Order Euryalida (Echinodermata, Ophiuroidea), new species and new records from the South China Sea and the Northwest Pacific seamounts Author Nethupul, Hasitha https://orcid.org/0000-0003-0590-2719 Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, CAS, 57200 Sanya, China & University of Chinese Academy of Sciences, Beijing 100039, China Author Stoehr, Sabine https://orcid.org/0000-0002-2586-7239 Swedish Museum of Natural History, Dept of Zoology, Box 50007, 10405 Stockholm, Sweden Author Zhang, Haibin https://orcid.org/0000-0001-5429-9851 Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, CAS, 57200 Sanya, China hzhang@idsse.ac.cn text ZooKeys 2022 2022-03-30 1090 161 216 http://dx.doi.org/10.3897/zookeys.1090.76292 journal article http://dx.doi.org/10.3897/zookeys.1090.76292 1313-2970-1090-161 3B13C71EE11B49D2891C050DBD514872 1E6F228182BA5078A6144181DB93F0DE Asteroschema salix Lyman, 1879 Figures 14 , 15 Asteroschema salix Lyman, 1879: 66-67, fig. 17, figs 466-469; 1882: 277, fig. 22, figs 13-15; Baker 1980 : 22; McKnight 2000 : 21-22, fig. 6; Olbers et al. 2015 : 85, fig. 1A, B; 2019: 51-52, fig. 24-25. Material examined. China • 1 specimen ; South China Sea , Zhongsha Islands , seamount; 15°36.64'N , 116°7.73'E ; depth 1775 m ; 19 Sep. 2020 ; Collecting event: stn. SC010; 'Shenhaiyongshi' msv leg; preserved in 95% ethanol; GenBank: OK044301, OL712214 ; IDSSE-EEB-SW0082 . Description. Disc diameter 10 mm, length of arms 145 mm (Fig. 12 ). Disc . Disc flat, strongly raised above arms (Fig. 14A, B ). Disc covered by thin skin with fine, small, rounded granular ossicles, dense in center (seven or eight grains in 1 mm), but separated at distal edge (six or seven grains in 1 mm) (Fig. 14C, D ). Radial shields long, narrow, widely separated distally, convergent proximally, meeting in disc center (Fig. 14C ). Genital slits narrow, and vertical on ventral interradii (Fig. 14E ). Jaws elongated, covered with granular ossicles but near apex fewer granular ossicles (Fig. 14E ). Flattened, spearhead-shaped teeth and granular ossicles that resemble lateral oral papillae at apex of jaw (Fig. 14E ). Ventral disc covered with granular ossicles similar to dorsal disc (six or seven grains in 1 mm), slightly separated (Fig. 14E ). Adoral shields large, connected to first ventral arm segment, concealed by thin skin with granular ossicles, but plate outline visible (Fig. 14E ). Oral shields not discernible and adoral shield spine covered with ossicles (Fig. 14E ). Figure 14. Asteroschema salix Lyman, 1879 (IDSSE-EEB-SW0082) A dorsal view B ventral view C dorsal disc D skin on the arm E ventral disc F dorsal arm (proximal) G lateral arm (middle) H ventral arm (proximal) I ventral arm (distal) J outer arm spine (proximal) K arm spines (middle) L arm spines (distal). Abbreviations: as adoral shield, ass adoral shield spine, ars arm spine, go granular ossicle, gs genital slit, iars inner arm spine, j jaw, oars outer arm spine, ots oral tentacle scale, rs radial shield, t teeth, tp tentacle pore. Scale bars: 2 mm ( A, B ); 1 mm ( C, E-H ); 500 µm ( J, K ); 200 µm ( D, I, L ). Arms . Arms sub-cylindrical, not swollen, narrower and more cylindrical in distal half of arm (Fig. 14F, G ). Dorsal and lateral arm base covered with granular ossicles similar to disc (six or seven grains in 1 mm), on middle segments granular coverage similar to arm base (six or seven grains in 1 mm), and distally decreasing in size and widely separated (grains six or eight in 1 mm) (Fig. 14F, G ). On lateral arm plate, granular ossicles continue toward base of arm spine (Fig. 14G, J ). Ventral surface of arm base covered with granular ossicles similar to ventral disc but less dense (six or seven grains in 1 mm), widely separated and decreasing in size to naked at middle to distal end of arm (Fig. 14H, I ). First tentacle pore without arm spine (Fig. 14E ). First arm spine appears at second arm segment, second arm spine at fifteenth or nineteenth segment. Inner arm spine cylindrical, one arm segment in length, flattened, with blunt, thorny tip, slightly club-shaped (Fig. 14J, K ). Outer arm spine half as long as inner, with thorny tip (Fig. 14K ). Both arm spines equal in length at distal end of arm, and turning into compound hook with 3-5 secondary teeth (Fig. 14L ). Color . In ethanol, pink but when dried, dull brown to whitish (Fig. 14 ). Ossicle morphology. Lateral arm plate with two arm spine articular structures, with two large muscle and nerve openings (Fig. 15A ). Inner arm spine at proximal and middle half of arm cylindrical, with thorny tip (Fig. 15B ). Outer arm spine cylindrical with pointed tip (Fig. 15C ). Distally arm spine turns into compound hook with secondary teeth (Fig. 15D ). Arm and disc concealed by wider polygonal to rounded granular ossicles (Fig. 15E ). Vertebrae with streptospondylous articulation, dorsally a median longitudinal furrow, ventrally with deep median longitudinal groove with lateral ambulacral canals, no oral bridge, podial basins relatively small (Fig. 15F-J ). Figure 15. Asteroschema salix Lyman, 1879 (IDSSE-EEB-SW0082) A lateral arm plate B outer arm spine (middle) C inner arm spine (middle) D arm spine (distal) E skin from dorsal arm base (granular ossicles) F-J vertebrae F proximal view G distal view H lateral view I dorsal view J ventral view. Abbreviations: d dorsal, dist distal, lac lateral ambulacral canals, mo muscle opening, no nerve opening, pb podial basin, prox proximal, st secondary teeth, v ventral. Scale bars: 800 µm ( B, F-J ); 300 µm ( A, C, E ); 100 µm ( D ). Distribution. 341-1800 m depth. New Zealand, Tasman Sea, Kermadec Islands, Bay of Plenty, Solomon Island, Coral Sea, Timor Sea, South Africa (off Glenmore), the South China Sea. Remarks. Asteroschema salix was first described by Lyman (1879) , then redescribed by Lyman (1882) , Baker (1980) , McKnight (2000) , and Olbers et al. (2015) . These redescriptions are useful to understand individual morphological character variation of A. salix . Specimens from our collection concur with previous redescriptions, but we noticed some variation such as: slightly separated granular ossicles on the disc, fewer granular ossicles on the ventral arm surface, and slightly longer arms. However, most of these morphological variations vary within individual specimens according to previous descriptions ( Baker 1980 ; McKnight 2000 ). Asteroschema salix strongly resembles A. tubiferum , A. rubrum , A. laeve , A. inoratum , A. arenosum , and A. glaucum but the characters of granulations and ossicle shape on the disc and arm, radial shield, and inner arm spine can be used to delimit A. salix from these species (Table 2 ). Previously, A. salix had been recorded from the South Pacific Ocean, and South African waters at a wide distribution range. This is the first record from the South China Sea.