''Cora arborescens'' is a little-known species of basidiolichen in the family

Hygrophoraceae The Hygrophoraceae are a family (biology), family of fungi in the order (biology), order Agaricales. Originally conceived as containing white-spored, thick-gilled agarics (gilled mushrooms), including ''Hygrophorus'' and ''Hygrocybe'' species (th ...

. It was formally described as a new species in 2016 by Manuela Dal Forno, José Luis Chaves, and

Robert Lücking Robert Lücking (born 1964) is a German lichenologist, known for his extensive research on foliicolous lichens (lichens that live on leaves) and his significant contributions to the taxonomy, ecology, and biodiversity of fungi and lichens. He e ...

. The

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

''arborescens'' refers to its growth on trees. The lichen is only known from the type locality near Cerro de la Muerte in

Costa Rica Costa Rica, officially the Republic of Costa Rica, is a country in Central America. It borders Nicaragua to the north, the Caribbean Sea to the northeast, Panama to the southeast, and the Pacific Ocean to the southwest, as well as Maritime bo ...

Taxonomy

''Cora arborescens'' is a basidiolichen in the family

(order

Agaricales The Agaricales are an order (biology), order of fungi in the division (mycology), division Basidiomycota. As originally conceived, the order contained all the agarics (gilled mushrooms), but subsequent research has shown that not all agarics are ...

). It was described in 2016 by Manuela Dal Forno, José Luis Chaves, and

from material collected in a high-elevation

cloud forest A cloud forest, also called a water forest, primas forest, or tropical montane cloud forest, is a generally tropical or subtropical, evergreen, Montane forest, montane, Tropical and subtropical moist broadleaf forests, moist forest characteri ...

near Cerro de la Muerte, Costa Rica. The

epithet An epithet (, ), also a byname, is a descriptive term (word or phrase) commonly accompanying or occurring in place of the name of a real or fictitious person, place, or thing. It is usually literally descriptive, as in Alfred the Great, Suleima ...

, ''arborescens'', refers to the lichen's

epiphytic An epiphyte is a plant or plant-like organism that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphyt ...

habit on tree branches and twigs. Although superficially similar to species such as '' C. canari'', '' C. smaragdina'', '' C. udebeceana'', '' C. viliewoa'', and '' C. boleslia'',

molecular A molecule is a group of two or more atoms that are held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemistry, ...

analyses show that these

taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

are not closely related.

Description

The

thallus Thallus (: 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. A thallus usually names the entir ...

of ''Cora arborescens'' is

and

foliose A foliose lichen is a lichen with flat, leaf-like , which are generally not firmly bonded to the substrate on which it grows. It is one of the three most common lichen growth forms, growth forms of lichens. It typically has distinct upper and lo ...

, forming rosettes up to 5 cm across. It comprises two to five semicircular, somewhat overlapping () lobes, each 1.5–4 cm wide and 2–2.5 cm long with short radial sutures. When fresh the upper surface is emerald green, even, and , showing faint concentric colour zoning; margins are thin, rolled in (), and also glabrous. Dried material turns uniformly light grey. The lower surface lacks a (it is ) and presents a light-grey, felty-arachnoid medulla. In section the thallus is 240–330

micrometre The micrometre (English in the Commonwealth of Nations, Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a uni ...

s (μm) thick. The upper cortex is viaduct-shaped: a 20–25 μm layer of densely packed periclinal hyphae overlies a 40–100 μm zone of anticlinal hyphae. The is 80–155 μm thick and aeruginous green, while the medulla is 45–90 μm thick and contains numerous hyphae 3–6 μm wide;

clamp connection A clamp connection is a hook-like structure formed by growing hyphal cells of certain fungi. It is a characteristic feature of basidiomycete fungi. It is created to ensure that each cell, or segment of hypha separated by septa (cross walls), rece ...

s are absent. The

hymenophore A hymenophore refers to the hymenium-bearing structure of a fungal fruiting body. Hymenophores can be smooth surfaces, lamellae, folds, tubes, or teeth. The term was coined by Robert Hooke Robert Hooke (; 18 July 16353 March 1703) was an ...

forms diffuse, concentric, patches up to 0.5 mm long and 5 mm broad with a pale yellow-orange, smooth surface and slightly felty, involute margins. Sections (80–115 μm thick) reveal plentiful palisade-like basidioles (15–25 × 4–6 μm) and scattered four-spored

basidia A basidium (: basidia) is a microscopic spore-producing structure found on the hymenophore of reproductive bodies of basidiomycete fungi. The presence of basidia is one of the main characteristic features of the group. These bodies are also ...

(20–30 × 4–6 μm);

basidiospore A basidiospore is a reproductive spore produced by basidiomycete fungi, a grouping that includes mushrooms, shelf fungi, rusts, and smuts. Basidiospores typically each contain one haploid Ploidy () is the number of complete sets of chromos ...

s have not been observed.

Thin-layer chromatography Thin-layer chromatography (TLC) is a chromatography technique that separates components in non-volatile mixtures. It is performed on a TLC plate made up of a non-reactive solid coated with a thin layer of adsorbent material. This is called the sta ...

detected no

secondary metabolite Secondary metabolites, also called ''specialised metabolites'', ''secondary products'', or ''natural products'', are organic compounds produced by any lifeform, e.g. bacteria, archaea, fungi, animals, or plants, which are not directly involved ...

Habitat and distribution

As of its original publication, the species was known to occur only in its type locality in Tapantí National Park,

Cartago Province Cartago (), which means Carthage in Spanish, is a Provinces of Costa Rica, province of central Costa Rica. It is one of the smallest provinces, however probably the richest of the Spanish Colonial era sites and traditions. Geography It is loca ...

, Costa Rica, at 3,300–3,400 m elevation. It grows epiphytically on tree branches and twigs in sub-Andean cloud forest conditions characterised by high humidity, frequent mists, and rapid wet-dry cycles. ''Cora arborescens'' is among the 18 '' Cora'' species found in Costa Rica and is one of 12 species in the genus for which Costa Rica is the type locality.

References

{{Taxonbar, from=Q107589543 arborescens Lichen species Lichens described in 2016 Lichens of Central America Basidiolichens Taxa named by Manuela Dal-Forno Taxa named by Robert Lücking