A mature adult female of Ito£tantulus misophricola Huys, Ohtsuka & Boxshall, 1992 (Crustacea: Tantulocarida: Deoterthridae) is described for the first time from the host misophrioid copepod Misophriopsis okinawensis Ohtsuka, Huys, Boxshall & ItO, 1992 collected off Okinawa, South Japan. The female contains 26 mature, spherical eggs of ca. 30 fJm in diameter in the trunk sac, and is characterized by the lack of an elongate neck region formed between the larval cephalon and the expanded trunk sac. Mature females of the families Basipodellidae, Deoterthridae and Doryphallopholidae possess a characteristic of the lack of an elongate neck region, whereas those of the families Microdajidae and Onceroxenidae, in particular, Microdajus spp., have a well-developed neck region.