Abstract
A single specimen of Plectranthias yamakawai Yoshino, 1972, 168.86 mm SL, obtained in a fish market in Zambales, Philippines, represents the first report in the country. Currently, the fish is only known to occur in Japan, Taiwan, and Samoa Islands. This anthiadine fish varies from other species of genus Plectranthias by having 30–33 lateral-line scales, a single red blotch below the lateral line, and numerous dark green blotches on the upper half of the body. The mitochondrial cytochrome oxidase subunit I (COI) is also described for the first time for this species in this article. The pairwise genetic distance computation reveals that P. yamakawai has a very low distance from the sequences of the other eight species of Plectranthias that have been submitted to GenBank. This is the sixth species of the genus Plectranthias to be reported from the western coast of Luzon, Philippines.