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

Abstract

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.

Comparative analyses of complete mitochondrial genomes of four sillaginids fish (Perciformes: Sillaginidae) and phylogenetic implications

“…RNA structure Web server (https://rna.urmc.rochester.edu/ RNA-structureWeb/ Servers/ Predict1/Predict1.html) was used to simulate and draw O L (WANCY) structure. The location of the control area was determined through the position of tRNA Phe and tRNA Pro and analyzed the structure of the control area by comparing with the recognition sites in other sillaginids (Xiao et al 2014;Cai et al 2014;Siyal et al 2015;Saha et al, 2022) and some other bony fishes (Cheng et al 2012;Zhang et al 2013). The online software Tandem Repeats Finder (Benson, 1999) was used to search and analyze the tandem repeats in the control region sequence.…”

“…These so-called S. sihama are externally similar to S. sihama (type locality, southern Red Sea), but are neither identical with this species nor to each other, as these cryptic species belong to structural differences in their swimbladder and well divergent mitochondrial DNA lineages. Two new species such as Sillago muktijoddhai and S. mengjialensis were recently identified and taxonomically described based on morphology and DNA barcoding approach using partial cytochrome oxidase subunit I (COI) and 16S ribosomal RNA (16SrRNA) gene sequences from the Bay of Bengal, Bangladesh (Saha et al 2022). These two new species were previously misidentified as S. sihama in Bangladesh (Saha et al 2022).…”

“…Two new species such as Sillago muktijoddhai and S. mengjialensis were recently identified and taxonomically described based on morphology and DNA barcoding approach using partial cytochrome oxidase subunit I (COI) and 16S ribosomal RNA (16SrRNA) gene sequences from the Bay of Bengal, Bangladesh (Saha et al 2022). These two new species were previously misidentified as S. sihama in Bangladesh (Saha et al 2022). Currently it was confirmed that S. sihama is only widely distributed in the Indian Ocean, the Red Sea (Eritrea and Saudi Arabia; Golani et al 2013;Bogorodsky et al 2014), Arabian Sea (Western India, Pakistan, Iran; Lakra et al 2011, Cheng et al 2020, South Africa (Mlalazi Estuary, Tugela Bank and Mhlathuze Estuary), and Bay of Bengal, Bangladesh (Saha et al 2024).…”