Morphological and Molecular Evidence for the Identity of Two Land Hermit Crabs Coenobita longitarsis De Man, 1902 and C. pseudorugosus Nakasone, 1988 (Crustacea: Decapoda: Anomura: Coenobitidae).

Two species of land hermit crabs, Coenobita longitarsis De Man, 1902 and C. pseudorugosus Nakasone, 1988 were described based on female specimens from Maluku, Indonesia and specimens from Cebu, the Philippines, respectively. However, no confirmed records of either species have been reported since their original descriptions. In this study, we examined specimens with typical morphological characters of C. longitarsis from Papua New Guinea and C. pseudorugosus from the Philippines and Indonesia, further supported by the analyses of the DNA barcoding marker, cytochrome oxidase subunit I (COI). The characters of male C. longitarsis are provided for the first time, with coxae of male fifth pereiopods subequal, without sexual tubes developed. Their slender morphology is suggested to be an adaptation to utilize native terrestrial snail shells in inland forests, which may also explain its rarity. Coenobita pseudorugosus is very similar to C. rugosus H. Milne Edwards, 1837, but can be distinguished by the adult sizes, as well as the morphology of sexual tubes of male fifth pereiopods and propodus of left third pereiopod. Morphological variation and the fresh coloration of C. longitarsis and C. pseudorugosus are also provided in this study.