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 mostly
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
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
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 biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
in the genus are
crustose
Crustose is a habit of some types of algae and lichens in which the organism grows tightly appressed to a substrate, forming a biological layer. ''Crustose'' adheres very closely to the substrates at all points. ''Crustose'' is found on rocks and ...
lichens that grow on rocks in open and
arid
A region is arid when it severely lacks available water, to the extent of hindering or preventing the growth and development of plant and animal life. Regions with arid climates tend to lack vegetation and are called xeric or desertic. Most ar ...
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, to the dark reddish-brown mountain cobblestone lichen, 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
The following is a glossary of terms used in the description of lichens, composite organisms that arise from algae or cyanobacteria living among filaments of multiple fungus species in a mutualistic relationship.
Until the end of the 18th cen ...
), like cracking-up old crust of paint (
rimose
''Rimose'' is an adjective used to describe a surface that is cracked or fissured.dry lake bed (
areolate
Lichens are composite organisms made up of multiple species: a fungal partner, one or more photosynthetic partners, and sometimes a basidiomycete yeast. They are regularly grouped by their external appearance – a characteristic known as their ...
), like the flakes of cracking up paint are peeling up at the edges (sub- squamulous), or like the flakes are growing over others like scales (squamulous).
Description
They may grow as a warty crust (
verrucose
The following is a glossary of terms used in the description of lichens, composite organisms that arise from algae or cyanobacteria living among filaments of multiple fungus species in a mutualistic relationship.
Until the end of the 18th cen ...
, a cracked crust
rimose
''Rimose'' is an adjective used to describe a surface that is cracked or fissured.dried lake (
areolate
Lichens are composite organisms made up of multiple species: a fungal partner, one or more photosynthetic partners, and sometimes a basidiomycete yeast. They are regularly grouped by their external appearance – a characteristic known as their ...
– with the “islands” being called “
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, 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 lichen
Crustose lichens are lichens that form a crust which strongly adheres to the Substrate (biology), substrate (soil, rock, tree bark, etc.), making separation from the substrate impossible without destruction. The basic structure of crustose lichen ...
s, their cross section is generally divided into three layers, the cortex, photobiont layer, and medulla, and generally without a lower cortex as in
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. 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
A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.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
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 ...
. 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
A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.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 ...
in 1852, with 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 ...
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
Norstictic acid is a depsidone produced as a secondary metabolites in lichen
A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.
,
gyrophoric acid
Gyrophoric acid is a depside that can be found in the lichen ''Cryptothecia rubrocincta'' and in ''Xanthoparmelia pokomyi''. It can also be found in most of the species of the '' Actinogyra'', ''Lasallia'', and ''Umbilicaria'' genera
Genus ( p ...
, or
fatty acid
In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, fr ...
s. Each wart, areola, or squamule, may each have 0 to many apothecia. Yellow
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
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
A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compo ...
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
A region is arid when it severely lacks available water, to the extent of hindering or preventing the growth and development of plant and animal life. Regions with arid climates tend to lack vegetation and are called xeric or desertic. Most ar ...
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 ...