''Diorygma microsporum'' 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

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 was described as new to science in 2011. It has a neotropical distribution, and has been collected in

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

, and India. Notable for its small ascospores, this lichen thrives in undisturbed rainforests and serves as an indicator of forest health.

Taxonomy

''Diorygma microsporum'' was first described by lichenologists Marcela Cáceres and

Robert Lücking Robert Lücking (born 1964) is a German lichenologist. He is a leading expert on foliicolous lichens–lichens that live on leaves. Life and career Born in Ulm in 1964, Lücking earned both his master's (1990) and PhD degree (1994) at the Univer ...

as a new species in 2011. The species epithet ''microsporum'' highlights its quite small , which are the smallest known in 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 ...

''. 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 discovered by the authors in the Charles Darwin Ecological Refuge in Igarassu, Pernambuco, Brazil. Initially, the newly discovered species was identified as ''

Anomomorpha aggregans ''Anomomorpha'' is a genus of lichens in the family Graphidaceae. The genus, described in 1891, has a pantropical A pantropical ("all tropics") distribution is one which covers Tropics, tropical regions of both hemispheres. Examples of specie ...

'' due to its small ascospores and

norstictic acid Norstictic acid is a depsidone produced as a secondary metabolites in lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.

chemistry. However, further examination and

DNA sequencing DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, guanine, cytosine, and thymine. Th ...

of a

collection revealed a lack of hymenial , a key in ''

Anomomorpha ''Anomomorpha'' is a genus of lichens in the family Graphidaceae. The genus, described in 1891, has a pantropical A pantropical ("all tropics") distribution is one which covers Tropics, tropical regions of both hemispheres. Examples of specie ...

''. The

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

of ''D. microsporum'' is more reminiscent of species within the genus ''Diorygma'', confirming its placement within the genus and setting it apart from similar species.

Description

''Diorygma microsporum'' has a

crustose Crustose is a habit of some types of algae and lichens in which the organism grows tightly appressed to a substrate, forming a biological layer. ''Crustose'' adheres very closely to the substrates at all points. ''Crustose'' is found on rocks and ...

thallus that can reach up to in diameter and has a thickness of 50–120

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 ...

. Its surface is smooth to uneven and has a light greyish-green colour. The lichen features dense clusters of stellately (star-like) branched , measuring 1–5 mm long, 0.15–0.25 mm wide, and 0.1 mm high. The is partly exposed, with a flesh-coloured to light red-brown hue and covered in white . Its is orange-brown and 15–25 μm thick. The 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 ...

, measure 12–15 by 6–7 μm in size, and strongly

iodine Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , and boils to a vi ...

-reactive. It contains norstictic acid as its sole lichen product.

Similar species

''Diorygma microsporum'' shares some similarities with '' D. poitaei'' in appearance; however, it is distinguished by its smaller ascospores and the presence of norstictic acid in its thallus. Another one of the few species with small spores, ''

Diorygma cameroonense ''Diorygma cameroonense'' is a little-known species of corticolous (bark-dwelling) script lichen in the family Graphidaceae. It is found in the pristine rainforests of eastern Cameroon. This lichen is distinct due to its larger with more septa ...

'', is distinguished from ''D. microsporum'' by its chemistry, as it contains

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 ...

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 ...

as major lichen products.

Habitat and distribution

''Diorygma microsporum'' has a relatively broad neotropical distribution, as evidenced by collections from northeastern Brazil, Colombia, and

. It has also been recorded in

Tamil Nadu Tamil Nadu (; , TN) is a States and union territories of India, state in southern India. It is the List of states and union territories of India by area, tenth largest Indian state by area and the List of states and union territories of India ...

, India. This lichen species is typically found on tree trunks in the shady understory of undisturbed lowland and lower montane rainforests, making it a bioindicator of forest health.

References

{{Taxonbar, from=Q16981369 microsporum Lichen species Lichens of the Southeastern United States Lichens of Brazil Lichens of Colombia Lichens of India Lichens described in 2011 Taxa named by Marcela Cáceres Taxa named by Robert Lücking