Umbilicaria nylanderiana

The thallus of Umbilicaria nylanderiana is typically monophyllous (having single lobe), rigid, and brittle, often with lacerated margins, although it can sometimes be polyphyllous (multi-lobed), particularly in wind-exposed habitats. It usually measures up to 6 cm (2.4 in) across, but Antarctic specimens are considerably smaller, growing to about 2 cm in diameter. The upper thallus surface is dark brown to grey, characterised by densely packed, high, rounded ridges, while the lower surface is black and smooth. Reproductive features of the lichen include black, adnate, and gyrose apothecia (fruiting bodies), which are more common in Neotropic specimens and rarer in European samples. Asci (spore-bearing cells) are club shaped (clavate). Ascospores typically number eight per ascus, ranging from unicellular to multicellular, and are hyaline or brown, measuring 7–16 by 5–9 μm. The thalloconidia are unicellular, dark brown to black, and oval or ellipsoid, typically covering the entire lower surface except at the peripheral areas.

Umbilicaria nylanderiana is primarily found on the vertical to horizontal faces of large boulders or cliffs in the alpine zone, frequently above the snow line in winter. Its distribution is global, occurring throughout Europe, North America, and South America. This species is the only common brown Umbilicaria in Ecuador and occupies ecological niches similar to those of several brown species in North America, Europe, and Asia, such as U. hyperborea, U. deusta, and U. arctica. In Antarctica, its distribution is restricted to the maritime Antarctic region, ranging from the South Orkney Islands in the north to as far south as 68°S along the west coast of the Antarctic Peninsula and its offshore islands. In this region, it is found only in coastal sites at elevations between 5 and 200 m (16 and 656 ft) above sea level, often on north-facing volcanic rocks. While generally rare in Antarctica, it can be locally abundant in some environments.

== References ==