinal interradial plates (Fig. 3B). (Figs 2B, 4) Each pedicellaria with a single fan-shaped valve rather than two or more valves normally observed in Ferdininae. Some Fromia eusticha Fisher, 1913: 213–214; Fisher 1919: 375– alveoli lacking a fan-shaped valve are present on some mar- 377; Domantay and Roxas 1938: 220; A. H. Clark 1952: ginal plates. 286; Jangoux 1978: 294–295; A. M. Clark 1993: 331; Arai Color in life is brownish on the abactinal surface and et al. 2018: 194, 196. white on the actinal. Bare areas on marginal plates are darker brown (Fig. 2A). Material examined. NSMT E-9298, 1 individual, KY-10- Notes on paratypes. The body dimensions in the para- 31, West of Hutami Port, Chichi-jima Island, 96.5–96.8 m. types are: R=10.0 mm, r=5.0 mm, and R/r=2.0 (NSMT NSMT E-10595, 1 individual, KY-17-24, West of Minami- E-8266); R=20.4 mm, r=9.7 mm, and R/r=2.1 (NSMT jima Island, 147–149 m. E-8267). The other characters are consistent with the de- Description. R=34.1 mm, r=7.8 mm, R/r=4.4, width scription of the holotype. of arm is 8.8 mm at base, 5.5 mm at half of R, and 3.0 mm DNA sequence. A partial sequence of COI (655 bp) was at 1/10 R from the tip in NSMT E-9298. R=26.1 mm, obtained from NSMT E-8265 and deposited in DDBJ (Acc. r=5.8 mm, R/r=4.5, width of arm is 7.1 mm at base, No. LC427072). 4.6 mm at half of R, and 2.6 mm at 1/10 R from the tip in Remarks. Mah (2017) established Bathyferdina with a de- NSMT E-10595. Abactinal surface is flat and actinal surface 12 M. Arai and T. Fujita

Fig. 4. Fromia eusticha, NSMT E-9298. A, abactinal side; B, actinal side; C, proximal portion of a partly denuded arm, abactinal view; D, arm tip, lateral view. Arrow indicates terminal plate; E, madreporite, F, proximal portion of a partly denuded arm, actinal view; G, pedicellariae on actinal plates (arrow); H, adambulacral spines. Scale bars: 10 mm (A, B); 5 mm (C, D, F), 1 mm (E), 500 µm (G, H). Abbreviations: sm, superomarginal plates; im, inferomarginal plates; fs, furrow spines; ss, subambulacral spines. is arched. Arms are five, slender, and tapering to blunt tips by four enlarged ossicles in NSMT E-10595; none are pres- (Fig. 4A, B). ent in NSMT E-9298. Terminal plates are conical and trun- Abactinal plates are polygonal with rounded corners and cated at the tip. The surfaces of the plates lack granules, and weakly developed lobes. The plates are arranged in five reg- are smooth, except the basal portions where glassy bosses ular, staggered longitudinal rows at the base of arms (Fig. occur (Fig. 4D). 4C). The median row extends toward the tip of arms. The Superomarginal plates are block-like, rounded, and larg- two adjacent rows terminate at 2/3R from the center of the er in diameter than neighboring abactinal plates. There are disc, and the outermost two rows at 1/4R. The entire sur- fifteen superomarginal plates on each side of the arm with face of abactinal plates is rough with numerous hemispheri- R=32.7 mm in NSMT E-9298. They are not alternating in cal glassy bosses (crystal bodies). Madreporite is circular, size but diminishing toward the tip of arms. Inferomarginal not conspicuously elevated from the abactinal surface, and plates also decrease in size toward the tip of arms, but they about 1.2 mm in diameter (Fig. 4E). Gyri partly radiate are smaller than the adjoining superomarginal plate. from, but absent at, the center. Anal aperture is surrounded Actinal plates are polygonal, mostly quadrangular, lack- Sea Stars from Ogasawara Islands 13 ing lobes, and leaving no space in between. They are ar- of 0.24 mm. ranged in three longitudinal series at one side of the arm Color in life is orange to vermilion on the disc, arm tip, base in NSMT E-9298 (Fig. 4F). The row adjacent to adam- and margins of skeletal plates, and pale yellow on other part bulacral plates extends 2/3R from the center of the disc, the of arms on the abactinal side in NSMT E-10595 (Fig. 2B). outer row 1/2R, and the outermost one 1/6R. There are only The actinal side is white, except margins of skeletal plates two rows in NSMT E-10595. Most actinal plates lack glassy which are orange to vermilion, just as on the abactinal side. bosses except some interradial plates. No color remained in both specimens after preservation in Each adambulacral plate bears three furrow spines and ethanol. two subambulacral spines followed by smaller granules on DNA sequence. A partial sequence of COI (655 bp) was the abradial side (Fig. 4H). The number of furrow spines obtained from NSMT E-9298 and deposited in DDBJ (Acc. is two or four on a relatively small number of plates, and No. LC427073). more plates are likely to bear only two furrow spines near Remarks. The present specimens differ from the descrip- the tip of arms (ca. 1/5R from the tip). Most furrow spines tion of the holotype of F. eusticha by Fisher (1919) in the ab- are truncated at and widening toward the tip, flattened, sence of intermarginal papulae, only a few actinal papulae, and constricted at the base. The proximal furrow spines on and less abundant pedicellariae. some plates are slightly