Shell Convergence: An Interspecific Molecular Phylogeny Of Neohelix (Gastropoda: Polygyridae)

Due to convergence in Neohelix von Ihering, 1892 and Mesodon Rafinesque in Férussac,1821, species boundaries among taxa remain ambiguous. Prior hypotheses of polygyrid ancestry using morphological and behavioral characteristics by Emberton have been compared to molecular phylogeny. However, a robust interspecific phylogenetic tree for Neohelix, a highly convergent genus of land snails in Polygyridae, has not yet been attempted. During this study, authors sequenced 28 specimens of Neohelix and outgroup species, testing four mitochondrial markers and two nuclear markers for specificity. Primers for the COI locus were modified to eliminate binding site polymorphism and increase amplicon length. The COI and 16S loci produced high node support for this interspecific phylogeny, but authors recommend testing 18S to expand nuclear support. Individuals were collected from known species ranges and identified using shell morphology but were not anatomically dissected to confirm species identity. Suspected misidentification among morphologically similar species like Neohelix major, Neohelix albolabris, and Mesodon normalis was present, resulting in a paraphyletic Neohelix clade. These findings confirm the necessity of reproductive dissections for identification and suggests that current hypotheses for species ranges need further investigation.