Global diversity of turtles (Chelonii; Reptilia) in freshwater

The turtles are an evolutionary ancient group of tetrapod vertebrates, and their present-day distribution and diversity reflects the long and complex history of the taxon. Today, about 250 of the total of 320 species recognized are freshwater turtles; most of these inhabit tropical and subtropical zones. Diversity hotspots occur in Southeast North America, regarding Emydidae, and in the Indo-Malayan region, mostly Geoemydidae and Trionychidae. Chelidae are predominantly Neotropical and Australasian, while Pelomedusidae are African. The majority of genus- and species-level taxa are regional or even local endemics. A majority of freshwater turtles are threatened in varying degrees, mostly by habitat modification and collection.