The first records of <i>Idarcturus trispinosus</i> and <i>Neastacilla paralongipectus</i> (Isopoda: Valvifera: Arcturidae) from Japan

Two arcturid isopod species, respectively belonging to the genera Idarcturus and Neastacilla, were collected by SCUBA diving from Izu Oshima, the Pacific coast of central Japan. Based on adult female specimens, these species were identified as I. trispinosus and N. paralongipectus, both of which were originally described from South Korea and represent the first records from Japan. Idarcturus trispinosus, in particular, was found in large numbers (N=25) on detrital red algae that accumulated on the seafloor. In this report, we also describe the pigmentation of these two species for the first time and provide partial sequences of cytochrome c oxidase subunit I (COI) and 16S rRNA (16S) from I. trispinosus.