''Parmelia'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of medium to large

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.Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, It has a global distribution, extending from the ArcticSkult H (1985) A New Subspecies of ''Parmelia omphalodes'' Ascomycetes Described from the Arctic. Annales Botanici Fennici 22, 201-6. to the Antarctic continentD.C. Lindsay (1973) Notes on Antarctic lichens: IV. The genera ''Cetraria'' Hoffm., ''Hypogymnia'' (Nyl.) Nyl., ''Menegazzia'' Massal, ''Parmelia'' Ach. and ''Platismatia'' Culb. et Culb. British Antarctic Survey Bulletin 36, 105-114. but concentrated in

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

regions. There are about 40 species in ''Parmelia''. In recent decades, the once large genus ''Parmelia'' has been divided into a number of smaller genera according to

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 ...

morphology and

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

relatedness. It is a foliaceous lichen, resembling a leaf in shape. The ends of the leaf-like lobes are often squarish-tipped. The upper surface is pale bluish-gray to light brown in direct sunlight, with a network web-like ridges and depressions. The lower surface is black and has rhizines anchoring it to the substrate. In general, ''Parmelia'' have a dark lower side with rhizines ('rootlets') that attach the lichen to its substrate. The upper side may be several colours - grey, yellow, brown - and may have reproductive organs on it. These may be

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 mos ...

( ascospore-producing bodies),

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 ...

or soralia (both vegetative structures). In between these two layers is the

medulla Medulla 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 ovary * Medulla of t ...

, which contains the algal component of the lichen.

Taxonomy

''Parmelia'' was circumscribed by Swedish lichenologist

Erik Acharius Erik Acharius (10 October 1757 – 14 August 1819) was a Swedish botanist who pioneered the taxonomy of lichens and is known as the "father of lichenology." Acharius was famously the last pupil of Carl Linnaeus. Life Acharius was born in 1 ...

in 1803. His idea of the genus, which included foliose species with lecanorine apothecia, was quite broad and included species that are now dispersed in many different genera and families, such as the

Peltigeraceae The Peltigeraceae are a family of lichens in the order Peltigerales. The Peltigeraceae, which contains 15 genera and about 600 species, has recently (2018) been emended to include the families Lobariaceae and Nephromataceae. Many Peltigeraceae sp ...

('' Lobaria''), the Pannariaceae (''

Pannaria ''Pannaria'' is a genus of lichen-forming fungi in the family Pannariaceae. The widespread genus contains an estimated 51 species, found primarily in tropical regions. Species *'' Pannaria aenea'' *'' Pannaria andina'' *'' Pannaria aotearoana ...

'', '' Parmeliella''), the Physciaceae ('' Physcia'', '' Heterodermia'', '' Physconia''), the Teloschistaceae (''

Xanthoria ''Xanthoria'' is a genus of lichenized fungi in the family Teloschistaceae. Common names include orange lichen,Cetraria'', '' Hypogymnia'', and '' Parmeliopsis''). Its broad circumscription meant that almost every lichen with a thalline apothecial rim was included by 19th-century authors. In an attempt to create more homogeneous groups of taxa, lichenologists created new segregate genera for species once in ''Parmelia''. These included '' Menegazzia'' (1854), ''

Parmotrema ''Parmotrema'' is a genus of lichen belonging to the family Parmeliaceae. It is a large genus, containing an estimated 300 species, with a centre of diversity in subtropical regions of South America and the Pacific Islands. Members of the genus ...

'' (1860), ''

Anzia ''Anzia'' is a genus of foliose lichens known as black-foam lichens in the large family Parmeliaceae. It was formerly included in the monogeneric family Anziaceae, but this has since been subsumed into the Parmeliaceae. Taxonomy The genus name ...

'' (1861), '' Parmeliopsis'' (1869), '' Hypogymnia'' (1896), '' Pseudevernia'' (1903), ''

Pannoparmelia ''Pannoparmelia'' is a genus of lichenised ascomycetes in the large family Parmeliaceae. It is a genus of five currently accepted species. ''Pannoparmelia'' species have a foliose growth habit. All members of the family have a symbiotic associati ...

