''Inoderma'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

lichen A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...

-forming

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

in the family

Arthoniaceae The Arthoniaceae are a family (biology), family of lichenized, Lichenicolous fungus, lichenicolous and saprobic fungi in the order Arthoniales. The Arthoniaceae is the largest family of Arthoniales, with around 800 species. Most species in Arthon ...

. It was resurrected for use in 2015 for a small group of species with the following features: elevated, white

pruinose Pruinescence , or pruinosity, is a "frosted" or dusty-looking coating on top of a surface. It may also be called a pruina (plural: ''pruinae''), from the Latin word for hoarfrost. The adjectival form is pruinose . Entomology In insects, a "bloom" ...

pycnidia A pycnidium (plural pycnidia) is an asexual fruiting body produced by mitosporic fungi, for instance in the order Sphaeropsidales ( Deuteromycota, Coelomycetes) or order Pleosporales (Ascomycota, Dothideomycetes). It is often spherical or inve ...

, immersed to adnate white pruinose

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 ...

, and a weakly gelatinized

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 ...

. '' Inoderma byssaceum'' was assigned as the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

for the genus.

Description

''Inoderma'' is a genus of lichens that typically forms broad, pale, whitish to light olive-grey patches on its substrate. These patches (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 ...

) can be continuous but often develop a network of fine cracks or appear as tiny, powdery . The surface is usually not covered by a protective "skin" () and can feel slightly soft or powdery. The lichen's green partner cells (the ) belong to '' Trentepohlia'', a genus of

green algae The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ...

. Some ''Inoderma'' species produce

—small, often rounded, and slightly raised structures where spores are formed. These may lie flush with the lichen's surface or sit just above it, and they sometimes carry a thin to thick white powdery coating (). The boundary between the apothecium and the main lichen body (the ) is not clearly defined. Inside the apothecium, the spore-producing tissue (the

) is colourless to pale yellowish-brown, with tiny pale crystals in its upper layer (the ). Beneath this, the is made of tangled fungal filaments within a jelly-like matrix, ranging in colour from pale to dark brown. Thin, thread-like structures called run through this layer, and their tips do not widen or darken. The asci, which are the spore-containing "sacs", follow the ''Arthonia''-type structure and do not show a blue

staining Staining is a technique used to enhance contrast in samples, generally at the Microscope, microscopic level. Stains and dyes are frequently used in histology (microscopic study of biological tissue (biology), tissues), in cytology (microscopic ...

reaction with

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

solutions. The spores are typically elongated, sometimes slightly egg-shaped (cylindric- or ), and divided into two to four compartments by internal walls (

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 ...

). They remain colourless and do not narrow at the dividing lines. In addition to apothecia, ''Inoderma'' may also form

conidiomata Conidiomata (singular: Conidioma) are blister-like fruiting structures produced by a specific type of fungus called a coelomycete. They are formed as a means of dispersing asexual spores call conidia, which they accomplish by creating the blister- ...

—tiny, elevated, spore-producing bumps called

. These pycnidia have dark brown to black walls and are often dusted with a thick layer of white powder. They release small, rod-shaped spores known as

conidia A conidium ( ; : conidia), sometimes termed an asexual chlamydospore or chlamydoconidium (: chlamydoconidia), is an asexual, non- motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also ...

. From a chemical perspective, ''Inoderma'' species may contain substances such as lepraric acid and confluentic acid, along with some compounds not yet fully identified ("byssaceum unknowns"). When tested with chemicals, the dark brown pigments in the apothecia and pycnidia turn greenish-black in the K spot test and slowly shift to an orange-brown colour when treated with

nitric acid Nitric acid is an inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but samples tend to acquire a yellow cast over time due to decomposition into nitrogen oxide, oxides of nitrogen. Most com ...

. These reactions, along with the lichen's distinct physical features and internal structures, help distinguish ''Inoderma'' from related genera.

Species

Species Fungorum ''Index Fungorum'' is an international project to index all formal names (Binomial nomenclature, scientific names) in the fungus Kingdom (biology), kingdom. As of 2015, the project is based at the Royal Botanic Gardens, Kew, one of three partn ...

(in the

Catalogue of Life The Catalogue of Life (CoL) is an online database that provides an index of known species of animals, plants, fungi, and microorganisms. It was created in 2001 as a partnership between the global Species 2000 and the American Integrated Taxono ...

) accepts six species of ''Inoderma'': *'' Inoderma afromontanum'' – Uganda *'' Inoderma byssaceum'' *'' Inoderma epigaeum'' *'' Inoderma nipponicum'' – Japan *'' Inoderma sorediatum'' – Poland *''

Inoderma subabietinum ''Inoderma'' is a genus of lichen-forming fungi in the family Arthoniaceae. It was resurrected for use in 2015 for a small group of species with the following features: elevated, white pruinose pycnidia, immersed to adnate white pruinose apotheci ...

'' – Europe

References

{{Taxonbar, from=Q102178606 Arthoniaceae Arthoniomycetes genera Lichen genera Taxa described in 1810 Taxa named by Erik Acharius