''Astrothelium aeneoides'' is a species of corticolous (bark-dwelling), crustose lichen in the family

Trypetheliaceae The Trypetheliaceae are a family of mainly lichen-forming fungi in the order Trypetheliales. Genera *'' Alloarthopyrenia'' – 1 sp. *''Aptrootia'' – 3 spp. *'' Architrypethelium'' – 8 spp. *''Astrothelium'' – ca. 275 spp. *'' Bathel ...

. It is found in Brazil,

Guyana Guyana ( or ), officially the Cooperative Republic of Guyana, is a country on the northern mainland of South America. Guyana is an indigenous word which means "Land of Many Waters". The capital city is Georgetown. Guyana is bordered by the ...

, and Puerto Rico, where it grows on the smooth bark of

rainforest Rainforests are characterized by a closed and continuous tree canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforest can be classified as tropical rainforest or temperate rainfores ...

trees.

Taxonomy

The lichen was formally described as a new species in 2016 by Dutch lichenologist

André Aptroot André Aptroot (Heemskerk, 1961) is a Dutch mycologist and lichenologist. In 1993 he did his PhD at the University of Utrecht under the supervision of Robbert Gradstein (nl). His dissertation was titled "Systematic studies on pyrenocarpous li ...

. The type specimen was collected by the author in 1997 from the Parque Natural do Caraça in ( Minas Gerais) at an altitude of . The

species epithet Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany) A botanical name ...

''aeneoides'' alludes to its resemblance with ''

Astrothelium aeneum ''Astrothelium'' is a genus of corticolous (bark-dwelling) lichens in the family Trypetheliaceae. The genus was circumscribed in 1824 by German botanist Franz Gerhard Eschweiler, with '' Astrothelium conicum'' assigned as the type species. Spe ...

''.

Description

''Astrothelium aeneoides'' has an olive-green to olive-grey, smooth and somewhat shiny thallus up to in diameter and about 0.2 mm thick. Its ascomata are immersed in the thallus; they are spherical, measuring 0.7–1.0 mm in diameter and arranged in groups of 2 to 5. They are contained in structures called pseudostromata (resembling a perithecium but containing both fungal tissue and substrate tissue) that have a raised surface texture distinct from that of the surrounding thallus. The ascospores, which number 8 per

ascus An ascus (; ) is the sexual spore-bearing cell produced in ascomycete fungi. Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some genera or s ...

, are

hyaline A hyaline substance is one with a glassy appearance. The word is derived from el, ὑάλινος, translit=hyálinos, lit=transparent, and el, ὕαλος, translit=hýalos, lit=crystal, glass, label=none. Histopathology Hyaline cartilage is ...

, spindle-shaped (''fusiform'') with rounded ends, have 3 septa, and measure 20–25 by 6–9

μm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

. The internal chambers formed by the septa (the ''lumina'') are diamond shaped. The use of thin-layer chromatography reveals the presence of a lichen product that the author suggests is parietin. The expected results of standard chemical spot tests are: thallus surface UV−, thallus medulla K−; pseudostroma surface UV+ (pink to orange), medulla of pseudostroma K+ (blood red). ''

'' is similar in morphology; ''A. aenoides'' differs by a lack of orange pigment on the thallus. Another similar species, '' A. aenascens'', is distinguished from ''A. aenoides'' by the presence of an inspersed hamathecium. '' Astrothelium flavostromatum'' is another lookalike that is distinguished by a strongly convex and swollen (''bullate'') thallus and a cream-coloured pseudostromata.

References

{{Taxonbar, from=Q95573596 aeneoides Lichen species Lichens described in 2016 Lichens of Brazil Lichens of Guyana Lichens of the Caribbean Taxa named by André Aptroot