''Imshaugia'' 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 ...

of seven species of

foliose lichen 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 ...

s in the family

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 ...

. They are commonly known as starburst lichens.

Taxonomy

The genus 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 ...

by Susan Meyer in 1985 as a segregate of '' Parmeliopsis''. The genus name of ''Imshaugia'' is in honour of

Henry Andrew Imshaug Henry Andrew Imshaug (1925–2010) was an American lichenologist notable for work on the genus ''Buellia'' and his "enormous and important collections from the Rocky Mountains, Great Lakes region, West Indies and subantarctic islands, together wit ...

(1925–2010), who was an American lichenologist. In a previous study of ''Parmeliopsis'', Meyer noted a group of species (represented by ''P. aleurites'' and ''P. placorodia'') that would be better accommodated in a separate genus. This had been previously noted by other lichenologists: in 1932, Vilmos Gyelnik proposed the section ''Pallidifera'' to include the grey species of ''Parmeliopsis''; in 1936 Johannes Hillmann proposed section ''Rectoconidia'' to contain species with short and straight conidia. Meyer created ''Imshaugia'' on the basis of its emergent and partly marginal pycnidia (they are immersed and laminal in ''Parmeliopsis''), its short, ampulliform (flask-shaped) or bifusiform (tapering at both ends)

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

(these are long and curved in ''Parmeliopsis''), and the presence of ''

Cetraria ''Cetraria'' is a genus of fruticose lichens that associate with green algae as photobionts. Most species are found at high latitudes, occurring on sand or heath. Species have a characteristic "strap-like" form, with spiny lobe edges. '' Cetra ...

''-type

lichenan Lichenin, also known as lichenan or moss starch, is a complex glucan occurring in certain species of lichens. It can be extracted from ''Cetraria islandica'' (Iceland moss). It has been studied since about 1957. Structure Chemically, lichenin i ...

in its cell walls rather than

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 ...

as in ''Parmeliopsis''. The generic name honours

, "in recognition of his contributions to lichenology." ''Imshaugia'' species are commonly known as "starburst lichens".

Description

''Imshaugia'' lichens are foliose with a mineral-grey to whitish-grey

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 ...

and a whitish to light brown lower surface. They grow as small rosettes, comprising small lobes measuring 1–2 mm wide.

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 soredia are absent from the thallus, but

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 ...

may be present. The upper cortex is paraplectenchymatous (a cell arrangement where the

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 are oriented in all directions), measuring 10–20

μm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

thick, and covered by an epicortex with pores. The apothecia are ''Lecanora''-type, resembling large, concave brown discs.

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 are colourless,

ellipsoid An ellipsoid is a surface that may be obtained from a sphere by deforming it by means of directional scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a surface that may be defined as the ...

, and 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 ...

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

have a short

bacilliform A bacillus (), also called a bacilliform bacterium or often just a rod (when the context makes the sense clear), is a rod-shaped bacterium or archaeon. Bacilli are found in many different taxonomic groups of bacteria. However, the name ''Bacillu ...

shape with a swelling towards one end, and measure 3–4.5 μm long. The

phycobiont A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.green alga 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 ...

e – ''

Trebouxia ''Trebouxia'' is a unicellular green alga.Silverside, A. J. (2009). Retrieved from http://www.bioref.lastdragon.org/Chlorophyta/''Trebouxia''.html It is a photosynthetic organism that can exist in almost all habitats found in polar, tropical, and ...

'' in ''I. aleurites'', and ''

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'' ...

'' in ''I. placorodia''. The thallus contains

thamnolic acid Thamnolic acid is a β-orcinol depside with the molecular formula C19H16O11. Thamnolic acid was first isolated from the lichen '' Thamnolia vermicularis'', but it also occur in ''Cladonia ''Cladonia'' is a genus of moss-like lichens in the fa ...

and atranorin.

Habitat and distribution

''Imshaugia'' grows most commonly on the bark and wood of

conifer Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single ...

s, and prefers woodland habitats that are open and well-lit. They have also been recorded on

hardwood Hardwood is wood from dicot trees. These are usually found in broad-leaved temperate and tropical forests. In temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen. Hardwood (which comes from ...

s and wood fences. The South American species ''I. sipmanii'', however, is saxicolous. ''Imshaugia placorodia'' has been noted to display a preference for the bark of the tree species

pitch pine ''Pinus rigida'', the pitch pine, is a small-to-medium-sized pine. It is native to eastern North America, primarily from central Maine south to Georgia and as far west as Kentucky. It is found in environments which other species would find unsuit ...

(''Pinus rigida'') and

Jack pine Jack pine (''Pinus banksiana'') is an eastern North American pine. Its native range in Canada is east of the Rocky Mountains from the Mackenzie River in the Northwest Territories to Cape Breton Island in Nova Scotia, and the north-central and ...

(''Pinus banksiana''). 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 ...

, ''Imshaugia aleurites'', is widely distributed in northern North America, having been recorded from the

tree line The tree line is the edge of the habitat at which trees are capable of growing. It is found at high elevations and high latitudes. Beyond the tree line, trees cannot tolerate the environmental conditions (usually cold temperatures, extreme snowp ...

in the Arctic south through all of the

boreal Boreal may refer to: Climatology and geography *Boreal (age), the first climatic phase of the Blytt-Sernander sequence of northern Europe, during the Holocene epoch *Boreal climate, a climate characterized by long winters and short, cool to mild ...

region and most of the

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 t ...

region.

Species

*'' Imshaugia aleurites'' *'' Imshaugia angustior'' *'' Imshaugia evernica'' –

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

*'' Imshaugia placorodia'' *'' Imshaugia pyxiniformis'' – Brazil *'' Imshaugia sipmanii'' – Venezuela *'' Imshaugia venezolana'' – Venezuela The species ''Imshaugia subarida'', proposed by John Elix in 2004 (a

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 ...

from genus ''

Canoparmelia ''Canoparmelia'' is a genus of lichen-forming fungi in the family Parmeliaceae. The widespread genus contains about 35 species. ''Canoparmelia'', a segregate of the parmelioid lichen genus ''Pseudoparmelia'', was circumscribed by John Elix and M ...

''), has since been transferred to ''

Austroparmelina ''Austroparmelina'' is a genus of foliose lichens in the large family Parmeliaceae. It contains species formerly placed in the genera '' Parmelina'' and '' Canoparmelia''. All species of ''Austroparmelina'' have an Australasian-South African dis ...

''.

References

{{Taxonbar, from=Q6008411 Parmeliaceae Lichen genera Lecanorales genera Taxa described in 1985