The Rhizocarpales are an

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

lichen A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...

-forming

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

in the subclass Lecanoromycetidae of the class

Lecanoromycetes Lecanoromycetes is the largest class of lichenized fungi. It belongs to the subphylum Pezizomycotina in the phylum Ascomycota. The asci (spore-bearing cells) of the Lecanoromycetes most often release spores by rostrate dehiscence. The group is ...

. It has two

families Family (from ) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictability, structure, and safety as ...

Rhizocarpaceae Rhizocarpaceae is a family of lichen-forming fungi; together with the family Sporastatiaceae it constitutes the order Rhizocarpales in the Ascomycota, class Lecanoromycetes. These lichens are primarily rock-dwellers that form thin, paint-like ...

and Sporastatiaceae, which contain mostly

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 ...

Taxonomy

The order was originally proposed by the lichenologists Jolanta Miądlikowska and Francois Lutzoni in 2007, following a

molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

analysis of the Lecanoromycetes. However, the name was not validly published according to article 32.1(d) of the

International Code of Nomenclature for algae, fungi, and plants The ''International Code of Nomenclature for algae, fungi, and plants'' (ICN or ICNafp) is the set of rules and recommendations dealing with the formal botanical names that are given to plants, fungi and a few other groups of organisms, all tho ...

, because it was not "accompanied by a description or diagnosis or by a reference to a previously and effectively published description or diagnosis". The same authors published the name validly in 2016. In 2017, Pradeep Divakar and colleagues used a then-recently developed "temporal phylogenetic" approach to identify temporal bands for specific

taxonomic rank In biology, taxonomic rank (which some authors prefer to call nomenclatural rank because ranking is part of nomenclature rather than taxonomy proper, according to some definitions of these terms) is the relative or absolute level of a group of or ...

s in the Lecanoromycetes, suggesting that groups of species that diverged within the temporal band of 176–194

myr Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to (i.e. years), or approximately 31.6 teraseconds. Usage Myr is in common use in fields such as Earth science and cosmology. Myr is also used w ...

(million years ago) represent orders. They proposed to split the Rhizocarpales into two orders, the Rhizocarpales ''

sensu stricto ''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular c ...

'', and the Sporastatiales, reasoning that these groups split from each other at 208 myr, outside the temporal band they set for orders. This split was not accepted in a later critical analysis of the temporal phylogenetic approach to fungal classification.

Description

Rhizocarpales species are mostly lichenised, with a few lichenicolous species. They have a

crustose Crustose is a Habit (biology), 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 Substrate (biology), substrates at all poin ...

thallus that is often underlain by a black prothallus. The

photobiont A lichen ( , ) is a hybrid colony of algae or cyanobacteria living symbiotically among filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualistic relationship.

partner is –a spherical, single-celled green

alga Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular microalgae, suc ...

l species. The

ascomata An ascocarp, or ascoma (: ascomata), is the fruiting body (sporocarp (fungi), sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded ascus, asci, each of which typically contains four to ...

are in the form of an apothecium that is either immersed in the substrate or sessile, or emarginate. The (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 o ...

e between the asci) consist of unbranched,

amyloid Amyloids are aggregates of proteins characterised by a fibrillar morphology of typically 7–13 nm in diameter, a β-sheet secondary structure (known as cross-β) and ability to be stained by particular dyes, such as Congo red. In the human ...

paraphyses Paraphyses are erect sterile filament-like support structures occurring among the reproductive apparatuses of fungi, ferns, bryophytes and some thallophytes. The singular form of the word is paraphysis. In certain fungi, they are part of the f ...

in the Sporastatiaceae, and branched and anastomosing paraphyses in the Rhizocarpaceae. The asci are semifissitunicate, meaning that the two walls of the ascus do not completely separate during the discharge of the ascospore. Asci have an amyloid (the thickened inner part of the apex of the ascus), which, in the Sporastatiaceae, lacks other structures; in the Rhizocarpaceae, the tholus is weakly amyloid with a stronger amyloid cap. number 1 to 8 in the Rhizocarpaceae, to many (about 100) in the Sporastatiaceae. The ascospores are non-

septate In biology, a septum (Latin for ''something that encloses''; septa) is a wall, dividing a cavity or structure into smaller ones. A cavity or structure divided in this way may be referred to as septate. Examples Human anatomy * Interatrial se ...

