Anthracothecium is a genus of lichen-forming fungi in the family Pyrenulaceae. It comprises five species of crustose lichen, bark-dwelling, lichens in the tropics and subtropics, and that in the current sense the genus is diagnosed by young that are euseptate (true septum) and remain mostly euseptate when mature, contrasting with Pyrenula, where and thickened is the norm. The ascomata (fruiting bodies) are (blackened and charcoal-like), usually simple or aggregated in predictable ways, and 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
are euseptate and remain mainly so at maturity with rectangular —whereas
Pyrenula has spores with a thickened ; organisation of the perithecioid
ascomata (typically , with apical or lateral
) 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 new 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 (or, less often, to other genera) 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 (including Anthracothecium) nested within it.
Habitat and distribution
Species of
Anthracothecium are crustose lichens that grow on bark in shaded and usually humid environments. They are characteristically found on smooth tree trunks in
tropical and
subtropical forests. The genus has a pantropical distribution, with species recorded from regions as far apart as Australasia, Africa, Asia, and the Americas. Within this broad range, most species are relatively uncommon, although a few, such as
A. prasinum and
A. macrosporum, occur more widely across multiple continents.
Species
Aptroot's 2021 global treatment of Pyrenulaceae accepted five species in
Anthracothecium:
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Anthracothecium australiense – pantropical
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Anthracothecium gregale – Australasian; possibly also Africa
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Anthracothecium interlatens – pantropical
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Anthracothecium macrosporum – pantropical
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Anthracothecium prasinum – pantropical