Porpidinia tumidula is quite a conspicuous lichen, characterized by large, grey to brown, densely pruinose, rounded to slightly lobate squamules and black lecideine apothecia. In the past, it belonged to the genus Toninia (Timdal 1992), from which it differs in the Porpidia-type of asci (a cylindrical apical structure), non-amyloid hymenial gel and less agglutinated paraphyses with a more conspicuous discrete pigmented drop on the top (Timdal 2010).
The species typically grows in rocks cracks of natural calcareous rocks on open stands. In Europe, it has a sub-Mediterranean distribution. It is quite rare in central Europe. In the Czech Republic it grows at a couple of localities in the Český kras (Bohemian Karst) and the surroundings of Prague, and a single Moravian locality at the Kotouč Hill near Štramberk (in the past).
Literature: Timdal E. (1992): A monograph of the genus Toninia (Lecideaceae, Ascomycetes). – Opera Botanica 110: 1–137. Timdal E. (2010): Porpidinia (Porpidiaceae), a new genus for Toninia tumidula. – Bibliotheca Lichenologica 104: 333–337.
taxonomic classification:Ascomycota → Lecanoromycetes → Lecanorales → Lecideaceae → Porpidinia
most frequented synonyms:Toninia tumidulaRed List (Liška & Palice 2010):VU – vulnerable
Red List (Malíček 2023):C2 – strongly endangered
Occurrence in the Czech Republic
All records: 13, confirmed 12. One click on a selected square displays particular record(s), including their source(s).