Melanelia stygia, the alpine camouflage lichen, is a species of lichen in the family Parmeliaceae. The dark-coloured lichen, first described by Carl Linnaeus in 1753, forms leafy growths on rocks in arctic and alpine regions throughout the Northern Hemisphere. The lichen has a dark brown to black, glossy surface with narrow, overlapping lobes and tiny pores called pseudocyphellae scattered across its surface. It is a slow-growing species well-adapted to harsh mountain environments, where it is commonly found on non-calcareous rocks at high elevations. While it tolerates extreme cold conditions, climate change may pose a threat to its survival. The species can be used to produce a brownish-coloured wool dye.
Taxonomy It was first formally described in 1753 by the Swedish taxonomist Carl Linnaeus, who classified it in the eponymous genus Lichen. The type specimen was collected in Uppland, Sweden. It was transferred to several different genera in its long taxonomic history, including Squamaria, Lobaria, Parmelia, and Cetraria. Ted Esslinger reclassified it in Melanelia in 1978; it is the type species of this genus. Modern systematic revisions have narrowed Melanelia to four species (M. stygia, M. hepatizon, M. agnata, and M. pseudoglabra), with many former members transferred to other genera based on molecular evidence. Later molecular phylogenetics analysis established it and its close relative Melanelia hepatizon as members of the "cetrarioid core". This is a phylogenetically defined group of lichens featuring an erect foliose to subfruticose thallus with reproductive structures, both sexual (apothecia) and asexual (pycnidia) located on the margins of lobes. Because species in this group can be hard to separate by appearance alone, molecular data are often used to support identifications. DNA barcoding of the nuclear ribosomal internal transcribed spacer (nrITS) region can identify M. stygia and its close relatives, but Icelandic material shows comparatively high nrITS variation, which Xu and colleagues interpreted as consistent with the possibility of previously unrecognized lineages within M. stygia; in their dataset it formed a strongly supported cluster in a distance-based analysis but was not recovered as a single clade in nrITS phylogenetic tree analyses. In the same Icelandic study, chemical profiling found M. stygia and M. agnata broadly similar in their major metabolites, reinforcing the usefulness of DNA data when specimens are ambiguous. A broader study of ITS variation, using Polish material together with sequences from elsewhere in the species' range, likewise found multiple haplotypes in M. stygia. Many of these were widely distributed, with some shared between temperate and polar populations, and the authors found no clear geographic pattern or consistent relationship between haplotype variation and morphological, anatomical, or chemical characters. Some earlier studies suggested that while Melanelia stygia was closely aligned with the cetrarioid clade, it should not be considered a true member of this group. Parmelia teretiuscula is a taxon that proposed by Alfred Oxner in 1940. Esslinger later considered it a synonym of Melanelia stygia. In North America, Melanelia stygia is commonly known as the alpine camouflage lichen. It has several common names in Northern European languages, alluding its dark colouration and growth form. In Finnish, it is called sysiruskokarve, meaning "sooty brown lichen," while the Icelandic name bikdumba translates to "pitch-dark" or "tar-dark". The Norwegian name blankkrinslav refers to its glossy appearance and means "shiny ring lichen". In Swedish, it is known as svart sköldlav, which translates to "black shield lichen".
Description
Melanelia stygia forms dark, leafy growths measuring 2–6 cm across, occasionally reaching 8 cm. The lichen body (thallus) attaches somewhat loosely to its substrate, with a fleshy texture. Its lobes are relatively narrow, measuring 0.5–2 mm in width, rarely reaching 3 mm. These lobes are thick and can be flat, convex, or almost cylindrical (terete) in cross-section. They extend outward in an irregular branching pattern. These lobes often overlap and intertwine with each other, creating a complex structure. The species can reach impressive sizes, with the largest documented thalli measuring up to 12 cm in diameter, though such large specimens are rare. Studies from Norwegian glacier forelands showed that average mature specimens typically reach around 62 mm in diameter. The upper surface appears dark brown to nearly black and has a glossy sheen. Under magnification, one can observe tiny dark brown dots called pseudocyphellae scattered across the surface, each surrounded by a slightly raised rim. The lower surface shares a similar dark colouration and displays a wrinkled texture, anchored by thick, mostly unbranched root-like structures called rhizines. The species regularly produces reproductive structures (apothecia), which can grow up to 5 mm in diameter. These disc-like structures start concave when young but flatten or become convex as they mature, maintaining a dark brown colour and glossy appearance. Their edges are notably warty and irregular, featuring the same tiny pores (pseudocyphellae) found on the main body. The lichen lacks both soredia and isidia, which are alternative reproductive structures common in other lichen species. Within the apothecia, which are constricted at their base, are microscopic spore-producing structures. The species also commonly produces pycnidia that are immersed in the lobes and release dumbbell-shaped conidia measuring 3.5–5.5 μm in length.
… excerpt ends here. Continue reading the full article.
