PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 109(2):31 1-317. 1996. Nannotheres moorei, a new genus and species of minute pinnotherid crab from Belize, Caribbean Sea (Crustacea: Decapoda: Pinnotheridae) Raymond B. Manning and Dairy 1 L. Felder (RBM) Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, U.S.A.; (DLF) Department of Biology, University of Southwestern Louisiana, Lafayette, Louisiana 70504, U.S.A. Abstract. — Nannotheres moorei is described from a small pteriid bivalve mollusk taken in the Caribbean Sea off Belize. This minute, ovigerous pin-notherid crab can be distinguished by its size and the 2-segmented palp on its third maxilliped. With a carapace width of about 1 .5 mm in a sexually mature female, it may be the smallest known species of crab. The minute crab described below was found on the edge of the shell of its host by Donald R. Moore, University of Miami, who gave it to us for study. The unique holotype is in the collections of the Nation-al Museum of Natural History, Smithsonian Institution, Washington, D.C. (USNM). Abbreviations used below include: cb, carapace breadth; m, meters; mm, milli-meters; Mxp3, third maxilliped; P1-P5, pereopods (PI is the cheliped, P2-P5 the walking legs); Pip, pleopod. Nannotheres, new genus Diagnosis. — Adult female: size very small, carapace length less than 2 mm. Car-apace soft, subcircular, lacking both sharp anterolateral border and longitudinal sulci anteriorly on dorsal surface. Front project-ing only slightly, deflected. Mxp3 with is-chium and merus indistinguishably fused; exopod present; palp 2-segmented, proximal longer than distal, segments articulated end-to-end; distal segment very short, rounded distally. Walking legs similar, dactyli sim-ple, subequal. Abdomen of 7 somites, in ovigerous female expanded well beyond bases of walking legs and mouthparts. Male: Unknown. Type species. — Nannotheres moorei, new species, by present designation and mono-typy. Etymology. — From the Greek, nannos, small, and tereo, to guard, as used in the name Pinnotheres. The gender is mascu-line. Host. — A bivalve mollusc of the family Pteriidae, Malleus candeanus (d'Orbigny). Waller & Macintyre (1982:490) reported that "In the vioihity of Carrie Bow Cay, Belize, specimens of Malleus candeanus are common from a depth of 5 m in the high-relief spur and groove zone seaward to the deepest area explored by SCUBA div-ing, 46 m on the steeply inclined fore-reef slope." Remarks. — Manning (1993b: 128) hsted four genera of pinnotherid crabs that were characterized by the presence of (1) simple dactyli on the walking legs and (2) a Mxp3 palp composed of only two segments: the American genera Calyptraeotheres Cam-pos, 1990 and Epulotheres Manning, 1993(a) and the Indo-west Pacific genera Ostracotheres Milne Edwards, 1853 and Xanthasia White, 1 846. In addition to being much smaller than species of any of these genera, Nannotheres differs from them as follows: (1) it lacks the sharp anterolateral
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