Deima Théel, 1879

Genus Deima Théel, 1879 View in CoL

Diagnosis. (following Hansen, 1975). Tentacles 18–20, retractile into the oral cavity; discs with rounded knobs on the margin. Circumoral papillae present. Ossicles perforated plates, consisting of one or several layers of meshwork.

Remarks. The taxonomy for the cosmopolitan genus Deima has remained consistent since Hansen’s uniting of the previous six species into one ( Deima validum ) represented as two subspecies, Deima validum validum Théel, 1879 , found worldwide, and Deima validum pacificum Ludwig, 1894 , known only from the Gulf of Panama in the eastern Pacific ( Hansen, 1975). Six lots of Deima were recorded from the IOT voyages at depths of 1175–4990 m, and further identified to: Deima validum validum (4 lots), and one new species Deima oloughlini Mackenzie and Davey sp. nov. (2 lots). The external morphology, clearly retractable tentacles, circumoral papillae and typically a wider oval shape are the easiest features to distinguish Deima from similar-looking animals ( Oneirophanta and Orphnurgus ) in this family. The Deima samples sequenced form two well-supported genetic clades ( D. validum and D. oloughlini Mackenzie and Davey sp. nov.) which are separated by net pairwise distances of 12.7% for COI and 3.8% for 16S (fig. S5).