Thursday, July 4, 2013

[Mammalogy • 2013] Crocidura sapaensis • Bones and genes: resolution problems in three Vietnamese species of Crocidura (Soricomorpha, Soricidae) and the description of an additional new species

adult male Crocidura sapaensis


Recent investigations of Southeast Asian white toothed shrews belonging to the genus Crocidura have revealed discrepancies between the results of morphological and molecular studies. The following study concerns three species of Crocidura occurring in Vietnam, namely C. attenuata, C. tanakae and C. wuchihensis, and an undescribed fourth species revealed by molecular analysis. For many years Crocidura attenuata has been known to occur in Vietnam but, until very recently, the morphologically similar and comparably sized C. tanakae was believed to be restricted to Taiwan. Following several molecular studies over the last few years, this species is now believed to be considerably more widespread and recognised as occuring also in Vietnam. The results of one of these recent molecular studies also revealed the presence of an undescribed species of Crocidura, similar in size and morphology to Crocidura wuchihensis, which is herein described. Data are provided on geographical variation in Vietnam and the problems of defining morphologically similar yet molecularly disparate species are discussed.

Keywords: Crocidura, new species, morphology, molecular analysis, geographical variation

Etymology: The new species is named after Sa Pa, the capital of Sa Pa District in Lao Cai Province of northern Vietnam, with the Latin suffix -ensis (belonging to).

Natural history: The series of type specimens was collected from a variety of habitats in the vicinity of Tram Ton Station of Hoang Lien National Park: mixed evergreen forest; forested banks of small streams; open grassy glades (Fig. 6); primary forest with large trees at an elevation 1930–2200m (Abramov et al. 2008b). During 2005–2010 a total of 190 shrews was captured in this area, including 4 species (Crocidura sapaensis, Blarinella griselda Thomas, 1912, Anourosorex squamipes Milne Edwards, 1872, and Episoriculus leucops (Horsfield 1855)). Crocidura sapaensis was the most numerous species (90% of the total captures), followed by Anourosorex squamipes and Blarinella griselda (5.3% and 4.2% respectively), while only one Episoriculus leucops was captured (Abramov et al. 2010). Crocidura sapaensis was more abundant in slightly disturbed mixed forest (2.2–3.0 specimens per 100 trap/nights), the occurrence in open glades, amongst shrubs on stream banks and in undisturbed primary forest was 0.3–2.6 specimens per 100 trap/nights. The proportion of males to females in Crocidura sapaensis was greater in all seasons; on average the male to female ratio is 2.3. Pregnant females were recorded from May to mid-July. Mean litter size in Crocidura sapaensis was 3.0 (2-4, n=15).

Distribution: Confirmed specimens of Crocidura sapaensis are recorded from Lao Cai Province, Sa Pa District on the basis of cyt b analysis and morphology of m3. On the basis of morphology, specimens from the northern part of Lao Cai Province, Ngai Tio (elevation 1450m) and from the vicinity of Cat Cat Village near Sa Pa Town (elevation 1400–1450m) in relatively close geographical proximity also probably belong to the same species.

Populations of Crocidura wuchihensis identified on the basis of cyt b and those probably representing this species on the basis of morphology (from Pa Kha and Thai Nien, both in Lao Cai Province) all occur in northeastern Vietnam in localities to the east of the Song Hong (Red River). The observation that this river marks the border between the two species, with Crocidura wuchihensis to the east and Crocidura sapaensis to the west, was made by Bannikova et al. (2011), however this apparent biogeographical separation is based on few locality records. These authors also observed that, in the cyt b analysis, the two northern Vietnamese populations of Crocidura wuchihensis (from Mt Tay Con Linh II [22°46'N, 104°49'E] and Tam Dao [21°27'N, 105°38'E]) were separated by a p- distance of 2.1% suggesting that they probably represent distinct geographic populations.

The population of Crocidura wuchihensis recorded from Huong Son, Ha Tinh Province in the southern Annamites by Lunde et al. (2004) and Jenkins et al. (2009), does of course, occur west of the Song Hong and samples have not been included in any of the previous molecular studies. Specimens from Mt Tay Con Linh II are larger on average (CIL 15.7–17.1, mean 16.4) than those from Huong Son (CIL 15.8-16.4, mean 16.0). The Canonical Variate Analysis reported in Jenkins et al. (2009: Fig. 10) shows that these two groups respectively from northern Vietnam and the southern Annamites are moderately well separated from each other. In view of the problems outlined in this paper, lacking further evidence from molecular studies, it is impossible to predict if the population from Huong Son is correctly assigned to Crocidura wuchihensis, could belong to Crocidura sapaensis, or might indeed represent a further undescribed species.

New Species of White Toothed Shrew Identified
 A genetic analysis of the Vietnamese white toothed shrew fauna, reported in the open access journal ZooKeys, has revealed a new species in the genus Crocidura, named Crocidura sapaensis.

Paula Jenkins, Alexei Abramov, Аnna Bannikova, Viatcheslav Rozhnov. 2013. Bones and genes: resolution problems in three Vietnamese species of Crocidura (Mammalia, Soricomorpha, Soricidae) and the description of an additional new species. ZooKeys. 313 : 61-79.