Molecular phylogenetic evidence that the Chinese viviparid genus Margarya (Gastropoda: Viviparidae) is polyphyletic

We investigated the phylogeny of the viviparid genus Margarya, endemic to Yunnan, China, using two mitochondrial gene fragments (COI and 16S rRNA). The molecular phylogeny based on the combined dataset indicates that Margarya is polyphyletic, as two of the three well-supported clades containing species of Margarya also comprise species from other viviparid genera. In one clade, sequences of four species of Margarya even cluster indiscriminately with those of two species of Cipangopaludina, indicating that the current state of Asian viviparid taxonomy needs to be revised. Additionally, these data suggest that shell evolution in viviparids is complex, as even the large and strongly sculptured shells of Margarya, which are outstanding among Asian viviparids, can apparently be easily converted to simple smooth shells. The molecular data also indicate that the species status of the six extant species of Margarya should be re-assessed.