New species of Gerres from the southern Malay Peninsula, belonging to the Gerres setifer complex (Perciformes : Gerreidae)

Gerres silaceus n. sp. is described from the holotype and two paratypes fro m the southern Malay Peninsula. The species is included as the fourth speci es in the "G. setifer complex" [G, chrysops Iwatsuki, Kimura and Yoshino, G . decacanthus (Bleeker), G. setifer (Hamilton), G. silaceus n. sp.], differ ing from all other congeners from the Indo-Pacific in having two supraneura l bones and small size (less than 100 mm in standard length vs three supran eural bones and adults > 100 mm SL). The new species is further characteriz ed by presence of IX, 10 dorsal fin rays, 34 or 35 lateral line scales, 3.5 scales betwveen the 5th dorsal fin spine base and lateral line, caudal fin short (mean 29% of SL), slender second anal fin spine, pelvic fin ray with a wide white margin posteriorly, and a uniformly silvery ocher body. Gerre s silaceus differs from G, setifer and G, decacanthus in body color, the la st dorsal fin spine slightly shorter or similar length to the penultimate s pine, higher gillraker counts and broadly rounded caudal fin lobes; it diff ers from G. chrysops in higher gillraker counts, rounded caudal fin lobe po sterior margin and body color. The four species are generally distributed a llopatically in the Indo-western Pacific.