lichen
A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.fungi in the family
Acarosporaceae
The Acarosporaceae are a family of fungi in the order Acarosporales. Members of this family have a widespread distribution, and are mostly lichenized with green algae. According to a 2021 estimate, the family contains 11 genera and about 260 spe ...
. Most species in the genus are crustose lichens that grow on rocks in open and arid places all over the world. They may look like a cobblestone road or cracked up old paint, and are commonly called cobblestone lichens or cracked lichens.Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, Name Search Results for Scientific Name Acarospora, USDA /ref> They usually grow on rock (are " saxicolous"), but some grow on soil (
terricolous A terricolous lichen is a lichen that grows on the soil as a substrate. An example is some members of the genus ''Peltigera
''Peltigera'' is a genus of approximately 100 species of foliose lichens in the family Peltigeraceae. Commonly known as ...
) or on other lichens. Some species in the genus are fungi that live as parasites on other lichens (
lichenicolous fungi
A lichenicolous fungus is a parasitic fungus that only lives on lichen as the host. A lichenicolous fungus is not the same as the fungus that is the component of the lichen, which is known as a lichenized fungus. They are most commonly specific to ...
). ''Acarospora'' is a widely distributed genus, with about 128 species according to a 2008 estimate.
Species in ''Acarospora'' may be shiny as if covered with a glossy varnish, or dull and powdery looking. They have a diverse range of colors, from the brilliant yellow
bright cobblestone lichen
''Acarospora socialis'' (bright cobblestone lichen) is a usually bright yellow areolate to squamulose crustose lichen in the family Acarosporaceae that grows up to 10 cm wide, mostly on rock in western North America.Lichen Flora of the G ...
, to the dark reddish-brown
mountain cobblestone lichen
''Acarospora elevata'', the mountain cobblestone lichen, is a shiny dark reddish brown to dark brown verrucose to aereolate crustose lichen that grows up to wide on granite in central and southern California to Baja California, and high elevat ...
, or they can appear tan, gray, or white, from a dusty-looking coating ( pruina). They may grow in crustose forms like a warty surface ( verrucose), like cracking-up old crust of paint ( rimose), like a bunch of "islands" in a dry lake bed ( areolate), like the flakes of cracking up paint are peeling up at the edges (sub-
squamulous
A squamulose lichen is a lichen that is composed of small, often overlapping "scales" called squamules. If they are raised from the substrate and appear leafy, the lichen may appear to be a foliose lichen, but the underside does not have a "skin ...
), or like the flakes are growing over others like scales (squamulous).
Description
They may grow as a warty crust ( verrucose, a cracked crust rimose, or with the cracks separating island-like sections like in a
dried lake
Drying is a mass transfer process consisting of the removal of water or another solvent by evaporation from a solid, semi-solid or liquid. This process is often used as a final production step before selling or packaging products. To be considered ...
areoles
In botany, areoles are small light- to dark-colored bumps on cactus, cacti out of which grow clusters of Thorns, spines, and prickles, spines. Areoles are important diagnostic features of cactus, cacti, and identify them as a family distinct fr ...
”).Acarospora, Lichen Flora of the Greater Sonoran Desert Region. Vol 3, Nash, T.H., Ryan, B.D., Gries, C., Bugartz, F., (eds.) 2001 /ref> The areolas may lift up at the edges (sub-
squamulose
A squamulose lichen is a lichen that is composed of small, often overlapping "scales" called squamules. If they are raised from the substrate and appear leafy, the lichen may appear to be a foliose lichen, but the underside does not have a "skin ...
), and these edges may overlap other areolas like scales (
squamulose
A squamulose lichen is a lichen that is composed of small, often overlapping "scales" called squamules. If they are raised from the substrate and appear leafy, the lichen may appear to be a foliose lichen, but the underside does not have a "skin ...
, with the areoles being called “ squamules”). The areoles may grow in lobes radiating from a center ( placodioid. They may grow in irregular or indeterminate forms, sometimes with the areoles disconnected from each other and dispersed among other lichens. Sometimes the squamules may be elevated with expansion of the mycelial base above the substrate (" gomphate"), or aside on “stems” called
stipes
Crucifixion is a method of capital punishment in which the victim is tied or nailed to a large wooden cross or beam and left to hang until eventual death from exhaustion and asphyxiation. It was used as a punishment by the Persians, Carthagin ...
, which are usually about usually half the diameter of areole. The outer rim of the areola is usually down-turned.
