Species diversity estimation of genus Ariophanta (Gastropoda: Ariophantidae) from the Western Ghats
The Western Ghats, a biodiversity hotspot, harbours many endemic species of flora and fauna including the cryptic and highly ignored taxa such as snails (Mollusca: Gastropoda). These are important indicators of ecosystem's health, cleaners of plant and animal debris, and sources of calcium for higher vertebrates. Owing to the difficulty in determining snail species solely based on morphology, species delimitation methods, based on the phylogenetic species concept, have been used which make use of pairwise distances, phylogenetic trees etc. This study includes COI and 16S rDNA mitochondrial gene sequences from 101 specimens of genus Ariophanta (plus one outgroup) as input for the various methods of delimitation, namely – ABGD, jMOTU, bPTP and GMYC. These reveal a huge number of putative new species from this genus compared to the 19 species described by conventional methods. The gene trees also show that genus Cryptozona (formerly included dextral individuals) could be integrated with Ariophanta (formerly included sinistral individuals) forming only one genus. It was found that the northern Western Ghat species do not occur in the same clade as the species from central or southern parts, signifying geographically-independent speciation events. There is one described species, Ariophanta basileus, which might require revision and re-elevation to the previously described genus Nilgiria. This conclusion is drawn from the phylogenetic trees which consistently show highly disjunctive clading of this species from all other Ariophanta of the Western Ghats. Thus, more studies are required to document the yet unknown diversity, behaviour, and distribution which would enable us to prioritise areas of high biodiversity for designing of conservation plans.
Keywords: ABGD, bPTP, GMYC, jMOTU, species delimitation