A new genus of Munnopsidae Lilljeborg, 1864 (Crustacea, Isopoda), with descriptions of two abyssal new species from the Clarion Clipperton Fracture Zone, north-eastern tropical Pacific

Abstract

A new deep-sea genus of the asellotan family Munnopsidae Lilljeborg, 1864, Pirinectes Malyutina & Brix gen. nov., including two new species, is described from the abyssal manganese nodule area of the Clarion Clipperton Fracture Zone in the north-eastern tropical Pacific. The new genus of the subfamily Eurycopinae Hansen, 1916, which is distinguished genetically, differs morphologically from the other six genera of this subfamily by the unique combination of the following characters: a rostrum approximately one third of the cephalon width and as long as antenna I article 1, with rounded margins, and the fingerprint pattern surface; pereonites 5 and 6 are fused dorsomedially, pereonite 7 is free; antenna I article 1 is without distomedial lobe and with small a distolateral projection; epipod of the maxilliped is less than two thirds of basis length and ovoid. Unique for the subfamily is the long pereopod II ischium, which is longer than the basis. Such characteristics can only be found in some munnopsid genera of the subfamily Munnopsinae Lilljeborg, 1864. Confirmed as distinct species by genetic analysis, the two new species can be morphologically distinguished from each other via a difference in width of the cephalon rostrum, the length of the palp and epipod of the maxilliped, length and width of distomedial lobes of pleopod 1, the width of carpi of the pereopods I, V and VI, and the different ratio of the uropod rami length. An illustrated identification key to the species of the Pirinectes gen. nov. is presented.