''Astrothelium duplicatum'' is a species of corticolous (bark-dwelling),

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

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 formally described as a new species in 2016 by 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 l ...

and Marcela Cáceres. The

type specimen In biology, a type is a particular 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 anchor or centralizes the ...

was collected by the authors in the Parque Natural Municipal de Porto Velho (

Porto Velho Porto Velho (, ''Old Port'') is the capital of the Brazilian state of Rondônia, in the upper Amazon River basin, and a Catholic Metropolitan Archbishopric. The population is 548,952 people (as of the IBGE 2021 estimation). Located on the border ...

Rondônia Rondônia () is one of the 26 states of Brazil, located in the northern subdivision of the country (central-western part). To the west is a short border with the state of Acre, to the north is the state of Amazonas, in the east is Mato Grosso ...

), where it was found growing on the smooth bark of a tree in a park near a

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 rainfo ...

, and on tree twigs in the forest. The lichen has a smooth and somewhat shiny,

olive The olive, botanical name ''Olea europaea'', meaning 'European olive' in Latin, is a species of small tree or shrub in the family Oleaceae, found traditionally in the Mediterranean Basin. When in shrub form, it is known as ''Olea europaea'' ...

-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 ...

surrounded by a black

prothallus A prothallus, or prothallium, (from Latin ''pro'' = forwards and Greek ''θαλλος'' (''thallos'') = twig) is usually the gametophyte stage in the life of a fern or other pteridophyte. Occasionally the term is also used to describe the young ...

(about 0.3 mm wide) and covers areas of up to in diameter. The presence of the lichen does not induce the formation of

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

s in its

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places *Host, Pennsylvania, a village in Berks County People * Jim Host (born 1937), American businessman * Michel Host ...

. The

ascomata An ascocarp, or ascoma (), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascocarps are mo ...

are roughly spherical () and typically aggregate in groups of about five to fifty, usually immersed in the bark tissue as . Its

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 o ...

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 () and measure 45–55 by 11–15

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 Uni ...

. The use of

thin-layer chromatography Thin-layer chromatography (TLC) is a chromatography technique used to separate non-volatile mixtures. Thin-layer chromatography is performed on a sheet of an inert substrate such as glass, plastic, or aluminium foil, which is coated with a t ...

on collected lichen samples revealed the presence of an

anthraquinone Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic organic compound with formula . Isomers include various quinone derivatives. The term anthraquinone however refers to the isomer, 9,10-anthraquinone (IUPAC: 9,10-dioxoan ...

compound, possibly

parietin Parietin is the predominant cortical pigment of lichens in the genus ''Caloplaca'', a secondary product of the lichen '' Xanthoria parietina'', and a pigment found in the roots of Curled Dock (''Rumex crispus''). It has an orangy-yellow color a ...

. The characteristics that distinguish ''Astrothelium duplicatum'' from other members of ''

Astrothelium ''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. Sp ...

'' include the internal, yellow

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic comp ...

of its ascomata; and the dimensions of its ascospores, which are about 3–4 times as long as they are broad. ''

Astrothelium mesoduplex ''Astrothelium mesoduplex'' is a species of lichen in the family Trypetheliaceae. It is similar to '' A. flavoduplex'' but has larger and lacks lichexanthone. This lichen species has been found only in Brazil, particularly in primary for ...

'' is similar in appearance, but that species lacks yellow to orange pseudostromata and has shorter ascospores.

References

duplicatum Lichen species Lichens described in 2016 Taxa named by André Aptroot Taxa named by Marcela Cáceres Lichens of North Brazil {{Dothideomycetes-stub