Insight into the Skin Mycobiota of Myotis myotis: How Age, Sex, and Biometric Traits Correlate with Fungal Diversity

This study examines fungal diversity on the wing and tail membranes of the Greater mouse-eared bat (<i>Myotis myotis</i>) in autumn, focusing on age, sex, forearm length, and weight. Samples from 15 bats in the Połom caves (Poland) were cultured at 5 °C, 24 °C, and 37 °C. A total of 39 fungal species were identified, with higher diversity on wing membranes. The highest species count occurred at 24 °C (35 species), followed by 5 °C (19 species), and 37 °C (11 species), indicating most isolates were psychrotolerant or mesophilic. The number of fungal species increased with the number of males (r_S = 0.181, <i>p</i> = 0.518) and with bat age (r_S = 0.190, <i>p</i> = 0.497), particularly in males (r_S = 0.455, <i>p</i> = 0.186), and female age showed a negative correlation (r_S = -0.363, <i>p</i> = 0.548). In turn, the length of the female forearm as well as their body weight negatively affected the number of species occurring on their wing and tail membranes (r_S = -0.667, <i>p</i> = 0.219, and r_S = -0.975, <i>p</i> = 0.004, respectively). In the case of <i>M. myotis</i> males, positive effects of forearm length (r_S = 0.341, <i>p</i> = 0.334) and body weight (r_S = 0.210, <i>p</i> = 0.559) on the number of fungal species inhabiting them were noted. The most frequently isolated species was <i>Apiospora arundinis</i>. The absence of <i>Pseudogymnoascus destructans</i> (Pd) suggests caves, rather than bats, are the primary Pd reservoirs. The observed fungal diversity and its correlation with biometric traits may have implications for the health and ecology of <i>M. myotis</i>. The study establishes a baseline for understanding fungal-bat interactions, with potential relevance for disease surveillance and conservation strategies.