A revision of the Trimmatom nanus species complex (Pisces, Gobiidae), with descriptions of three new species and redefinition of Trimmatom

Trimmatom is rediagnosed to include gobiids in which the first element of the anal fin is a bilaterally paired ray, the fifth pelvic ray is unbranched and reduced to 15% or less of the length of the fourth, the head, pectoral-fin base, and breast are scaleless, there are no head pores, and the gill opening extends anteroventrally at least to below the vertical limb of the preopercle. The Trimmatom nanus species complex is considered to be monophyletic by virtue of an unbranched fourth pelvic-fin ray. Trimmatom macropodus, n.sp., recorded from Taiwan, the Philippines, the Coral Sea, and the Great Barrier Reef, has a scaled body and the first three pelvic-fin rays are branched. Trimmatom zapotes, n.sp., from the Caroline and Gilbert islands and Great Barrier Reef, has a scaled body and all pelvic-fin rays are unbranched. Among the three scaleless species, Trimmatom offucius is restricted to the Chagos Archipelago and has two dark saddles crossing the bases of fin rays in the second dorsal fin. Trimmatom sagma, n.sp., from the Cocos-Keeling Islands, the Philippines, and the Moluccas, has a single dark saddle across the base of the second dorsal fin and a unique dorsal pterygiophore formula. Trimmatom nanus lacks dark saddles over the dorsum. The known geographic range of this species is greatly expanded, from the type locality in the Chagos Archipelago to include the Philippines, Papua New Guinea, the Caroline Islands, the Gilbert Islands, Fiji south to South Minerva Reef, Lord Howe Rise, the Coral Sea, western Australia, and the Maldives.
Winterbottom Richard .