| Usnocetraria | |
|---|---|
 | |
| Usnocetraria oakesiana | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Lecanoromycetes |
| Order: | Lecanorales |
| Family: | Parmeliaceae |
| Genus: | Usnocetraria M.J.Lai & J.C.Wei (2007) |
| Type species | |
| Usnocetraria oakesiana (Tuck.) M.J.Lai & J.C.Wei (2007) | |
| Species | |
Usnocetraria is a small genus of lichen-forming fungi in the family Parmeliaceae. It contains two species of corticolous (bark-dwelling), foliose lichens.
The genus was circumscribed in 2007 by M.J.Lai and J.C.Wei as a segregate genus of Allocetraria , with Usnocetraria oakesiana selected as the type species. [1] Although eleven species were proposed for transfer into the new genus, only two of them were validly published combinations (Usnocetraria oakesiana and U. kurokawae) because the others lacked basionym citations. A 2009 phylogenetic study suggested that the other proposed Usnocetraria species were not closely related to the type species, and recommended that the genus should be monotypic for U. oakesiana. [2]
Usnocetraria is a member of the large lichen family Parmeliaceae. [3] In 2017, Divakar and colleagues used a then-recently developed "temporal phylogenetic" approach to identify temporal bands for specific taxonomic ranks 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 Usnocetraria with Cetraria , because the former group of species originated relatively recently and fell under the timeframe threshold for genus level. [4] This synonymy was not accepted in a later analysis. [5]
Usnocetraria is a genus of lichens characterized by a leafy (foliose) and prostrate growth form. The thallus (lichen body) is composed of narrow, long lobes that can be either branched or simple. These lobes are clearly dorsiventral , meaning they have distinct upper and lower surfaces. Occasionally, the margins of the lobes may have soredia, which are powdery clusters of algal cells used for reproduction, and pseudocyphellae, which are small pores that facilitate gas exchange. These pseudocyphellae are primarily found on the underside of the thallus, though they can sometimes appear on both surfaces or be absent altogether. [1]
The lower surface of the thallus may have sparse rhizines, which are root-like structures that anchor the lichen to its substrate, or these rhizines may be absent. The cortex, or outer layer, of the thallus is somewhat prosoplectenchymatous , indicating a particular type of tissue structure. The medulla, the inner layer of the thallus, can be white or yellowish. [1]
Apothecia, the fruiting bodies where sexual spores are produced, are very rare in Usnocetraria. When present, they contain globose (spherical) or subglobose (nearly spherical) ascospores . Pycnidia, which are structures that produce asexual spores (pycnoconidia), are also uncommon but, when present, have filiform (thread-like) or slightly sublageniform (somewhat flask-shaped) pycnoconidia. [1]
A characteristic chemical feature of Usnocetraria is the consistent presence of usnic acid in the cortex, which contributes to the lichen's defense mechanisms and colouration. Additionally, various fatty acids, such as caperatic and types associated with lichesterinic and protolichesterinic acids, along with secalonic acids and other related yellow pigments, may also be present in the medulla. Some species within the genus also contain fumarprotocetraric and protocetraric acids, adding to the diversity of chemical compounds found in these lichens. [1]
As of June 2024 [update] , Species Fungorum accepts two species of Usnocetraria: [6]
The following new combinations, all proposed by Lai and Wei, [1] have been rejected as not validly published:
The type species, Usnocetraria oakesiana, has a wide distribution, having been recorded from Europe, Asia, and North America. [7] Usnocetraria kurokawae is a rare lichen species that is endemic to Japan. It was lectotypified in 2013. [8]
Parmelia is a genus of medium to large foliose (leafy) lichens. It has a global distribution, extending from the Arctic to the Antarctic continent but concentrated in temperate regions. There are about 40 species in Parmelia. In recent decades, the once large genus Parmelia has been divided into a number of smaller genera according to thallus morphology and phylogenetic relatedness.
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, Usnea, Parmotrema, and Hypotrachyna.
Allocetraria is a genus of lichenized fungi in the family Parmeliaceae. It consists of 12 species, with a center of distribution in China.
Kaernefeltia is a genus of lichenized fungi in the family Parmeliaceae.