tapering toward the tip. Subambula- Distribution. Sulu Archipelago, 44 m (Fisher 1913). cral spines are tapering toward the blunt tip, conical or py- Puerto Galera, Mindoro Island, Philippines, depth unknown ramidal, and flattened but thicker than furrow spines. The (Domantay and Roxas 1938). Bikini Atoll, 55 m (A. H. Clark granules abradial to the subambulacral spines are identical 1952). Obi Islands, Indonesia, on the beach and reef (Jan- in size and shape to those on actinal plates, thus these gran- goux 1978). Ogasawara Islands, Japan, 96.5–149 m (this ules and the subambulacral spines are discontinuous in size. study). Pedicellariae occur among the ossicles on a small number of Japanese name. Nameraka means smooth, referring to plates. Tubefeet are biserial and with a sucking disc. its fine granules and graduating superomarginal plates. Each oral plate bears five oral spines and four to five sub- Juzuberi-hitode is a Japanese name for the genus Fromia. oral spines in NSMT E-9298; there are five to six oral and three to four suboral spines in NSMT E-10595. The remain- Fromia labeosa sp. nov. ing abradial portion of the plate is covered with granules. [New Japanese name: Ogasawara-juzuberi-hitode] Oral spines are conical, tapering toward the pointed tip, (Figs 2C, 5) slightly curved, and longer than furrow spines. Those near the center of the mouth are more slender and longer than the Fromia sp.: Arai et al. 2018: 194, 196. distal ones. Suboral spines are similar to oral spines in size and shape near the mouth. However, they are shorter in the Material examined. Holotype: NSMT E-9297, KY-16-14, abradial portion of plates, and a few of them are intermedi- East of Ototo-jima Island, 56.6–62.9 m. Paratypes: NSMT ate in size between oral spines and granules. The granules are E-9293, KY-08-25, West of Nishi-jima Island, 127–129 m; slightly larger and coarser than those on actinal plates. NSMT E-9294 and E-9295, KY-16-06, Northwest of Ototo- The abactinal, marginal, and actinal plates are covered jima Island, 135–137 m; NSMT E-9296, KY-16-09, East of with a skin on which granules occur. There are 125 gran- Chichi-jima Island, 90.5–94.6 m; 1 individual each. ules per square millimeter on abactinal plates at the base of Diagnosis. A species of the genus Fromia with a small arms, and 79 granules on actinal interradial plates in NSMT disc and slender, slightly arched arms. At R=31.3 mm, E-9298. In NSMT E-10595, there are 124 and 75 per square abactinal plates arranged in five longitudinal rows at base millimeter, respectively. The granules on abactinal and su- of arms. Superomarginal plates only slightly convex, not al- peromarginal plates are fine and even in size. On the other ternating but regularly decreasing in size toward the tip of hand, those on actinal plates are larger at the center than the arms. Coarse granules enlarged at center of plates. Papulae periphery of plates. A few at the center of the distal nine to single and confined on the abactinal surface. Adambula- ten inferomarginal plates are enlarged and tubercular (Fig. cral plates bear three (rarely two or four) furrow spines and 4D). Papulae are isolated and confined to the corners of five to nine thicker subambulacral granules graduating in abactinal plates except only a few occurring between actinal size toward those on neighboring actinal/marginal plates. plates. They are absent in abactinal interradial areas. Oral plates bear five oral spines on the margin and four to Pedicellariae occur on some actinal plates and adambula- six suboral spines on the rest of the plate. Large, elliptical cral plates at the disc and basal part of arms (Fig. 4G). They pedicellariae on many actinal plates with their major axis are the most abundant on the proximal most actinal interra- oblique to the ambulacra. dial plates. The valves of pedicellariae are similar to the sur- Description of holotype. R=31.3 mm, r=8.6 mm, R/r= rounding granules, but two to three times larger. They are 3.6, width of arm is 9.0 mm at base, 5.4 mm at half of R, gathered in pairs or triplets except one pedicellaria with four and 2.9 mm at 1/10 R from the tip. Body is slightly arched valves, and meeting with each other at the smooth surface. at both sides, and the abactinal interradial areas are sunken. There is no alveolus under these pedicellariae, so they leave Arms taper to blunt tips. no trace on the underlying plates when detached. The longer Abactinal plates are polygonal, weakly lobate, arranged in axis or diameter measured 0.19–0.27 mm with the average staggered longitudinal series where there are five rows at the 14 M. Arai and T. Fujita

