Abstract

The six species and three subspecies in the genus Chimarrogale (Soricomorpha: Soricidae) are commonly referred to as Asiatic water shrews. The Chimarrogale are the most widely distributed group of Nectogaline shrews, extending throughout the Oriental region and Japan. Because of the limited numbers of specimens available for study, the phylogenetic relationships and biogeographical history of this genus have not been comprehensively discussed. We used mitochondrial cytochrome b gene sequences to estimate phylogenetic relationships and divergence times among four Chimarrogale species, including all three subspecies of Chimarrogale himalayica. We also conducted a species delimitation analysis and tested two alternative migration scenarios in Asia through species distribution modeling and a reconstruction of the ancestral distribution. Here, we present the first proposed hypothesis regarding the Asiatic water shrew phylogeny and reveal ten putative species within the four recognized species. Distinct phylogenetic statuses of Chimarrogale phaeura, Chimarrogale platycephala, and Chimarrogale styani were confirmed. Chimarrogale himalayica was strongly supported as paraphyletic. We suggest that three subspecies of Chimarrogale himalayica should be reconsidered as distinct species. However, these suggestions must be considered with caution because only a single locus of a mtDNA gene was used. Four additional putative species, possibly distributed in central southwestern China and Taiwan, are currently undescribed; therefore, comprehensive morphological analyses are warranted to test their taxonomic statuses. The estimated molecular divergence times indicated that rapid speciation occurred during the early Pliocene, and current distribution patterns may have been affected by global cooling during the Pliocene/Pleistocene boundary. Reconstruction of the ancestral distribution and species distribution modeling for Asiatic water shrews revealed a low-latitude migration route over which ancestral Chimarrogale migrated from Europe via Central Asia to their current distribution. Our results demonstrated that Asiatic water shrews could have evolved throughout the low-latitude migration route from Europe to East and Southeast Asia.

Highlights

  • Species in the genus Chimarrogale Anderson 1877 are commonly referred to as Asiatic water shrews

  • The results showed significant support for four monophyletic clades within Chimarrogale, while the relationships between them were left unresolved in the maximum likelihood (ML) and Bayesian analyses

  • C. platycephala from Japan was well-embedded within C. himalayica (BS=98, PP=1.0), indicating the latter as a paraphyletic species

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Summary

Introduction

Species in the genus Chimarrogale Anderson 1877 are commonly referred to as Asiatic water shrews. These small insectivores belong to the tribe Nectogalini in the family Soricidae and are adapted to a semi-aquatic lifestyle. Based on the latest review by Hutterer [1], six species are recognized in this genus: Chimarrogale himalayica Gray, 1842 [2] is distributed in northern India, Nepal, Laos, Myanmar, Vietnam, southwestern and southeastern China, and Taiwan; Chimarrogale styani de Witon 1899 is distributed in southwestern China and northwestern Myanmar; Chimarrogale platycephala Temmink, 1842 is endemic to Japan; Chimarrogale phaeura Thomas, 1898 is distributed in northern. Leander Thomas, 1902 in Fujian (China) and Taiwan Previous classifications of this genus have been based on external morphological and cranial characters and have been in doubt for several years (see Motokawa et al [5] for the details). The phylogenetic relationships and biogeographic history of Asiatic water shrews were left unresolved

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