''Psiloparmelia'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.Parmeliaceae The Parmeliaceae is a large and diverse family of Lecanoromycetes. With over 2700 species in 71 genera, it is the largest family of lichen-forming fungi. The most speciose genera in the family are the well-known groups: '' Xanthoparmelia'' ( 822 ...

. It contains 13 Southern Hemisphere species, most of which are found growing on rocks at high elevations in South America. There are several characteristic features of the genus that are used to distinguish it from the morphologically similar genera, such as ''

Arctoparmelia ''Arctoparmelia'' is a genus of ring lichens in the family Parmeliaceae. The genus was circumscribed by American lichenologist Mason Hale in 1986 with '' A. centrifuga'' (formerly in '' Xanthoparmelia'') as the type species. Hale include ...

'', '' Flavoparmelia'', and ''

Xanthoparmelia ''Xanthoparmelia'' (commonly known as green rock shields or rock-shield lichens) is a genus of foliose lichen in the family Parmeliaceae.Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, ''Xanthoparmelia'' is syn ...

''. These include a dark, velvety lower

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 ...

surface that usually lacks

rhizine In lichens, rhizines are multicellular root-like structures, arising mostly from the lower surface. A lichen with rhizines is termed rhizinate, while a lichen lacking rhizines is termed erhizinate. Rhizines serve only to anchor the lichen to their ...

s, a negative test for lichenan, and a high concentration of

usnic acid Usnic acid is a naturally occurring dibenzofuran derivative found in several lichen species with the formula C18H16O7. It was first isolated by German scientist W. Knop in 1844 and first synthesized between 1933-1937 by Curd and Robertson. Usnic a ...

and

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, ...

in the

cortex Cortex or cortical may refer to: Biology * Cortex (anatomy), the outermost layer of an organ ** Cerebral cortex, the outer layer of the vertebrate cerebrum, part of which is the ''forebrain'' *** Motor cortex, the regions of the cerebral cortex i ...

Taxonomy

''Psiloparmelia'' was

circumscribed In geometry, the circumscribed circle or circumcircle of a polygon is a circle that passes through all the vertices of the polygon. The center of this circle is called the circumcenter and its radius is called the circumradius. Not every polyg ...

Mason Hale Mason Ellsworth Hale, Jr. (September 23, 1929 – April 23, 1990) was one of the most prolific lichenologists of the 20th century. Many of his scholarly articles focused on the taxonomy of the family Parmeliaceae. Hale was one of the first liche ...

in 1989 with two species: ''

Psiloparmelia arhizinosa ''Psiloparmelia'' is a genus of lichen belonging to the family Parmeliaceae. It contains 13 Southern Hemisphere species, most of which are found growing on rocks at high elevations in South America. There are several characteristic features of t ...

'', and the

type species In 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 species that contains the biological type specimen ...

, '' Psiloparmelia distincta''. Hale had previously placed this

taxon In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...

(as ''Parmelia distincta'') in the genus ''

''. He also considered placement in ''

'' due to similarities in lobe configuration, cortical chemistry, and the presence of a velvety lower surface. However, other differing characteristics precluded this classification, including a complete lack of

s and the presence of

isolichenan Isolichenan, also known as isolichenin, is a cold-water-soluble alpha glucan, α-glucan occurring in certain species of lichens. This lichen product was first isolated as a component of an extract of Cetraria islandica, Iceland moss in 1813, a ...

in the

cell wall A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mech ...

s. Hales' subsequent discovery of a species similar to ''P. distincta'' in

Lesotho Lesotho ( ), officially the Kingdom of Lesotho, is a country landlocked country, landlocked as an Enclave and exclave, enclave in South Africa. It is situated in the Maloti Mountains and contains the Thabana Ntlenyana, highest mountains in Sou ...

