Descriptions of Two New Species, Sillago muktijoddhai sp. nov. and Sillago mengjialensis sp. nov. (Perciformes: Sillaginidae) from the Bay of Bengal, Bangladesh

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., Sillago muktijoddhai 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.