Fig. 5. Fromia labeosa sp. nov., NSMT E-9297, holotype. A, actinal surface of the disc; B, abactinal surface of interradial area showing a madreporite (arrow); C, abactinal surface of a denuded arm; D, pedicellaria on the actinal plate; E, proximal portion of a partly denuded arm, actinal side. Arrows indicate pedicellariae; F, adambulacral armature on proximal adambulacral plates. Scale bars: 5 mm (A, C), 1 mm (B, E), 500 µm (D, F). Abbreviations: fs, furrow spines; ss, subambulacral spines. base of arms (Fig. 5C). Hemispherical glassy bosses (crystal on one side of the ray when skin and granules are removed. bodies) occur on the abactinal plates. Madreporite is single, The second to fourth superomarginal plates average 1.7 mm circular, and about 0.9 mm in diameter, located at about one in length. half r from the anal aperture. Gyri do not regularly radiate Actinal plates are polygonal, without lobes, and leave no from the center of the madreporite. The anal aperture is sin- space in between. No glassy bosses occur on actinal plates. gle and surrounded by six slightly larger ossicles. Terminal These are arranged in three longitudinal series at the base of plates are conical, truncated at the tip. Several tubercles en- a denuded arm with a few odd plates on the interradial area. circle the top of terminal plates. Adambulacral plates bear three (exceptionally two or Superomarginal and inferomarginal plates are block-like, four), slender, flattened, cylindrical and bluntly pointed fur- rectangular, only slightly convex and not alternating but row spines and five to nine thicker, more sharply pointed regularly decreasing in size toward the tip of arms. There are subambulacral granules (Fig. 5F). The latter are not in regu- sixteen superomarginal and seventeen inferomarginal plates lar rows parallel to the ambulacrum, and are grading in size Sea Stars from Ogasawara Islands 15

Table 2. Variation in numerical characters of Fromia labeosa sp. nov.

Catalogue Number NSMT E-9297 NSMT E-9293 NSMT E-9294 NSMT E-9295 NSMT E-9296 Holotype Paratype Paratype Paratype Paratype R (mm) 31.3 11.7 3.9 25.5 11.6 R/r 3.6 3.5 1.9 4.4 2.5 Furrow spines per plate 3 (rarely 2–4) 3–4 3–4 3 (rarely 2–4) 2–3 Subambulacral spines per plate 5–9 7–9 7–8 5–8 5–7 Granules/mm2 on abactinal plates 20 40 87 26 36 Granules/mm2 on actinal plates 20 46 101 42 34 Longitudinal rows of abactinal plates 5 3 3 3 3 to the granules on neighboring actinal or marginal plates. L. Clark, 1921 and F. indica (Perrier, 1869); abactinal gran- Tubefeet are biserial with a stout terminal disc. ules are granular in F. labeosa while they are spinuous in F. Each oral plate bears five oral spines on the adoral margin armata Koehler, 1910; they are also coarse (20/mm2) in F. and four to six suboral spines on the rest of the plate. Oral labeosa while they are fine (80–90/mm2) in F. hadracantha spines are conical or pyramidal, larger than furrow spines. H. L. Clark, 1921; papulae are lacking on the actinal surface Suboral spines are similar to oral spines in the adradial por- in F. labeosa while there are two rows of actinal papulae in F. tion but abradially grading into actinal granules. balansae Perrier, 1875 and F. ghardaqana Mortensen, 1938. The abactinal, marginal, and actinal plates are concealed Five to nine subambulacral tubercles continuous in size and with a skin which is covered coarsely with granules (Fig. not arranged in definite rows in F. labeosa while subambula- 5B). These granules are domed at the top, polygonal in cral spines are conspicuously larger than outer granules on shape, and slightly enlarged at the center of plates, but never the adambulacral plate, and arranged in a straight row in F. spinous. The diameter is ca. 260–340 µm at center and ca. eusticha. In addition to these differences, large elliptical ped- 140–200 µm on periphery. There are 20 granules per square icellariae on actinal plates are specific to F. labeosa. millimeter on abactinal plates at the base of arms and acti- Distribution. Ogasawara Islands, 56.6–137 m (this nal interradial plates. The papular pores are isolated and study). confined around abactinal plates except on the interradial Etymology. The species epithet, labeosa, is a Latin femi- areas and tips of arms, where the pores are absent. nine adjective meaning having large lips and referring to the Many actinal plates possess a large elliptical pedicellaria large pedicellariae on the actinal surface. (Fig. 5D). It is typically 1 mm in length and 400 µm in width. Japanese name. Ogasawara is taken from the type lo- The pedicellariae are loosely arranged in a parallel series cality and juzuberi-hitode is a Japanese name for the genus to an ambulacrum on arms, and their major axis is often Fromia. oblique to the ambulacrum (Fig. 5A, E). Color in life is vermilion with white granules and termi- Ogmaster capella (Müller and Troschel, 1842) nal plates (Fig. 2C). [Japanese name: Hadaka-akasuji-hitode] Notes on paratypes. The difference in the numeric char- (Figs 2D, 6) acters among type specimens is shown in Table 2. R/r generally increases and the number of granules per square milli- Goniodiscus capella Müller and Troschel, 1842: 61. meter decreases as R increases. Other characters in the para- Goniaster (Ogmaster) capella Martens, 1865: 359–360. types are consistent with the description of holotype. Ogmaster capella: Sladen 1889: 261; Koehler 1910: 79; Fish- DNA sequence. A partial sequence of COI (655 bp) was er 1919: 262, 305; Döderlein 1935: 101–102; Guille and obtained from