Molecular markers based phylogenetic inferences reveals cryptic lineage within Sepiella inermis species complex

Over the last two decades genetic and phylogeographic studies in cephalopods around the world have identified many species complexes and cryptic species. Indian Ocean, in the tropical region remained least studied one. In the present study Sepiella inermis samples were collected from different landing centres along Indian coasts to investigate the distribution of these species in a phylogeographic context. Phylogenetic analyses were performed using the mitochondrial Cytochrome Oxidase I gene and 16S rRNA gene.The currently described species consists of two genetically distinct clades (pair-wise genetic divergence varied in between 7.7 to 9.1%). One clade composed of individuals collected in Arabian Sea and the other from Bay of Bengal (northern and north-eastern part of Indian Ocean). The study led to the identification of potential cryptic speciation within Sepiella inermis . Mean intraspecific and interspecific nucleotide distances for COI were 0–2% and 2–7%, respectively, while these values for 16S rRNA sequences were 0–1% and 1–4%. Furthermore, this study also provides evidence of previously undocumented sub-population structuring in the Indian waters.