Molecular phylogenetic analysis of white prawns species and the existence of two clades in Penaeus merguiensis

Abstract

Closely related species, Penaeus merguiensis and Penaeus silasi from Thai waters, were genetically examined using variation observed in 558 base pairs (bp) of sequence from cytochrome oxidase subunit I (COI) gene of mtDNA. The sequence divergences of COI between P. merguiensis and other Penaeus species were 5.76–6.15% ( P. silasi), 13.17–13.97% ( Penaeus indicus), 16.43% ( Penaeus vannamei), 16.63% ( Penaeus monodon), and 18.37% ( Penaeus japonicus). From the alignment reported that there were four clades on phylogenetic tree, the distinction of the two monophyletic clades was referred as P. merguiensis, one monophyletic clade within P. silasi and P. indicus. These results point toward the possibility of P. merguiensis being a complex of two cryptic species or a single species with strong phylogeographic subdivision.