Morphometric and bioacoustic profiling of Myotis cf. davidii/aurascens (Chiroptera, Vespertilionidae) in East Asia: evidence for a range extension and elevational record

During a Chiroptera resource survey conducted in 2023 on the Pamir Plateau of China's Xinjiang Uygur Autonomous Region, two adult male bat individuals were captured. External morphology examination revealed small-sized individuals characterized by long, narrow ears with straight tragus structures tapering to sharp tips-features diagnostic of the genus <i>Myotis</i>. Concurrently, we obtained free-flight echolocation calls from the bats: the signals showed an initial frequency of 65.12 ± 2.12 kHz, terminal frequency of 42.78 ± 1.27 kHz, peak energy frequency of 47.41 ± 1.46 kHz, pulse duration of 2.52 ± 0.26 ms, and inter-pulse interval of 94.01 ± 31.41 ms. Based on skull morphological traits and bioacoustic data, the specimens were preliminarily identified as <i>Myotis aurascens</i>. However, our phylogenetic analysis based on the mitochondrial cytochrome <i>b</i> (<i>Cytb</i>) gene revealed that sequences attributed to <i>M. aurascens</i> and <i>M. davidii</i> formed a single strongly supported clade, underscoring the unresolved taxonomic status of these species. Irrespective of the exact species assignment, this discovery constitutes the first documented occurrence of the <i>M. davidii</i>/<i>aurascens</i> complex on the Pamir Plateau, thereby extending the known distribution range in China. Notably, these specimens represent the highest-elevation record for this group to date (3200 m). Our study provides the first comprehensive description of cranial morphology and echolocation signatures for this taxon in a high-altitude habitat. These findings significantly enhance regional biodiversity inventories and offer critical baseline data for plateau ecosystem research.