Psychronaetes Pawson, 1983

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 : 227

Genus: Psychronaetes Pawson, 1983

Diagnosis (amended from Pawson, 1983). Body typically fusiform, maximum length approximately 30 cm. Ventrolateral radii each with approximately 15 tube feet, bare along midventral line. Dorsal papillae on each radii, and additionally forming an irregular anterior brim. Fifteen tentacles, no circumoral papillae. Ossicles in body wall are wheels, one type but variable size, typically 50 μm or more in diameter, usually with 9–12 spokes.

Remarks. Psychronaete s is a monotypic genus represented by P. hanseni , which was described from two type specimens in the eastern central Pacific CCZ and not previously recorded for Australia (WoRMS and ALA January 2024). Similar in morphology to Laetmogone , it can sometimes be split in underwater images thanks to a distinct “head” region and fused anterior fringe of dorsal papillae. A potential new species of Psychronaetes (sp. CCZ_101) was recently reported from the abyssal seafloor of the central CCZ at 3132–3562 m (Bribiesca et al., 2022). A single damaged specimen, Psychronaetes sp. MoV.7326, was collected from these IOT voyages at a depth of 3053–3144 m and is recorded below. Diagnosis of genus amended to be less restrictive with tube foot shape and papillae number and to clarify ossicle wheel description.