Umbilicaria africana
Umbilicaria africana is a species of foliose lichen in the family Umbilicariaceae. Initially described as a variety under Gyrophora haplocarpa by Antonio Jatta in 1908, it was elevated to species status in 1986. This lichen is predominantly found on boulders of siliceous rock in the high alpine zones of the tropical mountains of South America and parts of Africa.
Taxonomy
Umbilicaria africana was originally catalogued as Gyrophora haplocarpa var. africana by Antonio Jatta in 1908; it was recognised as a distinct species by Hildur Krog and T.D.V. Swinscow in 1986. The type specimen was collected in Uganda's Rwenzori Mountains. It is a member of the U. aprina species group, a set of closely related species that includes U. africana, U. antarctica, U. aprina, U. formosana, U. kappeni, and U. rhizinata.Description
The thallus of Umbilicaria africana is single-leaved and shield-like, reaching up to in diameter. It often features deeply divided, irregularly incised that curl when dry and may include perforations. The upper surface varies from grey to brownish-grey, is smooth to rough, and covered with a thin, dead layer. It displays a moderate network of ridges around the central attachment point and has sparser, worm-like ridges or is smooth towards the edges. The surface typically hosts clusters of thin, black, branched, and intertwined root-like structures. The underside is smooth, pale around the central attachment, and darkens to grey or black, dotted with patches of multi-cellular reproductive particles and scattered clusters of moderately branched rhizinomorphs.Reproductive features include black fruiting bodies which are rare in specimens from the Andes. The thalloconidia are dark brown to black, spherical to ellipsoid, and typically 4 to 10-celled, although simpler forms occur.