Distinguishing between two sympatric Acanthopagrus species from Dapeng Bay, Taiwan, using morphometric and genetic characters.

Morphometric and genetic data were used to compare two sympatric and morphologically similar species, Acanthopagrus berda and Acanthopagrus taiwanensis, in Dapeng Bay, South-western Taiwan. A principle component analysis of morphological data indicated a distinction between the two species, with pectoral fin length and eye diameter accounting for 32.27% of the variation. Interspecific sequence divergence, based on mtDNA cytochrome b (0.118 +/- 0.01), was larger than intraspecific divergences between haplotypes (0.007 for A. taiwanensis and 0.003 for A. berda). Individuals of the two species clustered into different groups in three phylogenetic trees with 100% bootstrap support. The mean observed heterozygosity for eight microsatellite loci was 0.471 +/- 0.202 for A. taiwanensis and 0.637 +/- 0.145 for A. berda. Nei's unbiased measure of interspecific genetic distance (D(S)) was 1.334. F(ST) (0.134) and R(ST) (0.404) values indicated significant differentiation between species. An unrooted neighbour-joining tree was constructed by allele-sharing distances and the factorial correspondence analysis split all specimens into two distinct clusters. The results of morphometric, mtDNA and microsatellite analyses indicated the presence of two species, A. taiwanensis and A. berda.