Hypogymnia is a genus of foliose lichens in the family Parmeliaceae. They are commonly known as tube lichens, bone lichens, or pillow lichens. Most species lack rhizines that are otherwise common in members of the Parmeliaceae, and have swollen lobes that are usually hollow. Other common characteristics are relatively small spores and the presence of physodic acid and related lichen products. The lichens usually grow on the bark and wood of coniferous trees.
Vulpicida is a genus of lichenized fungi in the family Parmeliaceae. Circumscribed in 1993 to contain species formerly placed in Cetraria, the genus is widespread in Arctic to northern temperate regions, and contains six species. The genus is characterized by the presence of the secondary metabolites pulvinic acid and vulpinic acid, compounds that when combined with usnic acid, give the species their characteristic yellow and green colors.
Tuckermannopsis is a genus of foliose lichens in the family Parmeliaceae.
Melanohalea is a genus of foliose lichens in the family Parmeliaceae. It contains 30 mostly Northern Hemisphere species that grow on bark or on wood. The genus is characterised by the presence of pseudocyphellae, usually on warts or on the tips of isidia, a non-pored epicortex and a medulla containing depsidones or lacking secondary metabolites. Melanohalea was circumscribed in 2004 as a segregate of the morphologically similar genus Melanelia, which was created in 1978 for certain brown Parmelia species. The methods used to estimate the evolutionary history of Melanohalea suggest that its diversification primarily occurred during the Miocene and Pliocene epochs.
Cetrelia is a genus of leafy lichens in the large family Parmeliaceae. They are commonly known as sea-storm lichens, alluding to the wavy appearance of their lobes. The name of the genus, circumscribed in 1968 by the husband and wife lichenologists William and Chicita Culberson, alludes to the former placement of these species in the genera Cetraria and Parmelia.
Punctelia is a genus of foliose lichens belonging to the large family Parmeliaceae. The genus, which contains about 50 species, was segregated from genus Parmelia in 1982. Characteristics that define Punctelia include the presence of hook-like to thread-like conidia, simple rhizines, and point-like pseudocyphellae. It is this last feature that is alluded to in the vernacular names speckled shield lichens or speckleback lichens.
Xanthoparmelia is a genus of foliose lichens in the family Parmeliaceae. This genus of lichen is commonly found in the United States, as well as Australia, New Zealand and Ecuador.
Everniopsis is a fungal genus in the family Parmeliaceae. It consists of a single species, the bark-dwelling lichen Everniopsis trulla, which occurs in Africa and South America.
Coelopogon is a genus of lichen-forming fungi in the family Parmeliaceae. The genus contains two species found in southern South America and South Africa.
Esslingeriana is a fungal genus in the family Parmeliaceae. The genus is monotypic, containing the single foliose lichen species Esslingeriana idahoensis, commonly known as the tinted rag lichen. It is found in northwestern North America.
Notoparmelia is a genus of foliose lichens in the family Parmeliaceae. It includes 18 species that grow on bark and rocks, and are mostly distributed in the Southern Hemisphere. The genus was created in 2014 as a segregate of Parmelia.
Parmelia mayi is a species of foliose lichen in the family Parmeliaceae. It is found in the northern Appalachian Mountains of eastern North America, where it grows on rocks and on the trunks of paper birch and balsam fir. Parmelia mayi is morphologically indistinguishable from Parmelia saxatilis, but is distinct in its distribution, chemistry, and genetics.
Allocetraria corrugata is a species of foliose lichen in the family Parmeliaceae. It is found in high-elevation locations in Yunnan, China, where it grows on rocks with mosses.
Parmelia fraudans is a species of foliose lichen in the family Parmeliaceae. It is found in Europe and North America, where it grows on rocks.
Tuckermannopsis orbata, commonly known as the variable wrinkle lichen, is a species of foliose lichen in the family Parmeliaceae. It is a small cetrarioid lichen, an informal growth form category that denotes lichens with erect, foliose thalli, and apothecia and pycnidia on the margins of the ruffled lobes. Tuckermannopsis orbata is found in Asia and North America, growing primarily on the wood and bark of mostly birch and coniferous tree branches and twigs.
Melanelia hepatizon, commonly known as the rimmed camouflage lichen or the rimmed brown-shield, is a species of saxicolous (rock-dwelling), foliose lichen in the family Parmeliaceae. Its thallus, ranging in colour from brown to black, features narrow, elongated lobes that can be flat, convex, or concave. This lichen has a circumpolar distribution, occurring in Asia, Europe, North America, Iceland, and Greenland.