Multiple genetic species in a halophilic non-marine ostracod (Crustacea)

Abstract

The discovery of animal genetic (mostly also cryptic) species has known an exponential increase since molecular techniques became available. Also in non-marine ostracods (small, bivalved crustaceans with an excellent fossil record), several morphospecies have been shown to comprise several genetic species. Here, we screen 13 populations from Central Europe and the circum-Mediterranean region of the halophilic continental ostracod species Heterocypris salina with DNA sequences from a mitochondrial (COI) and a nuclear (28S) marker. We apply four species delimitation methods to show that this nominal species consists of four genetic species in both DNA datasets, and that these two sets of genetic species show mitonuclear discordance. Most investigated specimens belonged to one of these four genetic species. There was no clear correlation between geographic and genetic distances, but we found that, apart from historical processes, environmental factors such as ecoregion, seasonality and salinity might have been important drivers shaping discrete genetic diversity. Following the palaeontological literature, the H. salina species cluster is at least 11-9 Myr old.