Squat lobsters of the genus Galathea (Decapoda: Anomura: Galatheidae) associated with comatulid crinoids from the Ryukyu Islands, Japan

Abstract

Four species of squat lobsters (Galathea amboinensis de Man, 1888, G. continua new species, G. inflata Potts, 1915, and G. leptocheir new species), all associates of comatulid crinoids, are described from material collected on coral reefs of the Ryukyu Islands. Galathea continua is found in association with Capillaster multiradiatus, Clarkcomanthus littoralis, Comatella maculata, C. nigra, C. stelligera, and Comanthus gisleni. It is distinguished from the other three species by the absence of a spine on the hepatic region lateral to the first transverse ridge of the carapace, the anterior margin of sternite 3 submedially produced into two spines instead of roughly bilobed, and epipods present on pereopod 1 only instead of pereopods 1-3. Galathea leptocheir associated with Phanogenia gracilis is distinguished from G. amboinensis by much more slender pereopod 1, the carapace with four uninterrupted and three interrupted transverse ridges placed alternately instead of one interrupted and six uninterrupted ridges on the posterior half surface, and abdominal somites 2-4 with two uninterrupted instead of three uninterrupted transverse ridges. Coloration is also different in each of these species. A key to the four species is provided.