Karyotypes of field mice of the genus Apodemus (Mammalia： Rodentia) from China

Karyotypes of four Chinese species of field mice of the genus Apodemus were examined,including Apodemus chevrieri （diploid chromosome number,2n=48,fundamental number of autosomal arms,FNa=56）,A.draco （2n=48,FNa=48）,A.ilex （2n=48,FNa=48）,and A.latronum （2n=48,FNa=48）.Karyotypes of A.chevrieri,A.draco,and A.ilex are reported here for the first time,providing useful information for their species taxonomy.Determining the karyotypes of all species of Apodemus in Asia,both in this and previous studies,provides a solid overview of the chromosome evolution and species differentiation of the genus in East Asia.In addition to allopatric speciation,chromosome rearrangements likely played an important role in the formation of the four Apodemus species groups as well as speciation within each group in East Asia.For example,increased centromeric heterochromatin in A.latronum may have contributed to the post-mating reproductive isolation from the A.draco-A.ilex-A.semotus clade.

Molecular phylogeographic analyses and species delimitations reveal that Leopoldamys edwardsi(Rodentia:Muridae)is a species complex

Leopoldamys edwardsi is a species with wide distribution ranges in southern China but is not discussed in stud­ies on geographic variation and species differentiation.We used 2 mitochondrial(Cytb,CO1)and 3 nuclear(GHR,IRBP and RAG1)genes to clarify species phylogeography and geographical differentiation.Maximum likelihood(ML)and Bayesian phylogenetic inference(BI)trees consistently indicated that L.edwardsi is a spe­cies complex containing 3 main lineages with high Kimura-2-parameter(K2P)divergences(i.e.lineages LN,LS and LHN)found in the northern and southern China and Hainan Island,respectively.The 3 species delimitation methods,automated barcoding gap discovery,Bayesian poisson tree process analysis and Bayesian phylogenet­ics and phylogeography,consistently supported the existence of cryptic species.Divergence times among the main lineages were inferred to be during the Pleistocene,with LHN/LS split at 1.33 Ma and LN/(LHN+LS)at 2.61 Ma;the diversifications of L.edwardsi complex might be caused by the rapid uplifts of Tibetan Plateau,paleo­climate change and complex topography.The divergence between LHN and LS was probably related to the sepa­ration of Hainan Island from the mainland via the formation of the Qiongzhou Strait.Lineages LN and(LS+LHN)likely diverged due to the Wuyi-Nanling mountain range forming a dispersal barrier.Our results suggested that L.edwardsi complex contains at least 3 distinct species:LHN represents L.hainanensis,endemic to Hainan Island and previously considered as a subspecies L.e.hainanensis;LS represents a cryptic species distributed through­out the southern Chinese continent;and LN represents the nominotypical species L.edwardsi.

Karyotypes of three shrew species(Soriculus nigrescens,Episoriculus caudatus and Episoriculus sacratus)from Nepal

The karyotypes of three shrew species(Mammalia,Soricomorpha,Soricidae)from Nepal were examined for the first time.Based on the karyotypes and overall differences in skull size,the current Episoriculus caudatus appeared to include two distinct species:the larger E.caudatus and the smaller Episoriculus sacratus.Episoriculus sacratus has three subspecies,E.s.soluensis in Nepal and Sikkim,E.s.umbrinus in Assam,Myanmar and the Yunnan Province of China,and E.s.sacratus in the Sichuan Province of China.Soriculus nigrescens had a diploid chromosome number(2n)and fundamental number(FN),including two X chromosomes,of 64 and 92,respectively,consisting of 11 metacentric or submetacentric,two subtelocentric and 18 acrocentric pairs of autosomes,a metacentric X and an acrocentric Y chromosome.Episoriculus sacratus soluensis had 2n=74 and FN=126,consisting of 12 metacentric or submetacentric,13 subtelocentric and 11 acrocentric pairs of autosomes,a submetacentric X and an acrocentric Y chromosome.Episoriculus caudatus had 2n=60 and FN=118,consisting of 19 metacentric or submetacentric,nine subtelocentric and one acrocentric pair of autosomes,a subtelocentric X and an acrocentric Y chromosome.The karyotypes of these three species are characterized by their large 2n and FN values compared with other Soricidae.