Sclerothyone Thandar, 1989

Thandar, Ahmed S., 2021, Nomenclatural changes in some sea cucumbers with the erection of a new genus and description of a Thyone? juvenile (? n. sp.) from the Gulf of California (Echinodermata: Holothuroidea: Dendrochirotida), Zootaxa 5026 (4), pp. 507-526 : 509

Genus Sclerothyone Thandar, 1989

? Cucumaria (partim) Ludwig & Heding, 1935: 192.

Sclerothyone Thandar, 1989: 296 ; 2008:14; Martinez & Brogger, 2014: 64 (passim); Martins & Tavares, 2018: 158 (passim); 2019: 376.

Type species.? Cucumaria velligera Ludwig & Heding, 1935 (by original designation Thandar 1989).

Type locality. Cape of Good Hope , South Africa, 318 m.

Diagnosis (from Thandar 1989, amended Martins & Tavares 2019).

A genus of the family Sclerothyonidae comprising small dendrochirotid holothuroids up to 35 mm long, with a barrel- to U-shaped body covered by thin but rigid skin. Tentacles 10, ventral pair reduced. Calcareous ring delicate, radial and interradial plates compact, meeting at base only, not forming a tube but with the radial plates carrying long, mostly undivided, paired processes several times the height of ring. Body wall ossicles comprise two-pillared tables and sometimes also plates. Tables with usually a 4-holed or multilocular, oval or lozenge-shaped disc with a short, often distorted and/or reduced spire, with or without teeth; plates smooth, elongate, also multilocular, representing reduced, spire-less stables.

Remarks. The genus is here again amended to take in the Japanese species Havelockia nozawai ( Mitsukuri, 1912) , which does not differ much from the type and other species of the genus. Although the genus may be characterised by both tables and plates in the body wall, the plates, occurring in combination with tables in S. nozawai at least, are clearly table discs which have lost their spire (an observation also made by Mitsukuri (1912) and by the reviewer).