Opsarius siangi, a new Chedrinae fish species from the Brahmaputra drainage, India

Abstract

Opsarius siangi sp. nov., a previously undocumented species, has been identified from Siang River, Pasighat, Arunachal Pradesh, India. This newly described species is distinguished by a suite of unique morphological characteristics, notably including a complete lateral line, consisting of 65–77 scales, 32–39 pre-dorsal scales, 12–15 scales positioned between dorsal fin origin and lateral line, presence of two pairs of barbels, body depth ranging from 18.80% to 27.42% of standard length and a distinct pattern of 8–15 vertical bars adorning the body. A comprehensive genetic analysis was conducted by scrutinizing 78 Cytochrome oxidase I (COI) sequences extracted from Chedrinae fishes, with particular focus on Opsarius and Barilius genera. Phylogenetic analysis revealed that O. siangi sp. nov. occupies a distinctive clade, displaying close affinity with O. shacra. Intraspecific K2P genetic divergence, assessed at 0.02, falls well within established species delineation thresholds, while interspecific divergence in comparison to O. shacra was recorded at 0.112. Complementary species delimitation methodologies, including BIN and bPTP, further underscore taxonomic uniqueness of O. siangi sp. nov., within Chedrinae family. This description enriches our understanding of biodiversity within Siang River ecosystem and underscores the merit of employing multi-pronged approaches in taxonomic investigations.

Keywords:

• Barilius
• new fish species
• Opsarius
• Brahmaputra basin
• Arunachal Pradesh

Acknowledgements

The authors express their gratitude to the Director of ICAR-Central Inland Fisheries Research Institute (ICAR-CIFRI) for providing the essential research facilities required for this study. They also extend deep appreciation to the Head, Aquatic Environment Biotechnology, and Nanotechnology Division, ICAR-CIFRI, for all support provided. Acknowledging the technical support provided by Mr. Asim Kumar Jana, Mr. Jayanta Pramanik in the laboratory and Rakesh Pal for data curation. We are also indebted to Dr. Laishram Kosygin, the Director of the Zoological Survey of India, Kolkata, and Dr. Waikhom Vishwanath, Department of Life Science at Manipur University, for guidance. Our gratitude extends to Dr. Rameshori Yumnam, Assistant Professor in the Department of Life Science at Manipur University, for granting us the necessary permission for examining the materials. We would also like to acknowledge ChatGPT, which we used for improving the language of this manuscript.

Ethical approval

Approval of the ethical committee for the collection of fish species under this study was not necessary because the fish species taken from the wild for the research work under this study belong to the food fish category and are not protected under The Wildlife Protection Act, 1972 (Last amended in 2017), Ministry of Environment and Forest, Government of India.

Consent to participate

All authors have given informed consent to participate in the research.

Disclosure statement

The authors declare no conflict of interest for the present study.

Data availability

The mitochondrial DNA sequences generated in this study are available at NCBI. The type specimens are available in the Zoological Survey of India, and fish collection of ICAR-Central Inland Fisheries Research Institute, Barrackpore.

Notes

1 The diagonal represents within species divergence values; between species divergence values are below diagonal. The within species divergence value of Opsarius signicaudus could not be calculated and represented as ‘NC’.

Additional information

Funding

The authors are thankful to the Indian Council of Agricultural Research, New Delhi, for financial help under the projects, Habitat Characterization, Fisheries and Socioeconomics of River Cauvery, Tapti, Siang, and Chaliyar [Project code: REF/17-20/07].