Four species of <i>Mesanthura</i> (Crustacea: Isopoda: Anthuroidea) from Japan, including the description of a new species

Abstract Anthuroid isopods in the genus Mesanthura (52 valid species) typically have a body with conspicuous dorsal pigmentation, with differences in the female pigmentation pattern being one of the main characters used to distinguish species. Five Mesanthura species have been reported to date from Japan. Here, we describe Mesanthura sol sp. nov. from Irabu Island and Okinawa main island, Okinawa, Japan, and illustrate its sexual dimorphism in colour pattern, with conspecificity between males and females confirmed with molecular data. We provide a description of Mesanthura miyakoensis based on specimens collected from Kochi, Shikoku, Japan. We present the first records of Mesanthura cinctula and Mesanthura nigrodorsalis , following their original descriptions. Finally, we provide partial sequences of the 16S rRNA gene for these four species and present a phylogenetic tree based on the sequences.