A new species of the genus Nebalia (Crustacea: Phyllocarida: Leptostraca) from hydrothermal vent fields of the submarine Piip Volcano (the southwestern Bering Sea) described through molecular and morphological analysis

Abstract

A new leptostracan species, Nebalia piipensis sp. nov., collected during the 82nd cruise of the RV Akademik M.A. Lavrentyev on the submarine Piip Volcano (the southwestern Bering Sea) at depths of 400–472 m, has been described. These leptostracans were abundant at bacterial mats and in assemblages of chemosymbiotrophic bivalves Calyptogena pacifica (Pliocardiinae). Nebalia piipensis sp. nov. differs from the known Nebalia species by a set of features including a distally tapering eye-stalk mostly covered by an ommatidial part; a rostrum with the length 2.5 times the width; an article 2 of mandibular palps bearing three thin plumose and one thin simple seta; an article 1 of the second maxilla endopod 1.8 times longer than an article 2; furcal rami longer than the combined length of the pleonite 7 and telson; rounded denticles of pleonites 6 and 7; an indistinct anal-plates ‘shoulder’. Nebalia piipensis sp. nov. is the second species of the genus Nebalia reported from hydrothermal vent fields after N. tagiri, described from hydrothermal vents in Kagoshima Bay, at 200 m. The sequences of COI barcoding region, 16S and Histon H3 loci for the new species were obtained. The phylogenetic analysis based on COI sequence showed that all the northwestern Pacific species, including N. tagiri and N. piipensis sp. nov. are clustering together. However, N. piipensis sp. nov. is genetically closer to N. dolsandoensis from regular habitats than to the vent species N. tagiri. A preliminary examination of the body surface of the new leptostracan species using scanning electronic microscopy revealed a variety of epibiotic bacteria.