<p>The new gobiid species <i>Acentrogobius nigromaculatus</i> sp. nov., distributed in tropical and subtropical areas of the Indo-West Pacific region from Rodrigues Island (Mascarene Islands) to Japan, and previously misidentified as <i>Acentrogobius suluensis</i> (Herre 1927), is described, together with a revised diagnosis of <i>A. suluensis</i>. The new species is distinguished from all other congeners by the following combination of characteristics: dorsal-fin rays VI-I, 9 (rarely 10); anal-fin rays I, 9 (rarely 10); pectoral-fin rays 15–17; longitudinal scale series 26–32 (modally 29); transverse scales 9–12 (modally 10); pre-dorsal scales absent; first to fourth spines of first dorsal fin each with a filamentous tip (usually fourth spine longest; second and third spines of similar length; first spine shortest); head and nape naked; body mostly covered with ctenoid scales; cycloid or weakly ctenoid scales on thorax and just above pectoral-fin base; two brown stripes from just behind pectoral-fin base to caudal-fin base; five dark brown lateral blotches (rarely 6) on body, between lateral stripes; blue spots (sometimes indistinct) between and just above lateral stripes when fresh, but indistinct or absent on lateral blotches; black blotch on opercle; paired black spots on chin; single black spot on spine tip of second dorsal fin; longitudinal yellow (sometimes reddish-yellow) stripe on upper margin of caudal fin, just above longitudinal bluish stripe. The new species is similar to <i>A. suluensis</i> and <i>Acentrogobius violarisi</i> Allen 2015 in having a ladder-like lateral pattern on the body and a black blotch on the opercle but differs in having a naked pre-dorsal area, paired black blotches on the chin, a distinct black spot in the spine tip of the second dorsal fin, and yellow and blue stripes on the upper margin of the caudal fin, and lacking transverse red stripes and vertical black blotches laterally on the body.</p>