Determination of Taxonomic Status and Phylogenetic Affinities of Common Edible Crab Species in Southern Coast of Sri Lanka Using DNA Barcoding Gene Region

Abstract

Edible crabs are among the known and valuable economic sea foods exported, as well as the consumed locally in southern Sri Lanka. However, genetic identification and taxonomic status of available crab species are less studied. This study identified ten selected varieties of edible crab species using information of barcoding gene region. Acquired consensus sequences of partially amplified mitochondrial COI gene region (710bp) were processed in BLAST option of NCBI database. Results identified six different species fallen within three genera, namely Scylla serrata, Scylla olivacea, Portunus pelagicus, Portunus sanguinolentus, Charybdis japonica and Charybdis natator which were confirmed with morphological keys. Identified sequences were analyzed with sequences from other geographical regions and Minimum Evolution Tree; sequence divergence levels among sequences were also estimated. Phylogenetic tree produced three separated clades with basal clade of Genus Portunus. Two P. pelagicus sequences have been linked with Australia and Russia independently, while two P. sanguinolentus sequences behaved as haplotypes, diverged slightly from South Korea, India and China. Scylla serrata sequences were promising a strong genetic uniformity with India and Thailand. However, in Scylla olivacea, two sequences related to India and Thailand separately. Sequence of Charybdis natator showed a greater similarity to Japanese sequence while samples collected as Charybdis japonica seems to be controversial and need further studies. As the first genetic study conducted to estimate taxonomic status of edible crabs in Sri Lanka, results are important for use in conservation strategies, as well as further research and prospective culturing programs.