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| Rasbora adisi
Sudasinghe, Pethiyagoda, Hettiarachchige, Ranasinghe, Raghavan, Dahanukar & Meegaskumbura, 2020
DOI: 10.1111/jzs.12395 facebook.com/HiranyaSudasinghe facebook.com/tharindu2010ac |
Abstract
The diversity of the freshwater‐fish genus Rasbora (Cyprinidae) on Sri Lanka (five species) is high compared with the four species reported from the peninsula of India, from which the island's cyprinid fauna is derived. The paucity of characters by which species of Rasbora can be phenotypically distinguished renders field identification difficult, adversely affecting the estimation of populations and distributions, with consequences for conservation and management, increasing also the risk of taxonomic inflation. From a sampling of 90 sites across Sri Lanka and based on phylogenetic and haplotype analyses of sequences of cox1 and cytb mitochondrial, and rag1 and irbp nuclear markers, we review the species diversity and phylogeography of Rasbora on the island. Molecular analyses recover, in addition to the five species previously reported, a new (cryptic) species: Rasbora adisi sp. nov. Uncorrected pairwise cox1 genetic distances between species range from 2.0 to 12.3 percent. The Sri Lankan diversification derives from a common ancestor which arrived from India during a sea‐level low‐stand in the mid‐Miocene (15.1 Ma [95% HPD: 11.5–19.8 Ma]), when the present‐day island was subaerially connected to the Indian subcontinent by a broad isthmus. This gave rise to a clade comprising five species—Rasbora adisi sp. nov., Rasbora armitagei, Rasbora microcephalus, Rasbora naggsi and Rasbora wilpita —with a crown age of 9.9 Ma (95% HPD: 7.1–13.3 Ma) and to a clade comprising Indian and Sri Lankan populations of Rasbora dandia, which themselves are reciprocally monophyletic. Morphological analysis of 334 specimens discriminates between most species which, however, are most reliably diagnosed by chromatic characters. The four endemic species exhibit a pattern of inter‐basin dispersal via headwater capture, followed by vicariance, explaining the high diversity of the genus on the island.
Keywords: cryptic species, diversification, freshwater fish, India, species delimitation
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| a new (cryptic) species: Rasbora adisi sp. nov. |
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| Live color pattern variation in species of Rasbora in Sri Lanka. (a) Rasbora adisi sp. nov., ~75 mm SL, Kotagama, Gal Oya basin; (b) Rasbora microcephalus, ~60 mm SL, Yakkala, Attanagalu Oya basin; (c) Rasbora naggsi, ~55 mm SL, Hambegamuwa, Walawe River basin; (d) Rasbora dandia, ~65 mm SL, Pitigala, Bentara River basin; (e) Rasbora armitagei, ~65 mm SL, Weralugahamula, Kalu River basin; (f) Rasbora wilpita, ~70 mm SL, Kottawa Forest Reserve, Gin River basin. |
Rasbora adisi, sp. nov
Etymology: The species name adisi, a noun in apposition, means mysterious or enigmatic in Sinhala: an allusion to the cryptic nature of this species.
Hiranya Sudasinghe, Rohan Pethiyagoda, Ranasinghe Hettiarachchige,Tharindu Ranasinghe, Rajeev Raghavan, Neelesh Dahanukar and Madhava Meegaskumbura. 2020. A Molecular Phylogeny of the Freshwater‐fish Genus Rasbora (Teleostei: Cyprinidae) in Sri Lanka reveals A Remarkable Diversification—And A Cryptic Species. Journal of Zoological Systematics and Evolutionary Research. DOI: 10.1111/jzs.12395