NSMT E-9295 and deposited in DDBJ (Acc. Jangoux 1978: 53; A. M. Clark 1993: 267; Liao and A. M. No. LC427074). Clark 1995: 94; A. M. Clark and Mah 2001: 337; Arai et al. Remarks. The present species is distinguished from its 2018: 194, 196. congeners by the following characters: superomarginal Dorigona reevesii Gray, 1866: 7. plates regularly decreasing in size toward the arm tip in F. Goniaster muelleri: Lütken 1871: 248–250. labeosa sp. nov. while they are alternating large and small, or small superomarginal plates are occasionally intercalated Material examined. NSMT E-9312, 1 individual, dry, between larger ones, in F. pacifica H. L. Clark, 1921, F. hef- KY-08-21, East of Chichi-jima Island, 95–98 m. fernani (Livingstone, 1931), F. monilis (Perrier, 1869), and Description. R=16.5 mm, r=6.9 mm, R/r=2.4, width of F. nodosa A. M. Clark, 1967; there are five abactinal plates arm is 8.5 mm at base, 4.8 mm at half of R, and 1.9 mm at between first superomarginal plates on each side of arms 1/10 R from the tip. Abactinal and actinal surface are flat. in F. labeosa while there are more than seven such plates in Arms are five, tapering toward a pointed tip (Fig. 6A). F. hemiopla Fisher, 1913, F. milleporella (Lamarck, 1816), Abactinal plates are polygonal, mostly pentagonal to hex- F. polypora H. L. Clark, 1916, and F. schultzei (Döderlein, agonal, and arranged in a regular tessellate manner leaving 1910); abactinal plates are uniform in size in F. labeosa while only small spaces around the corners. The plates on the in- several elliptical plates are larger than others in F. elegans H. terradial area are larger than those on the median of arms, 16 M. Arai and T. Fujita

Fig. 6. Ogmaster capella, NSMT E-9312. A, actinal side; B, abactinal surface of interradial area; C, arm tip, abactinal view; D, actinal, adambulacral and oral plates. Scale bars: 10 mm (A), 1 mm (B–D). and those neighboring the superomarginal plates are small- tagonal, and arranged in a regular tessellate manner leav- er (Fig. 6B). The plates are covered with a very thin skin ing no space in between. The surface of the plates is smooth without any granules, thus giving a naked appearance. The with a skin lacking granules. A few low, faint glassy bosses surface of the plates is rough with numerous glassy bosses. occur on some of the plates. Papulae are confined to the proximal portion of the abacti- Adambulacral plates bear four to five furrow spines and nal radial area. They are isolated, and occur at the corners of two to five subambulacral tubercles (Fig. 6D). Furrow spines abactinal plates. Madreporite is circular, domed, and about are cylindrical or conical with a blunt tip, and arranged on 1.0 mm in diameter; gyri radiate from the center. Anal ap- the curved adradial margin of adambulacral plates. The erture lies at the center of the disc, and is surrounded by five most distal spine on each plate is about two times wider at granular ossicles. the base than the others, and tapering more rapidly toward Terminal plates are bell-shaped (Fig. 6C). They have a the tip with the same width as the others. The subambula- smooth surface and lack any appendages except two plates cral spines are hemispherical, irregular in size, and mostly bearing a single cylindrical, blunt spine at either side of the arranged in a straight line at the abradial side of the plate. tip, suggesting that each terminal plate should bear a pair of On the distal plates corresponding to the final two to three such spines. inferomarginal plates, the number of furrow spines decreas- Marginal plates are block-like, and regularly decreasing es to 1–3 including the larger distal spine, and the subambu- in size from the interradius toward the arm tip. There are lacral ossicles disappear. Tubefeet are biserial and with a ter- nine superomarginal plates on each side of arms. The dis- minal disc. No pedicellariae occur on adambulacral plates talmost four plates are in contact with their counterparts on or other plates. the other side of the arm, though there are small rhomboi- Oral plates have a semicircular and domed abactinal sur- dal abactinal plates inserted at the median of arms between face. Each oral plate bears six oral spines at the margin and sixth and seventh superomarginal plates (also between sev- six to eight suboral tubercles on the abactinal surface. Oral enth and eighth on two arms). The inferomarginal plates spines are conical, slightly depressed with flanking spines. correspond to the superomarginal plates in shape, size and The most adradial one is the largest and about two times number. larger than the most abradial one which is almost identical Actinal plates are polygonal, mostly quadrangular or pen- with the neighboring furrow spines. Sea Stars from Ogasawara Islands 17

