Redefinition of Nipponbathynella based on the four new species from East Asia (Crustacea: Bathynellacea: Parabathynellidae)

Four new species of the parabathynellid genus Nipponbathynella Schminke, 1973 are described from South Korea (Nipponbathynella leesookyungae sp. nov., Nipponbathynella donggangensis sp. nov. and Nipponbathynella wanjuensis sp. nov.) and Japan (Nipponbathynella shigaensis sp. nov.), raising the number of known species to seven. Nipponbathynella leesookyungae is characterized by the convex ventral surface of the labrum and the rich ornamentation (with three spinules and two teeth) of the exopod of male thoracopod VIII; N. donggangensis by the distal spine on the distal maxillular segment with many dentils; N. wanjuensis by the endopod of the male thoracopod VIII with one seta (instead of two) and the serrated endopodal spur of the uropod; and N. shigaensis by the basipod of thoracopods II–VII carrying strong hairs on their outer margin. The three new and one known (Nipponbathynella pectina) South Korean species share a bur-like inner lobe of the male thoracopod VIII, suggesting their close relationship. Based on the one-segmented exopod on thoracopod I and two-segmented exopod on the thoracopods II–VII, the bell-shaped male thoracopod VIII and the uropod with sympod carrying a large distal spine in addition to several proximal spines of smaller size, with endopod drawn into a spur and with exopod carrying a seta, a close phylogenetic relationship between Nipponbathynella and Arisubathynella Park and Eun, 2012 is proposed.

http://zoobank.org/urn:lsid:zoobank.org:pub:9650379F-C249-473C-AAA4-B3D638B96322