convinced him that these two species were sufficiently distinct from both ''Arctoparmelia '' and ''Xanthoparmelia '' to warrant the creation of a new genus, ''Psiloparmelia'', to contain them. Some taxonomic inspiration was drawn from Vilmos Gyelnik's ''Parmelia'' sect. ''Xanthoparmelia'' subsect. ''Endocoerulea'', which he created in 1931; it was in this subsection that ''Parmelia distincta'' was originally classified. Scanning electron microscopy was used in a 1992 study to evaluate the structure of the epicortex in ''Psiloparmelia'', revealing the presence of a rudimentary pored epicortex, which established another

character Character or Characters may refer to: Arts, entertainment, and media Literature * ''Character'' (novel), a 1936 Dutch novel by Ferdinand Bordewijk * ''Characters'' (Theophrastus), a classical Greek set of character sketches attributed to The ...

of the genus. Nine newly described species and one

new combination ''Combinatio nova'', abbreviated ''comb. nov.'' (sometimes ''n. comb.''), is Latin for "new combination". It is used in taxonomic biology literature when a new name is introduced based on a pre-existing name. The term should not to be confused wi ...

were added to the genus in 1992 by John Elix and Tom Nash, who published a synopsis of the genus. In 2006,

molecular A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioche ...

data supported the transfer of ''Xanthoparmelia peruviensis'' to ''Psiloparmelia'', despite it not sharing all the morphological features characteristic of other species in the genus, particularly in having a densely rhizinate lower surface.

Description

''Psiloparmelia'' species are

foliose Foliose lichen is one of the morphological classes of lichens, which are complex organisms that arise from the symbiotic relationship between fungi and a photosynthetic partner, typically algae. This partnership allows lichen to live in diverse ...

lichens growing on rocks, to which they can be tightly or loosely attached, depending on the species. The

, which reaches a diameter of , is made of irregularly shaped lobes whose margins lack

cilia The cilium, plural cilia (), is a membrane-bound organelle found on most types of eukaryotic cell, and certain microorganisms known as ciliates. Cilia are absent in bacteria and archaea. The cilium has the shape of a slender threadlike projecti ...

. The upper cortex of ''Psiloparmelia'' is a palisade

plectenchyma Plectenchyma (from Greek πλέκω ''pleko'' 'I weave' and ἔγχυμα ''enchyma'' 'infusion', i.e., 'a woven tissue') is the general term employed to designate all types of fungal tissues. The two most common types of tissues are prosenchyma ...

– comprising

hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or ...

e arranged perpendicular to the surface. It is partly covered by a rudimentary epicortex (a thin homogeneous

polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with wa ...

layer on the surface of the cortex) with pores. The texture of the upper cortex ranges from smooth to wrinkled, and it is

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 "blo ...

Pustule A skin condition, also known as cutaneous condition, is any medical condition that affects the integumentary system—the organ system that encloses the body and includes skin, nails, and related muscle and glands. The major function of this sy ...

s and

soredia 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 gr ...

may be present or absent, depending on the species, while

pseudocyphella Pseudocyphellae (singular ''pseudocyphella'') are structures in lichens that appear as tiny pores on the outer surface (the cortex of the lichen. They are caused when there is a break in the cortex of the lichen, and the medullary hyphae extend t ...

e and

isidia An isidium is a vegetative reproductive structure present in some lichens. Isidia are outgrowths of the thallus surface, and are corticated (i.e., containing the outermost layer of the thallus), usually with a columnar structure, and consisting o ...

are always absent. The

s contain the

alpha glucan α-Glucans (alpha-glucans) are polysaccharides of D-glucose monomers linked with glycosidic bonds of the alpha form. α-Glucans use cofactors in a cofactor site in order to activate a glucan phosphorylase enzyme. This enzyme causes a reaction tha ...

molecule

Green algae The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/Streptophyta. The land plants (Embryophytes) have emerged deep in the Charophyte alga as ...

