''Astrothelium rubrocrystallinum'' is a species of corticolous (bark-dwelling), crustose lichen in the family Trypetheliaceae, first described in 2016. It is found in Brazil.

Taxonomy

The species ''Astrothelium rubrocrystallinum'' was formally described 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 Eugenia da Silva Cáceres in 2016. The type specimen was collected in Mata do Junco, Santa Luzia do Itanhy, Sergipe, Brazil, at an elevation of approximately , on 15 April 2011, by the second author.

Description

The thallus of ''Astrothelium rubrocrystallinum'' is , smooth, somewhat shiny, and continuous, covering areas up to 5 cm in diameter and about 0.2 mm thick. It is olive-brown in colour, surrounded by a black line approximately 0.2 mm wide, and 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 ascomata are roughly spherical, measuring 0.30–0.45 mm in diameter, mostly found in groups or lines of 2–5 in poorly distinguished . These are mostly distinctly raised above the thallus and are of thallus colour. Inside, there is a dense layer of red crystals about 0.2 mm wide around the ascoma wall, visible as dark through the

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 ...

cortex around the

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 ...

. The wall is black all around, up to 50

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. Ostioles are apical, not fused, flat, black, and surrounded by an ochraceous ring of about 0.2 mm, which sometimes has a grey margin. The is inspersed with hyaline oil globules.

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 8 each. Ascospores are hyaline, contains three septa, and have a shape. They measure 22–27 by 7–9 μm and have rounded ends and diamond-shaped . They are not surrounded by a gelatinous layer. were not observed to occur in this species. ''Astrothelium rubrocrystallinum'' belongs to the ''

Astrothelium annulare ''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. Spec ...

'' group and is characterised by the copious red crystals in a thick layer around the ascomata. It is most closely related to ''

Astrothelium buckii ''Astrothelium'' is a genus of corticolous lichen, corticolous (bark-dwelling) lichens in the family Trypetheliaceae. The genus was circumscription (taxonomy), circumscribed in 1824 by German botanist Franz Gerhard Eschweiler, with ''Astrothelium ...

'', but differs in having shorter with typical dimensions of 37–47 by 14–16 μm.

Chemistry

The thallus surface of ''Astrothelium rubrocrystallinum'' is UV negative. The crystals in the medulla react K+ (purple). Thin-layer chromatography analysis reveals the presence of an unidentified anthraquinone substance.

Habitat and distribution

This species is found on the smooth bark of trees in the

Atlantic Forest 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 th ...

and at the time of its publication was known only from Brazil.

References

{{Taxonbar, from=Q95573610 Trypetheliaceae Lichen species Lichens described in 2016 Lichens of Brazil Taxa named by André Aptroot Taxa named by Marcela Cáceres