Asteroschema salix Lyman, 1879

Nethupul, Hasitha, Stoehr, Sabine & Zhang, Haibin, 2022, Order Euryalida (Echinodermata, Ophiuroidea), new species and new records from the South China Sea and the Northwest Pacific seamounts, ZooKeys 1090, pp. 161-216 : 161

publication ID	https://dx.doi.org/10.3897/zookeys.1090.76292
publication LSID	lsid:zoobank.org:pub:3B13C71E-E11B-49D2-891C-050DBD514872
persistent identifier	https://treatment.plazi.org/id/6AA0A5B6-5BD5-53F3-BA59-D1CDDFD2CFBA
treatment provided by	ZooKeys by Pensoft
scientific name	Asteroschema salix Lyman, 1879
status

Treatment

Figures 14 View Figure 14 , 15 View Figure 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 GoogleMaps .

Description.

Disc diameter 10 mm, length of arms 145 mm (Fig. 12 View Figure 12 ).

Disc. Disc flat, strongly raised above arms (Fig. 14A, B View Figure 14 ). 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 View Figure 14 ). Radial shields long, narrow, widely separated distally, convergent proximally, meeting in disc center (Fig. 14C View Figure 14 ). Genital slits narrow, and vertical on ventral interradii (Fig. 14E View Figure 14 ). Jaws elongated, covered with granular ossicles but near apex fewer granular ossicles (Fig. 14E View Figure 14 ). Flattened, spearhead-shaped teeth and granular ossicles that resemble lateral oral papillae at apex of jaw (Fig. 14E View Figure 14 ). Ventral disc covered with granular ossicles similar to dorsal disc (six or seven grains in 1 mm), slightly separated (Fig. 14E View Figure 14 ). Adoral shields large, connected to first ventral arm segment, concealed by thin skin with granular ossicles, but plate outline visible (Fig. 14E View Figure 14 ). Oral shields not discernible and adoral shield spine covered with ossicles (Fig. 14E View Figure 14 ).

Arms. Arms sub-cylindrical, not swollen, narrower and more cylindrical in distal half of arm (Fig. 14F, G View Figure 14 ). 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 View Figure 14 ). On lateral arm plate, granular ossicles continue toward base of arm spine (Fig. 14G, J View Figure 14 ). 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 View Figure 14 ). First tentacle pore without arm spine (Fig. 14E View Figure 14 ). 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 View Figure 14 ). Outer arm spine half as long as inner, with thorny tip (Fig. 14K View Figure 14 ). Both arm spines equal in length at distal end of arm, and turning into compound hook with 3-5 secondary teeth (Fig. 14L View Figure 14 ).

Color. In ethanol, pink but when dried, dull brown to whitish (Fig. 14 View Figure 14 ).

Ossicle morphology.

Lateral arm plate with two arm spine articular structures, with two large muscle and nerve openings (Fig. 15A View Figure 15 ). Inner arm spine at proximal and middle half of arm cylindrical, with thorny tip (Fig. 15B View Figure 15 ). Outer arm spine cylindrical with pointed tip (Fig. 15C View Figure 15 ). Distally arm spine turns into compound hook with secondary teeth (Fig. 15D View Figure 15 ). Arm and disc concealed by wider polygonal to rounded granular ossicles (Fig. 15E View Figure 15 ). 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 View Figure 15 ).

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 View 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.

Kingdom	Animalia
Phylum	Echinodermata
Class	Ophiuroidea
Order	Euryalida
Family	Euryalidae
Genus	Asteroschema