''Rhizocarpon'' 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 ...

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 ...

saxicolous This glossary of mycology is a list of definitions of terms and concepts relevant to mycology, the study of fungi. Terms in common with other fields, if repeated here, generally focus on their mycology-specific meaning. Related terms can be found ...

(or sometimes lichenicolous), lichens in the family Rhizocarpaceae. The genus is common in arctic-alpine environments, but also occurs throughout

temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones immediately to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Ge ...

, and even

tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

regions. They are commonly known as map lichens because of the

prothallus A prothallus, or prothallium, (from Latin ''pro'' = forwards and Greek ''θαλλος'' (''thallos'') = twig) is usually the gametophyte stage in the life of a fern or other pteridophyte. Occasionally the term is also used to describe the young ...

forming border-like bands between colonies in some species, like the common map lichen (''

Rhizocarpon geographicum ''Rhizocarpon geographicum'' (the map lichen) is a species of lichen, which grows on rocks in mountainous areas of low air pollution. Each lichen is a flat patch bordered by a black line of fungal hyphae. These patches grow adjacent to each other ...

'').

Taxonomy and phylogeny

Together with three small genera ('' Catolechia'', '' Poeltinula'' and '' Epilichen''), ''Rhizocarpon'' constitutes the family Rhizocarpaceae. Historically, ca 389 names have been used. However, many species concepts are ill-defined, many names have been synonymized and new species are regularly being described, so true number of species is not entirely clear as of now, but is estimated to be around 200. In molecular work, the genus has also been shown to be paraphyletic, with closely related genera being nested within ''Rhizocarpon''.

Common traits

With so many species in a morphologically diverse genus it is difficult to say something general about morphology and anatomy and there will inevitably be some exceptions. However, they do share some key traits. They are all crustose and mostly saxicolous (rock-living), with some being lichenicolous (lichen parasites) on other saxicolous lichens. They are all lecideoid, meaning they have apothecia without a thallus margin containing algae.

Ascus and ascospores

The genus has a distinct type of

ascus An ascus (; : asci) 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 gen ...

, the Rhizocarpon-type, which is bitunicate with the inner ascus-wall being slightly apically thickened. Ascospores are considered important characters for determining species within the genus. They are either 2-celled (1-septate) or multi-celled (muriform) and are either hyaline or pigmented (green or brown), often with a characteristic halo () visible when viewed in a microscope. Asci contain eight, two or rarely one spore.

Species

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 75 species of ''Rhizopogon''. *'' Rhizocarpon advenulum'' *'' Rhizocarpon alpicola'' *'' Rhizocarpon amphibium'' *'' Rhizocarpon anaperum'' *'' Rhizocarpon austroalpinum'' – Australia *'' Rhizocarpon austroamphibium'' – Australia *'' Rhizocarpon badioatrum'' *'' Rhizocarpon bicolor'' – Australia *'' Rhizocarpon caeruleoalbum'' *'' Rhizocarpon caesium'' – Europe *'' Rhizocarpon chioneum'' *'' Rhizocarpon cinereonigrum'' *'' Rhizocarpon cinereovirens'' *'' Rhizocarpon clausum'' *'' Rhizocarpon cleptophilum'' – Greenland *'' Rhizocarpon copelandii'' *'' Rhizocarpon dahlii'' *'' Rhizocarpon dimelaenae'' *'' Rhizocarpon diploschistinum'' *'' Rhizocarpon disporum'' *''

Rhizocarpon distinctum ''Rhizocarpon'' is a genus of crustose lichen, crustose, saxicolous lichen, saxicolous (or sometimes lichenicolous fungus, lichenicolous), lichens in the family Rhizocarpaceae. The genus is common in arctic-alpine environments, but also occurs ...

'' *'' Rhizocarpon eupetraeoides'' *'' Rhizocarpon exiguum'' – Australia *'' Rhizocarpon expallescens'' *'' Rhizocarpon ferax'' *'' Rhizocarpon flavomedullosum'' – Australia *'' Rhizocarpon furfurosum'' *'' Rhizocarpon geminatum'' *''

'' *'' Rhizocarpon grande'' *'' Rhizocarpon haidense'' *'' Rhizocarpon hochstetteri'' *'' Rhizocarpon inarense'' *'' Rhizocarpon infernulum'' *'' Rhizocarpon intermediellum'' *'' Rhizocarpon jemtlandicum'' *'' Rhizocarpon johnstonii'' *'' Rhizocarpon kerguelense'' *'' Rhizocarpon lavatum'' *'' Rhizocarpon lecanorinum'' *'' Rhizocarpon lusitanicum'' *'' Rhizocarpon macrosporum'' *'' Rhizocarpon malvinae'' –

Falkland Islands The Falkland Islands (; ), commonly referred to as The Falklands, is an archipelago in the South Atlantic Ocean on the Patagonian Shelf. The principal islands are about east of South America's southern Patagonian coast and from Cape Dub ...

*'' Rhizocarpon mawsonii'' *'' Rhizocarpon ochrolechiae'' *'' Rhizocarpon oederi'' *'' Rhizocarpon oxydatum'' – New Zealand *'' Rhizocarpon ozsoyae'' – Antarctica *'' Rhizocarpon pallidum'' *'' Rhizocarpon petraeum'' *'' Rhizocarpon polycarpum'' *'' Rhizocarpon postumum'' *'' Rhizocarpon purpurascens'' – New Zealand *'' Rhizocarpon pusillum'' *'' Rhizocarpon quinonum'' –

Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...

Gallery

File:Rhizocarpon.jpg, ''Rhizocarpon'' sp. on a mountain Zlatibor, Serbia File:Rhizocarpon pycnocarpoides (10.3897-mycokeys.11.6670) Figure 10.jpg, ''Rhizocarpon pycnocarpoides''

References

{{Taxonbar, from=Q3018582 Rhizocarpaceae Lichen genera Lecanoromycetes genera Taxa named by Augustin Pyramus de Candolle Taxa described in 1805