Investigations on Snapper fish of the genus Lutjanus were conducted from October 2015 to April 2016 in the coral ecosystem of St. Martin's Island, Bangladesh. Twenty one individuals of 8 species of Lutjanus were collected from local fishermen. Both morphological characters and DNA barcoding approach by mitochondrial cytochrome oxidase I subunit (COI) were used to confirm the identification of all species. Present study recorded the first national occurrence of two reef associated Lutjanus species (L. xanthopinnis and L. indicus). In addition six species (L. rivulatus, L. lutjanus, L. vitta, L. lemniscatus, L. fulviflamma and L. johnii) were re-described. Distinct morphological differentiation were found between more closely related species L. xanthopinnis, L. vitta and L. lutjanus. Three different appearances of L. johnii, two different appearances of L. rivulatus and L. lemniscatus were confirmed as same species. Phylogenetic analysis showed monophylotic clade for conspecific individuals and paraphyletic clade for congeneric individuals. Average genetic divergence for intraspecific level was 1.5% and 12.5% for interspecific level. Current study increased the number of Lutjanus species in Bangladesh from 15 to 17 and extended the distribution range of those new recorded species in northeastern part of the Bay of Bengal.

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Due to difficulty in recognition, many true species have been covered under the synonyms of wide-spread species. To justify the identification of a widely distributed species, Sillago sihama from the Bay of Bengal, Bangladesh, an integrated approach including morphology and DNA barcoding was used. Two unrecognized species of Sillago, i.e., Sillagomuktijoddhai sp. nov. and S. mengjialensis sp. nov., were identified from the coastal area of Bangladesh. S. muktijoddhai sp. nov. has marked differences in the body color, anal fin color, number of gill rakers, snout length, and swimbladder. S. mengjialensis sp. nov. has notable differences in the anal fin color, snout length, and swimbladder and is distinguished from S. muktijoddhai sp. nov. by the body color and swimbladder. The morphological characters of 14 documented Sillago species with two posterior extensions of the swimbladder were referenced and distinguished to accredit the two new species. Genetic analyses of partial mitochondrial cytochrome oxidase subunit I and 16S ribosomal RNA also supported the validity of the new species. This study has increased the number of recognized species of Sillago in the world and confirmed the prevailing misidentification of these two new species in Bangladesh as so-called S. sihama. Moreover, the study confirmed the misidentification of S. mengjialensis sp. nov. in Indonesia as S. sihama and the identification of unknown Sillago sp.1 in India.