PROC. BIOL. SOC. WASH. 103(2), 1990, pp. 364-371 CALYPTRAEOTHERES, A NEW GENUS OF PINNOTHERIDAE FOR THE LIMPET CRAB FABIA GRANTI GLASSELU 1933 (CRUSTACEA, BRACHYURA) Ernesto Campos Abstract.— Fabia granti Glassell, 1933 is incorrectly assigned to the genus Fabia Dana, 1851. Its unique morphological features include: (1) lack of two longitudinal sulci on the carapace; (2) the anterolateral margins of the carapace are sharp-edged; (3) the third maxilliped has a palp of two articles, carpus longer and wider than propodus, and (4) abdomen, in both sexes, of seven free somites, and these support the placement of i^. granti as type species of a new pinnotherid crab genus, Calyptraeotheres. In addition to the morphological differences, this genus is ecologically different from others in the Pinnotheridae, since it is a symbiont of gastropods, family Calyptraeidae. Resumen.— Fabia granti Glassell, 1933 ha estado incorrectamente asignada dentro del genero Fabia Dana, 1851. Sus caracteristicas exclusivas incluyen: (1) ausencia de dos surcos longitudinales sobre el caparazon; (2) margenes del caparazon agudos; (3) tercer maxilipedio con su palpo formado de dos artejos, el carpus mas ancho y largo que el propodus y (4) el abdomen, en el macho y la hembra, formado de siete somitos libremente articulados. Lo anterior apoya la asignacion de F. granti como especie tipo de un nuevo genero de cangrejo en la familia Pinnotheridae, Calyptraeotheres. Adicional a las caracteristicas morfologicas, Calyptraeotheres es ecologicamente diferente de otros generos en los Pinnotheridae dado que es simbionte de Mollusca— Gastropoda, familia Calyptraeidae. The pinnotherid crab genus i^flZjza was es-1968) revealed several morphological dif-tablished by Dana, 1851 with F. subquad-ferences of taxonomic importance. In F. rata Dana, 1851, from the northeastern Pa-subquadrata two longitudinal sulci, which cific, as its type species. Subsequently, eleven arise from the upper margin of the orbit, species were assigned within this genus are present on the carapace of the female, (Schmitt et al. 1973, Rodrigues da Costa the palp of the third maxilliped is composed 1 970, De Melo 1971, Cobb 1 973, Dai 1980, of three articles in both sexes and the ab-Gore 1986). Of these, two species have been domen of the male has somites 3-5 fused transferredto other genera. Pregenzer( 1979) (Rathbun 1918, pers. obs.). In contrast, F. assigned F. hickmani to Pinnotheres Bosc, granti does not show the sulci, the palp is 1802, and Campos (1989a) included F. un-composed of two articles in both sexes, and quifalcula in Orthotheres Sakai, 1965. Re-the abdomen of the male is formed by seven cent examination of males and females of free somites. These morphological differ-F. granti Glassell, 1933, and their compar-ences suggest that {\) F. granti should not ison with specimens and descriptions of 7^. be considered as congeneric with F. subquadrata (Rathbun 1918, Davidson subquadrata; (2) its inclusion within genus
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