White-toothed shrew (genus Crocidura) diversity in Iran: Molecular evidence and taxonomic implications

Abstract

White-toothed shrews (genus Crocidura), with a wide distribution across the Palearctic, are among the lesser-known small mammals in Iran. Recent molecular studies uncovered several deep divergences within traditional nominal species, challenging their taxonomic status. Specimens from across Iran were collected to explore the diversity and taxonomy of the small white-toothed shrew (Crocidura suaveolens) and the bicoloured shrew (Crocidura leucodon) using both morphological and molecular data. Mitochondrial cytochrome b (Cytb) analysis identified five distinct lineages, two of which are endemic to Iran. The specific position of the Iranian bicoloured shrew (Crocidura persica Thomas, 1907) is supported by morphological and genetic (Cytb and Brca1) evidence. Three lineages of C. suaveolens sensu lato were classified as C. suaveolens sensu stricto, Crocidura gueldenstaedtii and Crocidura caspica; the first species also contains sequences from Dasht-Bujnurd which is the type locality of Crocidura gmelini. An unnamed lineage from central Iran (lineage VIII) is described as a new species, Crocidura darvishi n. sp. The three suaveolens group species clearly differ in Cytb sequences but less so in the nuclear Brca1 tree. Morphological differences are also slight. These findings, along with a taxonomic annex of Iranian species, enhance our understanding of Iran's unique fauna. Despite its peripheral location in temperate biotas, Iran is a hotspot for basal lineages of small mammals, especially in refugial areas like the Hyrcanian Forest (C. persica, C. caspica), Zagros (C. darvishi n. sp.), and Kopet-Dagh.