Orphnurgus glaber Walsh, 1891

Mackenzie, Melanie, Davey, Niki, Burghardt, Ingo & Haines, Margaret L., 2024, A report of sea cucumbers collected on the first dedicated deep-sea biological survey of Australia’s Indian Ocean Territories around Christmas and Cocos (Keeling) Islands (Echinodermata: Holothuroidea), Memoirs of Museum Victoria (Mem. Mus. Vic.) 83, pp. 207-316 : 272

Orphnurgus glaber Walsh, 1891 sensu stricto

Orphnurgus asper Théel var. glaber Walsh, 1891: 198 .

Orphnurgus glaber Walsh, 1891 .— Koehler and Vaney 1905: 60– 62, pls. 8: 3, 12: 1–3.— Fisher, 1907: 706 (comment).— Hansen 1967: 491–493, figs 9, 10.— Hansen 1975: 39–46 (part, non O. insignis synonymy: 43–46), fig. 12, fig. 13 (part): 1–27 and 34–39, pl. 8: 5–7 (non O. insignis synonymy: fig. 13: 28–33 and 40–45).— Thandar, 1992: 175 (comment).— Rowe et al., 2017: 479–480, fig. 11.18.

Non Orphnurgus insignis . — Hansen 1975: 39–46 (part): fig. 13 (part): 28–33 and 40–45.

Orphnurgus invalidus Koehler and Vaney, 1905: 62-64 , pl. 12: 9.

Orphnurgus rigidus Ohshima, 1915: 234–235 .—Ohshima 1916– 1919, with one figure.

Amphideima investigatoris Koehler and Vaney, 1905: 59–60 , pls. 4: 6, 12: 8.

Material examined. NMV F296849 * (1) [IN 2021 V 04 022] ; NMV F296869 * (7) [IN 2021 V 04 035] ; NMV F296874 * (20) [IN 2021 V 04 046] ; NMV F296876 * (7) [IN 2021 V 04 048] ; NMV F308163 (7) , NMV F308164 (1) , NMV F308165 (1) and NMV F308166 (3) [IN 2022 V 08 108] ; NMV F308168 (17) [IN 2022 V 08 111] ; NMV F308254 * (1) and NMV F308255 (1) [IN 2022 V 08 141] ; NMV F308299 (1) and NMV F308300 (2) [IN 2022 V 08 157] .

Diagnosis of IOT material. Body elongated, strongly raised dorsally, flattened ventrally, and rounded at ends. Colour salmon-pink to orange or white. White when preserved but often brown or orange at tips of appendages. Body wall smooth, leathery, semitransparent. Papillae variable length, two rows on each dorsal radii plus lateral series above tube feet. Conspicuous, non-retractile ventrolateral tube feet of variable size in single to paired zigzag series along each side (e.g. ~24–25 each side NMV F308164). Extended tube feet can be almost same length as papillae but more cylindrical and less tapered at tip, with an obvious dark end disc (fig 41b). Midventral median line typically visible, mostly bare, sometimes partially scattered to two rows of much smaller tube feet often clearer anteriorly (e.g. ~22 midventral, one tenth size of ventrolateral in NMV F308254). Anus terminal and open. Mouth anterior, ventral, with non-retractile tentacles (~18 visible in NMV F308254). Tentacle disc margins with ramified (branching) processes. Body wall ossicles include smooth rods or spinous rods with solid (rarely flat), thorny ends and/or branched extremities dorsally (fig 41g – k) often the same but shorter and thicker ventrally (fig 41l–o). Lacking large ellipsoids, dumbbell-shaped transformed rods or spatulated rods or crosses. IOT specimens small to medium size (e.g. 36 mm long, 7 mm wide, 10 mm high; NMV 296849, preserved) to 60 mm long, 20 mm wide, 10 mm high ( NMV F296869, largest specimen in lot, preserved).

Remarks. Hansen synonymised four species into Orphnurgus glaber , made major revisions to the species diagnosis, and applied this to his key for the Orphnurgus genus ( Hansen, 1975). Cherbonnier and Féral (1981) subsequently raised O. insignis back out of synonymy and added new species O. bacillus to the genus. Thander (1992) agreed with Cherbonnier and Féral and added two new species, O. aspersignis and O. natalasper . Pawson (2002) added the most recent new species, O. dorisae . These changes make Hansen’s 1975 keys and images for O. glaber unreliable until further investigation can be undertaken. The more recent key ( Pawson, 2002) was based only on ossicles and attempted to clarify some of the changes since Hansen (1975), but suggests that spinous rods are absent and spatulate rods present in O. glaber . We note that this is based on Hansen’s amended diagnosis, which at the time nominated spatulated rods as the dominant ossicle for O. glaber , presumably from one of his synonymies because the original description only notes ossicles as “spinous rods or smooth rods with branched extremities” ( Walsh, 1891). Hanson does not mention re-examining type material to amend this diagnosis. Identifications here are based on Walsh’s (1891) sensu stricto description of O. glaber , with IOT specimens matching the colour, external morphology and ossicles of the type description. Ossicles in IOT specimens are smooth rods with branching or thorny ends but lacking ventral “fat” ellipsoid or dumbbell-shaped transformed rods, which agrees with Thander (1992) (sensu Walsh) and Fisher (1907) (referring to Koehler and Vaney, 1905), and with no spatulated rods. Genetics show sampled IOT O. glaber as a new lineage on GenBank, grouping together well but separately from O. glaber previously identified (with limited confidence – NMV catalogue) from northwest Australia (fig. S5). We identify the IOT material as Orphnurgus glaber Walsh, 1891 sensu stricto, noting that this genus requires further genetic and morphological work to establish clear characters between species. Finally, we report that parasitic Eulimid gastropods (Field number IN 2022 V 08 141 129) were found attached ventrally to specimen NMV F308254.

Distribution. Widely distributed in Indo-west Pacific, recorded from off southern Africa in the Indian Ocean to Hawaii and Tahiti in the Pacific Ocean.

Full bathymetric range. 397–1553 m (IOT 1019–1533 m).

Type locality. Bay of Bengal , 1025 m .

In Australia this species was not previously recorded in AFD but recorded (identified with limited confidence) from off northwest Australia at depths of 397–990 m in ALA (January 2024). These records and IOT material extend the previously known bathymetric range from 700–1025 m to 397–1553 m, with Australian examples showing the full known depth range of the species, but with the comment that many O. glaber as currently known may need revision .

References. AFD (2024), ALA (2024), Cherbonnier and Féral (1981), EOL (2024), Fisher (1907), Hansen (1975), Ohshima (1915), Pawson (2002), Thander (1992), Théel (1879), Walsh (1891).