Cladonia scotteri
Cladonia scotteri is a species of lichen in the family Cladoniaceae. Described in 2011 from Nahanni National Park Reserve in the Northwest Territories, Canada, this mainly tundra lichen forms a persistent mat of small, grey-to-brown . It also produces short, club-shaped podetia with a distinctly checkered surface, usually topped with brown apothecia. It grows mainly on calcareous soils in Arctic and subarctic regions, and is recorded from western North America, Greenland, and northeastern Asia.
Taxonomy
Cladonia scotteri was described as a new species by Teuvo Ahti and Eric Steen Hansen in 2011, based on collections from northern North America and Greenland. The type specimen was gathered in 1977 in Nahanni National Park, on a trampled path near Virginia Falls. The species epithet scotteri and a vernacular name, "Scotter's lichen", honours the Canadian wildlife range ecologist George Scotter, who collected large numbers of lichens in Arctic and boreal Canada, including material of this species.The species is placed in the Cladonia cariosa group and appears most closely related to C. cariosa and C. symphycarpa. Compared with C. symphycarpa, C. scotteri typically has smaller squamules that are usually not pruinose, and generally has smaller podetia. It also differs in chemistry: many specimens contain the lichen substance homosekikaic acid in addition to atranorin. In Greenland, several chemotypes have been recorded, based on different combinations of lichen substances detected using thin-layer chromatography.
A DNA-based study of relationships within the Cladonia cariosa group suggested that C. scotteri is closely related to C. cariosa. However, it was not included in the study's main phylogenetic analysis because only one publicly available ITS sequence was available, and that sequence appeared to be uneven in quality.
Description
The forms a persistent mat of small that are grey to brown, often darkening with age or weathering. Podetia are produced sparingly. They are usually short, about 5–20 mm tall, and typically club-shaped to slender. The podetia have a firm outer layer along their full length. Their surface is distinctly "checkered", made up of small, flat patches, and they do not form cups. Small squamules on the podetia occur mainly near the base and are not abundant.Fruiting bodies are common. The podetia become fertile early and usually bear apothecia with brown discs. Asexual spore-producing structures can occur on the primary squamules, but they are uncommon and can be easy to miss. In standard chemical spot tests, the thallus shows a yellow K reaction and a weak yellow PD reaction. The lichen substances reported for the species include atranorin and homosekikaic acid. More rarely, specimens contain only homosekikaic acid, and rangiformic acid has been reported only exceptionally.
Habitat and distribution
Cladonia scotteri grows on soil, most often on calcareous ground, but it has also been recorded on somewhat acidic, humus-rich soils. It is primarily a tundra species, though it has also been recorded in boreal forest habitats. The type collection from Nahanni National Park was made on disturbed ground along a trampled path near a waterfall lookout, indicating that the species can occur on lightly disturbed soil surfaces.In Greenland, it is fairly common in the west but much rarer in the east. Beyond Greenland, records extend across western North America and northeastern Asia. Its full range is still being clarified because older herbarium material from several regions likely includes additional specimens that have not yet been reviewed. Documented records include Arctic and subarctic North America, montane sites farther south in western North America, northeastern Asia, and one locality on the Antarctic Peninsula.