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

Abstract

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.

The first record of Episoriculus umbrinus from Vietnam, with notes on the taxonomic composition of Episoriculus (Mammalia, Soricidae)

“…These data have confirmed the previous morphological and karyological data (Motokawa & Lin, 2005;Motokawa et al, 2008Motokawa et al, , 2009) and testified the species rank of most studied taxa. However, the distance between E. baileyi and E. leucops was low, just 3.4%, that contradicts the morphological findings by Motokawa & Lin (2005).…”

“…** species of Episoriculus were allocated based on geographic origin of specimens (according to Motokawa & Lin, 2005;Motokawa et al, 2008Motokawa et al, , 2009 …”

“…According to their data, E. baileyi is known from Sikkim and Assam in India, Myanmar and Vietnam, whereas E. leucops is restricted to Nepal. Further karyological studies revealed large differences in the karyotypes of E. caudatus s. lato (Motokawa et al, 2008(Motokawa et al, , 2009. Shrews from Sichuan Province of China with 2n=58, FN=108 were treated as a distinct species E. sacratus (Thomas, 1911), the smaller form from Nepal with 2n=74, FN=126 -as E. soluensis Gruber, 1969 and the large form from Nepal with 2n=60, FN=118 -as E. caudatus.…”

“…Earlier, Soriculus Blyth, 1854 was treated in a broad sense and also included Episoriculus Ellerman et Morrison-Scott, 1966 andChodsigoa Kastchenko, 1907 as the subgenera/synonyms (Hoffmann, 1986;Corbet & Hill, 1992;Motokawa & Lin, 2005). Only recently these taxa were given a full generic rank (Hutterer, 2005;Motokawa et al, 2008Motokawa et al, , 2009He et al, 2010). The distinctions between these genera involve differences in the shape of articular facets of the mandible, the amount of brownish dental pigmentation, the number of upper unicuspid teeth, and the relative proportions of teeth, forefeet and tail (see Hoffmann, 1986).…”

High Diversity of Small Insectivorous Mammals on Qinghai-Tibet Plateau and First Description of Karyotype for four Endemics of China

“…hypsibia and most of other species of this genus. In the genus Episoriculus, closely related to Chodsigoa, there are also large differences in the number of metacentric and acrocentric chromosomes between E. caudatus with 2n = 60, NF = 118 (M + SM = 19, ST = 9, A = 1) and E. soluensis with 2n = 74, NF = 126 (M + SM = 12, ST = 13, A = 11) 39 . Those authors consider E. soluensis a subspecies of E. saсratus soluensis.…”