Comanthus Scintillus, a New Species of Featherstar (Echinodermata: Crinoidea: Comatulida: Comatulidae) from Southern Japan

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Species Diversity 22: 201–206 25 November 2017 DOI: 10.12782/sd.22_201

Comanthus scintillus, a New Species of Featherstar (Echinodermata: Crinoidea: Comatulida: Comatulidae) from Southern Japan

Masami Obuchi1,3 and Yoshihisa Fujita2 1 Faculty of Science, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213, Japan E-mail: [email protected] 2 Okinawa Prefectural University of Arts, 1-4 Shuri-Tonokura, Naha, Okinawa 903-8602, Japan 3 Corresponding author (Received 17 March 2017; Accepted 16 June 2017)

http://zoobank.org/BFB51880-2ABA-4DAA-9E46-23304BE0B5C4

A new species of comatulid crinoid, Comanthus scintillus n. sp., is described based on specimens from southern Japan. The general appearance is similar to congeners having a small centrodorsal with few cirri, such asComanthus gisleni Rowe, Hoggett, Birtles, and Vail, 1986, and C. suavia Rowe, Hoggett, Birtles, and Vail, 1986. However, the new species is characterized by the distribution of the terminal combs to middle arms, lack of secondary teeth on the combs, and the presence of fringing spines on the segments of the distal pinnules. Live specimens of the new species show striking coloration in which the whole body is red with scattered small yellow spots, which also makes it easily distinguishable from congeners. Key Words: Comatulidae, Comanthus, feather stars, Ashizuri-Uwakai Sea, Ryukyu Islands.

C. delicata (A. H. Clark, 1909); C. gisleni Rowe, Hoggett, Introduction Birtles, and Vail, 1986; C. kumi Fujita and Obuchi, 2012; C. suavia Rowe, Hoggett, Birtles, and Vail, 1986; C. wahlber- The family Comatulidae Fleming, 1828, is the most com- gii (Müller, 1843). They can be distinguished mainly by the mon and diverse group of extant comatulids in the shal- number of cirri, distribution of pinnule combs, and pres- low waters of the Indo-West Pacific (Clark and Rowe 1971; ence or absence of distal fringe of spines on segments of dis- Messing 1998, 2001; Kogo and Fujita 2014). Within the tal pinnules. family, the genus Comanthus A. H. Clark, 1908 is restricted During our recent survey of the shallow-water comatulid to shallow habitats with all members distributed at depths fauna around the Ashizuri-Uwakai Sea, Shikoku Island, and shallower than 100 m. The genus includes eleven nominal the Ryukyu Islands, southern Japan (see Obuchi 2013, 2016; species characterized by a circular to pentagonal centrodor- Obuchi and Omori 2015; Fujita et al. 2015), we discovered sal; zero to chiefly fewer than 25 cirri (to 40 in C. wahlbergii unusual specimens of Comanthus. In this paper, these speci- and possibly 51 in C. imbricata) arranged in a single row; mens are described as new to science. terminal combs composed of large teeth confluent with the exterior edge of the pinnular, and a saucer-like transverse proximal tooth (Summers et al. 2014). The configuration Materials and Methods of terminal combs was considered diagnostic for genera in subfamily Comasterini A. H. Clark, 1909, to which Coman- The specimens examined were collected by SCUBA on thus is referred, based on taxonomic revisions by Hoggett the rocky shores of the Ashizuri-Uwakai Sea, Shikoku Is- and Rowe (1986) and Rowe et al. (1986) (Messing 2001). land, and on coral reefs of the Ryukyu Islands, southern However, recent research combining molecular and mor- Japan. They were deposited in the Osaka Museum of Natu- phological characters found that the comb form does not ral History (OMNH), the Biological Institute on Kuroshio necessarily agree with phylogenetic status (Summers et al. (BIK), and The University Museum (Fujukan), University of 2014). As for Comanthus, the comb form described above is the Ryukyus (RUMF). common to all members, although the same type is found The terminology for the description follows Messing in some species assigned to the related genus, Clarkcoman- (2001). The abbreviations used in this paper are below. thus Rowe, Hoggett, Birtles, and Vail, 1986 (Summers et al. R: radius, length from the center of the centrodorsal 2014). to the tip of the arms (longest anterior–shortest posterior Six species of Comanthus have been recorded from Japa- arms), measured to the nearest 5 mm. nese waters (Kogo 1998; Fujita and Obuchi 2012; Obuchi c: cirral, segment of cirrus, numbered from the base (e.g.,

2013; Kogo and Fujita 2014): C. parvicirrus (Müller, 1841); c1, c2).