Color in life is dull pink with red lines between plates on 190). NSMT E-9277, 1 individual, SY-09-21, West of Ototo- the abactinal surface and white on the actinal surface (Fig. jima Island, 159–161 m. 2D). Description. R=30.0 mm, r=6.2 mm, R/r=4.8, width DNA sequence. A partial sequence of COI (655 bp) was of arm is 7.3 mm at base, 4.6 mm at half of R, and 3.0 mm obtained from NSMT E-9312 and deposited in DDBJ (Acc. at 1/10 R from the tip in NSMT E-8285. R=26.0 mm, No. LC427075). r=5.4 mm, R/r=4.8, width of arm is 6.7 mm at base, 3.6 mm Remarks. The specimen from the Ogasawara Islands at half of R, and 2.1 mm at 1/10 R from the tip in NSMT is small but generally agrees with all the past descriptions. E-9277. Body is arched on the abactinal side and flat on the Pedicellariae are lacking on adambulacral plates in the pres- actinal side. Arms are five and tapering toward the tip even- ent specimen unlike larger specimens with R around 30 mm ly from the base (Fig. 7A). (Döderlein 1935; Guille and Jangoux 1978). Additionally, Abactinal plates are four-lobed and arranged in three reg- the present specimen differs from the original description ular longitudinal rows which reach the tip of arms. The rows since none of its plates covered with granules. According are partly disrupted at base of an arm of NSMT E-8285, to Döderlein (1935), who examined the type specimen, the and the shortest arm of NSMT E-9277. Five to six carinal original description by Müller and Troschel (1842) misinter- plates in the middle of arms and a few distal actinolateral preted the crystal bodies (glassy bosses) as granules. In the plates are devoid of skin and granules in an elevated circu- present specimen, the surface of all the abactinal plates and lar area at the center (Fig. 7F). Madreporite is circular, not some of the actinal plates shows numerous glassy bosses. elevated from the abactinal surface of disc; gyri radiate from Liao and A. M. Clark (1995) suggested that Stellaster sep- the center in a complex pattern. Tubefeet are biserial with a temtrionalis Oguro, 1991, which was described from 105 m terminal disc. Terminal plates are spherical, devoid of gran- deep in the East China Sea (Oguro 1991), may be a junior ules, and bearing about ten tubercles at the apex in NSMT synonym of O. capella although they did not give a detailed E-9277 (Fig. 7F). In NSMT E-8285, the tubercles are very description or comparison of the two species. The two spe- low and faint, and the number is about three. cies are indeed very similar in having 5–6 furrow spines, Superomarginal and inferomarginal plates are similar in 2–3 short subambulacral spines, and in lacking tubercles or shape and size to abactinal plates, and arranged in two regu- spines on abactinal and marginal plates. However, O. capella lar longitudinal series. Distal superomarginal plates (twelve can be distinguished from S. septemtrionalis by the absence to thirteen plates from the arm tip in NSMT E-9277 and of coarse granules on abactinal, marginal, and actinal plates seven to nine in NSMT E-8285) are devoid of a skin and and conical tubercles on actinal plates. We consider that granules like some of the abactinal plates (Fig. 7F). More these differences are sufficient to separate the two species distal plates have a larger, more swollen and more elliptical and S. septemtrionalis should be maintained as valid. naked area. In NSMT E-8285, three to four distalmost in- Distribution. Southern coast of China, 60–129 m (Liao feromarginal plates are denuded and swollen like distalmost and A. M. Clark 1995). Kai Islands, Indonesia, 90 m; Timor superomarginal plates. Island, 112 m; Small Sunda Islands, depth unknown (Döder- Actinal plates are rectangular and arranged in three lon- lein 1935). Seram Island, depth unknown (Guille and Jan- gitudinal series at the base of arms: the innermost series goux 1978). Ogasawara Islands, Japan, 95–98 m (this study). reach about 3/4R, the outer 1/2R, and the outermost 1/6R in Japanese name. Hadaka-akasuji-hitode means a bare NSMT E-8285 (in NSMT E-9277, there are two series reach- red-lined sea star, referring to the body hardly covered with ing 2/3R and 1/4R respectively, and a few interradial plates). granular skin and conspicuous red lines bordering abactinal Each adambulacral plate bears two furrow spines and a plates in life. subambulacral spine (Fig. 7D). Furrow spines are truncated, flattened, and polygonal but rounded at corners and slight- Family Ophidiasteridae Verrill, 1870 ly concave at the furrow surface. Each plate carries a pair Tamaria tenella (Fisher, 1906) of subequal spines. Subambulacral spines are obovate but [Japanese name: Birodo-hime-hokiboshi] more circular in the distal part of arms. Between two furrow (Figs 2E, 7) spines and a subambulacral spine, there are granules one of which is occasionally larger than the surroundings to appear Ophidiaster tenellus Fisher, 1906: 1082. like a tubercle. Ophidiaster sp.: McKnight 1975: 56–57. Oral plates are covered with granules like actinal plates. Tamaria tenellus: McKnight 1993: 172–173. A plate bears five to six oral spines and a suboral spine (Fig. Tamaria tenella: H. L. Clark 1921: 88, 91; A. M. Clark 1993: 7B). They are identical in shape to furrow spines and sub- 354; McKnight 2001: 176–177; Arai et al. 2018: 198–199. ambulacral spines respectively. The entire body is overlaid with a skin except some abac- Material examined. NSMT E-8285, 1 individual, coll. tinal plates and distal superomarginal plates as mentioned by Dr. Minoru Imajima in 1969, labeled as “Hyotan-jima, above. The skin is covered with fine granules homogenous Ogasawara Islands, intertidal” but probably a mislabeled in size (Fig. 7B, C). The number of granules per square mil- specimen collected by a coral fisherman Akio Kihara limeter is 379 on proximal carinal plates and 167 on proxi- around Ani-jima, Chichi-jima, Haha-jima or Yome-jima Is- mal actinal plates in NSMT E-9277; 281 and 295 respective- land in depth ranging from 150 to 160 m (see Imajima 1970: ly in NSMT E-8285. 18 M. Arai and T. Fujita

