''Architrypethelium hyalinum'' is a species of corticolous (bark-dwelling),

crustose lichen Crustose lichens are lichens that form a crust which strongly adheres to the Substrate (biology), substrate (soil, rock, tree bark, etc.), making separation from the substrate impossible without destruction. The basic structure of 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 ...

. Found in Costa Rica and Brazil, it was formally described as a new species in 2008 by 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 In biology, a type is a particular wiktionary:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to a ...

was collected by

Harrie Sipman Henricus (Harrie) Johannes Maria Sipman (born 1945) is a Dutch lichenologist. He specialises in tropical and subtropical lichens, and has authored or co-authored more than 250 scientific publications. He was the curator of the lichen herbarium ...

from the Las Cruces Biological Station in Puntarenas. The lichen has a smooth to uneven, olive-green

thallus Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms wer ...

. Its ascomata occur solitarily, have an apical

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 ...

, and measure 0.7–1.5 mm in diameter.

Ascospore 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 ...

s number 4 to 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 ...

, have an oblong to

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 with 3

septa The Southeastern Pennsylvania Transportation Authority (SEPTA) is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly 4 million people in five coun ...

, and measure 100–150 by 30–50

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 ...

. These spores are among the largest of the 3-septate lichens in the Trypetheliaceae. Both the thallus and ascomata contain lichexanthone, a lichen product that causes these structures to glow yellow when lit with a long-wavelength

UV light Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...

; ''A. hyalinum'' is the only species in genus ''

Architrypethelium ''Architrypethelium'' is a genus of lichen-forming fungi in the family Trypetheliaceae. The genus was circumscribed in 1991 by Dutch lichenologist André Aptroot, with '' A. seminudum'' assigned as the type species. It is a segregate of ge ...

'' that contains lichexanthone.

References

Trypetheliaceae Lichen species Lichens described in 2008 Taxa named by André Aptroot Lichens of Central America Lichens of Brazil {{Dothideomycetes-stub