''Astrothelium curvatum'' is a species of

corticolous lichen A corticolous lichen is a lichen that grows on bark.Alan Silverside's Lichen Glossary (a-f), Alan Silverside/ref> This is contrasted with lignicolous lichen, which grows on wood that has had the bark stripped from it,Alan Silverside's Lichen Glos ...

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 ...

. Found in Brazil, it was described as a new species in 2016. It is characterised by its immersed ascomata with lateral

ostiole An ''ostiole'' is a small hole or opening through which algae or fungi release their mature spores. The word is a diminutive of "ostium", "opening". The term is also used in higher plants, for example to denote the opening of the involuted ...

s and bent, ascospores.

Taxonomy

''Astrothelium curvatum'' was formally described as a new species in 2016 by the lichenologists

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 ...

and Marcela Cáceres. The type specimen was collected in Sergipe, Brazil, at the

Serra de Itabaiana National Park Serra de Itabaiana National Park ( pt, Parque Nacional Serra de Itabaiana) is a national park in the state of Sergipe, Brazil. Location The park lies in the Atlantic Forest biome, and covers . It was created on 15 June 2005, and is administered b ...

, on the southern slope at an elevation of approximately . It was found by the authors on the bark of a tree in May 2014.

Description

The thallus of ''Astrothelium curvatum'' is , smooth, and somewhat shiny. It is continuous, covering areas up to in diameter and less than 0.1 mm thick. The colour is olive-green, surrounded by a black , and it does not induce

gall Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants, fungi, or animals. Plant galls are abnormal outgrowths of plant tissues, similar to be ...

formation on the host bark. The are , measuring 0.4–0.7 by 0.3–0.5 mm, and are single, immersed in the thallus, and mostly immersed in the bark. The wall around the ascomata is and can be up to 100

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 ...

thick. The ostioles are lateral, not fused, and can be flat or depressed, with a brown colour. The is interspersed with hyaline oil globules, and the

asci ASCI or Asci may refer to: * Advertising Standards Council of India * Asci, the plural of ascus, in fungal anatomy * Accelerated Strategic Computing Initiative * American Society for Clinical Investigation * Argus Sour Crude Index * Association of ...

contain 4–8 . These ascospores 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 ...

, ,

ellipsoid An ellipsoid is a surface that may be obtained from a sphere by deforming it by means of directional scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a surface that may be defined as the ...

, usually bent, with rounded ends, measuring 74–90 by 25–34 μm. They do not have a distinctly thickened median

septum In biology, a septum (Latin for ''something that encloses''; plural septa) is a wall, dividing a cavity or structure into smaller ones. A cavity or structure divided in this way may be referred to as septate. Examples Human anatomy * Interatri ...

and are not surrounded by a gelatinous layer. have not been observed in this species. In terms of chemistry, the thallus surface is UV-negative, and the thallus medulla is K-negative. Thin-layer chromatography, a technique used to identify chemical substances, revealed that no secondary substances ( lichen products) are detectable. ''Astrothelium curvatum'' is notable for its immersed pyriform ascomata with lateral ostioles and the curved ascospores. It is most closely related to '' Astrothelium puiggarii'' . The main difference between these species is that ''A. puiggarii'' typically has two ascospores in the ascus compared to the 4–8 found in ''A. curvatum''.

Habitat and distribution

''Astrothelium curvatum'' is found on the smooth bark of trees in the

Atlantic rainforest The Atlantic Forest ( pt, Mata Atlântica) is a South American forest that extends along the Atlantic coast of Brazil from Rio Grande do Norte state in the northeast to Rio Grande do Sul state in the south and inland as far as Paraguay and the ...

. At the time of its original publication, it was known to occur only in its type locality in Brazil.

References

{{Taxonbar, from=Q95573597 curvatum Lichen species Lichens described in 2016 Lichens of Brazil Taxa named by André Aptroot Taxa named by Marcela Cáceres