Frigidopyrenia Grube, Phyton, Horn 45(2): 307 (2005).
Lichenized with chroococcale cyanobacteria. Asexual morph: Thallus squamulose when well-developed. Squamules up to 0.5 mm in diameter, globose to flattened, dark olive to brownish black, with pseudoparenchymatic outer wall; thallus squamules interconnected with the ascomata by brown hyphae, hyphae. Pseudothecia globose to broadly pear-shaped, with preformed ostiole. Peridium dark chestnut brownish, distinctly delimited at the outer edge; pigments distinctly in intercellular spaces. Hamathecium of filamentous, strongly branched and anastomosing hyphae (paraphysoids). Asci fissitunicate, rigid and cylindrical; endotunica layers becoming thicker towards the top but without abrupt thickening in the upper half of the ascus; ocular chamber distinct. Ascospores hyaline. Cell walls not reacting with Toluidine Blue. Asexual morph: Unknown (Adapted from Grube 2005).
Type species: Frigidopyrenia bryospila (Nyl.) Grube
Notes: Frigidopyrenia was introduced by Grube (2005) with F. bryospila as type species. Frigidopyrenia is characterized by squamulose, well-developed thallus, globose to broadly pear-shaped pseudothecia, dark chestnut brownish peridium, fissitunicate, rigid and cylindrical asci and hyaline ascospores. Frigidopyrenia bryospila was previously described as Verrucaria bryospila but was not congeneric with the type species of Verrucaria. The squamules of Frigidopyrenia bryospila comprises coccale cyanobacteria. Frigidopyrenia resembles Zwackhiomyces and Anisomeridium in having clod-like pigments deposited in the intercellular spaces of the peridium but differs in having larger peridial cells, and the cell walls do not stain metachromatically red-violet with Toluidine Blue. Frigidopyrenia is also similar to Collemopsidium, Magmopsis, and Pyrenocollema but differs in having more cylindrical asci (Grube and Hafellner 1990). Frigidopyrenia also differs from Collemopsidium in that the latter has peridia which are paler in basal layers of the ascomata (Grube 2005). The amazing thallus squamules of F. bryospila is classified as goniocysts in the original sense of Norman, who used the term to describe thallus of Moriola Norman (Normal 1872; Serusiaux 1985) but Moriola is not closely related to Frigidopyrenia (Grube 2005). There has been no phylogenetic study on Frigidopyrenia as molecular data is lacking for the genus. Frigidopyrenia is a distinct genus in Xanthopyreniaceae but DNA sequence data is needed to confirm this taxonomic placement.