Zoological Studies 38(3): 279-286 (1999) Molecular Systematics of the Thornfishes Genera Terapon and Pelates (Perciformes: Teraponidae) with Reference to the New Genus

(Perciformes: Teraponidae) with reference to the new genus Pseudoterapon. Zoological Studies 38(3): 279-286. The aim of this study is to clarify whether the systematic status of 3 externally similar thornfishes can be resolved to posit them at specific or generic levels by using allozyme electrophoresis and partial 12S rRNA sequences of mitochondrial DNA. Three externally similar thornfishes, Terapon jarbua, T. theraps, and Pelates quadrilineatus, can be distinguished by several fixed isozyme loci: IDHP-2*, LDH-A*, LDH-B*, MDH-1*, MDH-2*, SDH-1*, SOD-1*, SOD-2*, and SOD-3*. Nei’s unbiased genetic identity of isozymes ranged 0.321-0.454 (or distance 0. 790-1.137), and the nucleotide base difference of mtDNA ranged 7.3%-10.9 % among the 3 species, enabling them to posit as 3 separate genera. Nei’s genetic similarity between congeneric T. theraps and T. jarbua (0.441) is very low. The position of T. theraps with T. jarbua on the trees constructed from both isozyme and mtDNA data show similar profiles of grouping on separate nodes. This may support T. theraps being removed from the genus Terapon as an independent new genus, Pseudoterapon. The main diagnostic morphological characters distin-guishing Pseudoterapon from Terapon are: larger scales, absence of teeth on vomer and palatines, and horizon-tal dark stripes on body sides