Ophiopristis shenhaiyongshii, Nethupul & Stöhr & Zhang, 2022

Nethupul, Hasitha, Stöhr, Sabine & Zhang, Haibin, 2022, New species, redescriptions and new records of deep-sea brittle stars (Echinodermata: Ophiuroidea) from the South China Sea, an integrated morphological and molecular approach, European Journal of Taxonomy 810 (1), pp. 1-95 : 34-39

Ophiopristis shenhaiyongshii sp. nov.

urn:lsid:zoobank.org:act:31D1CA52-EBB3-4BCB-9327-BF43B085AB6D

Figs 17–19

Diagnosis

Disc spines rugose with two to three small terminal thorns on truncated tip or minutely bifurcated tip. Radial shields with distal end exposed. Oral shield distal edge with series of thick, rugose thorny spines. Ventralmost arm spine with longer thorns at lateral edge, distally with some ventrally directed thorns. Tentacle scales oval and pointed, two on the first three segments, thereafter one large scale.

Etymology

The specific name is dedicated to the manned submersible vessel ‘Shenhaiyongshi’, which collected the specimen.

Material examined

Holotype

CHINA • South China Sea , SE of Zhongsha Islands, seamount; 13°23.98′ N, 114°51.50′ E; depth 1360 m; 23 Sep. 2020; collection event: stn SC012; MSV Shenhaiyongshi leg.; preserved in 95% ethanol; GenBank: MZ 198776 ; IDSSE EEB-SW0022 .

Description

MEASUREMENTS. Disc diameter 6.3 mm, base of arm width 1.5 mm.

DiSC. Pentagonal and covered with translucent, perforated, rounded, overlapping scales bearing one or two tall spines ( Fig. 17A–C ). Disc spines 0.4 to 0.8 mm high, glassy, hollow, rugose with two to three small terminal thorns on truncated tip or minutely bifurcated tip. Disc spine height and shape change from center to periphery of disc ( Fig. 17C–G ). Central disc spines short (0.3–0.4 mm high), smooth, with one to two terminal thorns. Peripheral disc spines and around radial shields taller (0.6–0.8 mm high), strongly rugose, with subterminal tooth and two to three terminal thorns on truncated or bifid tip ( Fig. 17D–E ). Edge of disc periphery and distal margin of radial shield with few short thorny stumps with crown of two spinelets ( Fig. 17E ). Proximal ends of radial shields largely covered by disc scales, distal ends exposed, triangular, pair of shields widely separated ( Fig. 17G ). Ventral disc covered by scales with spines, but shorter and less dense than a dorsal disc. Oral shield wider than long, triangular with obtuse proximal angle, curved lateral margins, rounded to truncated distal edge with series of short, thick, rugose, thorny-tipped spines ( Figs 17H , 18A–B ). Adoral shield long, with straight lateral margin, but near first ventral arm plate slightly curved, pair of shields meeting proximally ( Fig. 18A ). Adoral shields enclose proximal edges of oral shield, curving to lateral plate of first arm segment, separating oral shield from arm. Jaw slightly longer than wide, opening of second tentacle pore superficial ( Fig. 18A ). Mostly two (one jaw has three) small, pointed tooth papillae on apex of jaw, below large pointed single column of teeth. Up to five finger-like, tapering, pointed lateral oral papillae. Two enlarged and flattened, pointed oral papillae arising from adoral shield and separated from other oral papillae, probably adoral shield spines ( Fig. 18A ). Genital slits conspicuous and extending from oral shield to periphery of disc ( Fig. 18B ). Oral surface covered by transparent integument, partially obscuring oral frame beneath, but only visible in live wet condition (fresh) ( Fig. 17H ).

