''Imshaugia'' is a genus of seven species of foliose lichens in the family Parmeliaceae. 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 po ...

by Susan Meyer in 1985 as a segregate of ''

Parmeliopsis ''Parmeliopsis'' is a genus of lichens 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 gen ...

''. 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 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 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. Ascospores 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 algae – '' Trebouxia'' 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 (''Pinus banksiana''). The type species, ''Imshaugia aleurites'', is widely distributed in northern North America, having been recorded from the tree line 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 region.

Species

*''

Imshaugia aleurites ''Imshaugia'' is a genus of seven species of foliose lichens in the family Parmeliaceae. They are commonly known as starburst lichens. Taxonomy The genus was circumscribed by Susan Meyer in 1985 as a segregate of '' Parmeliopsis''. The genus nam ...

'' *''

Imshaugia angustior ''Imshaugia'' is a genus of seven species of foliose lichens in the family Parmeliaceae. They are commonly known as starburst lichens. Taxonomy The genus was circumscribed by Susan Meyer in 1985 as a segregate of '' Parmeliopsis''. The genus nam ...

'' *''

Imshaugia evernica ''Imshaugia'' is a genus of seven species of foliose lichens in the family Parmeliaceae. They are commonly known as starburst lichens. Taxonomy The genus was circumscribed by Susan Meyer in 1985 as a segregate of '' Parmeliopsis''. The genus nam ...

'' – New South Wales *''

Imshaugia placorodia ''Imshaugia'' is a genus of seven species of foliose lichens in the family Parmeliaceae. They are commonly known as starburst lichens. Taxonomy The genus was circumscription (taxonomy), circumscribed by Susan Meyer in 1985 as a segregate of ''Pa ...

'' *''

Imshaugia pyxiniformis ''Imshaugia'' is a genus of seven species of foliose lichens in the family Parmeliaceae. They are commonly known as starburst lichens. Taxonomy The genus was circumscribed by Susan Meyer in 1985 as a segregate of ''Parmeliopsis''. The genus n ...

'' – Brazil *''

Imshaugia sipmanii ''Imshaugia sipmanii'' is a species of saxicolous (rock-dwelling) lichen in the family Parmeliaceae. Found in Venezuela, it was formally described as a new species in 2004 by Australian lichenologist Jack Elix. The species epithet honours Dut ...

'' – Venezuela *''

Imshaugia venezolana ''Imshaugia'' is a genus of seven species of foliose lichens in the family Parmeliaceae. They are commonly known as starburst lichens. Taxonomy The genus was circumscribed by Susan Meyer in 1985 as a segregate of ''Parmeliopsis''. The genus n ...

'' – Venezuela The species ''Imshaugia subarida'', proposed by John Elix in 2004 (a new combination 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