Abstract <p>Myxomycetes are one of the examples of fungus-like protists with hidden diversity. Their trophic stages are usually hidden from the eye. The species is identified on the basis of the characteristics of mature sporocarps. Morphological characteristics, including the structure and color of the peridium and capillitium as well as belonging to a certain ecological and trophic group, are an issue of important value. In August 2024, ten specimens were found in the vicinity of Krasnoufimsk (Sverdlovsk oblast, Russia), which were classified as <i>Nannengaella alpina</i> (≡<i>Physarum alpinum</i>) on the basis of morphological characteristics. They were shown to have variable color and structure of the peridium depending on the illumination of the substrate on which the sporocarps was found. The reliability of the identification of the collected specimens and the taxonomic history of the species are discussed. On the basis of the variability of morphological and ecological characteristics, it can be assumed that either this morphospecies is highly variable, or <i>N. alpina</i> is a group of cryptic species of different ecology.</p>