A phylogeny of the cannibal snails of southern Africa, genus Natalina sensu lato (Pulmonata: Rhytididae): Assessing concordance between morphology and molecular data

The genus Natalina Pilsbry, 1893 is a southern African endemic belonging to the Gondwanan family of carnivorous snails, Rhytididae. We present a well-resolved molecular phylogeny of the genus based on the mitochondrial 16S and COI genes and the nuclear ITS2 gene, and assess this in light of Watson’s [Watson, H., 1934. Natalina and other South African snails. Proc. Malacol. Soc. Lond. 21, 150–193] supra-specific classification via a re-examination of 23 morphological characters including features of the shell, radula, external anatomy and distal reproductive tract. Ancestral reconstruction and character mapping based on the MK1 model reveals broad concordance between morphology and the molecular phylogeny at the supra-specific level. Given this concordance and exceptionally deep divergences in the molecular data, we recommend the elevation of the subgenera Natalina s.s., Afrorhytida, and Capitina to generic status. At the species level, we identify several species complexes for which additional fine scale morphological and molecular appraisal is needed to qualify on the one hand incipient speciation with notable differentiation in shell form and body pigmentation, and on the other, phylogenetically deep yet morphologically cryptic diversity.