L/W, W/L: length-to-width and width-to-length ratios of +: articulation joined by syzygy. ossicles. P: pinnule, numbered from the most proximal with nu-

Br: division series. Preceding Roman character indicates merals on the outer side of arm bifurcation (e.g., P1), and the position from the base, and following numeral indicates alphabetically on the inner side (e.g., Pa). Subscript Roman the number of components (e.g., IIBr2 indicating second di- character indicates the division series where it arises (e.g., vision series composed of two ossicles). PII). br: brachial, ossicle of ray, numbered from the base of each division series or free arm.

Fig. 1. Comanthus scintillus n. sp., holotype, OMNH-Iv6230. A, centrodorsal and proximal ray, aboral view; B, cirrus, lateral view; C, proximal pinnules (P1 to P3, left to right), lateral view; D, terminal comb on 1P , lateral view. Scale bars 5 mm for A and C, 1 mm for B and D. New Comanthus from southern Japan 203

Other materials. OMNH-Iv6234, R 85–50 mm, same Results and Discussion locality as holotype, 15.0 m depth, 11 November 2013; OMNH-Iv6235, R 100–65 mm, same locality as holotype, Family Comatulidae Fleming, 1828 5.0 m depth, 15 July 2016; BIK-EC-CR0091, R 135–70 mm, Genus Comanthus A. H. Clark, 1908 same locality as holotype, 3.0 m depth, 6 May 2014; BIK- Comanthus scintillus n. sp. EC-CR0092, R 135–70 mm, same data as BIK-EC-CR0091 (Figs 1–3A, B) except depth, 1.7 m; BIK-EC-CR0093, R 180–90 mm, [New Japanese name: Hanabi-Umishida] same locality as holotype, 5.6 m depth, 6 July 2014; BIK- EC-CR0095, R 105–45 mm, same locality as holotype, Comanthus sp.: Fujita et al. 2015: 76, unnumbered fig. 9.3 m depth, 28 July 2014; RUMF-ZE-00432, R 90–35 mm, (RUMF-ZE-00437) in color. Takenchi, Kume Island, Ryukyu Islands, 11.3 m depth, 4 March 2005, SCUBA, coll. Y. Fujita; RUMF-ZE-00438, R Material examined. Holotype. OMNH-Iv6230, R 130– 130–60 mm, Garasaa-oki, Kume Island, Ryukyu Islands, 70 mm, Nishidomari, Otsuki, Kochi Pref., southwestern Shi- 9.2 m depth, 6 March 2005, SCUBA, coll. Y. Fujita; RUMF- koku Island, Japan, 6.1 m depth, 20 July 2014, SCUBA, coll. ZE-02005, R 60 mm, Shimoji Island, Miyako Island Group, M. Obuchi. Ryukyu Islands, 18.0 m depth, 15 March 2006, SCUBA, coll. Paratypes. OMNH-Iv6231, R 150–65 mm, same local- Y. Fujita. ity as holotype, 5.0 m depth, 10 June 2011; OMNH-Iv6232, Comparative materials. Comanthus gisleni Rowe, Hoggett, R 155–70 mm, same locality as holotype, 3.0 m depth, 21 Birtles, and Vail, 1986: BIK-EC-CR0107, R 135–55 mm, July 2012; OMNH-Iv6233, R 115–80 mm, same locality as Cape Zanpa, Yomitan, Okinawa Island, the Ryukyu Islands, holotype, 7.0 m depth, 16 April 2014; RUMF-ZE-00437, R Japan, 13.0 m depth, 30 April 2017, SCUBA, coll. M. Obu- 90–45 mm, Shimajiriguchi, Kume Island, Ryukyu Islands, chi. Comanthus suavia Rowe, Hoggett, Birtles, and Vail, southwestern Japan, 6.8 m depth, 5 March 2005, SCUBA, 1986: BIK-EC-CR0096, R 175–95 mm, Nishidomari, Ot- coll. Y. Fujita; RUMF-ZE-00532: R 160–60 mm, Maeda-mi- suki, Kochi Pref., southwestern Shikoku Island, Japan, 4.6 m saki, Okinawa Island, Ryukyu Islands, 4.5 m depth, 22 No- depth, 4 May 2013, SCUBA, coll. M. Obuchi. vember 1997, SCUBA, coll. Y. Fujita. Diagnosis. A medium-sized species with anterior arm

