Do Cryptic Species Exist in <i>Hoplobatrachus rugulosus</i>? An Examination Using Four Nuclear Genes, the <i>Cyt b</i> Gene and the Complete MT Genome

<div><p>he Chinese tiger frog <i>Hoplobatrachus rugulosus</i> is widely distributed in southern China, Malaysia, Myanmar, Thailand, and Vietnam. It is listed in Appendix II of CITES as the only Class II nationally-protected frog in China. The bred tiger frog known as the Thailand tiger frog, is also identified as <i>H</i>. <i>rugulosus</i>. Our analysis of the <i>Cyt b</i> gene showed high genetic divergence (13.8%) between wild and bred samples of tiger frog. Unexpected genetic divergence of the complete mt genome (14.0%) was also observed between wild and bred samples of tiger frog. Yet, the nuclear genes (<i>NCX1</i>, <i>Rag1</i>, <i>Rhod</i>, <i>Tyr</i>) showed little divergence between them. Despite this and their very similar morphology, the features of the mitochondrial genome including genetic divergence of other genes, different three-dimensional structures of ND5 proteins, and gene rearrangements indicate that <i>H</i>. <i>rugulosus</i> may be a cryptic species complex. Using Bayesian inference, maximum likelihood, and maximum parsimony analyses, <i>Hoplobatrachus</i> was resolved as a sister clade to <i>Euphlyctis</i>, and <i>H</i>. <i>rugulosus</i> (BT) as a sister clade to <i>H</i>. <i>rugulosus</i> (WT). We suggest that we should prevent Thailand tiger frogs (bred type) from escaping into wild environments lest they produce hybrids with Chinese tiger frogs (wild type).</p>