Umbilicaria angulata
Umbilicaria angulata, commonly known as the asterisk rocktripe, is a species of saxicolous, foliose lichen in the family Umbilicariaceae. It is found in northwestern North America and east Eurasia, where it grows on acidic rock.
Taxonomy
Umbilicaria angulata was formally described as a new species in 1848 by the American lichenologist Edward Tuckerman. The type specimen was collected from the northwest coastal region of California. In 1891, William Nylander thought the species was more suitably classified as a variety of Gyrophora vellerea. In 1911, Albert Herre proposed that the taxon should be accepted as a full species, but in the genus Gyrophora. This genus has since been subsumed into Umbilicaria.It is classified in the subgenus Gyrophora of the genus Umbilicaria, according to a 2017 reorganisation of that genus informed by molecular phylogenetics. This subgenus consists of two groups, the monophyletic U. vellea group, and the U. angulata group, which consists of paraphyletic lineages.
"Asterisk rocktripe" is a vernacular name that has been used for this species in North America.
Description
The lichen has an thallus, meaning that it is attached to its rock via a single attachment point, and typically reaches up to in diameter, although specimens up to are known. The thallus is brown to grayish-brown, while the lower surface is dark brown to black, with slender rhizines ranging in frequency from scarce to densely tangled. Although it does not have soredia or isidia, it produces apothecia that are initially level with the thallus surface before becoming. The ascospore made by Umbilicaria angulata are, with typical dimensions of 17–23 by 8–13 μm.The thallus contains gyrophoric acid as a major secondary metabolite, and smaller amounts of lecanoric acid and zeorin.