''Allocetraria'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

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 ...

ized

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 family

Parmeliaceae The Parmeliaceae is a large and diverse family of Lecanoromycetes. With over 2700 species in 71 genera, it is the largest family of lichen-forming fungi. The most speciose genera in the family are the well-known groups: '' Xanthoparmelia'' ( 82 ...

. It consists of 12 species, with a center of distribution in China.

Systematics

The genus was

circumscribed In geometry, a circumscribed circle for a set of points is a circle passing through each of them. Such a circle is said to ''circumscribe'' the points or a polygon formed from them; such a polygon is said to be ''inscribed'' in the circle. * Circum ...

by Syo Kurokawa and Ming-Jou Lai in 1991, with three species: both '' A. ambigua'' and the

type species In International_Code_of_Zoological_Nomenclature, 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 spe ...

'' A. stracheyi'' recombined from different genera, and a newly described species, '' A. isidiigera''. Sunsequent

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 ...

analyses showed that ''Allocetraria'' forms a

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

group within the cetrarioid

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

in the family Parmeliaceae. In 2017, 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 family Parmeliaceae, suggesting that groups of species that diverged within the time window of 29.45–32.55 million years ago represent genera. They proposed to synonymize ''Allocetraria'' (and several other genera) with ''

Cetraria ''Cetraria'' is a genus of fruticose lichens that associate with green algae as photobionts. Most species are found at high latitudes, occurring on sand or heath, and are characterised by their "strap-like" form with spiny edges. The lobes can ...

'', because the former group of species originated relatively recently and fell under the timeframe threshold for genus level. The net result of this proposal was to reduce 13 previously accepted genera in the cetrarioid clade down to two. This synonymy was not accepted in a later critical analysis of this technique for lichen systematics.

Arve Elvebakk Arve Elvebakk (born 1951) is a Norwegian mycologist and professor working from the Arctic University of Norway in Tromsø. He has published widely on Arctic biology, and climatology. Additionally, he collaborates with many mycologists across t ...

and colleagues expressed a similar opinion, stating that they would "prefer a model of 13 imperfectly defined cetrarioid core genera in addition to ‘orphaned’ species, over an alternative of only two widely defined ones, as a starting point for further phylogenetic studies".

Description

Distinguishing features of the genus include a palisade plectenchymatous upper

cortex Cortex or cortical may refer to: Biology * Cortex (anatomy), the outermost layer of an organ ** Cerebral cortex, the outer layer of the vertebrate cerebrum, part of which is the ''forebrain'' *** Motor cortex, the regions of the cerebral cortex i ...

, asci with a broad axial body,

ascospore In fungi, an ascospore is the sexual spore formed inside an ascus—the sac-like cell that defines the division Ascomycota, the largest and most diverse Division (botany), division of fungi. After two parental cell nucleus, nuclei fuse, the ascu ...

s that are more or less spherical, and threadlike (filiform) pycnoconidia. Species in the genus produce the secondary chemical

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 and 1937 by Frank H. Curd and Al ...

, but never

atranorin Atranorin is a chemical substance produced by some species of lichen. It is a secondary metabolite belonging to a group of compounds known as depsides. Atranorin has analgesic, anti-inflammatory, antibacterial, antifungal, cytotoxic, antioxidant, ...

. Lichesterinic and

protolichesterinic acid Protolichesterinic acid is a naturally occurring γ-lactone compound found in various lichen species. Its structure consists of a combination of a lactone ring with a carboxylic acid group and a long aliphatic side chain. First isolated in the ...

s are found in most species.

Habitat and distribution

The main area of distribution of ''Allocetraria'' is China, as nearly all the species occur there.

Species

*'' Allocetraria ambigua'' – China; India; Nepal *'' Allocetraria capitata'' – China *'' Allocetraria corrugata'' – China *'' Allocetraria denticulata'' *'' Allocetraria endochrysea'' – China *'' Allocetraria flavonigrescens'' – China; Nepal *'' Allocetraria globulans'' – China; Nepal *'' Allocetraria isidiigera'' – China; Nepal *'' Allocetraria madreporiformis'' – China; Mongolia; Turkistan; North America; Europe *'' Allocetraria sinensis'' – China; Nepal *'' Allocetraria stracheyi'' – China; India; Nepal; North America *'' Allocetraria yunnanensis'' – China Former ''Allocetraria'' species: *''Allocetraria cucullata'' (now '' Flavocetraria cucullata'') *''Allocetraria nivalis'' (now '' Flavocetraria nivalis'') *''Allocetraria oakesiana'' (now '' Usnocetraria oakesiana'') *''Allocetraria potaninii'' was synonymized with ''Allocetraria stracheyi'' in 1995.

References

{{Taxonbar, from=Q4733009 Parmeliaceae Lecanorales genera Lichen genera Taxa described in 1991 Taxa named by Syo Kurokawa