Multigene phylogeny reveals the ribbed shell morphotypes in the land snail genus Sarika (Eupulmonata: Ariophantidae), with description of two new species from Thailand and Myanmar

The speciose land snail genus Sarika is widely distributed throughout mainland Southeast Asia. This genus is generally recognized by a smooth and polished shell. However, we recognize four species with a ribbed shell surface (S. siamensis, S. theodori, S. costabilis sp. nov., and S. costata sp. nov.) exhibiting genital characters similar to those of Sarika s.s. and so a rearrangement in the systematics of the genus is suggested. Here, we analysed these four ribbed shell species together with Sarika s.s. by a combined morphological and molecular approach to species delineation, the latter based on both mitochondrial (coi and 16S) and nuclear (28S) markers. Our molecular phylogeny affirms the monophyly of the genus Sarika including both smooth and ribbed shell morphotypes that is statistically well supported. The ribbed shell morphotype in the land snail genus Sarika is also well defined in terms of diagnostic morpho-anatomical characters that can be divided into two species groups. The S. costata species group consists of only one species, S. costata sp. nov., while the S. siamensis species group comprises S. siamensis, S. theodori and S. costabilis sp. nov. These findings provide a solid basis for the systematics of family Ariophantidae.