''Diorygma cameroonense'' is a little-known species of corticolous (bark-dwelling)

script lichen A script lichen, or graphid lichen, is a member of a group of lichens which have spore producing structures that look like writing on the lichen body. The structures are elongated and narrow apothecia called lirellae, which look like short scribbles ...

in the family

Graphidaceae The Graphidaceae are a family of lichens in the order Ostropales. Distribution and ecology The vast majority of Graphidaceae species are restricted to the tropics. Most Graphidaceae species are epiphytic (i.e. they grow only on plants). Gener ...

. It is found in the pristine

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 ...

s of eastern

Cameroon Cameroon (; french: Cameroun, ff, Kamerun), officially the Republic of Cameroon (french: République du Cameroun, links=no), is a country in west-central Africa. It is bordered by Nigeria to the west and north; Chad to the northeast; the C ...

. This lichen is distinct due to its larger with more

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 ...

compared to the closely related '' Diorygma sticticum''.

Taxonomy

''Diorygma cameroonense'' was formally described as a new species in 2020 by German lichenologist

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 ...

. The species name, ''cameroonense'', refers to the country where it was collected. 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 on 1 April 1999 in Bewala II Village near Ngatto, East Province, Cameroon, in a pristine rainforest along the

Boumba River Boumba River is a river in the South Cameroon Plateau of southeast Cameroon. Geography The river rises in the Abong-Mbang region. The Boumba is almost 530 km long, and has a catchment of 27.400 km²

Description

The

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 ...

of ''Diorygma cameroonense'' is corticolous, greenish-grey, and can reach up to in diameter. It has a smooth to uneven surface and is 100–125

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. The lichen's

fruit bodies The sporocarp (also known as fruiting body, fruit body or fruitbody) of fungi is a multicellular structure on which spore-producing structures, such as basidia or asci, are borne. The fruitbody is part of the sexual phase of a fungal life cyc ...

are in the form of , which are single, unbranched or stellately to irregularly branched, and immersed to with a thick, complete . Ascospores are

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 ...

and somewhat , measuring 15–20 by 5–8 μm, with 3–5 transverse and 0–1 longitudinal

in 1 or 2 segments. The lichen contains three lichen products:

stictic acid Stictic acid is an aromatic organic compound, a product of secondary metabolism in some species of lichens. Stictic acid is the subject of preliminary biomedical research. Stictic acid has cytotoxic and apoptotic effects ''in vitro''. Computation ...

(major), menegazziaic acid (minor), and

constictic acid Constictic acid is a chemical compound of the depsidone class. It was first isolated in 1968 from lichen of the genus ''Usnea''. It has since been found in many other lichen genera including ''Menegazzia'', '' Crespoa'', and ''Xanthoparmelia ...

(submajor).

Similar species

''Diorygma cameroonense'' is part of the genus ''

Diorygma ''Diorygma'' is a genus of lichen-forming fungi in the family Graphidaceae. The genus was circumscription (taxonomy), circumscribed by Franz Gerhard Eschweiler in 1824. Species of the genus are widely distributed in tropical and subtropical regio ...

'', which includes other species with small ascospores, such as '' D. microsporum'' from Brazil, Colombia, and the United States (Florida); '' D. pauciseptatum'' from Brazil; and '' D. sticticum'' from Thailand. ''Diorygma cameroonense'' is distinguished from these species by its larger and more septate ascospores, as well as its unique chemistry.

Habitat and distribution

''Diorygma cameroonense'' is found in Cameroon, specifically in the East Province. It grows on the bark of trees in pristine rainforests along the Boumba River at an elevation of about .

References

{{Taxonbar, from=Q107638473 cameroonense Lichen species Lichens described in 2020 Lichens of West-Central Tropical Africa Taxa named by Klaus Kalb