Fig. 7. Tamaria tenella, NSMT E-9277. A, actinal side; B, actinal surface around mouth; C, proximal portion of ray; D, proximal adambulacral plates. Right to arm tip; E, pedicellaria on the abactinal interradial plate; F, distal portion of the arm, oblique lateral view. Arrow indicates bare area on superomarginal plate. Scale bars: 10 mm (A), 1 mm (B, C), 500 µm (D, E), 5 mm (F).

A papular area bears one to three pores on the disc and Color in life is unknown. The ex-ethanol specimens show one to five on the arms. The areas occur between carinal, brown transverse bands on arms with darker papular areas abactinolateral, superomarginal and inferomarginal plates and transverse lines between plates on the abactinal surface. but never below the inferomarginal plates. They are ar- DNA sequence. A partial sequence of COI (655 bp) was ranged in six longitudinal series although the numbers of sequenced from NSMT E-9277 and deposited in DDBJ pores change irregularly. (Acc. No. LC427076). Pedicellariae presents on superomarginal plates (from the Remarks. Fisher (1906) described two closely similar base to the middle of arms), abactinal interradial plates, and species, Ophidiaster sclerodermus Fisher, 1906 and O. tenel- exceptionally on an abactinolateral plate in NSMT E-9277, lus, distinguishing them by the length of arms, granulation, on actinolateral, superomarginal, and inferomarginal plates thickness of skin, number of papular pores in each area, and in NSMT E-8285. Each pedicellaria with two valves, which number of pedicellariae. Both species were subsequently fit in an entrenched piece of ossicle with an alveolus at the transferred to the genus Tamaria by H. L. Clark (1921). center (Fig. 7E). The ossicle is merged with the subjacent The present Ogasawara specimens resemble these two spe- plate. The valve is gradually broadening from the base to cies, but show discordance in some characters from each form a smooth, unserrated, and slightly curved contour. species. Tamaria scleroderma has a larger number of papu- Sea Stars from Ogasawara Islands 19 lar pores (9–14) and shorter arms (R/r=4.8) than Tamaria Distribution. Hawaii Islands, 238–276 m (Fisher 1906). tenella. The Ogasawara specimens are consistent with T. Three Kings Rise and Norfolk Ridge, New Zealand, 403– tenella in the number of papular pores (1–3) while it has 503 m (McKnight 1993, 2001). Ogasawara Islands, Japan, longer arms (R/r=6.9). The New Zealand specimens ofT. 159–161 m (Arai et al. 2018; this study). tenella described by McKnight (1975, 2001) differ from the Japanese name. Birodo means velvet, referring to the Ogasawara specimens in the proportion of arms, number of smooth skin with minute granules. Hime-hokiboshi means a papulae, distribution of pedicellariae, and spines on actinal small comet. plates. The rays are longer in proportion to the disc: R/r=5.5 at R=22 mm and 7.5 at R=48 mm. All the papulae are isolated, and the pedicellariae occur on actinal plates. In the Discussion larger specimen with R=48 mm, spines similar to the subambulacral ones occur on some actinal plates. In addition Five species of sea stars from the Ogasawara Islands are to these differences, the Ogasawara specimens also have a described in this study; two are new to science. Summariz- central naked area on the distal carinal and superomarginal ing the published records of sea stars in the Ogasawara Is- plates which is not present in the Hawaiian or New Zealand lands and this study, we recognize 31 species of 23 genera specimens. The present specimens are temporarily consid- in 10 families (Table 3). It should be noted that most of the ered to be T. tenella, based on the small number of papular historical records were not verified by specimens, images, pores per area. However, we believe that these species re- or other data. This number of asteroid species is lower than quire a detailed revision in regard to morphological varia- those in the neighboring subtropical/tropical islands such tion with a greater number of specimens. as the Nansei Islands and the Mariana Islands, which are

Table 3. Sea stars reported from the coasts of the Ogasawara Islands and adjacent waters. References as follows: aHayashi (1938); bImajima (1969); cShigei (1970); dPope and Rowe (1977); eAmemiya and Yanagisawa (1991); fKogure and Tachikawa (2009); gSaba (2011); hFujita et al. (2015); iArai et al. (2018); jthis study.

