''Lecidea atrobrunnea'' is a group of

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 family

Lecideaceae The Lecideaceae are a family (biology), family of lichen-forming fungi in the order Lecideales. It contains about 30 genus, genera and roughly 250 species. A major distinguishing characteristic of the family is the form of the ascomata, fruit ...

. Previously though to represent a single, widely distributed

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 ...

, recent research has shown that the name represents many unique lineages of morphologically and chemically variable lichen-forming fungi that have not yet been precisely characterized. Members of this group are most diverse in mountains of the continental western United States and

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 ...

. With other lichen communities, it forms dark vertical drip-like stripings along drainage tracks in the rock faces, resulting in Native Americans giving the name " Face of a Young Woman Stained with Tears" to

Half Dome Half Dome is a quartz monzonite batholith at the eastern end of Yosemite Valley in Yosemite National Park, California. It is a well-known rock formation in the park, named for its distinct shape. One side is a sheer face while the other three s ...

. This combined lichen community appears black from a distance, but brown up close. It varies greatly in its overall appearance from colony to colony. ''L atrobrunnea'' subsp. ''atrobrunnea'' has been found to be common in very common in high

montane Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures lapse rate, fall as elevation increases, causing the ecosystem to stratify. This stratification is ...

zones and

alpine zone Alpine tundra is a type of natural region or biome that does not contain trees because it is at high elevation, with an associated alpine climate, harsh climate. As the latitude of a location approaches the poles, the threshold elevation for alp ...

s. ''L atrobrunnea'' subsp. ''saxosa'' ("saxosa" meaning "rock") has been found in high elevations in the San Francisco Peaks and

San Bernardino Mountains The San Bernardino Mountains are a high and rugged mountain range in Southern California in the United States. Situated north and northeast of San Bernardino and spanning two California counties, the range tops out at at San Gorgonio Mountain ...

. 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 ...

and

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

are black, while the

thallus Thallus (: 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. A thallus usually names the entir ...

areole 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 ...

s are brown. The upper surface is usually pale to dark reddish brown in the center of areoles. In squamulous specimens, the lower surface can be seen, and is shiny and dark. The scientific name ''atrobrunnea'' is a combination of two

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

words: ''Ater'' from "atro", meaning "black" and "brunnea" from ''brunneus'' meaning "dark brown". The combination of the two means "blackish-brown". It is commonly found on rock faces in the Sierra Nevada. The communities often completely cover the exposed surface of the rock, or form intricate multicolored mosaics with other lichen communities. Its communities are part of the aesthetic appeal to visitors of

Yosemite National Park Yosemite National Park ( ) is a List of national parks of the United States, national park of the United States in California. It is bordered on the southeast by Sierra National Forest and on the northwest by Stanislaus National Forest. The p ...

and

Sequoia National Park Sequoia National Park is a List of national parks of the United States, national park of the United States in the southern Sierra Nevada (U.S.), Sierra Nevada east of Visalia, California. The park was established on September 25, 1890, and toda ...

. It is found in the Rocky Mountains, including in

s, and in the United States

Sierra Nevada The Sierra Nevada ( ) is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primari ...

range. It tightly adheres to the rock faces giving it the appearance of being painted on. It is a known host species for the

lichenicolous fungus A lichenicolous fungus is a member of a specialised group of fungi that live exclusively on lichens as their host organisms. These fungi, comprising over 2,000 known species across 280 genera, exhibit a wide range of ecological strategies, includ ...

'' Muellerella pygmaea'' var. ''pygmaea''.Helgi Hallgrímsson & Guðríður Gyða Eyjólfsdóttir (2004)
''Íslenskt sveppatal I - smásveppir'' [Checklist of Icelandic Fungi I - Microfungi
Fjölrit Náttúrufræðistofnunar. Náttúrufræðistofnun Íslands [Icelandic Institute of Natural History]. ISSN 1027-832X

Diversity of the species complex

The ''Lecidea atrobrunnea'' species complex has been the subject of extensive study due to its vast diversity, particularly in western North America. This group presents a variety of morphologies and chemical compositions even within local scales. Traditionally considered a

cosmopolitan species In biogeography, a cosmopolitan distribution is the range of a taxon that extends across most or all of the surface of the Earth, in appropriate habitats; most cosmopolitan species are known to be highly adaptable to a range of climatic and en ...

, recent (2023) research suggests that what was thought to be a single, widespread species might actually be a complex of distinct species-level lineages. The complexity of this group is highlighted by the morphological and chemical variability that masks its true

biodiversity Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distribut ...

. Recent studies, using both single-marker candidate species delimitation analyses and species delimitation analyses support the notion that ''Lecidea atrobrunnea'' comprises multiple distinct species-level lineages. This finding challenges previous assumptions about the

monophyly 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 comm ...

of commonly occurring taxa like ''L. atrobrunnea'', '' L. protabacina'', and '' L. syncarpa'' in

habitats of western North America, which are now shown to be

polyphyletic A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...

. The research also reveals narrow geographical distributions for many of these candidate species-level lineages, although sampling is still incomplete. This complex scenario suggests that the species-level diversity within the ''Lecidea atrobrunnea'' complex may be significantly underestimated. The authors suggest that the findings call for a re-evaluation of species boundaries and the total number of species within this complex.

References

* {{Taxonbar, from=Q10555999 atrobrunnea Lichen species Lichens described in 1805 Lichens of the United States Taxa named by Augustin Pyramus de Candolle Fungi without expected TNC conservation status

Diversity of the species complex

See also

References