Larval development and distributional pattern of Diagramma pictum are described on the basis of specimens collected from Nakagusuku Bay, Okinawa Island, southwestern Japan. Pre-flexion to post-flexion larvae were readily distinguished from other haemulid larvae by head spination, the number of dorsal spines and pigmentation pattern. The former (3.61 notochord length – 6.36 mm SL) occurred at offshore stations in Nakagusuku Bay from August to October, coinciding with high gonadosomatic index values of adult individuals collected from coastal waters around Okinawa Island. However, no larval D. pictum were collected from Nakagusuku Bay tidal flats. Morphological differences were found in supraocular serration and melanophore pattern compared to larvae collected from Tosa Bay (Japan) and the Great Barrier Reef (Australia). Such apparently support a recent division of D. pictum into five subspecies, the two larval morphotypes in Japanese waters being suggestive of local populations or subspecies.
