2015 Volume 20 Issue 1 Pages 1-12
A new species of triplefin (Tripterygiidae), Enneapterygius phoenicosoma, is described on the basis of 71 type specimens (17.2-37.2mm standard length: SL) from southern Japan. An additional five specimens from the Caroline Islands and Vanuatu are also identified as belonging to this species. Males of the new species have the same distinct nuptial coloration as males of the Hawaiian endemic species E. atriceps (Jenkins, 1903). Comparisons of the present material with the holotype and 46 non-type specimens of E. atriceps show, however, that E. phoenicosoma differs from the latter in having a simple nasal tentacle (vs a bilobed tentacle in E. atriceps); lower counts of the anal-fin soft rays (16-18, mode 17 vs 19-21, 19); second dorsal-fin spines (11-13, 12 vs 12-15, 14); scale rows in longitudinal series (32-35, 33 vs 35-37, 36); and pored lateral-line scales (16-19, 17 vs 17-20, 19); a higher count of the pectoral-fin rays (15-17, 16 vs 14-17, 15); and several morphometric features, including the lengths of the dorsal-fin spines and rays, the second dorsal-fin base, and the anal-fin base. The new species grows larger than E. atriceps (largest recorded size, 37.2mm SL vs 26.9mm SL in E. atriceps).