''Psoroma'' 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

Pannariaceae The Pannariaceae are a family of lichens in the order Peltigerales (suborder Collematineae). Species from this family have a widespread distribution, but are especially prevalent in southern temperate In geography, the temperate clima ...

. The widespread genus contains about 30 species, most of which are found in south

temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...

regions.

Taxonomy

The genus was

circumscribed In geometry, a circumscribed circle for a set of points is a circle passing through each of them. Such a circle is said to ''circumscribe'' the points or a polygon formed from them; such a polygon is said to be ''inscribed'' in the circle. * Circum ...

by the French botanist

André Michaux André Michaux (' → ahn- mee-; sometimes Anglicisation, anglicised as Andrew Michaud; 8 March 174611 October 1802) was a French botanist and explorer. He is most noted for his study of North American flora. In addition Michaux collected specime ...

in 1803. Some species formerly in ''Psoroma'' were transferred to the new genera '' Psorophorus'' and '' Xanthopsoroma'' in 2010. The genus ''

Joergensenia ''Joergensenia'' is a fungal genus in the family Pannariaceae. It comprises a single species, ''Joergensenia cephalodina'', which is a corticolous (bark-dwelling), squamulose lichen found in southern South America. Taxonomy ''Joergensenia'' co ...

'' was erected in 2008 to contain the species formerly known as ''Psoroma cephalodinum''.

Description

The genus ''Psoroma'' is characterised by its small scale-like

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 ...

, with an underlying layer that is barely noticeable. It houses a green algal , possibly the algae ''

Myrmecia Myrmecia can refer to: * ''Myrmecia'' (alga), genus of algae associated with lichens * ''Myrmecia'' (ant), genus of ants called bulldog ants * Myrmecia (skin), a kind of deep wart on the human hands or feet See also * '' Copromorpha myrmecias'' ...

'', which collaborates with the fungus to perform

photosynthesis Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...

. ''Psoroma'' species have

cephalodia A cephalodium () is a small gall-like structure found in some lichens. They occur only in lichens which contain both cyanobacterial and green algal partners. Cephalodia can occur within the tissues of the lichen, or on its upper or lower surface. ...

, structures containing the cyanobacterium ''

Nostoc ''Nostoc'', also known as star jelly, troll's butter, spit of moon, fallen star, witch's butter (not to be confused with the fungi commonly known as witches' butter), and witch's jelly, is the most common genus of cyanobacteria found in a variety ...

''. The reproductive organs, known as

ascomata An ascocarp, or ascoma (: ascomata), is the fruiting body (sporocarp (fungi), sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded ascus, asci, each of which typically contains four to ...

, are apothecial in form—essentially sessile and somewhat cup-shaped with a raised, enduring edge. Within these structures, the supporting filaments, or

paraphyses Paraphyses are erect sterile filament-like support structures occurring among the reproductive apparatuses of fungi, ferns, bryophytes and some thallophytes. The singular form of the word is paraphysis. In certain fungi, they are part of the f ...

, may be simple or branch towards their tips, which do not expand or form a cap, staining a dusky blue when

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 ...

is applied. The spore-producing asci are elongated, either club-shaped or cylindrical, featuring a distinctive structure at their tips where a central tube

stains A stain is an unwanted localized discoloration, often in fabrics or textiles. Stain(s) or The Stain(s) may also refer to: Color * Stain (heraldry), a non-standard tincture * Staining, in biology, a technique used to highlight contrast in samples ...

blue with iodine within a lighter-staining area, surrounded by a clear

amyloid Amyloids are aggregates of proteins characterised by a fibrillar morphology of typically 7–13 nm in diameter, a β-sheet secondary structure (known as cross-β) and ability to be stained by particular dyes, such as Congo red. In the human ...

ring.

Spore In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...

s produced by ''Psoroma'' are single-celled, colourless, and often contain one or two large oil droplets. Their shape is

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 ...

al, with a surface that is warty or ridged, and somewhat pointed at the ends. For asexual reproduction, ''Psoroma'' develops

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 ...

, which are pale brown, and produces simple, rod-shaped, colourless

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 ...

. Chemically, ''Psoroma'' usually lacks detectable

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 ...

s (

lichen product Lichen products, also known as lichen substances, are organic compounds produced by a lichen. Specifically, they are secondary metabolites. Lichen products are represented in several different chemical classes, including terpenoids, orcinol deri ...

s) through

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 ...

, although in rare cases, porphyrilic acid and related compounds may be present.

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 28 species of ''Psoroma''. * '' Psoroma absconditum'' * '' Psoroma antarcticum'' – Antarctica * '' Psoroma asperellum'' * '' Psoroma caliginosum'' * '' Psoroma capense'' – South Africa * '' Psoroma cinnamomeum'' * '' Psoroma cyanosorediatum'' * '' Psoroma dichroum'' * '' Psoroma echinaceum'' * '' Psoroma esterhuyseniae'' – South Africa * '' Psoroma filicicola'' * '' Psoroma fruticulosum'' * '' Psoroma geminatum'' * '' Psoroma hirsutulum'' * '' Psoroma hypnorum'' * '' Psoroma inflatum'' – New Zealand * '' Psoroma macquariense'' – Antarctica * '' Psoroma macrosporum'' * '' Psoroma multifidum'' * '' Psoroma nigropunctatum'' – Australia * '' Psoroma nivale'' –

Quebec Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, ...

, Canada * '' Psoroma obscurius'' * '' Psoroma orphninum'' * '' Psoroma paleaceum'' * '' Psoroma pholidotoides'' * '' Psoroma polychidioides'' * '' Psoroma saccharatum'' – Argentina * '' Psoroma sphinctrinum'' * '' Psoroma xanthorioides'' * '' Psoromaria rosulata'' * '' Psoromaria versicolor''

References

{{Taxonbar, from=Q7256123 Pannariaceae Peltigerales genera Lichen genera Taxa described in 1803 Taxa named by André Michaux