Cryptocalciella - a new Mortierellaceae genus from Alpine glacier forefields

Mortierellaceae are cosmopolitan, soil-inhabiting fungi that can be found in nearly all terrestrial habitat types and are therefore considered an essential part of the core soil microbiome. Many species of this family are known to endure harsh environments, including highly exposed and nutrient-depleted terrains such as glacier forefields. In these environments, microbial communities are taxonomically and functionally diverse, greatly contributing to nutrient cycling, soil organic matter formation, and plant establishment. However, there is growing understanding that Mortierellaceae diversity in these habitats remains largely undescribed. In this study, we isolated multiple fungal strains belonging to a previously unknown Mortierellaceae taxon from early stages of soil development in calcareous glacier forefields of the Alps and comprehensively characterized them using different tools: physiological tests, detection of associated bacteria, and microscopic observations (e.g., light, fluorescence, and scanning electron microscopy) to visualize their morphology and surface structure. Additionally, whole-genome sequencing and phylogenomics were used to determine their placement within Mortierellaceae. Our results show that the isolated strains represent a new species within a previously undescribed fungal genus. Due to the strains' origin in hidden, calcareous sediments of the earliest soil developmental stages at glacier forefields, we propose the name Cryptocalciella humilis Mandolini, Szedlacsek & Peintner for this fungus.