They may be shiny or dull, and in many shades from pale to blackish brown. They may be smooth or rough ( rugulose). They may be different colors from brilliant yellow (from
rhizocarpic acid
Rhizocarpic acid is an organic compound with the molecular formula C28H23NO6 which has been isolated from the lichen ''Rhizocarpon geographicum'' and other lichens
A lichen ( , ) is a composite organism that arises from algae or cyanobacter ...
) to brown to white. They may or may not be covered with a powdery-looking surface (
pruinose 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 ...
), which when present, may make them appear lighter in color, to almost white.
Internal structure
Like other crustose lichens, their cross section is generally divided into three layers, the cortex, photobiont layer, and medulla, and generally without a lower cortex as in foliose lichens. The cortex itself is usually differentiated, with three layers including a syncortex (sometimes absent),
epinecral layer
A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.eucortex, which is where the pigment is located in the upper parts. The photobiont of ''Acarospora'' are algae in the genus ''
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 ...
''.
Fruiting structures
Each wart, areola, or squamule may have 0 to many apothecia. The apothecia are usually immersed in the thallus. Sometimes the apothecia are raised on a wart and surrounded by a margin of thallus-like tissue, sometimes with the margin being a true exciple. The apothecia are usually immersed, and round to very irregular in shape. The apothecal disc is round to squished and irregular, and ranges in colors: black, brown, red, or yellow, or in-between. The disc may be smooth or it may be rough. The
asci ASCI or Asci may refer to:
* Advertising Standards Council of India
* Asci, the plural of ascus, in fungal anatomy
* Accelerated Strategic Computing Initiative
* American Society for Clinical Investigation
* Argus Sour Crude Index
* Association of ...
range from being narrow to being club shaped (clavate). Spores are colorless, spherical to
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 range from tens to hundreds 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 ...
.
Taxonomy
The genus was published by Italian lichenologist
Abramo Bartolommeo Massalongo
Abramo Bartolommeo Massalongo (13 May 1824 – 25 May 1860) was an Italian paleobotanist and lichenologist. He was born in Tregnago in the Province of Verona and took a great interest in botany as a young man. Massalongo joined the faculty of med ...
Acarospora schleicheri
''Acarospora schleicheri'', the soil paint lichen, is a bleached to bright yellow areolate to squamulose lichen that commonly grows to on soil (terricolous) in arid habitats of southern California and Baja California, also in Europe and Africa. ...
'' (originally described as ''Urceolaria schleicheri'' by Erik Acharius in 1810). Other species included by Massalongo in his original conception of the genus were ''A. chlorophana'' (now ''
Pleopsidium chlorophanum
''Pleopsidium chlorophanum'' (gold cobblestone lichen)The Laws Field Guide to the Sierra Nevada, John Muir Laws , 2007 is a distinctively colored, bright lemon-yellow to chartreuseCrustose Rock Lichens, Wayne P. Armstrong, Wayne's World online te ...
Yellow members of the genus may resemble members of ''
Pleopsidium
''Pleopsidium'' is a genus of lichenized fungi in the family Acarosporaceae. The widespread genus, which contains four species, was circumscribed by lichenologist Gustav Wilhelm Körber
Gustav Wilhelm Körber (10 January 1817, Hirschberg – ...
''. Non-yellow members may resemble members of ''
Aspicilia
''Aspicilia'' (sunken disk lichen) is a genus of mostly crustose areolate lichens that grow on rock. Most members have black apothecia discs that are slightly immersed in the areolas, hence the common name.Field Guide to California Lichens, Step ...
''.
Species include:
Chemistry
''Acarospora'' species often lack secondary metabolites. Each wart, areola, or squamule may each have 0 to many apothecia. Some have norstictic acid, gyrophoric acid, or fatty acids. Each wart, areola, or squamule, may each have 0 to many apothecia. Yellow species have
rhizocarpic acid
Rhizocarpic acid is an organic compound with the molecular formula C28H23NO6 which has been isolated from the lichen ''Rhizocarpon geographicum'' and other lichens
A lichen ( , ) is a composite organism that arises from algae or cyanobacter ...
, a pigment that makes them yellow. Each wart, areola, or squamule, may each have 0 to many apothecia.
Range and habitat
They grow all over the world, but usually in open arid habitats. They can grow on
acidic rock
Acidic rock or acid rock refers to the chemical composition of igneous rocks that has 63% wt% SiO2 content. Rocks described as acidic usually contain more than 20% of free quartz. Typical acidic rocks are granite or rhyolite.
Term is used in che ...
and
basic rock
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks inclu ...