Coleodesmium wrangelii is a filamentous cyanobacterium belonging to the order Nostocales, known from freshwater and terrestrial habitats in arctic and subarctic regions including high-latitude islands. Members of the genus Coleodesmium form trichomes within gelatinous sheaths, contributing to microbial mats and biological soil crusts in cold, harsh environments where they play important roles in nitrogen fixation and primary productivity. As a heterocystous cyanobacterium, Coleodesmium possesses specialized cells called heterocysts capable of fixing atmospheric nitrogen, making the organism a critical contributor to nitrogen cycling in nutrient-poor arctic ecosystems. The species may be found in moist rock surfaces, soil crusts, stream margins, and wet tundra, tolerating freezing temperatures, desiccation, and intense UV radiation. Its occurrence in remote polar regions including areas bearing the name Wrangel Island reflects adaptations to extreme environmental conditions. The taxonomy of arctic cyanobacteria has historically been based on morphological characteristics and is being revised with molecular phylogenetic approaches that often reveal cryptic diversity. Coleodesmium wrangelii contributes to the foundation of polar food webs and is sensitive to environmental change associated with arctic warming.