Abstract
Two new mite species of the genus Thinoseius are described and illustrated on the basis of material collected from intertidal zones in northern Japan. Another intertidal species, Thinoseius occidentalipacificus Klimov, 1998, is recorded from Japan for the first time. Thinoseius sawadai sp. nov. and T. occidentalipacificus inhabit tidal wrack, and T. setifer sp. nov. was found on the pleopods of the sea slater Ligia cinerascens Budde-Lund, 1885 (Isopoda). This is the first record of eviphidid mites from a ligiid isopod. The deutonymphs of T. occidentalipacificus and T. setifer show a probable sexual dimorphism in the number of dorsal and/or opisthogastric setae.