Fig. 2. Comanthus scintillus n. sp. A, feeding posture, RUMF-ZE-00437; B, whole animal, aboral view, BIK-EC-CR0095; C, centrodorsal and proximal rays, aboral view, OMNH-Iv6233; D, disk, oral view, RUMF-ZE-00437. 204 M. Obuchi and Y. Fujita

Fig. 3. Middle segments of distal pinnules, lateral view. A and B, Comanthus scintillus n. sp., holotype, OMNH-Iv6230 (distal fringe of spines distinct in A, but not in B); C, Comanthus gisleni Rowe, Hoggett, Birtles, and Vail, 1986, BIK-EC-CR0107; D, Comanthus suavia Rowe, Hoggett, Birtles, and Vail, 1986, BIK-EC-CR0096. Scale bars 0.5 mm. length 100–150 (to 180) mm. Centrodorsal small, thin dis- all 4(3+4); IIbr2 bearing PII. Twelve IIIBr series all 4(3+4); coidal. Cirri weak, II–IX, 11–16 segments, 5.5–8.0 mm long, IIIbr2 bearing PIII. arranged in single row with gaps; longest cirrals 1.3 times Arms 32. Anterior arms 123 mm long; posterior arms longer than broad; distal cirrals with low transverse ridge. 60 mm long. Proximal brachials short; br1 W/L 2.1, interi- Radials narrowly exposed. Arms 21–38 in number; anteri- orly united with neighbor; br2 trapezoid with longer exterior or arms about twice as long as posterior. IIBr and IIIBr of margin, W/L 2.5, totally separated from neighbor, bearing mostly 4(3+4), rarely 2; each division series well separated, P1; br3+4, united by first arm syzygy, oblong, W/L 1.9; br4 except first ossicle of each in lateral contact interiorly. First bearing Pa; br5–br7 cuneate, W/L 1.8–2.3. Middle brachials arm syzygy at br3+4, second at br9+10 to br11+12, and follow- triangular thickened at distal margin, gradually becoming ing at 4 intervals of muscular articulations. Pinnules on di- cuneate again distally. Distal brachials of anterior arms elon- vision series and P1 longest; P2 shortest, about half length of gated, cylindrical, W/L 0.4, smooth; brachials of posterior P1; following gradually longer; distal pinnules slender, with arms shorter, with W/L 0.6–0.8. Second arm syzygy at br9+10 distal fringe of spines on middle segments, but sometimes to br11+12; following syzygies at 4 intervals of muscular ar- indistinct. Terminal combs of 6–11 teeth, always present to ticulations.

P2 and at intervals to P11–P18, about proximal third of anteri- Pinnules on division series and P1 similar, longest, com- or arms; teeth large, triangular, confluent, basally in contact, posed of 35–40 segments, 12.0–13.0 mm long (Fig. 1C); without secondary teeth; proximal segment with transverse proximal four to five pinnulars rhombic, broader than long; spoon-like tooth; terminal segment with discrete tooth. In following cylindrical, as broad as long. P2 shortest, com- life, whole body red with scattered small yellow spots. posed of 22–26 segments, 5.0–6.5 mm long; all pinnulars

Description of holotype. Centrodorsal small, thin, broader than long. P3 same length as, or slightly longer than stellate, 3.2 mm across, slightly raised above level of radials P2, composed of 18–25 segments, 5.0–6.5 mm long, first (Figs 1A, 2C); polar area smooth, slightly concave at center, genital pinnule; all pinnulars broader than long, with fine about 0.7 times as wide as centrodorsal; few cirri and obso- spines on aboral side. Following middle pinnules to P12–P16 lete sockets present at margin. similar to P3, successively becoming longer; P4 of 24–27 seg- Cirri weak, III, plus V rudimentary, 15 segments, 6.5– ments, 6.0–8.0 mm long; P5 of 15–16 segments (no terminal 7.0 mm long, arranged in single row (Fig. 1A, B); c1 short, comb), 6.5–7.0 mm long. Distal pinnules on anterior arms cylindrical; c2–c3 as long as wide; c4–c7 longest, L/W up to slender, composed of 19–22 segments, 8.5–10.0 mm long; 1.2; followings decreasing in length; distal margin of distal middle segments L/W 3.0, with fringe of distal spines (Fig. cirrals aborally thickened, becoming transverse ridge on 3–5 3A); spines sometimes indistinct (Fig. 3B); pinnules on pos- segments preceding penultimate; penultimate L/W 0.6, with terior arms shorter, almost same length as or slightly longer small conical, occasionally transversely chisel-shaped, op- than middle pinnules on same arm. posing spine on distal part; terminal claw curved, pointed, Terminal combs consisting of 6–11 teeth, always present and slightly longer than penultimate. to P2 and at intervals to P11–P18, about proximal one third Radials narrowly exposed, not exceeding 0.2 times as of anterior arms and half of posterior arms (Fig. 1D); teeth long as centrodorsal (Figs 1A, 2C). Each division series well large, triangular, curved inward, basally in contact, conflu- separated, except first ossicles laterally united interiorly. IBr ent with exterior side of pinnular; proximal segment with series of 2 ossicles; Ibr1 short, oblong, W/L 3.3; Ibr2 pen- transverse spoon-like tooth; terminal segment with discrete tagonal with short lateral margins, W/L 2.2. Ten IIBr series tooth not fused to others; no secondary teeth. New Comanthus from southern Japan 205

