我国巢鼠属分类和分子系统学分析

本研究对2018至2021年采集的9号巢鼠(Micromys minutus)标本、22号红耳巢鼠(M. erythrotis)标本和19号待厘定的巢鼠属标本，进行形态分类和分子系统学分析，进一步揭示我国巢鼠属的分类和系统分化问题。待厘定的巢鼠属标本形态特征为：标本体背毛黑棕，体腹毛基灰色，毛尖灰白，体侧毛色具明显区分，尾背部毛色黑棕，尾腹部毛色灰棕色；尾长长于头体长的120%；头骨背面观可见颧弓明显弯曲；颅全长[(18.59 ± 0.48)mm]和颅基长[(17.43 ± 0.48 mm)]较长，腭长[(9.35 ± 0.11)mm]较长，脑颅高[(7.43 ± 0.06)mm]较高。待厘定的巢鼠属标本形态特征与巢鼠和红耳巢鼠均存在差异。待厘定巢鼠属标本与巢鼠和红耳巢鼠之间的遗传距离分别为0.115和0.136，接近于巢鼠与红耳巢鼠之间的遗传距离(0.126)。利用Cyt b基因全序列和核基因IRBP1、RAG1和RAG2序列分别构建的巢鼠属系统发生树均以较高的置信度分化成3个进化支，即巢鼠、红耳巢鼠和待厘定的巢鼠属样本的进化支。形态学和分子系统学分析结果均支持待厘定的巢鼠属标本为独立物种分类单元，对应于文献记载的巢鼠川西亚种(M. m. pygmaeus)。根据产地、遗传距离和形态分化，建议将巢鼠川西亚种提升为种，命名为川西巢鼠(M. pygmaeus comb. nov.)。利用Cyt b基因全序列构建的巢鼠系统发生树分化成6个进化谱系：日韩谱系、欧洲谱系、俄罗斯新西伯利亚谱系、中国东北和俄罗斯远东谱系、中国安徽谱系和中国台湾谱系。

Taxonomic and Molecular Phylogenetic Analyses of Micromys in China

[Objectives] In order to clarify taxonomy and molecular phylogenetics of Micromys in China,this study analyzed morphological and molecular data of 9 specimens of M. minutus, 22 specimens of M. erythrotis, and 19 pending specimens of Micromys collected between 2018 and 2021. [Methods] Themorphological characteristics of specimens and skulls were described and measured. Molecular phylogenetic studies include the calculation of genetic distance (the Kimura 2-parameter model) and the construction of phylogenetic trees (maximum likelihood, ML). [Results] The morphological characteristics of pending specimens of Micromys showed differences from M. minutus and M. erythrotis. The back of the body is black-brown (Fig. 1). The base of the hair on the abdomen is gray (Fig. 1). The tip of the hair is gray-white (Fig. 1). The color of the hair on the sides of the body is clearly differentiated (Fig. 1), the dorsal surface of the tail is dark brown (Fig. 1) and the ventral surface of the tail is gray-brown (Fig. 1). Tail length is longer than 120% of head and body length (Table 2). The zygomatic arch is clearly curved inward (Fig. 2). Greatest length of the skull and Condyloincisive length (18.59 ± 0.48 mm and 17.43 ± 0.48 mm) is longer (Table 2). Palatal length (9.35 ± 0.11 mm) is longer (Table 2). Braincase height (7.43 ± 0.06 mm) is higher (Table 2). The genetic distances between pending specimens of Micromys and M. minutus and M. erythrotis are 0.115 and 0.136, which are near the genetic distance (0.126) between M. minutus and M. erythrotis. Based on the complete sequence of the Cyt b of mtDNA and nuclear gene sequences (IRBP1, RAG1, and RAG2), two phylogenetic trees were constructed. Samples were clustered into 3 clades in both phylogenetic trees (M. minutus clade, M. erythrotis clade, and pending specimens of Micromys clade) with high confidence (Fig. 4, 5). [Conclusion] The results of morphological analyses and the molecular phylogenetics supported that the pending specimens of Micromys arean independentspecies, corresponding to M. m. pygmaeus reported in previous studies. Based on the locality, genetic distance, and morphological differentiation, it is suggested that the M. m. pygmaeus should be elevated to a species and named M. pygmaeus comb. nov.. The samples of M. minutus in phylogenetic tree based on the Cyt b of mtDNA were clustered into 6 lineages:Japanese and Korean lineage, European lineage, Novosibirsk Russia lineage, Northeast China and Far East Russia lineage, Anhui China lineage, and Taiwan China lineage.