Abstract
A new species of sesarmine crab, Sesarmoides ultrapes (Brachyura: Grapsidae) is described from anchialine caves in the Florida and Malaita Islands, Solomon Islands. This species has probably the longest ambulatory legs of any grapsid and one of the longest in any known Brachyuran. The new species is allied to S. cerberus (Holthuis, 1964) and 8. novabritannia Ng, 1988, but differs distinctly in the shape of the carapace, structure of the basal antennal segment, proportionately much longer ambulatory legs, in the form of the anterior sternites of the sternal plastron, by the broader male abdomen and by the male first pleopod.
