| Relicina | |
|---|---|
 | |
| Relicina eximbricata , in Florida | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Lecanoromycetes |
| Order: | Lecanorales |
| Family: | Parmeliaceae |
| Genus: | Relicina (Hale & Kurok.) Hale (1974) |
| Type species | |
| Relicina eumorpha (Hepp) Hale (1974) | |
| Synonyms [1] | |
| |
Relicina is a genus of foliose lichens belonging to the large family Parmeliaceae. It contains 60 species. [2]
Relicina was originally conceived as a series of the large genus Parmelia by lichenologists Mason Hale and Syo Kurokawa in 1964. A decade later, they promoted it to the status of genus. [3]
The genus Relicinopsis, proposed by Australian lichenologists John Elix and Doug Verdon in 1986 as a segregate of Pseudoparmelia , [4] was shown to be nested within Relicina in a 2017 molecular phylogenetics study. [5]
Relicina lichens have a leaf-like (foliose) body (thallus) with flat, two-sided lobes that are typically attached by a somewhat swollen, bulbous base. The edge of each lobe is lined with short, black, hair-like structures called cilia . The upper surface is generally yellow to yellow-green and may sometimes show small spots; it lacks the typical hairs and minute pores (pseudocyphellae) seen in some other lichens. Instead, the surface is covered by a continuous, pored layer (the epicortex ). On the underside, the color ranges from pale brown to black, and it bears simple or branched, root-like structures (rhizines) that extend to the edges, helping secure the lichen to its substrate. [6]
The lichen's photosynthetic partner is a green alga similar to those in the genus Trebouxia . Reproduction occurs through apothecia, which are open, disc-like fruiting bodies located on the surface of the lobes. These apothecia have a margin that resembles the thallus (a condition described as lecanorine ) and display a solid, uninterrupted disc that ranges in color from pale to dark red-brown. The disc lacks a powdery coating ( epruinose ) and is surrounded by a cup-shaped layer. The thallus-like margin is smooth or slightly scalloped and is often fringed with cilia at its base; in some cases, this edge appears almost crown-like due to the influence of swollen and bulbous pycnidia. [6]
Inside the apothecia, delicate filament-like cells called paraphyses are present; these are about 2–3 μm thick, mostly straight, and only lightly branched, with their tips being brown, rounded, and slightly expanded. The spore-bearing sacs, or asci, typically contain eight spores each. Each ascus features a well-developed, iodine-reactive (amyloid) zone known as the tholus that is pierced by a narrow, non-reactive central strand with parallel sides; there is no distinct ocular chamber. The resulting sexual spores are simple in structure, translucent (hyaline), ellipsoid in shape, and have walls about 0.5 μm thick. [6]
In addition to these sexual structures, Relicina produces asexual fruiting bodies known as pycnidia. These are embedded in the lichen's surface ( laminal and immersed ) and often appear somewhat swollen. They release conidia—small, asexual spores—that can be spindle-shaped ( bifusiform ) or more uniformly cylindrical to fusiform . [6]
Chemically, members of the genus Relicina contain usnic acid along with various other secondary metabolites such as depsidones, depsides, or fatty acids. [6]
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.
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.
Myelochroa is a genus of foliose lichens in the family Parmeliaceae. They are commonly known as axil-bristle lichens. It was created in 1987 to contain species formerly placed in genus Parmelina that had a yellow-orange medulla due to the presence of secalonic acids. Characteristics of the genus include tightly attached thalli with narrow lobes, cilia on the axils, and a rhizinate black lower surface. Chemical characteristics are the production of zeorin and related triterpenoids in the medulla. Myelochroa contains about 30 species, most of which grow on bark. The genus has centres of distribution in Asia and North America.
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.
Flavoparmelia is a genus of foliose lichens in the family Parmeliaceae. Because of their appearance, they are commonly known as greenshield lichens. The widely distributed genus contains 32 species. It was circumscribed by American lichenologist Mason Hale in 1986 to contain 17 former Pseudoparmelia species with broad lobes, usnic acid in the cortex, and isolichenan in the cell walls.
Canoparmelia is a genus of lichen-forming fungi in the family Parmeliaceae. The widespread genus contains about 35 species. Canoparmelia, a segregate of the parmelioid lichen genus Pseudoparmelia, was circumscribed by John Elix and Mason Hale in 1986.
Bulbothrix is a genus of lichen-forming fungi in the family Parmeliaceae. This genus is synonymous with Bulbothricella V.Marcano, S.Mohali & A.Morales. Bulbothrix was circumscribed by lichenologist Mason E. Hale in 1974 with Bulbothrix semilunata as the type species.
Parmelinella is a genus of lichen belonging to the family Parmeliaceae. The genus was circumscribed in 1987 by John Elix and Mason Hale as a segregate of Parmelina, from which it differs in having larger ascospores and containing salazinic acid. Although the genus had been assumed to be well-defined morphologically, a 2021 molecular phylogenetic study suggests that the generic delimitations need to be revised.
Parmotrema is a genus of lichen belonging to the family Parmeliaceae. It is a large genus, containing an estimated 300 species, with a centre of diversity in subtropical regions of South America and the Pacific Islands.
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, South America, southern Africa, Europe, Australia, and New Zealand.
Imshaugia is a genus of seven species of foliose lichens in the family Parmeliaceae. They are commonly known as starburst lichens.
Pseudoparmelia is a genus of lichen-forming fungi in the family Parmeliaceae. The genus has a pantropical distribution.
Crespoa is a genus of five species of lichen in the family Parmeliaceae. Species in this genus are characterized by having an upper thallus surface that is wrinkled and reticulately ridged to coarsely foveolate.
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.
Punctelia subflava is a species of foliose lichen in the family Parmeliaceae that occurs in Australia.
Hypotrachyna catawbiensis, the powder-tipped antler lichen, is a species of foliose lichen in the family Parmeliaceae. First described in 1941, it forms pale ivory to greenish-gray leaf-like growths that attach loosely to tree bark or rocks. The lichen has narrow, forking lobes that often curl inward, and produces powdery structures called soredia for asexual reproduction. Though originally discovered in the Appalachian Mountains of the eastern United States, it has since been found across tropical and temperate regions worldwide, including Mexico, South America, East Africa, China, and Papua New Guinea. It usually grows at high elevations. Genetic studies have shown that despite this widely scattered distribution, populations from different continents belong to the same species. It typically grows as an epiphyte on hardwood trees, though it can also be found on conifers and rocks.