''Astrothelium rhinothallinum'' 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 ...

, first described in 2018. It is found in Brazil.

Taxonomy

''Astrothelium rhinothallinum'' was formally described by the lichenologists

Klaus Kalb Klaus Kalb (born 1942) is a German lichenologist and an authority on tropical lichens. Biography Klaus Kalb was born in Nuremberg in 1942 and grew up in southern Bavaria. From 1960 to 1965 he studied biology, chemistry, and geography at t ...

and

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 ...

in 2018. The type specimen was collected by the first author in the

Mantiqueira Mountains The Mantiqueira Mountains (Portuguese: ''Serra da Mantiqueira iterally: Mantiqueira Mountains Chain') are a mountain range in Southeastern Brazil, with parts in the states of São Paulo, Minas Gerais and Rio de Janeiro. It rises abruptly from the ...

, Rio de Janeiro, Brazil on 15 March 1980. In a dense and humid submontane

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 ...

in the lower mountains, at an elevation of , the lichen was growing on tree bark. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

''rhinothallinum'' refers to the thallus, which, according to the authors, resembles the skin of a rhinoceros.

Description

The thallus of ''Astrothelium rhinothallinum'' is dull and

olivaceous Olive is a dark yellowish-green color, like that of unripe or green olives. As a color word in the English language, it appears in late Middle English. Shaded toward gray, it becomes olive drab. Variations Olivine Olivine is the typical ...

green, and not surrounded by a . The ascomata are spherical to (pear-shaped), 0.7–1.2 mm in diameter, solitary in warts. The is hemispherical, completely covered by a thallus layer, about 1.5 mm in diameter, and without pigmentation. Ostioles are apical, depressed, and brown. The is with oil droplets. number eight 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 ...

, and 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 ...

, regularly , and measure 65–71 by 16–19.5

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 ...

. They have a long-

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 ...

shape, lack 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 wide gelatinous sheath. were not observed to occur in this species. The thallus of ''Astrothelium rhinothallinum'' is patchily UV+ (yellow), C−, K−, KC−, and P−. Thin-layer chromatography analysis confirms the presence of lichexanthone.

Habitat and distribution

''Astrothelium rhinothallinum'' is found on tree bark in forest environments and at the time of its original publication, was known to occur only in Brazil.

References

{{Taxonbar, from=Q107504020 Trypetheliaceae Lichen species Lichens described in 2018 Lichens of Brazil Taxa named by André Aptroot Taxa named by Klaus Kalb