''Malmidea allopapillosa'' is a species of

corticolous This glossary of mycology is a list of definitions of terms and concepts relevant to mycology, the study of fungi. Terms in common with other fields, if repeated here, generally focus on their mycology-specific meaning. Related terms can be found ...

(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

Malmideaceae Malmideaceae is a family of crustose and corticolous lichens in the order Lecanorales. It contains eight genera and about 70 species. Taxonomy Malmideaceae was created in 2011 to accommodate a group of species, formerly placed in genus '' Malc ...

. It is found in Venezuela.

Taxonomy

The lichen was

formally described A species description is a formal scientific description of a newly encountered species, typically articulated through a scientific publication. Its purpose is to provide a clear description of a new species of organism and explain how it differ ...

as a new species in 2021 by the German lichenologist

Klaus Kalb Klaus Kalb (born 1942) is a German lichenologist and an authority on tropical lichens. Born in Nuremberg, he studied at the University of Erlangen–Nuremberg before pursuing a career that significantly advanced the field of lichenology, parti ...

. The

type specimen In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...

was collected by the author in 1980 from a

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 ...

in the surroundings of Tovar, Páramo de Mariño, ( Mérida) at an altitude of . The

species epithet Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In Taxonomy (biology), taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany) ...

refers to its resemblance to ''

Malmidea papillosa ''Malmidea'' is a genus of crustose lichens and the type genus of the family Malmideaceae. It was established in 2011 to contain a phylogenetically distinct group of species formerly placed in the genus ''Malcolmiella''. The crust-like thallus of ...

''.

Description

''Malmidea allopapillosa'' is a

with a

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 ...

that is either continuous or cracked and measures 50–100

μm The micrometre (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 unit of length in the International System ...

in thickness. The surface of the thallus is smooth and dull, with warts that are 0.2–0.3 mm in diameter and with a whitish-grey colour. This species lacks both

isidia An isidium (plural: isidia) is a tiny, wart- or finger-like outgrowth on the thallus surface of certain lichen species. It is one of two principal types of vegetative reproduction, vegetative reproductive structures in lichens, the other being ...

and

soralia Soredia are common reproductive structures of lichens. Lichens reproduce asexually by employing simple fragmentation and production of soredia and isidia. Soredia are powdery propagules composed of fungal hyphae wrapped around cyanobacteria or g ...

. The of the thallus reacts to a solution of

potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which utili ...

(i.e., the K

spot test Spot analysis, spot test analysis, or a spot test is a chemical test, a simple and efficient technique where analytic assays are executed in only one, or a few drops, of a chemical solution, preferably in a great piece of filter paper, without usin ...

) with a yellow colouration, while the

medulla Medulla (Latin for "marrow") or medullary may refer to: Science * Medulla oblongata, a part of the brain stem * Renal medulla, a part of the kidney * Adrenal medulla, a part of the adrenal gland * Medulla of ovary, a stroma in the center of the ...

of the thallus is white is K−. The medulla of the warts is peach-coloured to pink, with an orange-red reaction with K+, which soon changes to lemon-yellow. The of this species is , with cells measuring 6–8 μm in diameter. The

apothecia An ascocarp, or ascoma (: ascomata), 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. As ...

of ''Malmidea allopapillosa'' are

sessile Sessility, or sessile, may refer to: * Sessility (motility), organisms which are not able to move about * Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant * Sessility (medicine), tumors and polyps that ...

and rounded, measuring 0.3–0.8 mm in diameter and 0.4–0.5 mm in height. The apothecial are flat and range in colour from light to dark brown. The margin of the apothecia is thin, approximately 0.05 mm thick, and varies in colour from whitish-grey to dark brownish-grey. As the lichen ages, the margin is excluded, forming a ''piperis''-type excipulum that is more or less

hyaline A hyaline substance is one with a glassy appearance. The word is derived from , and . Histopathology Hyaline cartilage is named after its glassy appearance on fresh gross pathology. On light microscopy of H&E stained slides, the extracellula ...

(translucent) or brown at the periphery, with the inner part being hyaline and lacking

hydrophobic In chemistry, hydrophobicity is the chemical property of a molecule (called a hydrophobe) that is seemingly repelled from a mass of water. In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, thu ...

granules. The is about 15 μm high and varies from hyaline to light brown, while the centrally located is 70–90 μm high, narrowing towards the margin, and has a reddish to dark brown colour unreactive to K. The is brown, and the

hymenium The hymenium is the tissue layer on the hymenophore of a fungal fruiting body where the cells develop into basidia or asci, which produce spores. In some species all of the cells of the hymenium develop into basidia or asci, while in oth ...

is hyaline, measuring 130–150 μm in height. The base of the apothecia is partially filled with opaque granules that react K+ (greenish-yellow). The asci of ''Malmidea allopapillosa'' measure 90–120 by 20–25 μm. Each ascus contains 6–8 broadly

ellipsoid An ellipsoid is a surface that can be obtained from a sphere by deforming it by means of directional Scaling (geometry), scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a Surface (mathemat ...

, ascospores that lack

septa SEPTA, the Southeastern Pennsylvania Transportation Authority, is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly four million people througho ...

. These ascospores have walls that are equally thickened and , measuring 14–17 by 8–10 μm with a of 1 μm. Chemically, this species is characterised by the presence of

atranorin Atranorin is a chemical substance produced by some species of lichen. It is a secondary metabolite belonging to a group of compounds known as depsides. Atranorin has analgesic, anti-inflammatory, antibacterial, antifungal, cytotoxic, antioxidant, ...

as a major component, along with approximately 10 unidentified xantholepinone substances, detectable using

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 ...

. Its lookalike ''Malmidea papillosa'' lacks atranorin and has a different set of xantholepinones.

References

{{Taxonbar, from=Q123983219 allopapillosa Lichen species Lichens described in 2021 Lichens of Venezuela Taxa named by Klaus Kalb