Black-footed Reindeer Lichen

Like other members of its genus, C. stygia has a two-part (dimorphic) structure: it begins life with a crust-like layer growing on the substrate, but this eventually disappears as the more prominent upright, branching structures (the podetia) develop. The lichen is distinguished by several characteristic features of its structure. The podetia typically reach heights of 5–15 cm tall, occasionally reaching 30 cm, with the living (active) portion measuring up to 10 cm. The main stem is about 1 mm thick, with segments between branches about 5 mm long. The branching pattern is distinctive, typically dividing into three unequal branches (anisotomic trichotomous), though sometimes splitting into four or two branches. Where the branches divide, they form small holes or perforations called axils. The base of its branches shows a distinctive ash-grey to black colouration on the inside. This dark background is dotted with irregular patches of greenish-white outer tissue (known as the ectal layer), creating a distinctive speckled appearance. These patches often have uneven edges and can sometimes appear almost scale-like. While this mottled, darkened area typically covers the lower half of the branches, in some specimens it may be limited to just the very base. When wet, the lichen can take on an olive-grey colouration. The podetia of C. …

Cladonia stygia is widespread across the Northern Hemisphere but has a fragmented distribution in some regions. In Germany, although the species was recorded in Lower Saxony as early as 1908, it was not observed again until 2012—when new populations were discovered in the lichen‐rich pine forests of the Carrenziener Dünen. Since then, conservation efforts, including experimental lichen reintroduction, have successfully established additional populations within the dune system, where C. stygia co-occurs with other reindeer lichens such as C. portentosa, C. arbuscula, and C. rangiferina. It has also been confirmed in parts of Central Europe – including Germany (with recent reports from the federal state of Hesse) and the Czech Republic – as well as in Canada, Finland, and parts of Asia, suggesting a broad boreal or circumboreal distribution. In the Alps, it occurs from valley bottoms to the subalpine belt (mainly between 300 and 2400 m elevation), but is relatively rare and restricted to raised bogs. It has been documented across multiple Alpine regions, including parts of Austria, Germany, Switzerland, France, Italy, and Slovenia. Although primarily a boreal species, C. …

In boreal and subarctic regions, Cladonia stygia is ecologically significant. Like other reindeer lichens, Cladonia stygia often dominates groundcover and is a key winter food source for reindeer. The species shows a strong preference for treeless, ombrotrophic bogs, where it may outnumber species such as C. rangiferina. It is tolerant of wet conditions – able to survive prolonged periods of inundation during spring and autumn – and in such consistently moist habitats, growth can reach up to 2 cm per year. In Austrian high moor/bog habitats, C. stygia typically occurs in relatively undisturbed areas dominated by Mountain Pine (Pinus mugo), where it grows alongside characteristic bog vegetation. Common vascular plant associates include the dwarf shrubs Calluna vulgaris (heather) and Andromeda polifolia (bog rosemary), the sedge Eriophorum vaginatum (tussock cottongrass), and Rhynchospora alba (white beak-sedge). Other lichens found in these communities include Cladonia pyxidata, C. coniocraea, and C. fimbriata, while typical bryophyte associates are Pleurozium schreberi, Aulacomnium palustre, Sphagnum rubellum, and Leucobryum glaucum. Although C. …