Disk rounded, 14 mm diameter, four to eight times as wide as centrodorsal, largely smooth but with fleshy conical Acknowledgments papillae on anal cone (Fig. 2D); mouth marginal; anal cone central. We would like to thank H. Kohtsuka (University of Notes on other materials. Large specimen (RUMF- Tokyo) for providing the information about the new spe- ZE-00532, paratype): centrodorsal 2.8 mm across; cirri VII, cies, and Dr. J. D. Reimer, T. Kunishima (University of the plus III rudimentary, to 14 segments, 7.5 mm long; eight Ryukyus) and Dr. K. N. White (University of Tampa) for IIBr series 4(3+4), and two of 2; most IIIBr series 4(3+4), helpful advice. We appreciate I. Kogo (Osaka Museum of and one of 2; arms 36, 155–55 mm long; terminal combs National History) and Dr. C. G. Messing (Nova Southeast- distributed to P12–P14 at intervals; disk 15 mm across. ern University) providing valuable comments to improve Small specimen (OMNH-Iv6234): centrodorsal 2.3 mm the manuscript. We are grateful to A. Hashimoto, S. Naka- across; cirri IX, plus II rudimentary, to 13 segments, 7 mm chi, and J. Fukada (Kuroshio Biological Research Founda- long; all IIBr and IIIBr series 4(3+4); arms 21, 80–45 mm tion) for their kind support. This research was partially sup- long; terminal combs to P10–P14 at intervals; disk 5 mm ported by the Japan Society for the Promotion of Science across. “Zuno-junkan” grant entitled “Studies on origin and main- Juvenile specimen (RUMF-ZE-02005): radials more ex- tenance of marine biodiversity and systematic conservation posed, length one third of centrodorsal diameter; arms 13, planning” to the first author, and the JSPS Grant-in-Aid for