'' (1912), and '' Pseudoparmelia'' (1914). In the 1970s and 1980s, electron microscopy was used to help divide several ''Parmelia'' species groups into different genera based on the structure of their

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 ...

. These include '' Arctoparmelia'', ''

Bulbothrix ''Bulbothrix'' is a genus of lichen-forming fungi in the family Parmeliaceae. This genus is synonymous with ''Bulbothricella'' V.Marcano, S.Mohali & A.Morales. ''Bulbothrix'' was circumscribed by lichenologist Mason E. Hale in 1974 with '' Bul ...

'', '' Canoparmelia'', '' Cetrariastrum'', '' Concamerella'', '' Everniastrum'', '' Flavoparmelia'', '' Hypotrachyna'', '' Neofuscelia'', '' Paraparmelia'', '' Parmelina'', ''

'', '' Pseudoparmelia'', '' Relicina'', '' Relicinopsis'', '' Xanthomaculina'', and '' Xanthoparmelia''. Another group of species was segregated on the basis of the presence of pseudocyphellae: '' Punctelia'', '' Flavopunctelia'', and '' Melanelia''. In Mason Hale's 1987 monograph on ''Parmelia'', he commented: "The group has been further subdivided ... now leaving in ''Parmelia'' a small, apparently irreducible assemblage of species typified by ''P. saxatilis''". In 2016, however, sixteen mostly Australasian species were moved to the new genus '' Notoparmelia''; these species had been shown by molecular phylogenetic analysis to form a monophyletic lineage in ''Parmelia''.

Fossil record

There are two foliose fossil taxa, ''

Parmelia ambra ''Parmelia ambra'' is a fossilised species of foliose lichen in the family Parmeliaceae. Found in Dominican amber and described as a new species in 2000, the fossil has been used in subsequent studies of lichen evolution. Taxonomy The fossil wa ...

'' and '' P. isidiiveteris'', that have been placed provisionally in genus ''Parmelia'' due to their overall resemblance to members of this genus. Later authors have suggested, however, that this generic placement is not appropriate for the current concept of ''Parmelia'', and that because of the dearth of specimens available for analysis, it is impossible to know for certain which of the many foliose genera in the family Parmeliaceae is best suited for these fossils.

Description

''Parmelia'' species have a

(leafy) thallus with a substrate attachment ranging from loose to tight. The lobes comprising the thallus are rounded, more or less straight, and may be contiguous or overlapping (imbricate). The texture of the upper thallus ranges from smooth to foveolate (covered with puts and depressions). The colour is typically green to whitish grey to greyish brown, and some species have a coating of

pruina 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 ...

on the surface. Most species have pseudocyphellae (tiny pores that allow for

gas exchange Gas exchange is the physical process by which gases move passively by diffusion across a surface. For example, this surface might be the air/water interface of a water body, the surface of a gas bubble in a liquid, a gas-permeable membrane, or a ...

), and vegetative propagules such as

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 ...

, or both. The lower surface of the thallus is black (or close to it), and has

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 (either simple or branched) that function as holdfasts to attach it to its substrate. The

cortex (botany) In botany, a cortex is an outer layer of a stem or root in a vascular plant, lying below the epidermis but outside of the vascular bundles. The cortex is composed mostly of large thin-walled parenchyma cells of the ground tissue system and shows ...

is paraplectenchymatous – a cell arrangement where the hyphae are oriented in all directions. The ascomata of ''Parmelia'' species are in the form of

, which have a zeorine structure (an apothecium in which a proper exciple is enclosed in the thalline exciple) and are laminal (superficial on the surface) to somewhat stipitate. The exposed upper surface of the hymenium, the disc, is brown, rarely blackish. The asci are eight-spored, while the spores are colorless, ellipsoid, and measure 10–18 by 5–13 μm. The

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-l ...

are in the form of

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 inverse ...

