| Roccella | |
|---|---|
 | |
| Roccella fuciformis | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Arthoniomycetes |
| Order: | Arthoniales |
| Family: | Roccellaceae |
| Genus: | Roccella DC. (1805) |
| Type species | |
| Roccella fuciformis (L.) DC. (1805) | |
| Synonyms [1] | |
Roccella is a genus of 23 species of lichens in the family Roccellaceae. [2] The genus was circumscribed by Swiss botanist Augustin Pyramus de Candolle in 1805, with Roccella fuciformis as the type species. [3]
Roccella presents a fruticose (shrub-like), thallus that is either erect or pendulous (hanging) with sparse dichotomous branching. The main and terminal branches , varying in shape from flattened to rounded ( terete ), typically measure 2 to 5 mm (up to 10 mm) in thickness and 5 to 15 cm in length. These branches has colours ranging from creamy white-greyish to greyish-brown and have surfaces that are either smooth or wrinkled, with some being sparsely pruinose (powdery) or lacking pruina (epruinose). Soredia, reproductive propagules for asexual reproduction, are present in many species within the genus. [4]
The cortex of Roccella lichens is made of hyphae that are arranged in an anticlinal manner and are about 40 to 70 µm thick. The medulla (the inner layer) is loosely structured above, having a byssoid (fibrous) or chalky texture, and below it becomes plectenchymatous (tightly packed cells) near the basal plate (holdfast) area, often showing a (yellowish) brown colouration. These lichens primarily associate with the photobiont Trentepohlia , with no secondary photobiont present. They attach to surfaces using holdfasts, including a hypomedulla which usually appears brown to dark brown, sometimes with a yellowish tinge. [4]
The ascomata (spore-producing structures) of Roccella are in the form of apothecia, lateral, and circular in outline. They can be either immersed in the thallus or sessile with a constricted base and can reach up to 2.5 mm in diameter. The disc of the apothecia is exposed, white, and features a rimose , pruinose layer. The exciple (the outer layer of the ascomata) initially contains algae and a cortex, but over time, the algae may be displaced, and the cortex eroded. The proper exciple forms a thin parathecium and is sometimes inconspicuous. [4]
The epithecium (upper layer of the ascomata) is about 40 to 50 µm high, brown, with intertwined paraphysoids (supporting structures in the hymenium) that are sparsely branched. The hymenium (spore-bearing layer) itself is 70 to 90 µm high. Paraphysoids within the hymenium are sparsely branched, hyaline (translucent), and measure 1 to 2 µm in diameter. The hypothecium (layer beneath the hymenium) is distinct, dark brown, carbonaceous , and does not extend into the medulla. The asci (spore-bearing cells) are clavate (club-shaped), measuring 60 to 85 by 12 to 14 µm. Ascospores are fusiform (spindle-shaped), curved, smooth, contains three septa (internal partitions), and are hyaline. [4]
Conidiomata (asexual reproductive structures) are pycnidial (flask-shaped), solitary, immersed in the thallus, and black, measuring about 0.1 mm in diameter. The conidia (asexual spores) are filiform (thread-like), curved, measuring 16 to 21 by less than 1 µm. In terms of chemistry, Roccella lichens contain orcinol and β-orcinol depsides, as well as aliphatic acids. Roccella lichens grow on rock or on bark. [4]
The Arthoniales is the second largest order of mainly crustose lichens, but fruticose lichens are present as well. The order contains around 1500 species, while the largest order with lichenized fungi, the Lecanorales, contains more than 14000 species.
Lecanographa is a genus of about 40 species of lichens in the family Lecanographaceae. It was circumscribed in 1994 by José M. Egea and Pilar Torrente, with Lecanographa lyncea as the type species.
Roccellographaceae is a family of lichen-forming fungi in the order Arthoniales. It contains three genera: Dimidiographa, Fulvophyton, and Roccellographa.
Vigneronia is a genus of lichen-forming fungi in the family Roccellaceae. It has five species. The genus was circumscribed in 2014 by Damien Ernst, with Vigneronia spieri assigned as the type species. This species, originally described as Schismatomma spieri from collections made in the Galápagos Islands, has since been recorded from mainland Ecuador and the Antilles (Curaçao). The genus is named after Ernst's wife, Nathalie Vigneron, who accompanied him on collecting trips.
