Tsuranarthrura shinsei, a New Genus and Species in Anarthruridae (Crustacea: Tanaidacea) from the Northwestern Pacific

We establish the new anarthrurid genus Tsuranarthrura gen. nov. based on the new species T. shinsei sp. nov. collected from 1890 m depth off the eastern coast of Japan, northwestern Pacific Ocean. Tsuranarthrura gen. nov. is the third paratanaoid genus with members having a fused segment composed of pereonite 6 and the pleon, a character state previously restricted to the genera Coalecerotanais Larsen, 2003 (Family incertae sedis) and Metagathotanais Bird and Holdich, 1988 (Family Agathotanaidae). Among anarthrurid genera, Tsuranarthrura gen. nov. is similar to Anarthrura Sars, 1882, Anarthrurella Bird, 2004, and Crenicarpus Drumm and Bird, 2016 in having the labrum not laterally compressed and the antenna with naked fourth and fifth articles from the distal end. However it differs from the latter three in having pereonite 6 fused with the pleon, the maxillipedal endite with a distal seta, the chelipedal merus with a ventral simple seta, and the merus naked on pereopods 2 and 3. We also present the nucleotide sequence for part of the cytochrome c oxidase subunit I (COI) gene in T. shinsei for future use in DNA barcoding or phylogeny.