The Effectiveness of Molecular, Karyotype and Morphological Methods in the Identification of Morphologically Conservative Sibling Species: An Integrative Taxonomic Case of the Crocidura attenuata Species Complex in Mainland China

Simple Summary Morphological conservation has always been a problem in the identification of sibling species. In this study, molecular, karyotype and morphological methods are integrated to revise the species classification and distribution of the Crocidura attenuata species complex in mainland China. The results show that there are five species in the C. attenuata species complex. In addition to four known species, namely, C. attenuata, C. tanakae, C. anhuiensis and C. dongyangjiangensis, there was an undescribed species distributed in Guangxi. Among them, C. tanakae is widely distributed in Southern China, C. attenuata is situated only around the Sichuan Basin, and C. anhuiensis and C. dongyangjiangensis are present in Southeast China. The effectiveness of molecular, karyotypic and morphological methods in the taxonomy of the C. attenuata species complex is also discussed in the present study, which will provide a reference for the taxonomic study of other morphologically conserved species. Abstract The conservation of morphology has resulted in considerable issues in the taxonomy of small mammals, especially for the identification of sibling species. Moreover, it is often difficult to completely solve such taxonomic problems by relying only on a single research method. The genus Crocidura is one of the genera with a conservative morphology and high species diversity. Among them, Crocidura attenuata has been considered in the field as the most widely distributed and common species. In fact, it is a species complex containing multiple species, and the classification and distribution of this species is controversial. In this study, the species and distribution of the Crocidura attenuata species complex experienced an integrated revision using three different levels of research methods: molecular, karyotype and morphology. The results show that (1) the C. attenuata species complex contains four known species (C. attenuata, C. tanakae, C. anhuiensis and C. dongyangjiangensis) and a cryptic species distributed in Guangxi, which may be the same undescribed species as the “C. attenuata” distributed in Vietnam. (2) C. attenuata is only distributed around the Sichuan Basin, C. tanakae is the most widely distributed throughout Southern China, and C. anhuiensis and C. dongyangjiangensis are almost sympatric in Southeast China. Furthermore, (3) although the molecular method lacks a unified threshold for species classification, it can rapidly and effectively identify the species of the C. attenuata species complex. Although karyotype and morphology methods cannot completely solve the species classification issues in respect of the C. attenuata species complex, they can provide supplemental information for taxonomic purposes. Therefore, the integrated taxonomic method can present the advantages of different methodological levels, and will provide further evidence for the taxonomy of sibling species with a conservative morphology.