Calomyscidae is a monotypic family of muroid rodents with nine valid allopatric species distributed in southwestern Asia of which seven species have been so far recognized from Iran. The western and southern Zagros Mountains were thought to be home to a single species, Calomyscus bailwardi, but new researches revealed that the region is also home to four highly divergent molecular lineages. One of them was recently described as a new species (C. behzadi) but the taxonomic position of the other lineages remained unclear. Here we did an extensive sampling in southern Iran (2017-2018), during which 99 Calomyscus specimens were collected. Based on an integrated approach including karyotypic, mitochondrial as well as morphological data, we describe Calomyscus kermanensis sp. nov. as a new endemic species from the southern Zagros Mts (including Kohgiluyeh and Boyer- Ahmad, Fars, Kerman, Yazd and Hormozgan provinces), in the region that was previously thought to be occupied by C. bailwardi. The new species emerged as a new lineage with high intraspecific mtDNA and chromosome variations. The multivariate and univariate statistical analyses of craniodental measurements also separated C. kermanensis sp. nov. from other examined Calomyscus species with the highest maximum cranial height being the most distinctive of its craniodental features.

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