Diversity and biogeography of South American mud turtles elucidated by multilocus DNA sequencing (Testudines: Kinosternidae).

[Display omitted] • Biogeographic and taxonomic assessment of South American representatives of the most speciose and most widely distributed genus of turtles, Kinosternon , using mtDNA sequences and 17 nuclear loci and fossil-calibrated molecular clock. • Two main radiations in Kinosternon , one Nearctic and one mainly Neotropical. • Recognition of three subgenera, Kinosternon , Cryptochelys and Thyrosternum. • Redefinition of former Kinosternon scorpioides group as subgenus Kinosternon , containing 19 distinct species-level lineages, 14 of which are currently named. • Kinosternon colonized South America at least three times, once in the Miocene, and then twice in the Plio-Pleistocene. • Phylogenetic discordance between mitochondrial and nuclear phylogenies suggests repeated mitochondrial introgressions and capture, with the possibility of mitochondrial capture from an extinct basal kinosternine lineage in one clade. Kinosternon is the most speciose genus of extant turtles, with 22 currently recognized species, distributed across large parts of the Americas. Most species have small distributions, but K. leucostomum and K. scorpioides range from Mexico to South America. Previous studies have found discordance between mitochondrial and nuclear phylogenies in some kinosternid groups, with the current taxonomy following the nuclear-based results. Herein, based on extended molecular, geographic, and taxonomic sampling, we explore the phylogeographic structure and taxonomic limits for K. leucostomum and the K. scorpioides group and present a fossil-calibrated nuclear time tree for Kinosternon. Our results reveal contrasting differentiation patterns for the K. scorpioides group and K. leucostomum , despite overlapping distributions. Kinosternon leucostomum shows only shallow geographic divergence, whereas the K. scorpioides group is polyphyletic with up to 10 distinct taxa, some of them undescribed. We support the elevation of K. s. albogulare and K. s. cruentatum to species level. Given the deep divergence within the genus Kinosternon , we propose the recognition of three subgenera, Kinosternon , Cryptochelys and Thyrosternum, and the abandonment of the group-based classification, at least for the K. leucostomum and K. scorpioides groups. Our results show an initial split in Kinosternon that gave rise to two main radiations, one Nearctic and one mainly Neotropical. Most speciation events in Kinosternon occurred during the Quaternary and we hypothesize that they were mediated by both climatic and geological events. Additionally, our data imply that at least three South American colonizations occurred, two in the K. leucostomum group, and one in the K. scorpioides group. Additionally, we hypothesize that discordance between mitochondrial and nuclear phylogenetic signal is due to mitochondrial capture from an extinct kinosternine lineage. [ABSTRACT FROM AUTHOR]