; these black spots are laminal and immersed in the thallus surface. They produce dumbbell-shaped conidia with dimensions of 5.5–8 μm. The photobiont partners of ''Parmelia'' are green algae from the genera '' Asterochloris'' or '' Trebouxia''.

Ecology

''Parmelia'' lichens are food for the caterpillars of certain Lepidoptera, such as the bagworm moth '' Taleporia tubulosa''.

Conservation

Two species of ''Parmelia'' have been assessed by the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of nat ...

for the global

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...

. Both ''Parmelia saxatilis'' and ''P. sulcata'' are considered species of

least concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...

due to their widespread distribution, abundance, and stable populations.

Distribution

Eleven ''Parmelia'' species were recorded for Europe in 2008. Nine occur in the Nordic lichen flora, of which ''P. saxatilis'' and ''P. sulcata'' are most common and widespread.

Species

*'' Parmelia adaugescens'' *† ''

'' – extinct; fossilized in Dominican amber *'' Parmelia asiatica'' – China *'' Parmelia barrenoae'' – Europe *'' Parmelia cochleata'' *''

Parmelia discordans Parmelia may refer to: * Parmelia (barque), the vessel that in 1829 transported the first settlers of the British colony of Western Australia * ''Parmelia'' (fungus), a genus of lichens with global distribution * Parmelia, Western Australia Pa ...

'' – Europe *'' Parmelia encryptata'' *'' Parmelia ernstiae'' – Europe *'' Parmelia fertilis'' *'' Parmelia fraudans'' *'' Parmelia hygrophila'' – North America *'' Parmelia hygrophiloides'' – India *'' Parmelia imbricaria'' *† '' Parmelia isidiiveteris'' – extinct; fossilized in Dominican amber *'' Parmelia lambii'' – Antarctica *'' Parmelia marmariza'' *'' Parmelia mayi'' – northeastern North America *'' Parmelia meiophora'' *'' Parmelia neocaledonica'' *'' Parmelia neodiscordans'' *'' Parmelia niitakana'' *''

Parmelia omphalodes ''Parmelia omphalodes'' is a species of foliose lichen in the family Parmeliaceae. It is one of the several dozen lichen species first described in 1753 by Carl Linnaeus. Swedish lichenologist Erik Acharius transferred it to the genus ''Parmelia ...

'' – Europe *''

Parmelia pinnatifida Parmelia may refer to: * Parmelia (barque), the vessel that in 1829 transported the first settlers of the British colony of Western Australia * ''Parmelia'' (fungus), a genus of lichens with global distribution * Parmelia, Western Australia Pa ...

'' – Europe *'' Parmelia protosignifera'' – Australia *''

Parmelia pseudoshinanoana Parmelia may refer to: * Parmelia (barque), the vessel that in 1829 transported the first settlers of the British colony of Western Australia * ''Parmelia'' (fungus), a genus of lichens with global distribution * Parmelia, Western Australia Pa ...

'' *'' Parmelia rojoi'' – Europe *'' Parmelia saxatilis'' – Europe *''

Parmelia sectilis Parmelia may refer to: * Parmelia (barque), the vessel that in 1829 transported the first settlers of the British colony of Western Australia * ''Parmelia'' (fungus), a genus of lichens with global distribution * Parmelia, Western Australia Pa ...

'' *'' Parmelia serrana'' – Europe *'' Parmelia shinanoana'' *'' Parmelia skultii'' – Europe *'' Parmelia squarrosa'' – Europe *'' Parmelia submontana'' – Europe *'' Parmelia submutata'' *''

Parmelia sulcata ''Parmelia sulcata'' is a foliose lichen in the family Parmeliaceae. It is very tolerant of pollution and has a cosmopolitan distribution, making it one of the most common lichens. It harbours a unicellular '' Trebouxia'' green algal symbiont. ...

'' – Europe *'' Parmelia sulymae''

References

Cited literature

* {{Taxonbar, from=Q310585 * Lichen genera Taxa named by Erik Acharius Lecanorales genera Taxa described in 1803