ARMS. Five moniliform arms, with glassy plates ( Fig. 18C–F ). Dorsal arm plates separate, as long as wide, bell-shaped, with straight proximal end, slightly wavy distal margin covered with minute spines ( Fig. 18C–D ). Ventral arm plates as wide as long, with convex distal end, slightly obtuse proximal end, lateral edges concave, well separated along arm, axe head-shaped proximalmost arm plates ( Fig. 18E–F ). Lateral arm plates meeting above and below. Six arm spines. Three dorsal spines, three arm segments in length, laterally compressed, thorny, lateral margins with row of widely spaced, tall sharp thorns, apex truncated or bluntly rounded ( Fig. 18H ). Three ventral arm spines, one to two arm segments in length, laterally compressed, dense row of shorter, sharp thorns, apex truncated or blunt ( Fig. 18H ). Ventralmost arm spines with longer thorns at lateral edge, distally with some ventrally directed thorns, but without true hook-shape ( Fig. 18H ). Tentacle pores large, on up to three proximalmost segments with two scales, oval to pointed, one on lateral arm plate, other on ventral plate. Beyond third segment with single large tentacle scale on lateral plate, covering pore ( Fig. 17A, E–F ).

COLOR. In dried specimen glassy, darker in center but rest of specimen white and arm spines transparent ( Fig. 17A–B ). When alive, disc glassy dark brown, arms creamy white and arm spines transparent ( Fig. 17G–H ).

OSSiCLE MORPHOLOGY. Arm spine articulations well developed, volute-shaped, on protruding distal part of lateral plate with porous stereom, delimited from smooth middle part of lateral plate by thin wavy edge. Proximal edge of spine articulation entire, but connected with main part of lateral arm plate by short ridge. Arm spine articulation with large muscle opening and small nerve opening ( Fig. 19A–C ). Dorsal arm spine laterally compressed, thorny, several longitudinal rows of perforations with widely spaced, tall thorns, apex truncated ( Fig. 19D ). Vertebrae with zygospondylous articulation, with moderately expressed narrow dorsal furrow, distally abruptly truncated, and podial basins moderate in size ( Fig. 19E–I ). Ambulacral furrow with greatly widened middle, without oral bridge ( Fig. 19G ).

Remarks

The genera Ophiopristis and Ophiotreta are at present poorly delimited from each other. On the phylogenetic tree in Christodoulou et al. (2019) they are both polyphyletic and several species may have to be reassigned to other genera in a future taxonomic revision. Assigning our new species to either of them is therefore difficult. We compared the new species to the type species of both genera, Ophiotreta lineolata ( Lyman, 1883) and Ophiopristis hirsuta ( Lyman, 1875) . Both are present on the tree in Christodoulou et al. (2019), in different clades, suggesting that they indeed represent two different genera. According to the original description, O. lineolata has a cluster of tooth papillae, a dense dorsal disc cover of coarse grains intermingled with a few short spines, the radial shields are obscured by granules and there are 8–9 translucent, almost smooth arm spines and a single large tentacle scale on all but the first pore ( Lyman 1883). Ophiopristis hirsuta has elongated jaws with seven spiniform lateral oral papillae and no tooth papillae (although the illustration seems to show two tooth papillae), the dorsal disc is covered by short, fine spines (which on the illustration look rather long), the distal ends of the radial shields are exposed and swollen, the six arm spines are flattened, glassy and strongly serrated, and there are two large tentacle scales ( Lyman 1875). There was also a striking size difference, with O. lineolata having a disc diameter of 18 mm and O. hirsuta just 3.7 mm.

Ophiopristis shenhaiyongshii sp. nov. shares the disc spines, distally exposed radial shields, few or no tooth papillae, flat serrated arm spines and the small size with Ophiopristis hirsuta and differs from Ophiotreta lineolata in all respects. Hence, we propose to assign it to the genus Ophiopristis due to its similarity to the generic type species. It can be delimited from other species currently assigned to Ophiopristis as follows:

Ophiopristis dissidens ( Koehler, 1905) is similar to O. shenhaiyongshii sp. nov. by having exposed distal radial shields, the oral shield wider than long and widely separated ventral and dorsal arm plates, but differs by having smooth disc spines, two to three tentacle scales until the twelfth segment and a brown line running discontinuously along the dorsal surface of each arm ( O’Hara & Stöhr 2006).

