Asteroschema rubrum 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/42A26B36-728D-5797-8383-B380FCAE07A5

treatment provided by

ZooKeys by Pensoft

scientific name

Asteroschema rubrum Lyman, 1879
status

 

Asteroschema rubrum Lyman, 1879

Figures 10 View Figure 10 , 11 View Figure 11

Asteroschema rubrum Lyman, 1879: 68-69, fig. 17, figs 454-457.

Material examined.

China • 3 specimens; South China Sea , near Zhongsha Islands, seamount; 13°55.44'N, 115°25.37'E; depth 958 m; 09 Mar. 2020; Collecting event: stn. SC007; ‘Shenhaiyongshi’ msv leg; preserved in -80 °C; GenBank: OK044293, OL712209, OK044294, OL712210, OK044295, OL712211 ; IDSSE-EEB-SW0071, IDSSE-EEB-SW0072, IDSSE-EEB-SW0073 • 1 specimen; South GoogleMaps China Sea , near Zhongsha Islands, seamount; 14°21.93'N, 115°23.89'E; depth 922 m; 17 Mar. 2020; Collecting event: stn. SC035; ‘Shenhaiyongshi’ msv leg; preserved in -80 °C; IDSSE-EEB-SW0088 GoogleMaps .

Description.

IDSSE-EEB-SW0072: disc diameter 12 mm, length of arms from 165-175 mm (Fig. 10 View Figure 10 ).

Disc. Disc flat, slightly raised above arms, swollen in center, and small in relation to total body size of specimen (Fig. 10A, B View Figure 10 ). Disc covered with smooth, dense, evenly distributed, small rounded or irregular granular ossicles, similar in size (seven or eight granular ossicles in 1 mm; Fig. 10C, D View Figure 10 ). Radial shields closely together, parallel, raised above distal disc edge, but mostly concealed by skin with granular ossicles (Fig. 10C View Figure 10 ). Radial shields do not meet in center. Genital slits wide and vertical on ventral interradii (Fig. 10E View Figure 10 ). Jaw large, long and covered with dense irregular ossicles (Fig. 10F View Figure 10 ). Spearhead-shaped teeth and granular ossicles that resemble lateral oral papillae at apex of jaw (Fig. 10F View Figure 10 ). Adoral shields large, connected to first ventral arm segment, and concealed by granular ossicles (Fig. 10F View Figure 10 ). Oral shields not discernible and adoral shield spine naked. Whole oral region swollen nearly to genital slit. Ventral disc covered with dense granular ossicles (seven or eight grains in 1 mm; Fig. 10F View Figure 10 ).

Arms. Arms at base wide, not arched, dorsally flattened, and slightly swollen in first few free segments (Fig. 10A, G View Figure 10 ). Arms distalwards from middle part narrowing and more cylindrical (Fig. 10H View Figure 10 ). Dorsal arm base covered with smooth rounded granular ossicles (six or seven grains in 1 mm), middle segments with dense granular ossicles all the way to the arm spine base (seven or eight grains in 1 mm), and distally decreasing in size and separated (seven or eight grains in 1 mm) (Fig. 10G-L View Figure 10 ). Ventral arm base covered with dense granular ossicles similar to the ventral disc (eight or nine grains in 1 mm), distally decreasing in size and separated to naked (Fig. 10H-K View Figure 10 ). First one to two tentacle pores without arm spine (Fig. 10F View Figure 10 ). First arm spine appears at second or third arm segment, and second arm spine at ninth or eleventh segment (Fig. 10I View Figure 10 ). Outer arm spine half as long as inner spine in middle region, thorny pointed tip, distally compound hook (Fig. 10K, L View Figure 10 ). Inner arm spine cylindrical, one to one and a half arm segment in length, initially tapering to a pointed thorny tip, in middle blunt, slightly swollen with thorny surface on more than half its length, distally compound hook with three or four secondary teeth (Fig. 10I-L View Figure 10 ).

Color. In live specimen, reddish brown (Fig. 10 View Figure 10 ).

Ossicle morphology.

Lateral arm plate with two arm spine articular structures, with slightly separate large muscle and nerve openings (Fig. 11A View Figure 11 ). A depression on inner side of lateral arm plate (Fig. 11B View Figure 11 ). Inner arm spine from proximal and middle half of arm cylindrical, slightly swollen, with thorny tip (Fig. 11C View Figure 11 ). Distally arm spine turns into compound hook with secondary teeth (Fig. 11D View Figure 11 ). Arm and disc concealed by granular ossicles, slightly wider than high, round to short stumps with convex tip (Fig. 11E View Figure 11 ). Vertebrae with streptospondylous articulation, with deep slope between proximal and distal end, dorsally a median longitudinal groove, ventrally with median deep longitudinal groove with lateral ambulacral canals, podial basins moderate in size (Fig. 11F-J View Figure 11 ).

Distribution.

730-958 m depth. Near Brandella, Chile and in the South China Sea.

Remarks.

Asteroschema rubrum was first described by Lyman (1879), with type locality in the Southwest Pacific Ocean near South America. This is the first rediscovery after the original description. The specimens from our collection concur well with Lyman’s holotype description, the only difference was the starting point of the second arm spines. However, this morphological character is highly variable among individuals. According to the holotype description, A. rubrum belongs in the clade with granular ossicles only in the genus Asteroschema , but Okanishi and Fujita (2009) considered A. rubrum in the clade with conical and granular ossicles. Although, the SEM images of granular ossicles in the skin appear as granular to somewhat small stumps with convex tip (Fig. 11E View Figure 11 ). However, the description of the holotype is identical with our specimen, and it was described as granular ossicles. The characters of the swollen oral region, smooth granulation on the disc, and innermost spine can be used to distinguish A. rubrum from other species of Asteroschema (Table 2 View Table 2 ). The dorsal disc of A. rubrum seems naked in wet condition due to its smooth granulation which can lead to misidentification as Ophiocreas species (Fig. 10A View Figure 10 ). This is the first record from the South China Sea.

Kingdom

Animalia

Phylum

Echinodermata

Class

Ophiuroidea

Order

Euryalida

Family

Euryalidae

Genus

Asteroschema

Loc

Asteroschema rubrum Lyman, 1879

Nethupul, Hasitha, Stoehr, Sabine & Zhang, Haibin 2022
2022
Loc

Asteroschema rubrum

Lyman 1879
1879