Hermit crabs (Crustacea: Decapoda: Anomura: Paguroidea) from submarine caves in the Ryukyu Islands, south-western Japan

Hermit crabs collected from submarine caves in the Ryukyu Islands, southwestern Japan, were represented by one species of the Diogenidae and six species of the Paguridae, including two new species of Catapaguroides A. Milne-Edwards and Bouvier, 1892. Two new species named Catapaguroides iejimensis and C. kasei are described and illustrated in detail. These taxa appear most closely allied to C. foresti McLaughlin, 2002a, in the shape of carpus and chela of the right cheliped and completely unarmed left chela. However, C. iejimensis is immediately distinguished from C. foresti and C. kasei by having slightly dilated and semi-sphere-shaped corneas of the ocular peduncles (in the latter two species, reduced and cone-shaped corneas) and two or three spines proximally on the dorsal surface of the palm of the right cheliped (in the latter two species, unarmed on the dorsal surface of the right palm). Catapaguroides kasei closely resembles C. foresti, but differs from the latter in the length of the carpus of the left cheliped. This unusual species has tapering ocular peduncles with reduced and cone-shaped corneas, very long antennular peduncles, and antennal flagella with numerous long, simple setae; these characters are presumed to be adaptations for the dark and oligotrophic environment of submarine caves. Paguristes jalur Morgan, 1992 is redescribed in order to supplement the original description. Intraspecific morphological variations in Pagurixus nomurai Komai and Asakura, 1995 and Catapagurus tuberculosus (Asakura, 1999) are noted.