The Paramesotriton Chang, 1935 genus of Asian warty newts is the second most diverse genus in the family Salamandridae, currently containing 14 recognized species from northern Vietnam to southwest-central and southern China. Although species of this genus have been included in previous phylogenetic studies, the origin and interspecific relationships of the genus are still not fully resolved, especially at key nodes in the phylogeny. In this study, we sequenced mitochondrial genomes and 32 nuclear genes from 27 samples belonging to 14 species to reconstruct the interspecific phylogenetic relationships within Paramesotriton and explore its historical biogeography in southern China. Both Bayesian inference and maximum-likelihood analyses highly supported the monophyly of Paramesotriton and its two recognized species groups ( P. caudopunctatus and P. chinensis groups) and further identified five hypothetical phylogenetic cryptic species. Biogeographic analyses indicated that Paramesotriton originated in southwestern China (Yunnan-Guizhou Plateau/South China) during the late Oligocene. The time of origin of Paramesotriton corresponded to the second uplift of the Himalayan/Qinghai-Xizang (Tibetan) Plateau (QTP), rapid lateral extrusion of Indochina, and formation of karst landscapes in southwestern China. Principal component analysis (PCA), independent sample t-tests, and niche differentiation using bioclimatic variables based on locations of occurrence suggested that Paramesotriton habitat conditions in the three current regions (West, South, and East) differ significantly, with different levels of climatic niche differentiation. Species distribution model (SDM) predictions indicated that the most suitable distribution areas for the P. caudopunctatus and P. chinensis species groups are western and southern/eastern areas of southern China. This study increases our knowledge of the taxonomy, biodiversity, origin, and suitable distribution areas of the genus Paramesotriton based on phylogenetic, biogeographic, and species distribution models.
亚洲蝾螈瘰螈属（ Paramesotriton Chang, 1935）是蝾螈科物种多样性第二高的属，目前有14个公认的有效物种（仅次于有36个物种的疣螈属 Tylototriton），分布于越南北部至中国西南部、中部和南部地区。尽管瘰螈属的物种已被纳入到先前的系统发育研究中，但该属的起源和种间关系仍未完全解析，特别是在系统发育的关键节点上。该研究对瘰螈属14个物种的27个样本进行线粒体基因组和32个核基因测序，重建了瘰螈属的种间系统发育关系，探讨了中国南方地区瘰螈属的历史生物地理学。贝叶斯推断和最大似然法分析都高度支持瘰螈属及其尾斑瘰螈种组（ P. caudopunctatus species group）和中国瘰螈种组（ P. chinensis species group）单系性，并识别出5个系统发生隐蔽种。生物地理学分析表明，瘰螈属在渐新世晚期（约25.42百万年）起源于中国西南地区（云贵高原/华南）。瘰螈属的起源时间与喜马拉雅/青藏高原的第二次隆起、中南半岛的快速侧向挤压以及中国西南地区岩溶地貌的形成相一致。主成分分析、独立样本 t检验和基于发生点生物气候变量的生态位分化结果表明，瘰螈属3个当前的分布区域（西部、南部、东部）栖息地的生境条件存在显著差异，且具有不同程度的气候生态位分化。物种分布模型预测结果表明，尾斑瘰螈种组和中国瘰螈种组最适合的分布区域在中国南方的西部和南部/东部地区。综上所述，该研究在系统发育、生物地理和物种分布模型的基础上，增加了对瘰螈属在分类学、生物多样性起源和适宜分布区等方面的认识。.
Keywords: Biogeography; Paramesotriton; Southern China; Systematics.