A new species of Pinnixa (Crustacea: Brachyura: Pinnotheridae) from Mazatlan, Sinaloa, Mexico

Abstract

A new pinnotherid crab, Pinnixa hendrickxi n. sp., is described from Isla de la Piedra, Mazatlán, Sinaloa, Mexico. The new species canbe distinguished from most species of Pinnixa of the Eastern Pacific because males have an abdomen narrowed medially and widened distally.However, due to this characteristic, P. hendrickxi resembles P. darwini Garth, 1960, P. plectrophoros Glassell, 1935, P. transversalis Milne-Edwards& Lucas, 1842, and P. bahamondei Garth, 1957 from the eastern Pacific and P. faxoni Rathbun, 1918, from the western Atlantic. Pinnixa hendrickxican easily be distinguished from P. plectrophoros and P. transversalis by the absence of spines on third and fourth legs. On the other hand, the newspecies can be separated from P. transversalis, P. bahamondei, and P. faxoni by the absence of dorsal ridges on the carapace. It can be distinguishedfrom P. darwini by the fingers of the chelae (which, when closed, leave a gap in P. darwini, but close almost completely in the new species), theexopod of the third maxiliped with a non-segmented flagellum in the new species, and first pleopod with slender terminal process and withoutbulbous subterminal swelling in the new species.