Pethia sanjaymoluri, a new species of barb (Teleostei: Cyprinidae) from the northern Western Ghats, India

Molecular phylogeny and phylogeography of the freshwater-fish genus Pethia (Teleostei: Cyprinidae) in Sri Lanka

BACKGROUND

Sri Lanka is a continental island separated from India by the Palk Strait, a shallow-shelf sea, which was emergent during periods of lowered sea level. Its biodiversity is concentrated in its perhumid south-western 'wet zone'. The island's freshwater fishes are dominated by the Cyprinidae, characterized by small diversifications of species derived from dispersals from India. These include five diminutive, endemic species of Pethia (P. bandula, P. cumingii, P. melanomaculata, P. nigrofasciata, P. reval), whose evolutionary history remains poorly understood. Here, based on comprehensive geographic sampling, we explore the phylogeny, phylogeography and morphological diversity of the genus in Sri Lanka.

RESULTS

The phylogenetic analyses, based on mitochondrial and nuclear loci, recover Sri Lankan Pethia as polyphyletic. The reciprocal monophyly of P. bandula and P. nigrofasciata, and P. cumingii and P. reval, is not supported. Pethia nigrofasciata, P. cumingii, and P. reval show strong phylogeographic structure in the wet zone, compared with P. melanomaculata, which ranges across the dry and intermediate zones. Translocated populations of P. nigrofasciata and P. reval in the Central Hills likely originate from multiple sources. Morphological analyses reveal populations of P. nigrofasciata proximal to P. bandula, a narrow-range endemic, to have a mix of characters between the two species. Similarly, populations of P. cumingii in the Kalu basin possess orange fins, a state between the red-finned P. reval from Kelani to Deduru and yellow-finned P. cumingii from Bentara to Gin basins.

CONCLUSIONS

Polyphyly in Sri Lankan Pethia suggests two or three colonizations from mainland India. Strong phylogeographic structure in P. nigrofasciata, P. cumingii and P. reval, compared with P. melanomaculata, supports a model wherein the topographically complex wet zone harbors greater genetic diversity than the topographically uniform dry-zone. Mixed morphological characters between P. bandula and P. nigrofasciata, and P. cumingii and P. reval, and their unresolved phylogenies, may suggest recent speciation scenarios with incomplete lineage sorting, or hybridization.

On the freshwater fish fauna of Krishna River, Sangli District, Maharashtra, India

Freshwater fish fauna of Krishna River, Sangli district was studied from 2013 to 2017. A total of 73 species belonging to 10 orders, 22 families, and 49 genera were recorded, of which, 29 species are endemic to the Western Ghats and 11 species endemic to the Krishna River system. Labeo kontius, an endemic barb of the Cauvery River System was recorded for the first time from the Krishna River, Maharashtra. As per the IUCN Red List of Threatened Species, 54 species are assessed as ‘Least Concern’, four species as ‘Near Threatened’, three species as ‘Vulnerable’, five as ‘Endangered’, and two as ‘Data Deficient’. The conservation status of two species has not yet been assessed. Fish fauna of the Krishna River within the study area is threatened as a result of alien species, and several anthropogenic stressors such as pollution from industrial as well as agricultural sources, human settlements, and overfishing.  Since, this small study area harbours 28 endemic and eight threatened species, their conservation should be given high priority.