Roccella albida is a species of saxicolous (rock-dwelling), fruticose lichen in the family Roccellaceae.[1] 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 (fruiting bodies) with wavy margins.
| Roccella albida | |
|---|---|
| |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Arthoniomycetes |
| Order: | Arthoniales |
| Family: | Roccellaceae |
| Genus: | Roccella |
| Species: | R. albida
|
| Binomial name | |
| Roccella albida Tehler (2009)
| |
Taxonomy
editThe lichen was formally described as a new species in 2009 by the mycologist Anders Tehler. The species epithet albida is derived from its whitish thallus, distinguishing it from the more brownish-grey thalli of its closely related species such as Roccella galapagoensis, R. margaritifera, and R. nigerrima.[2]
Description
editRoccella albida has a distinctively shaped thallus, which forms branches that are terete (cylindrical and smooth) or slightly foveate (marked with small depressions). These branches generally range in length from 5 to 20 cm and have a colouration that varies from white to white-greyish. Soredia, which are reproductive structures for asexual reproduction, are infrequently found in this species and show a negative reaction to the C spot test.[2]
The medulla, the inner tissue of the thallus, is byssoid or nearly byssoid, meaning it has a fibrous or cottony texture. Its colouration is predominantly white, though it can sometimes appear pale yellowish-brown, especially in the lower parts of the lichen. Ascomata, the spore-producing structures, are a common feature in Roccella albida. They often appear sessile (directly attached without a stalk) and have strongly undulating margins, which give them a knotty appearance. The ascospores of Roccella albida measure between 22 and 26 μm in length and 5 to 6 μm in width, with an average size of approximately 23.8 by 5.5 μm.[2]
Chemical spot tests yield negative results for the medulla with both potassium hydroxide (K) and calcium hypochlorite (C), indicated as K− and C−, respectively. However, the cortex is C+ (red), and K−. The disc of the ascomata is C−. In terms of its chemical makeup, Roccella albida contains secondary metabolites (lichen products) such as erythrin, lecanoric acid, and protocetraric acid, as identified by high-performance thin-layer chromatography.[2]
Habitat and distribution
editRoccella albida is native exclusively to the Galápagos Islands, with its presence confirmed on the islands Santa Fe, Floreana, Pinzón, Rábida, San Cristóbal, Santa Cruz, and Española.[3] This species thrives in coastal areas, predominantly on vertical rocks and cliffs.[2]
References
edit- ^ "Roccella albida Tehler". Catalogue of Life. Species 2000: Leiden, the Netherlands. Retrieved 22 December 2023.
- ^ a b c d e Tehler, Anders; Irestedt, Martin; Bungartz, Frank; Wedin, Mats (2009). "Evolution and reproduction modes in the Roccella galapagoensis aggregate (Roccellaceae, Arthoniales)". Taxon. 58 (2): 438–456. doi:10.1002/tax.582010.
- ^ Bungartz, F.; Ziemmeck, F.; Yánez Ayabaca, A.; Nugra, F.; Aptroot, A. (2011). Bungartz, F.; Herrera, H.; Jaramillo, P.; Tirado, N.; Jímenez-Uzcategui, G.; Ruiz, D.; Guézou, A.; Ziemmeck, F. (eds.). CDF Checklist of Galapagos Lichenized Fungi - FCD Lista de especies de Hongos liquenizados de Galápagos (PDF) (Report). Puerto Ayora, Galapagos: Charles Darwin Foundation. p. 59.