Recent hybrid origin of three rare Chinese turtles

Abstract

Three rare geoemydid turtles described from Chinese trade specimens in the early 1990s, Ocadia glyphistoma, O. philippeni, and Sacalia pseudocellata, are suspected to be hybrids because they are known only from their original descriptions and because they have morphologies intermediate between other, better-known species. We cloned the alleles of a bi-parentally inherited nuclear intron from samples of these three species. The two aligned parental alleles of O. glyphistoma, O. philippeni, and S. pseudocellata have 5–11.5 times more heterozygous positions than do 13 other geoemydid species. Phylogenetic analysis shows that the two alleles from each turtle are strongly paraphyletic, but correctly match sequences of other species that were hypothesized from morphology to be their parental species. We conclude that these rare turtles represent recent hybrids rather than valid species. Specifically, “O. glyphistoma” is a hybrid of Mauremys sinensis and M.␣cf. annamensis, “O.␣philippeni” is a hybrid of M. sinensis and Cuora trifasciata, and “S. pseudocellata” is a hybrid of C. trifasciata and S. quadriocellata. Conservation resources are better directed toward finding and protecting populations of other rare Southeast Asian turtles that do represent distinct evolutionary lineages.