''Xanthoparmelia lineola'', commonly known as the tight rock-shield, is a
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 ...
species in the genus ''
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 ...
''. It is a common species with a
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 ...
distribution. Found in North America and South Africa, it
grows on rocks.
Taxonomy
It was originally
described in 1941 as a species of ''
Parmelia 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 ...
'' by
Edward Cain Berry
Edward is an English given name. It is derived from the Anglo-Saxon name ''Ēadweard'', composed of the elements '' ēad'' "wealth, fortune; prosperous" and '' weard'' "guardian, protector”.
History
The name Edward was very popular in Anglo-Sax ...
.
It was one of 93 species that was transferred to ''Xanthoparmelia'' when
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 ...
promoted that taxon from
subgeneric
In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus.
In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between t ...
to generic status in 1974.
It is
commonly known as the tight rock-shield.
Description
''Xanthoparmelia lineola'' has a
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 ...
that is tightly attached (adnate) on its rock substrate. Yellowish green in colour, it grows to in diameter. The lobes are irregular in shape and measure 0.8–2 mm wide.
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 ...
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 ...
are not present on the thallus. 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 th ...
is white with a flat lower surface. The
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 are pale, unbranched, and measure 0.2–0.4 mm long. The lichen has well-developed apothecia (2–5 in diameter) that sit on rudimentary stalks. 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 are 6–7 by 9–12
um.
''Xanthoparmelia lineola'' contains the compounds
salazinic,
consalazinic,
constipatic,
protoconstipatic, and
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 ...
s.
Similar species
''Xanthoparmelia lineola'' is one of several morphologically similar species that contain
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 ...
and form a continuum based on the degree of agnation to the substrate. ''
X. coloradoensis'' is loosely attached, ''
X. wyomingica'' is even more loosely attached, while ''
X. chlorochroa'' at maturity is not attached to a substate (a
vagrant lichen A vagrant lichen is a lichen that is either not attached to a substrate, or can become unattached then blow around, yet continue to grow and flourish. Some authors reserve the expression "vagrant lichen" for those lichens that never attach, that is, ...
).
Habitat and distribution
''Xanthoparmelia lineola'' is known from northern North America and South Africa. Populations from Australia previously considered ''X. lineola'' have been since characterized with DNA analysis and assigned to a new species, ''
X. knudsenii''.
It has a widespread distribution in western North America. In a study of ''Xanthoparmelia'' lichens in
Arizona
Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...
,
Thomas Nash observed that this species seemed to develop best at elevations of , where individuals grew to cover half or more of the exposed rock face beneath
ponderosa pine
''Pinus ponderosa'', commonly known as the ponderosa pine, bull pine, blackjack pine, western yellow-pine, or filipinus pine is a very large pine tree species of variable habitat native to mountainous regions of western North America. It is the ...
s. It is common on north-facing rocks in the Arizona desert.
The lichen can also be found growing in dry habitats on tree bases covered with wind-blown dust.
Five
morphologically similar
chemotype A chemotype (sometimes chemovar) is a chemically distinct entity in a plant or microorganism, with differences in the composition of the secondary metabolites. Minor genetic and epigenetic changes with little or no effect on morphology or anatomy m ...
s of ''Xanthoparmelia lineola'' are known from North America: ''
X. subdecipiens'', ''
X. cumberlandia'', ''
X. oleosa'', and ''
X. novomexicana''.
See also
*
List of ''Xanthoparmelia'' species
References
{{Taxonbar, from=Q10721365
lineola
Lichen species
Lichens described in 1941
Lichens of South Africa
Lichens of North America