are the

photobiont A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship. The lower surface of the thallus is black and velvety. It is covered with tiny bumps (minutely papillate), and usually lacks

s. Most species have an even finer velvety zone around the margin that is yellowish-grey or mouse-grey. The

apothecia An ascocarp, or ascoma (), 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. Ascocarps are mo ...

are either attached directly to the thallus surface (adnate), or are mounted on a small stalk (substipitate); they measure 2–5 mm in diameter. The

ascospore An ascus (; ) is the sexual spore-bearing cell produced in ascomycete fungi. Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some genera or s ...

s, which number eight per

ascus An ascus (; ) is the sexual spore-bearing cell produced in ascomycete fungi. Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some genera or s ...

, have a spherical to elliptical shape, and measure 9–12 by 5–9 μm. ''Psiloparmelia'' has a relatively diverse secondary chemistry. Metabolites that have been recorded from the genus include

, and the following β-orcinol derivatives: constipatic acid, protoconstipatic acid, diffractiac acid, fumarprotocetraric acid, hypostictic acid, 4-O-methylhypoprotocetraric acid, isousnic acid,

norstictic acid Norstictic acid is a depsidone produced as a secondary metabolite Secondary metabolites, also called specialised metabolites, toxins, secondary products, or natural products, are organic compounds produced by any lifeform, e.g. bacteria, fun ...

, and

salazinic acid Salazinic acid is a depsidone with a lactone ring. It is found in some lichens, and is especially prevalent in ''Parmotrema'' and ''Bulbothrix'', where its presence or absence is often used to help classify species in those genera. History I ...

. There are several other lichen acids that are found in trace amounts. The presence of these lichens compounds helps to distinguish between morphologically similar species in the genus.

Habitat and distribution

''Psiloparmelia'' is a genus of

saxicolous lichen A saxicolous lichen is a lichen that grows on rock. The prefix "sax" from the Latin means "rock" or "stone". Characteristics Saxicolous lichens exhibit very slow growth rates. They may develop on rock substrates for long periods of time, give ...

s, although ''Psiloparmelia distincta'' was recently recorded growing on old bones, the first reported time on that substrate. The genus has a Southern Hemisphere distribution, with most of the species located in South America. Twelve of the thirteen species in the genus are found in high altitudes on the

Andes Mountains The Andes, Andes Mountains or Andean Mountains (; ) are the List of mountain ranges#Mountain ranges by length, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range i ...

, ranging from Ecuador and Peru south to Bolivia and northern Argentina. They are typically the most common saxicolous foliose lichens that are collected in these locales. ''Psiloparmelia arhizinosa'' is the only species to break this distributional pattern; it is found at

alpine Alpine may refer to any mountainous region. It may also refer to: Places Europe * Alps, a European mountain range ** Alpine states, which overlap with the European range Australia * Alpine, New South Wales, a Northern Village * Alpine National Pa ...

habitats at high elevations in Lesotho.

Species

*''

'' – Lesotho *'' Psiloparmelia denotata'' – Argentina; Peru *'' Psiloparmelia dichotoma'' – Peru *'' Psiloparmelia diffractaica'' – Argentina *'' Psiloparmelia distincta'' – Argentina; Bolivia; Chile; Ecuador; Peru *'' Psiloparmelia flavobrunnea'' – Argentina; Bolivia; Chile; Ecuador; Peru *'' Psiloparmelia hypostictica'' – Argentina; Bolivia *'' Psiloparmelia norstictica'' – Argentina; Ecuador; Peru *'' Psiloparmelia peruviensis'' – Peru; Bolivia *'' Psiloparmelia pustulata'' – Argentina *'' Psiloparmelia salazinica'' – Argentina; Chile *'' Psiloparmelia sorediosa'' – Argentina *'' Psiloparmelia subcrustosa'' – Peru

References

{{Taxonbar, from=Q7256038 Parmeliaceae Lichen genera Taxa named by Mason Hale Lecanorales genera Taxa described in 1989