Gyrographa is a genus of lichen-forming fungi in the family Roccellaceae. The genus was circumscribed in 2014 by Damien Ernst and Anders Tehler, with Gyrographa gyrocarpa assigned as the type species. This lichen, originally described by Julius von Flotow in 1825, was first placed in the genus Opegrapha. Species in the genus have a crustose thallus lacking a cortex, and a dark brown prothallus. The photobiont partner is trentepholioid. The hypothecium is thick and carbonised, and the ascospores lack a gelatinous sheath; these characteristics distinguish it from Opegrapha species. The genus name alludes to the gyrose ascomata of the type species.
Diromma is a monotypic fungal genus in the family Roccellaceae. It contains the single species Diromma dirinellum, a rare crustose lichen that grows as a parasite on the lichen Dirina ceratoniae. It has a distribution restricted to the Mediterranean Basin.
Dirina catalinariae is a species of saxicolous (rock-dwelling), crustose lichen in the family Roccellaceae. It occurs in the southwestern United States, Mexico, and the Galápagos Islands.
Vigneronia spieri is a species of corticolous (bark-dwelling), crustose lichen in the family Roccellaceae. It is found in the Galápagos Islands, mainland Ecuador and the Antilles (Curaçao).
Dirina monothalamia is a species of corticolous (bark-dwelling) in the family Roccellaceae. It occurs in Cape Verde and the nearby mainland of Senegal, where it is found in coastal outcrops on the bark of various trees; Senegalese populations are often on the bark of African baobab.
Dimidiographa is a genus of lichen-forming fungi in the family Roccellographaceae. It has three species of crustose lichens, with Dimidiographa loandensis serving as the type species.
Fulvophyton is a genus of lichen-forming fungi in the family Roccellographaceae. It has 11 species. Fulvophyton is characterised by its crust-like thallus, which is often pale yellowish-brown in colour. This genus features a photobiont from the green algal genus Trentepohlia and exhibits a unique arrangement of reproductive structures.
Glyphis frischiana is a species of corticolous (bark-dwelling) script lichen in the family Graphidaceae. It is distinguished by its large ascospores, single-spored asci, and the presence of stictic acid as a major metabolite. Found on the trunk of Eucalyptus trees in Cameroon, it is similar in appearance to Glyphis atrofusca but can be distinguished by these key characteristics.
Aspiciliopsis is a genus of lichen-forming fungi in the family Trapeliaceae. It has two species, both of which occur in the Southern Hemisphere.
Placomaronea fuegiana is a species of saxicolous (rock-dwelling), crustose lichen in the family Candelariaceae. Found in South America, it was formally described as a new species in 2009 by Martin Westberg and Patrik Frödén. The type specimen was collected by the second author in Tierra del Fuego, Argentina, where it was found growing on sandstone. The species epithet fuegiana refers to the type locality. It also occurs in Pali-Aike National Park, where it grows in the pits of volcanic rocks.
Roccella albida is a species of saxicolous (rock-dwelling), fruticose lichen in the family Roccellaceae. It is found on the Galápagos Islands. The lichen is characterised by its distinctively shaped, cylindrical or slightly depressed branches that vary in length from 5 to 20 cm and are white to white-greyish in colour, with infrequent soredia. The lichen has a cottony medulla, commonly white or sometimes pale yellowish-brown, and has frequent ascomata with wavy margins.
Placolecis kunmingensis is a species of saxicolous (rock-dwelling), crustose lichen in the family Catillariaceae. It is found in Yunnan, China. The lichen is characterised by a thallus that is areolate to squamulose in its centre, forming irregular patches or clumps 10–50 mm wide, as well as its ellipsoid or spherical ascospores with slightly thickened wall.
Byssoloma xanthonicum is a species of corticolous (bark-dwelling), crustose lichen in the family Pilocarpaceae. It is found in New Caledonia.
Roccella gracilis is a species of fruticose lichen in the family Roccellaceae. Flourishing in coastal environments, Roccella gracilia predominantly grows along the coasts of Baja California and the Galápagos Islands, preferring the trunks, branches, and twigs of trees, but it is also found on rocks and cliffs. Its distribution spans coastal habitats from California south to Peru, including the Galápagos Islands and parts of the Caribbean.
Caloplaca lecapustulata is a species of saxicolous (rock-dwelling), crustose lichen in the family Teloschistaceae. Found in Brazil, it was described as a new species in 2016.
Roccella galapagoensis is a species of fruticose lichen in the family Roccellaceae. It is endemic to the Galápagos Islands.