A new species of Succinea (Gastropoda: Stylommatophora) from the Puna highlands of Argentina

Abstract

A new species of Succinea Draparnaud, 1801, S. puna sp. nov., from the Puna highlands in Catamarca Province, Argentina, is described. Seventeen water bodies were surveyed in the Puna ecoregion of Catamarca, with gastropods being found only at two localities, El Peñón and Guanchín River. We explored the morphological features of shells, reproductive system, radulae, and mandibles of specimens from each site. Although we found slight differences in the shell and the terminal genitalia, with specimens exhibiting an epiphallus folding over itself with terminal globular appearance, whereas others with an epiphallus cylindrical, we conclude that these are intraspecific variabilities. We used DNA sequences of the 16S-rRNA gene to explore genetic distances and genealogical relationships among both populations and other species of Succinea. We found maximum genetic interpopulation distances of up to 2.38%. Mean interspecific divergences among S. puna sp. nov. and other Succinea species ranged between 7.14% and 15.21%. A secondary structure model of domains IV and V of the 16S-rRNA gene was developed, with polymorphic sites being concentrated in loop regions. A GIS analysis was carried out using a selection of bioclimatic variables to characterize the environment of the new species in comparison to other close Succinea species from South America. The analysis showed that the particular environmental conditions of the Puna in Catamarca are hardly present in other zones of South America, supporting our hypothesis that S.puna is endemic to that area. The restricted distribution of S. puna sp. nov. in a single ecoregion with extreme climatic and physiographic characteristics, high altitude habitat and its microhabitat specialization, makes this species potentially vulnerable to impacts of future anthropogenic changes.