Order Family Species References Valvatida Acanthasteridae Acanthaster planci (Linnaeus, 1758) b Asterinidae Aquilonastra anomala (H. L. Clark, 1921) g, h, i Aquilonastra sp. i Pseudonepanthia briareus (Bell, 1894) e, g, h, i Asterodiscididae Asterodiscides japonicus Oguro, 1991 i Chaetasteridae Chaetaster moorei Bell, 1894 e, g Goniasteridae Astroceramus boninensis Kogure and Tachikawa, 2009 f Bathyferdina caelator sp. nov. i, j Fromia eusticha Fisher, 1913 i, j Fromia indica (Perrier, 1869) a, e, h, i Fromia labeosa sp. nov. i, j Fromia monilis (Perrier, 1869) e, g Fromia pacifica H. L. Clark, 1921 h Nardoa sp. a, e, g, h, i Neoferdina cumingi (Gray, 1840) e Ogmaster capella (Müller and Troschel, 1842) i, j Mithrodiidae Mithrodia clavigera (Lamarck, 1816) e, g, h Thromidia catalai Pope and Rowe, 1977 d, g, h Ophidiasteridae Leiaster coriaceus Peters, 1852 h Linckia guildingi Gray, 1840 e, g, i Linckia laevigata (Linnaeus, 1758) b, e Linckia multifora (Lamarck, 1816) a, c, e, g, h, i Ophidiaster cribrarius Lütken, 1871 a, h, i Ophidiaster hemprichi Müller and Troschel, 1842 e Tamaria tenella (Fisher, 1906) i, j Oreasteridae Choriaster granulatus Lütken, 1869 e Culcita novaeguineae Müller and Troschel, 1842 g, h Protoreaster nodosus (Linnaeus, 1758) f Poraniidae Marginaster paucispinus Fisher, 1913 i Solasteridae Lophaster sp. i Seriaster regularis Jangoux, 1984 i Spinulosida Echinasteridae Echinaster luzonicus (Gray, 1840) a, c, e, g, h Forcipulatida Asteriidae Coronaster pauciporis Jangoux, 1984 g, h Coscinasterias acutispina (Stimpson, 1862) a, h 20 M. Arai and T. Fujita

49 species and 34 species, respectively (Paulay 2003; Saba 2011). Arai et al. (2018) argued that relatively lower diver- References sity of valvatid sea stars in the Ogasawara Islands than in the Nansei Islands is possibly due to the sampling density, small Amemiya, S. and Yanagisawa, T. 1991. [Change in abundance and coastal area and isolated location. current status of Echinoderms in the Ogasawara Islands]. Pp. In the Ogasawara Islands, the five species described in 297–308 In: Ono, M., Kimura, M., Miyashita, K., and Nogami, M. (Eds) Report of the Second General Survey on Natural Environment this study occurred only in the mesophotic zone between of the Ogasawara (Bonin) Islands. Tokyo Metropolitan University, 56–161 m. None of them have ever been reported from the Tokyo. [In Japanese] shallower zone (0–30 m) of the Ogasawara Islands (Arai et al. Arai, M., Tanaka, Y., Miyazaki, T., and Fujita, T. 2018. Valvatida (Echi- 2018). This suggests that the mesophotic zone has a unique nodermata: Asteroidea) of the Ogasawara Islands, Japan. Memoirs sea star fauna in the Ogasawara Islands. Moreover, the five of the National Museum of Nature and Science 52: 191–203. [In species have not been recorded from shallower water in any Japanese] localities save for Fromia eusticha, which is known from Baldwin, C. C., Tornabene, L., and Robertson, D. R. 2018. Below the 0–55 m of Philippines, Indonesia and Marshall Islands (Fish- mesophotic. Scientific Reports 8: 4920. er 1913; Domantay and Roxas 1938; A. H. Clark 1952; Jan- Clark, A. H. 1952. Echinoderms from the Marshall Islands. Proceedings of the United States National Museum 102: 265–303. goux 1978). Tamaria tenella is reported from deeper waters Clark, A. M. 1993. An index of names of recent Asteroidea—Part 2: below the mesophotic zone in the Hawaii Islands and New Valvatida. Pp. 187–366. In: Jangoux, M. and Lawrence, J. M. (Eds) Zealand (Fisher 1906; McKnight 1993, 2001). Echinoderm Studies 4. A. A. Balkema, Rotterdam. The two new species, Bathyferdina caelator sp. nov. and Clark, A. M. and Downey, M. E. 1992. Starfishes of the Atlantic. Chap- Fromia labeosa sp. nov., were collected only in the Ogasa man & Hall, London, xxvi+663 pp., 113 pls. wara Islands, and it is possible that they are endemic to the Clark, A. M. and Mah, C. 2001. An index of names of recent Asteroi- islands. There is only a single species of sea star currently dea—Part 4: Forcipulatida and Brisingida. Pp. 229–347. In: