A review of the species heretofore known as Pagurus japonicus (Stimpson, 1858), P. similis (Ortmann, 1892) and P. barbatus (Ortmann, 1892) has shown that the identity of the latter two species has been misinterpreted. Stimpson's species is identical with P. barbatus. Two species have been confounded under the name P. similis, one of which is herein described as new, P. rubrior n. sp. Pagurus japonicus and P. similis are fully redescribed and illustrated. Pagurus rubrior n. sp. can be distinguished from P. similis by the shorter ocular peduncle, more numerous accessory teeth on the ischium of the third maxilliped, more numerous spines and tubercles on the palm of the right cheliped, less slender dactylus of the right third pereopod, and red or reddish purple, rather than light orange, general coloration in life. The presence of slender capsules on the tubercles on the chelipeds is documented for P. japonicus, P. similis and P. rubrior n. sp. for the first time. Relationships among these three species and four other known species, P. sinuatus (Stimpson, 1858), P. hirtimanus (Miers, 1880), P. pergranulatus (Henderson, 1896) and P. capsularis McLaughlin, 1997, are also discussed.
Crustacea, Decapoda, Anomura, Paguridae, Pagurus, northwestern Pacific, new species.