The Chinese Soft-shelled Turtle Pelodiscus sinensis (Testudines: Trionychidae) near the High and Upper Rhine in Germany and Switzerland
Soft-shelled turtles (Trionychidae) comprise 33 species and are distributed from North America to Africa and Asia (Uetz et al., 2021). This ancient and highly aquatic group can be found in freshwater streams, ponds and lakes, as well as brackish waters (with at least a single species, Trionyx triunguis (Forskål, 1775), occurring partly in marine habitats of the Levantine Sea (e.g., Taskavak and Akcinar, 2009)), particularly in tropical or subtropical regions. Although not comparable to the occasional presence of leatherback sea turtles Dermochelys coriacea (Vandelli, 1761) even above the Arctic circle (Willgohs, 1957), soft-shelled turtles of the genus Pelodiscus occur also at high latitudes of temperate regions and can be found in the Amur and Ussuri River basins of south-eastern Siberia in the Russian Far East (Van Dijk et al., 2014). While various representatives of this genus had been assigned to a single taxon, the Chinese soft-shelled turtle Pelodiscus sinensis (Wiegmann, 1835), both phylogenetic and taxonomic studies revealed that this complex actually represents seven distinct lineages (Fritz et al., 2010; Stuckas and Fritz, 2011), including P. maackii (Brandt, 1857) showing the northernmost distribution, or the recently discovered and highly endangered P. variegatus Farkas et al., 2019 from Vietnam.