Jan- known to be endemic in the Ogasawara Islands: Astrocera- goux, M. and Lawrence, J. M. (Eds) Echinoderm Studies 6. A. A. mus boninensis. This species has never been reported from Balkema, Lisse. other localities since the original description. Extensive sur- Clark, H. L. 1921. The Echinoderm Fauna of Torres Strait: Its Composi- tion and Its Origin. Carnegie Institution of Washington, viii+223 veys in the neighboring islands such as the Izu Islands are pp., 38 pls. required to clarify the geographic distribution of these spe- Döderlein, L. 1935. Die Asteriden der Siboga-Expedition. III. Oreast- cies and to understand diversity and endemism of the sea eridae. Siboga-Expeditie 46(3): 71–110. stars of the Ogasawara Islands. Domantay, J. S. and Roxas, H. A. 1938. The littoral Asteroidea of Port Galera Bay and adjacent waters. The Philippine Journal of Science 65: 203–237. Acknowledgments Fisher, W. K. 1906. The starfishes of the Hawaiian Islands. Bulletin of the United States Fish Commission 23: 987–1130. We express our cordial thanks to the captain and crews Fisher, W. K. 1913. New starfishes from the Philippine Islands, Celebes, and Moluccas. Proceedings of the United States National Museum of R/V Koyo, Mr. Yuhei Tanaka and other officers of Tokyo 46: 201–224 Metropolitan Ogasawara Fisheries Center for providing Fisher, W. K. 1919. Starfishes of the Philippines Seas and adjacent wa- their professional support during sampling. We also thank ters. United States National Museum Bulletin 100(3): 1–712. the captains and crews of TR/V Shin’yo-maru (Tokyo Uni- Forbes, E. 1841. A History of British Starfishes, and Other Animals of the versity of Marine Science and Technology) and R/V Tansei- Class Echinodermata. John Van Voorst, London, xx+267 pp. maru (Japan Agency for Marine-Earth Science and Technol- Fujita, Y., Irimura, S., Kogure, Y., Okanishi, M., Michonneau, F., and ogy) for the precious opportunities of sampling they pro- Naruse, T. 2015. Catalogue of Echinodermata Specimens Deposit- vided. Drs. Hiroshi Hasegawa, Hiroshi Namikawa, Hironori ed in the University Museum (Fujukan), University of the Ryuky- Komatsu and Taiju Kitayama of National Museum of Nature us. Catalogue of Materials Deposited in the University Museum (Fujukan), University of the Ryukyus 10: 1–106. and Science offered valuable specimens and great help on Gray, J. E. 1866. Synopsis of the Species of Starfish in the British Museum. board. We are grateful to Dr. Christopher Mah of National John Van Voorst, London, iv+18 pp., 16 pls. Museum of Natural History, Smithsonian Institution and Guille, A. and Jangoux, M. 1978. Astérides et Ophiurides littorales Dr. Christina Piotrowski of California Academy of Sciences de la région d’Amboine (Indonésie). Annales de l’Institut Océ- for enabling us to study a paratype specimen of Bathyferdina anographique 54: 47–74. aireyae. We also thank Drs. Mah, Daisuke Uyeno of Kago Hayashi, R. 1938. Sea-stars of the Ogasawara Islands. Annotationes shima University, and two anonymous reviewers for valu- Zoologicae Japonenses 17: 59–69. able comments on the manuscript. Hoareau, T. B. and Boissin, E. 2010. Design of phylum-specific hybrid This work was supported by project studies of National primers for DNA barcoding: addressing the need for efficient COI amplification in the Echinodermata. Molecular Ecology Resources Museum of Nature and Science (Biological Properties of 10: 960–967. Biodiversity Hotspots in Japan; Geological, biological, and Imajima, M. 1969. [Marine organisms in the Ogasawara Islands]. Pp. anthropological histories in relation to the Kuroshio Cur- 145–177. In: Tokyo-to Kensetsukyoku Koenryokuchibu (Ed.) rent), and the raising grant of the Research Institute of Ma- Ogasawara Shotou Shizenkeikan Chousa Houkokusho [Report on rine Invertebrates (2016IKU-2) given to MA. the landscape of the Ogasawara Islands]. Tokyo. [In Japanese] Imajima, M. 1970. [Marine organisms]. Pp. 179–196. In: Tuyama, T. Sea Stars from Ogasawara Islands 21

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