C~NTRIBUTION No q FROM a 17 August 1984 BERMUDA BIOLOGICAL ATION For Research Inc PROC. BIOL. SOC. WASH. 97(3), 1984, PP. 637-644 NEW RECORDS OF THE TROGLOBITIC MYSID GENUS STYGIOMYSIS: S. CLARKEI, NEW SPECIES, FROM THE CAICOS ISLANDS, AND S. HOLTHUISI (GORDON) FROM GRAND BAHAMA ISLAND (CRUSTACEA: MYSIDACEA) Thomas E. Bowman, Thomas M. Iliffe, and Jill Yager Abstract. -Stygiomysis clarkei, is described from Conch Bar Cave, Middle Cai- cos Island, and Snake Cave, Providenciales Island. Stygiomysis holthuisi, previ- ously reported from the Antilles (St. Martin, Anguilla, Puerto Rico), is recorded from Lucayan Caverns, Grand Bahama Island, including a female with four fully developed oostegites, a number unique among the Mysidacea. The species of Stygiomysis, the only genus in the family Stygiomysidae, are blind, troglobitic mysidaceans characterized by a rather vermiform body, a re- duced carapace, endopods of thoracopods 2-4 (=pereopods 1-3) prehensile, and protopod of uropod produced into a long distomedial process. The known species are S. hydruntina Caroli, 1937, from the Salentine Peninsula, Italy; S. holthuisi (Gordon, 1958) from St. Martin, Puerto Rico (Bowman 1976), and Anguilla (Botosaneanu 1980); S. major Bowman, 1976, from Jamaica, and Stygiomysis, sp. Pesce, 1975, from the Salentine Peninsula, Italy. We describe herein a new species from the Caicos Islands and extend the known range of S. holthuisi to Grand Bahama Island. Stygiomysis clarkei, new species Figs. 1-3 Material. -Turks and Caicos Islands: Middle Caicos Island, Conch Bar Cave, 28 Oct 1'982, leg. Jill Yager and Thomas M. Iliffe, female holotype 6.2 mm (USNM 204900) and female paratype 4.8 mm (USNM 204901) collected by hand from very small pools, about 1.5 m in diameter, in a totally dark section of the cave; Providenciales Island, Snake Cave, 3 1 Oct 1982, leg. Thomas M. Iliffe, fragments of paratype (length and sex uncertain-USNM 204902) were collected from depths to several meters using a suction bottle while free diving. Distribution.-Known only from anchialine habitats of inland caves on the Caicos Bank, Turks and Caicos Islands. Habitat. -The Turks and Caicos Islands are geologically and geographically a southeastward extension of the Bahamas. Two shallow water platforms, the Caicos and the Turks banks are separated by a 35 km wide deep water channel, the Turks banks are separated by a 35 km wide deep water channel, the Turks Island Passage. The major islands consist of a broad expanse of low lying flat land facing the interior of the platform, while a range or series of ranges of eolian carbonate hills 20 to 40 m in elevation front the seaward margin, parallel to the long axis of the islands. The youngest hills closest to the seashore are unconsolidated dunes con-