Genus Psolus Oken, 1815

Type species. Psolus phantapus (Strussenfelt, 1765) [ Holothuria] by monotypy. Genus masculine. [ICZN, Opinion 2367, 2015: 237–238].

Remarks. Psolus stands out from other psolids mainly by the absence of tube feet in the dorsal region and by the set of the following characters: large imbricating or contiguous dorsal and lateral scales; ventro-lateral scales at margin clearly demarcated from thin sole which lacks conspicuous scales; tube feet absent on dorsum, except sometimes present adjacent to mouth and anus. Ten dendritic tentacles, eight large and two small ventrally (O’Loughlin & Whitfield, 2010).

In the southwestern Atlantic and Magellanic region, six species of Psolus are currently recognized (Tommasi, 1971; Mackenzie & Whitfield 2011; Davey & Whitfield, 2013; Martinez, 2016), pending the validity of P. marcusi Tommasi, 1971 (see below): P. vitoriae Tommasi, 1971 (São Paulo, Brazil); P. patagonicus Ekman, 1925 (Mar del Plata to Tierra del Fuego, Argentina; and Cape Horn and Strait of Magellan Chile); P. segregatus Perrier, 1905 (Patagonia, Argentina; Chilean part of the Strait of Magellan; Hikurangi Margin and Chatham Rise, New Zealand); P. antarcticus (Phillipi, 1857) (Strait of Magellan; South Georgia Island, southern Atlantic Ocean; Macquarie Island and Ridge, New Zealand); P. lawrencei Martinez & Penchaszadeh, 2017 (Mar del Plata, Argentina) and Psolus murrayi Théel, 1886 (Montevideo, Uruguay). Two new species from off the southeastern Brazilian coast are described below.