A new species of Athelges (Crustacea, Isopoda, Epicaridea, Bopyridae) from Japan, with morphological and DNA barcode data

Athelges pileus sp. nov. is described as an abdominal bopyrid of the hermit crab Diogenes edwardsii collected from the Noto Peninsula, Japan. Athelges pileus sp. nov. is distinguished from its congeners by the following combination of characters. Female: head deeply sunk in thorax, anterolateral margin of head with pair of notches; anterior margin of frontal lamina concave; merus of pereopod 1 with broad and long projection ventrally; pereopods 5 and 6 with large gap between them; pleomeres 1–4 each with subovate biramous pleopods; each pleopod with peduncle, becoming smaller posteriorly; pleotelson with mushroom-shaped end.

Male: pleon subovate with anal cone distally. The present species is the 14 th member of the genus Athelges, and the second species from Asia. This is the second species of Athelges infesting Diogenes edwardsii.

We also provide a partial sequence of the mitochondrial cytochrome c oxidase subunit 1 (COI) gene (658 bp), mitochondrial 16 S rRNA gene (482 bp), and nuclear 18 S rRNA (724 bp) as a DNA barcode for the species. We show by molecular phylogenetic analysis that the present species is distinct from A. takanoshimensis.