Genetic and morphological identification of Sebastiscus tertius in the East China Sea (Scorpaeniformes : Scorpaenidae)

The allozymes and morphology of 110 specimens of three Sebastiscus species (S. marmoratus, S. tertius, and S. albofasciatus) in the East China Sea and near Japan were compared. Results of 20 allozyme loci studied showed that all three species were closely related (Nei's unbiased genetic distances, 0 .057-0.133) but could be identified on the basis of informative loci with a few exceptions. Initial identification based on color patterns agreed with allozyme identification in more than 98% of Sebastiscus specimens and agre ed completely in S. albofasciatus. One specimen that was initially identifi ed as S. marmoratus because of the dark body color was actually S. tertius according to two informative allozyme loci. Number of pectoral fin rays dif fered between S. marmoratus (18 or fewer, 98%) and S. tertius (19 or more, 85%) in this study. The previously mentioned dark specimen had 19 pectoral fin rays, which are characteristic in S. tertius. Using seven morphological measurements, canonical discriminant analysis between S. marmoratus and S. tertius classified less than 90% of specimens into the original groups (sp ecies). Some specimens of S. tertius resembled S. marmoratus in body shape and vice versa. A combination of genetic characterization and morphological examination is necessary to identify S. marmoratus and S. tertius accurate ly. Distinction based on allozymes and color patterns with numbers of pecto ral fin rays should provide satisfactory identification.