Diversity of Potamolithus (Littorinimorpha, Truncatelloidea) in a high-diversity spot for troglobites in southeastern Brazil: role of habitat fragmentation in the origin of subterranean fauna, and conservation status

Phylogeography and molecular species delimitation reveal cryptic diversity in Potamolithus (Caenogastropoda: Tateidae) of the southwest basin of the Andes

The species of the genus Potamolithus inhabiting the southwestern basin of the Andes are difficult to distinguish due to small size and similar shell morphology. Only Potamolithus australis and Potamolithus santiagensis have been traditionally recognized in this region, but the occurrence of several morphologically similar undescribed populations could increase the regional richness. Here we delimit described and potentially undescribed cryptic species of the genus using partial sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene. Network analysis and diversity indices inferred six highly differentiated haplogroups, many of them sympatric and widespread in the study area. Phylogeographic analyses suggest a scenario of recent diversification and the occurrence of multiple refuges during the successive Pleistocene glaciations. Phylogenetic analysis also recovered six major clades that showed no relationship with physiography. Species delimitation analyses consistently recognized three or four candidate species apart from P. australis and P. santiagensis. Divergence times indicate that speciation of Chilean Potamolithus began at the end of the Pliocene, probably driven by climatic rather than geographic events. Considering the high inter- and intra-basin genetic diversity, conservation efforts should be focused on protecting sympatric taxa in the basins with the highest species richness.

Freshwater micro-gastropods from the Iguaçu National Park, Brazil: two new truncatelloid caenogastropods and anatomy of Chilina megastoma Hylton Scott, 1958

Collecting in Foz do Iguaçu National Park, Paraná, Brazil, an important tourist region with preserved rainforest, has revealed three micro-gastropod species which required morphological and taxonomic studies. One of them is a chilinid Chilina megastoma Hylton Scott, a member of a poorly studied group. Another two are new species of truncatelloid caenogastropods: Potamolithus mirim n. sp. and Heleobia iguassu n. sp. The three species are described in detail and discussed from taxonomic and phylogenetic point of view. As they are highly endemic, protective measures are suggested.