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. In the present study, Sepiella inermis samples were collected from different landing centres along the Eastern Arabian Sea and Bay of Bengal to investigate the distribution of this species in a phylogeographic context. Morphological analysis did not show distinct differences between two populations. Phylogenetic analyses were performed using the mitochondrial Cytochrome Oxidase I gene and 16S rRNA gene. In our study, we observed two genetically distinct clades (pair-wise genetic divergence varied between 7.7 and 9.1%) of Sepiella inermis. One clade is composed of individuals collected from the Arabian Sea and the other from the Bay of Bengal (the northern and north-eastern part of the Indian Ocean). The mean intraspecific and interspecific nucleotide distances for COI were 0%–1% and 0%–7%, respectively, while these values for 16S rRNA sequences were 0%–1% and 1–4%. This study led to the identification of potential cryptic speciation within Sepiella inermis. Furthermore, this study also provides evidence of previously undocumented sub-population structuring in the Northern Indian Ocean. [ABSTRACT FROM AUTHOR]