PROC. BIOL. SOC. WASH. 94(3), 1981, pp. 866-872 CALASELLUS LONGUS, A NEW GENUS AND SPECIES OF TROGLOBITIC ASELLID FROM SHAVER LAKE, CALIFORNIA (CRUSTACEA: ISOPODA: ASELLIDAE) Thomas E. Bowman Abstract. — A new genus, Calasellus, is proposed for Asellus californicus and a new species from Shaver Lake, Fresno Co., CaHfornia, C. longus. The latter is described and illustrated and compared with C. californicus. Calasellus appears to be most similar to Asellus (Phreatoasellus) from Ja-pan. Three species of asellid isopods are known from California. Caecidotea tomalensis Harford, 1877, has been collected in 3 counties adjoining San Francisco Bay: Marin, San Francisco, and San Mateo (Bowman, 1974). Caecidotea sequoiae Bowman, 1975, has been found only in Liburn Cave, Tulare County. Asellus {Phreatoasellus) californicus (Miller, 1933) has been reported from a well in Lake County and springs in Santa Clara and Napa Counties (Bowman, 1975). The last 2 species are blind and unpig-mented troglobites. Caecidotea tomalensis is an epigean species. The new species described herein, the third California troglobitic asellid, is obviously congeneric with A. californicus, which I assigned provisionally to the subgenus Phreatoasellus Matsumoto, 1962 (Bowman, 1975). The present study has convinced me that the distinctive characters common to both species entitle them to be separated from other Asellidae and placed in a new genus. Calasellus, new genus Diagnosis. — Blind, unpigmented. Body slender, elongate. Mandible with 3-merous palp. Maxilla 1 inner ramus with 5 setae. S pereopod 1 propus slender, palm without processes but with several proximal spines. Dactyl of pereopods 2-7 with accessory unguis. S pleopod 2 endopod with basal spur; bulbous base with fissure and labial spur; distal part produced into long cylindrical process; fissure contained in fine stylet (cannula) originating on base and running parallel to cylindrical process. Pleopod 4 exopod pyr-iform. Pleopod 5 exopod rudimentary or absent. Type-species. — Asellus californicus Miller, 1933. Etymology. — Cal from C«/ifornia, + Asellus. Gender masculine. Relationships. — Calasellus most closely resembles Asellus {Phreatoasel-
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