Is there more than one Crocodile Lizard? An Integrative Taxonomic Approach Reveals Vietnamese and Chinese Shinisaurus crocodilurus Represent Separate Conservation and Taxonomic Units

The Crocodile lizard Shinisaurus crocodilurus, the only living representative of the family Shinisauridae, is a habitat specialist adapted to remote freshwater habitats within evergreen broadleaf forests. Its current distribution is restricted to few small and isolated remnant occurrences in South China and North Vietnam. Multiple anthropogenic threats such as massive habitat destruction and unsustainable over-collection for the international pet trade brought the species to the brink of extinction. We herein employed an integrative taxonomic approach including comprehensive molecular comparisons based on fragments of mitochondrial genes (cytochrome b, partial ND6, and partial tRNA-Glu) in concert with in-depth morphological and ecological analyses in order to determine the status of the extant populations. Based on molecular, morphological, and ecological differences, we herein describe a new subspecies, Shinisaurus crocodilurus vietnamensis ssp. n., from Vietnam. Our findings emphasize the importance of improved in situ conservation measures in both countries, as both China and Vietnam harbor unique Crocodile lizard forms. We also recommend additional ex situ conservation measures, i.e., separate conservation breeding management of the subspecies in order to maintain genetic integrity and adjust husbandry conditions according to detected differences in ecological niche occupation.