Cave ecosystems represent environmentally constrained habitats that host diverse and highly specialized fungal communities. Many cave-dwelling fungi act as decomposers, transient colonizers, or cave fauna symbionts. During a mycological survey of Sesalačka cave (Serbia), a previously undescribed species was isolated from the skin of a Miniopterus schreibersii. The aim of this study was to characterize this isolate using an integrative taxonomic approach combining morphology, physiology, and multilocus phylogenetics. The fungus was cultured on different media under and its morphophysiological traits were recorded. DNA sequences of ITS, LSU, SSU, and TEF1α were compared with existing Gamsia species and phylogenetic analysis placed the isolate within the Gamsia clade, forming a well-supported lineage the most closely related to G. aggregata, but differing from it by 8–12 base pairs across loci. Distinctive morphological features of this species include obovoid to pyriform polyblastic conidia, hyaline to pale-brown annelloconidia, and reduced conidiophores, clearly separating the species from described congeners. It is psychrotolerant and does not grow at 37 °C, suggesting it is a cave-associated saprobe rather than a mammalian pathogen. This study expands the known diversity of Gamsia species and contributes to the growing evidence that subterranean habitats harbor numerous undescribed fungal kingdom members.