Ophiopristis gadensis Rodrigues et al., 2011 is similar to O. shenhaiyongshii sp. nov. by having exposed radial shields, rugose disc spines with two or three thorns, the oral frame covered by a transparent integument and glassy arm plates and arm spines, but differs by having rounded pentagonal oral shields, contiguous dorsal and ventral arm plates, and two to three tentacle scales along the arm ( Rodrigues et al. 2011).

Ophiopristis shenhaiyongshii sp. nov. differs from most species of Ophiopristis by having a series of thorny spines on the distal margin of the oral shield. This character is only shared by O. luctosa ( Koehler, 1904) and O. procera ( Koehler, 1904) , and both species were first recorded from Indonesian waters. Ophiopristis luctosa differs from O. shenhaiyongshii sp. nov. by having long, thin, sharp, hollow, smooth disc spines, the radial shield largely obscured, small rounded oral papillae, ventral arm plates twice as long as wide, rectangular and contiguous, the ventralmost spine with a hook-like appearance and one oval tentacle scale, and a yellow color with a few broad brown bands on the arms ( Koehler 1904; O’Hara & Stöhr 2006). Ophiopristis procera differs from O. shenhaiyongshii sp. nov. by having completely concealed radial shields, the ventral arm plate twice as long as wide, rectangular and contiguous, the first pair of tentacle pores covered by tentacle scales variable in size and overlapping, and the following pairs only covered by one large, elongated oval scale, equal to the length of an arm segment. Ophiopristis shenhaiyongshii sp. nov. shares similar disc spine and arm spine characteristics with O. procera ( Koehler 1904) .

Distribution

South China Sea (1360 m). Near Zhongsha Islands, found on a deep-sea seamount.

Family Ophiacanthidae Ljungman, 1867

Genus Ophientrema Verrill, 1899

Figures

Fig. 17. Ophiopristis shenhaiyongshii sp. nov., holotype (IDSSE EEB-SW0022). A. Dorsal side of the specimen. B. Ventral side of the specimen. C. Overlapping disc scales. D–F. Various sizes of disc spines. G–H. Fresh specimen. G. Dorsal disc. H. Ventral disc. Abbreviations: ds = disc spine; dsc = disc scale; oss = oral shield spine; tts = thin transparent skin. Scale bars: A–B = 2 mm; C–E = 200 µm; F = 500 µm; G–H = 1 mm.

Fig. 18. Ophiopristis shenhaiyongshii sp. nov., holotype (IDSSE EEB-SW0022). A. Oral frame. B. Lateral disc. C–D. Dorsal arm (distal margin with minute spines highlighted on D). E–F. Ventral arm. G. Dorsal arm spines. H. Ventral arm spines. Abbreviations: as = adoral shield; dap = dorsal arm plate; das = dorsal arm spine; gs = genital slit; os = oral shield; oss = oral shield spine; ots = oral tentacle scale; tp = tentacle pore; ts = tentacle scale; vap = ventral arm plate; vas = ventral arm spine. Scale bars: A–C = 1 mm; D, G–H = 200 µm; E–F = 500 µm.

Fig. 19. Ophiopristis shenhaiyongshii sp. nov., SEM, holotype (IDSSE EEB-SW0022). A–C. Lateral arm plate. D. Dorsal arm spine. E–I. Vertebrae. E. Proximal view. F. Distal view. G. Ventral view. H. Dorsal view. I. Lateral view. Abbreviations: asa = arm spine articulation; D = dorsal; Dist = distal; mo = muscle opening; no = nerve opening; Prox = proximal; V = ventral; vs = volute-shaped. Scale bars: A, G–H = 500 µm; B–F, I = 300 µm.