Echinopsolus Gutt, 1990

O’Loughlin, P. Mark, 2016, The Discovery Expedition sea cucumbers (Echinodermata: Holothuroidea), Memoirs of Museum Victoria 75, pp. 53-70 : 65-68

1. Echinopsolus Gutt, 1990 .

Bohn & Hess (2014) reassigned a group of Antarctic cucumariid species to genus Echinopsolus Gutt, 1990 , based on their shared and unique set of morphological characters related to their reproductive mode. The group comprised: Echinopsolus acanthocola Gutt, 1990 ; E. acutus ( Massin, 1992) ; E. charcoti ( Vaney, 1906) ; E. koehleri ( Vaney, 1914) ; E. mollis ( Ludwig & Heding, 1935) ; E. parvipes ( Massin, 1992) ; E. splendidus ( Gutt, 1990) . In the same paper Bohn & Hess (2014) reassigned genus Echinopsolus to family Cucumariidae .

Taxon Type status Station collected Locality collected Depth Date collected Institution lodged Registration Clarkiella discoveryi Heding (in Heding & Panning, 1954) 1Holotype D 474 W of Shag Rocks South Georgia 199 m 19 Nov 1930 ZMUC HOL–000064 Clarkiella discoveryi Heding, 1954 1Paratype D 474 W of Shag Rocks South Georgia 199 m 19 Nov 1930 ZMUC HOL–000247 Parathyonidium incertum Heding (in Heding & Panning, 1954) 2, 3Holotype 3Lost specimen 3HOL–000093 Parathyonidium incertum Heding, 1954 Paratypes (3) D 170 Clarence Island 342 m 23 Feb 1927 ZMUC HOL–000300 Parathyonidium incertum Heding, 1954 Paratypes (3) D 170 Clarence Island 342 m 23 Feb 1927 NHMUK NHMUK 2011.171–173 Parathyonidium incertum Heding, 1954 Partypes (2) No record Elephant Island 600 m No record MNHN MNHN– IE–2013–2479

S Shetland Islands

O’Loughlin et al. (2009a) discussed the “ Cucumaria georgiana ( Lampert, 1886) group” of Antarctic species that was created by Gutt (1988), and followed by Massin (1992). O’Loughlin et al. (2009a) listed 11 species in this “group”: Cucumaria acuta Massin, 1992 ; Cucumaria analis Vaney, 1908 ; Cucumaria aspera Vaney, 1908 ; Cucumaria attenuata Vaney, 1906 ; Cucumaria georgiana ( Lampert, 1886) ; Cucumaria joubini Vaney, 1914 ; Cucumaria lateralis Vaney, 1906 ; Cucumaria perfida Vaney, 1908 ; Cucumaria periprocta Vaney, 1908 ; Cucumaria secunda Vaney, 1908 ; Cucumaria vaneyi Cherbonnier, 1949 . Bohn & Hess (2014) also discussed this “group”, and we agree that the systematic status of the species in this group requires resolution. Foundational to this systematic resolution must be an establishment of the systematic status of Cucumaria georgiana ( Lampert, 1886) . Bohn & Hess (2014) did not assign the “group” to Echinopsolus . We have assigned some Discovery Expedition lots to this “group”. Based on the general similarity of their reproductive morphological features with those of the Echinopsolus species we have also assigned this “group” to Echinopsolus .

Bohn & Hess (2014) were not able to confirm the systematic status of Echinopsolus excretiospinosus Massin, 2010 , but noted that no brood pouches were reported and the ventral tentacle pair were apparently not smaller than the other tentacles.

CO1 genetic data (Gustav Paulay pers. comm.; see phylogenetic tree in O’Loughlin et al. 2011) support a generic clade that includes Echinopsolus acanthocola (with apparently two or three cryptic species with geographic congruence), the “ georgiana group” (with apparently two or three cryptic species with geographic congruence), and the reassigned Echinopsolus mollis (apparently two or three cryptic species with geographic congruence). Generic data thus support in part the work of Bohn & Hess (2014). We note that these species also have mid-body dorsal papillae or tube feet, and lack cup (bowl) ossicles in the body wall.

But CO1 genetic data (Gustav Paulay pers. comm.; see phylogenetic tree in O’Loughlin et al. 2011) support a generic clade for Psolus koehleri and Psolus charcoti that is separate from the Echinopsolus clade and do not support the reassignment of these two species to Echinopsolus . We note that these two species lack mid-body dorsal tube feet or papillae, and do have cup (bowl) ossicles in the body wall. Genetic data to date do not support their assignment to a Psolus Oken, 1815 clade. We leave these two species in their current reassignment to Echinopsolus until a necessary reassessment of dendrochirotid generic assignments is supported by additional genetic data.

We do not have a CO1 sequence for the recently reassigned Echinopsolus splendidus . This species lacks dorsal and lateral tube feet / papillae, but also lacks cups / bowls in the body wall. It falls morphologically into neither Echinopsolus genetic /generic clade. We judge that it will probably fall into another generic clade but in the absence of supportive genetic data we do not change the current reassignment to Echinopsolus .