Anthracothecium
Anthracothecium is a genus of lichen-forming fungi in the family Pyrenulaceae. It comprises five species of crustose, bark-dwelling, lichens in the tropics and subtropics, and that in the current sense the genus is diagnosed by young ascospores that are euseptate and remain mostly euseptate when mature, contrasting with Pyrenula, where and thickened is the norm. The ascomata are, usually simple or aggregated in predictable ways, and ostioles may be apical or lateral depending on species.
Taxonomy
The genus Anthracothecium was established in the mid-19th century by Abramo Bartolommeo Massalongo from material collected by Georg Ernst Ludwig Hampe. Modern usage is narrower: André Aptroot’s world key re-examined types, keyed all published names and reduced the genus to five accepted, pantropical species, reallocating most nineteenth- and twentieth-century names to other pyrenocarpous genera, chiefly Pyrenula. In this framework Anthracothecium is diagnosed chiefly by spore anatomy—young ascospores are euseptate and remain mainly so at maturity with rectangular —whereas Pyrenula has spores with a thickened ; organisation of the perithecioid ascomata and the number of ascospores per ascus are auxiliary, but septation provides the most reliable separation of the two genera.Under this circumscription, Aptroot accepted five species. He formalised the combination Anthracothecium interlatens and proposed that Massalongo's A. doleschallii is best treated as a synonym of A. macrosporum. The remaining names historically placed in Anthracothecium, including widely cited species such as A. thwaitesii, A. variolosum, A. subvariolosum, A. sinapispermum, and many more, are assigned to Pyrenula with notes where the placement is tentative.
Aptroot also comments on family-level context: available phylogenetic trees suggest that Pyrenula may be paraphyletic with several morphologically coherent small genera nested within it.