60 mm long; terminal comb to P2–P4. Scientific Research (S) (No. JP16H06309) to the second au- Habitat and feeding posture. Dwelling within infra- thor. structure of rocky reefs or between branches of stony corals (Fig. 2A). Anterior arms extended with pinnules arranged alternately to make two planes along each side of arms References (multidirectional posture of Meyer and Macurda (1980)). Color in life. Uniformly red with scattered small yellow Clark, A. H. 1908. Preliminary notice of a collection of recent crinoids spots (Fig. 2); distal arms and pinnules often almost yellow from the Philippine Islands. Smithsonian Miscellaneous Collec- with dense spots (Fig. 2B). tions 52: 199–234. Clark, A. M. and Rowe, F. W. E. 1971. Monograph of Shallow-Water Distribution. From southwestern Shikoku Island to the Indo-West Pacific Echinoderms. British Museum (Natural History), Ryukyu Islands, southern Japan: Ashizuri-Uwakai Sea, Oki- London, x+238 pp., 30 pls. nawa Island, Kume Island, and Shimoji Island of Miyako Is- Fleming, J. 1828. A History of British Animals, Exhibiting the Descriptive land Group. Depth range subtidal to 18 m. Characters and Systematical Arrangement of the Genera and Spe- Etymology. The specific name scintillus indicates spark cies of Quadrupeds, Birds, Reptiles, Fishes, Mollusca, and Radiata of from Latin, named after its impressive coloration in life, in the United Kingdom; Including the Indigenous, Extirpated, and Ex- which scattered yellow spots are associated with sparks. tinct Kinds, Together with Periodical and Occasional Visitants. Bell Remarks. Comanthus scintillus n. sp. is diagnosed by and Bradfute, Edinburgh, 565 pp. the following characters: (1) the centrodorsal is small with Fujita, Y., Irimura, S., Kogure, Y., Okanishi, M., Michonneau, F., and Naruse, T. 2015. Catalogue of Materials Deposited in The University few cirri; (2) terminal combs occur to the middle of the Museum (Fujukan), University of the Ryukyus No. 10. Catalogue arms; (3) middle segments of distal pinnules bear a distal of Echinodermata Specimens Deposited in The University Museum fringe of spines, and (4) secondary comb teeth are absent. (Fujukan), University of the Ryukyus. The University Museum (Fu- The new species seems most closely related to Comanthus jukan), University of the Ryukyus, 106 pp. [In Japanese] gisleni in that both have a distal fringe of spines on the mid- Fujita, Y. and Obuchi, M. 2012. Comanthus kumi, a new shallow-water dle segments of the distal pinnules (Fig. 3C). However, in C. comatulid (Echinodermata: Crinoidea: Comatulida: Comasteri- gisleni, the terminal combs are distributed to the distal pin- dae) from the Ryukyu Islands, Japan. In: Naruse, T., Chan, T.-Y., nules on the arm tip (see Rowe et al. 1986). Distribution of Tan, H. H., Ahyong, S. T., and Reimer, J. D. (Eds) Scientific Results the combs distinguishes the new species from Comanthus of the Marine Biodiversity Expedition—KUMEJIMA 2009. Zootaxa parvicirrus and Comanthus kumi, which both have combs 3367: 261–268. Hoggett, A. K. and Rowe, F. W. E. 1986. A reappraisal of the family Co- to near the arm tips as in C. gisleni (Rowe et al. 1986; Fujita masteridae A. H. Clark, 1908 (Echinodermata: Crinoidea), with and Obuchi 2012). The new species shares with Comanthus the description of a new subfamily and a new genus. Zoological suavia combs as far as the middle of the arms: up to P18 and Journal of the Linnean Society 88: 103–142. P15 respectively, and more restricted in small specimens of Kogo, I. 1998. Crinoids from Japan and its adjacent waters. Special Pub- both species (Rowe et al. 1986). However, C. suavia lacks lications from the Osaka Museum of Natural History 30: 1–148. cirri in mature specimens, and has radials largely exposed, Kogo, I. and Fujita, T. 2014. The Feather Stars of Sagami Bay. Tokai Uni- and distinct secondary comb teeth. In addition, in C. suavia, versity Press, Hadano, 162 pp. [In Japanese with English abstract] middle segments of the distal pinnules are distally smooth Messing, C. G. 1998. An initial re-assessment of the distribution and without spines (Fig. 3D). When living, C. scintillus n. sp. can diversity of the East Indian shallow-water crinoid fauna. Pp. 187– 192. In: Mooi, R. and Telford, M. (Eds) Echinoderms: San Francis- be easily recognized by the unique coloration. The spotted co. Balkema, Rotterdam. pattern is similar to some individuals of Comatella stelligera Messing, C. G. 2001. A key to genera of Comasteridae (Echinodermata: (Carpenter, 1888), rather than other members of Comanthus Crinoidea) with the description of a new genus. Bulletin of the (see Obuchi 2016: pl. 1A). 206 M. Obuchi and Y. Fujita

Biological Society of Washington 10: 277–300. ly Antedonidae (Echinodermata: Crinoidea) from southern Japan. Meyer, D. L. and Macurda Jr., D. B. 1980. Ecology and distribution of Zootaxa 3972: 441–449. the shallow-water crinoids of Palau and Guam. Micronesica 16: Rowe, F. W. E., Hoggett, A. K., Birtles, R. A., and Vail, L. L. 1986. Revi- 59–99. sion of some comasterid genera from Australia (Echinodermata; Obuchi, M. 2013. Two tropical comatulids (Echinodermata: Crinoidea: Crinoidea), with descriptions of two new genera and nine new Comatulida) from Okinoshima Island, Kochi, new records for species. Zoological Journal of the Linnean Society 86: 197–277. Japan. Kuroshio Biosphere 9: 15–26, pls 1–2. Summers M. M., Messing, C. G., and Rouse, G. W. 2014. Phylogeny Obuchi, M. 2016. Field guide: Comatulids of Ashizuri-Uwakai Sea. Ku- of Comatulidae (Echinodermata: Crinoidea: Comatulida): a new roshio Biosphere 12: 1–20, pls 1–7. [In Japanese with English ab- classification and an assessment of morphological characters for stract] crinoid taxonomy. Molecular Phylogenetics and Evolution 80: Obuchi, M. and Omori, A. 2015. A new genus and new species of fami- 319–339.