in the Sporastatiaceae or transversally septate to muriform in the Rhizocarpaceae. In both families, they are

ellipsoid An ellipsoid is a surface that can be obtained from a sphere by deforming it by means of directional Scaling (geometry), scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a Surface (mathemat ...

hyaline A hyaline substance is one with a glassy appearance. The word is derived from , and . Histopathology Hyaline cartilage is named after its glassy appearance on fresh gross pathology. On light microscopy of H&E stained slides, the extracellula ...

to dark brown, and non-amyloid. The

conidiomata Conidiomata (singular: Conidioma) are blister-like fruiting structures produced by a specific type of fungus called a coelomycete. They are formed as a means of dispersing asexual spores call conidia, which they accomplish by creating the blister- ...

are in the form of

pycnidia A pycnidium (plural pycnidia) is an asexual fruiting body produced by mitosporic fungi, for instance in the order Sphaeropsidales ( Deuteromycota, Coelomycetes) or order Pleosporales (Ascomycota, Dothideomycetes). It is often spherical or inve ...

. Secondary chemicals associated with the Rhizocarpales include

depside A depside is a type of polyphenolic compound composed of two or more monocyclic aromatic units linked by an ester group. Depsides are most often found in lichens, but have also been isolated from higher plants, including species of the Ericaceae, ...

depsidone Depsidones (+ " depside" + "one") are chemical compounds that are sometimes found as secondary metabolites in lichens. They are esters that are both depsides and cyclic ethers. An example is norstictic acid Norstictic acid is a depsidone produ ...

s, and chemical derivatives of

pulvinic acid Pulvinic acids are natural chemical pigments found in some lichens, derived biosynthetically from the aromatic amino acids phenylalanine and tyrosine, via dimerization and oxidative ring-cleavage of arylpyruvic acids, a process that also produces ...

Habitat

Rhizocarpales species grow on rocks, or are lichenicolous on other lichens that grow on rocks. In a few instances they are

epiphytic An epiphyte is a plant or plant-like organism that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphyt ...

on bark.

Families and genera

Species Fungorum ''Index Fungorum'' is an international project to index all formal names (Binomial nomenclature, scientific names) in the fungus Kingdom (biology), kingdom. As of 2015, the project is based at the Royal Botanic Gardens, Kew, one of three partn ...

(in the

Catalogue of Life The Catalogue of Life (CoL) is an online database that provides an index of known species of animals, plants, fungi, and microorganisms. It was created in 2001 as a partnership between the global Species 2000 and the American Integrated Taxono ...

) accepts 2 families, 6 genera, and 91 species in the Rhizocarpales. *

::''

Catolechia ''Catolechia'' is a genus of lichen-forming fungi in the family Rhizocarpaceae. It is a monotypic genus, containing the single species ''Catolechia wahlenbergii''. The genus was circumscribed by German botanist Julius von Flotow in 1850. He did ...

'' – 1 sp. ::''

Epilichen ''Epilichen'' is a small genus of lichen-forming fungi in the family Rhizocarpaceae. These parasitic lichens live on other lichens, beginning as thin, crust-like patches that may break into small islands or scales, and in some cases produce no ...

'' – 1 sp. ::''

Poeltinula ''Poeltinula'' is a genus of lichenized fungi in the family Rhizocarpaceae. The genus name of ''Poeltinula'' is in honour of Josef Poelt (1924-1995), who was a German-Austrian botanist (Bryology, Mycology and Lichenology) and was Professor of Sys ...

'' – 2 spp. ::''

Rhizocarpon ''Rhizocarpon'' is a genus of crustose, saxicolous (or sometimes lichenicolous), lichens in the family Rhizocarpaceae. The genus is common in arctic-alpine environments, but also occurs throughout temperate, subtropical, and even tropical reg ...

'' – 80 spp. * Sporastatiaceae ::'' Sporastatia'' – 4 spp. ::'' Toensbergia'' – 3 spp.

References

{{Taxonbar, from=Q10652798 Lecanoromycetes Lichen orders Lecanoromycetes orders Taxa described in 2016