Astrothelium squamosum
species of lichen-forming fungus
Astrothelium squamosum is a corticolous (bark-dwelling) lichen in the family Trypetheliaceae. Described in 2022 from specimens collected in mountain rainforest in Minas Gerais, southeastern Brazil, this species is characterized by its unusual growth form of isolated glossy scales and exceptionally long ascospores divided into 14–17 segments. Unlike most related species, its brown fruiting bodies emerge directly from the bark between the lichen scales rather than being grouped together in raised structures. Known only from its type locality in the Santuário do Caraça area, it grows on tree bark in humid forests at elevations of 1,200 to 1,400 m (3,900 to 4,600 ft).
Taxonomy
Astrothelium squamosum was described in 2022 by André Aptroot from material collected on tree bark in rainforest at Santuário do Caraça, Minas Gerais, Brazil, at elevations of 1,200 to 1,400 m (3,900 to 4,600 ft). The holotype (Aptroot 51260 & L.A. dos Santos) is deposited in the herbarium of the Instituto de Botânica (ISE), with an isotype (duplicate) in the herbarium of the Federal University of Mato Grosso do Sul (CGMS). Within Astrothelium, the species was compared to A. puiggarii: both have brown, emergent ascomata on bark, but A. puiggarii has muriform (multichambered) ascospores, whereas A. squamosum has long, narrowly ellipsoid, multi-septate ascospores that are 14–17-septate and significantly larger than those of A. puiggarii. These spore characters, together with the squamulose thallus, were used to justify its recognition as a distinct species, and it is placed in the world key to the genus in the couplet dealing with squamulose species with long, transversely septate ascospores.
Description
The thallus of Astrothelium squamosum is formed by isolated squamules that create glossy patches up to about 10 cm (3.9 in) across; the squamules are olivaceous green and not bordered by any conspicuous prothallus. Individual squamules measure 0.6–1.7 × 0.5–1.6 mm, are lobate and irregularly convex, and are 0.3–0.6 mm thick, with most of the lower surface attached to the bark.
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This entry incorporates text from “Astrothelium squamosum” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.