Pseudostolus, Thandar, 2021

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 : 512

Pseudostolus n. gen.

Stolus (partim) Selenka, 1867: 355; Panning, 1949: 462; Clark & Rowe, 1971: 204; Pseudothyone (partim) Panning, 1949: 456.

Diagnosis. A genus of Thyonidae with body wall comprising tables and complex, multilayered or reticulated, smooth plates; no knobbed buttons/plates in body wall.

Type species. Stolus kilberti Rajpal & Thandar, 1999 .

Type locality. N.E. of Lieveldt’s Rock , KZN, South Africa, 27° 42.9’ S, 32° 39.1’ E .

Other species included. Stolus rapax Koehler & Vaney,1908 .

Remarks. Both Pseodostolus kilberti ( Rajpal & Thandar, 1999) and P. rapax ( Koehler & Vaney, 1908) are well described and hence there is no need for further descriptions. They are well characterised by the presence of smooth reticulated plates in the body wall, made up of more than one layer of calcareous material, although some plates may be simple (non-reticulate) they are still smooth. Those of P. rapax are rounded, up to 1 mm in length, whereas those of P. kilberti are elongated, up to 0.5 mm in length. The deposits in the former also include tables with a reduced spire whereas those of the latter also include tables which, in contrast, possess an elongated, spine-like spire. The podia of the former species ( P. rapax ) are better developed ventrally as hair-like outgrowths while those of the latter are shorter, villose and evenly distributed. Another species with ossicles like those of P. rapax is Pseudothyone mosaica ( Koehler & Vaney 1910) from the Arabian Sea but since the calcareous ring of this species consists of compact, unfragmented plates it is left to stand in Pseudothyone . The differences between the three species are well tabulated by Rajpal & Thandar (1999). Panning (1949) considered S. punctatus Ohshima, 1915 from Japan as being also a form with smooth plates and this error was reiterated by Rajpal & Thandar (1999) and Thandar (2005) in their key. Although Ohshima (1915) does not illustrate the ossicles of his species he does state that they resemble those of T. belli Ludwig, 1887 (now Pseudothyone belli ) and Thyone similis Ludwig, 1887 [(now a junior synonym of Neothyone gibber Selenka (1867) ]. It is therefore here left to stand in Stolus as accepted by WoRMS (529676, accessed 16 June 2021).