Nebaliella ochotica sp. nov.—new deep-sea species of leptostracans (crustacea: phyllocarida: leptostraca) from the North-west Pacific

Abstract

Eleven specimens of leptostracans were collected with the help of the camera-epibenthic sledge (C-EBS) in August 2015 at depth 3287–4469 m in the Kurile depression of the Sea of Okhotsk and in the Pacific Ocean to the east of the Boussole Strait (Kurile Islands) during the Russian-German expedition Sokho-Bio. All these specimens relate to new species of genera Nebaliella Thiele, 1904 from family Nebaliidae: N. ochotica. Nebaliella ochotica sp. nov. varies from the other species of Nebaliella by the unique values of the ratio of the rostral flange to exposed keel (2 : 1 in N. ochotica, 3 : 1 in N. antarctica, and 1 : 1 in other species). In this species, article 2 of mandible palp has 1 long seta by distodorsal corner, without stout spicular process and small setae; exopod of pleopod 1 has 5 stout long spicular setae on lateral border, with 1–2 stout long spicular setae on terminal border and with 1–3 distal spicular setae and 10–17 simple setae on medial border. Moreover, N. ochotica differentiates from N. brevicarinata, N. extrema and N. kurila by the absence of carina on anterolateral lower corner of carapace, arom N. brevicarinata and N. extrema—by the absence of ventroproximal tuberculate process on rostrum, and from N. antarctica and N. kurila—by compound articles 1 and 2 on peduncle of antenna.