lichen
A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.Xylographaceae, 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 ...
of the genus ''
Xylographa
''Xylographa'' is a genus of lichenized fungi in the family Xylographaceae.
The genus was first taxonomically described and named by Elias Magnus Fries
Elias Magnus Fries (15 August 1794 – 8 February 1878) was a Swedish mycologist ...
''. Although it has been recorded mostly in montane and
boreal forest
Taiga (; rus, тайга́, p=tɐjˈɡa; relates to Mongolic and Turkic languages), generally referred to in North America as a boreal forest or snow forest, is a biome characterized by coniferous forests consisting mostly of pines, spruces, ...
s between
latitude
In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pol ...
s of about 35°N to 65°N, it is, however, the only species of ''Xylographa'' that has also been recorded from the Southern Hemisphere. It usually grows on
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 ...
wood (very rarely on conifer
bark
Bark may refer to:
* Bark (botany), an outer layer of a woody plant such as a tree or stick
* Bark (sound), a vocalization of some animals (which is commonly the dog)
Places
* Bark, Germany
* Bark, Warmian-Masurian Voivodeship, Poland
Arts, ...
), such as logs,
snags
In forest ecology, a snag refers to a standing, dead or dying tree, often missing a top or most of the smaller branches. In freshwater ecology it refers to trees, branches, and other pieces of naturally occurring wood found sunken in rivers and ...
Elias Magnus Fries
Elias Magnus Fries (15 August 1794 – 8 February 1878) was a Swedish mycologist and botanist.
Career
Fries was born at Femsjö (Hylte Municipality), Småland, the son of the pastor there. He attended school in Växjö.
He acquired ...
transferred it to the genus ''Xylographa'' in 1849. Because the name ''Xylographa parallela'' has been used by researchers for ''Xylographa'' species with linear ascomata that are much longer than wide, it has historically been applied to a number of taxa that are now known to be different species.
Description
The lichen forms narrow,
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 ...
ascomata (called lirellae) that measure 0.45–1.14 by 0.09–0.23 mm. The ascomata typically grow by extending one end laterally, although in rare circumstances the ascomata grow on both ends. In some older specimens, the ascomata peel off. 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 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 ...
, and are ellipsoid, usually measuring 11.3–14.5 by 5.9–7.6
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 ...
.
'' Xylographa pallens'' is a lookalike species that is almost identical to ''X. parallela'' in both macroscopic and microscopic characteristics. It can be distinguished from the latter species by its growth habit: it develops ascomata in clusters with multiple leading tips that grow outward from a central point, and it has much ascoma-free space between each cluster.