A lichen is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship. Lichens are important actors in nutrient cycling and act as producers which many higher trophic feeders feed on, such as reindeer, gastropods, nematodes, mites, and springtails. Lichens have properties different from those of their component organisms. They come in many colors, sizes, and forms and are sometimes plant-like, but are not plants. They may have tiny, leafless branches (fruticose); flat leaf-like structures (foliose); grow crust-like, adhering tightly to a surface (substrate) like a thick coat of paint (crustose); have a powder-like appearance (leprose); or other growth forms.
Aspicilia is a genus of mostly crustose areolate lichens that grow on rock. Most members have black apothecia discs that are slightly immersed in the areolas, hence the common name.
Megasporaceae are a family of fungi belonging to the order Pertusariales. Taxa are lichenized with green algae, and grow on rocks, often in maritime climates close to fresh water. Phylogenetic analysis has shown that this family is related to the Pertusariaceae, another family of lichens. The genus Aspicilia was moved here from the Hymeneliaceae.
Acarospora is a genus of mostly lichen-forming fungi in the family Acarosporaceae. Most species in the genus are crustose lichens that grow on rocks in open and arid places all over the world. They may look like a cobblestone road or cracked up old paint, and are commonly called cobblestone lichens or cracked lichens. They usually grow on rock, but some grow on soil (terricolous) or on other lichens. Some species in the genus are fungi that live as parasites on other lichens. Acarospora is a widely distributed genus, with about 128 species according to a 2008 estimate.
Aspicilia mansourii is a species of lichen in the family Megasporaceae. Found in Asia, it was described as new to science in 2011.
Dictyonema hernandezii is a species of basidiolichen in the family Hygrophoraceae. Found in montane rainforests of Costa Rica and in Colombia, it was described as new to science in 2011. The specific epithet hernandezii honours Venezuelan lichenologist Jesús Hernández.
Cora hirsuta is a species of basidiolichen in the family Hygrophoraceae. Found in the páramo region near Bogotá at over 3,000 m (9,800 ft) elevation, it was described as new to science in 2011. The lichen, characterised by its distinctively hairy upper surface and smaller lobes, thrives in a variety of habitats, including soil, bryophytes, and as epiphytes on trees.
Ramalina hyrcana is a species of fruticose lichen in the family Ramalinaceae. Found in the Hyrcanian forest area along the Caspian coast in Iran, it was described as new to science in 2011.
Crustose lichens are lichens that form a crust which strongly adheres to the substrate, making separation from the substrate impossible without destruction. The basic structure of crustose lichens consists of a cortex layer, an algal layer, and a medulla. The upper cortex layer is differentiated and is usually pigmented. The algal layer lies beneath the cortex. The medulla fastens the lichen to the substrate and is made up of fungal hyphae. The surface of crustose lichens is characterized by branching cracks that periodically close in response to climatic variations such as alternate wetting and drying regimes.
Lichens are symbiotic organisms made up of multiple species: a fungus, one or more photobionts and sometimes a yeast. They are regularly grouped by their external appearance – a characteristic known as their growth form. This form, which is based on the appearance of vegetative part of the lichen, varies depending on the species and the environmental conditions it faces. Those who study lichens (lichenologists) have described a dozen of these forms: areolate, byssoid, calicioid, cladoniform, crustose, filamentous, foliose, fruticose, gelatinous, leprose, placoidioid and squamulose. Traditionally, crustose (flat), foliose (leafy) and fruticose (shrubby) are considered to be the three main forms. In addition to these more formalised, traditional growth types, there are a handful of informal types named for their resemblance to the lichens of specific genera. These include alectorioid, catapyrenioid, cetrarioid, hypogymnioid, parmelioid and usneoid.
Circinaria is a genus of crustose lichens in the family Megasporaceae. It was circumscribed by Johann Heinrich Friedrich Link in 1809.
Circinaria caesiocinerea is a species of lichen belonging to the family Megasporaceae. It was first described as Lecanora caesiocinerea in 1869 by William Nylander, but was transferred to the genus Circinaria in 2010 by Anders Nordin, Sanja Savić, and Leif Tibell.
Teuvoa is a genus of lichen-forming fungi in the family Megasporaceae. The genus was circumscribed in 2013 by Mohammad Sohrabi and Steven Leavitt with Teuvoa uxoris assigned as the type species. The genus was segregated from the large genus Aspicilia after molecular phylogenetic analysis revealed that the Aspicilia uxoris species group formed a monophyletic clade that represented an independent lineage within the Megasporaceae. Three species were initially placed in the genus; two additional species from China were added in 2018. Teuvoa is distinguished from Aspicilia by its small ascospores and conidia, and the lack of secondary metabolites. The genus name honours Finnish lichenologist Teuvo Ahti, "one of the prominent lichen taxonomists of the 20th century".
Peltigera rufescens, commonly known as the field dog lichen, is a species of terricolous (ground-dwelling), foliose lichen in the family Peltigeraceae. The common and widespread species has a cosmopolitan distribution.
Ochrolechia upsaliensis is a species of crustose lichen in the family Ochrolechiaceae. Found in the Northern Hemisphere, it is commonly known as the tundra saucer lichen.
Solorina crocea, commonly known as the orange chocolate chip lichen, is a species of terricolous (ground-dwelling) and foliose (leafy) lichen in the family Peltigeraceae. The lichen, which was first formally described by Carl Linnaeus in 1753, has an arctic–alpine and circumpolar distribution and occurs in Asia, Europe, North America, and New Zealand. It generally grows on the bare ground in sandy soils, often in moist soil near snow patches or seepage areas. Although several forms and varieties of the lichen have been proposed in its history, these are not considered to have any independent taxonomic significance.
Peltigera granulosa is a species of terricolous (ground-dwelling), foliose lichen in the family Peltigeraceae. Found in Papua New Guinea, it was formally described as a new species in 2009 by Emmanuël Sérusiaux, Bernard Goffinet, Jolanta Miądlikowska, and Orvo Vitikainen. The type specimen was collected from open grassland between Gumum and Sape villages, where it was found growing on sand. The species epithet granulosa refers to its characteristic granulose margin.
Heppia arenacea is a species of terricolous (ground-dwelling) lichen in the family Lichinaceae. Discovered in Yemen, it is characterized by its sand-coloured thallus and the incorporation of soil particles throughout its vegetative parts. The lichen is found in soil crust communities over limestone and basaltic rock in desert habitats, as well as in partially sheltered areas between large boulders.
Catenarina desolata is a species of lichen in the family Teloschistaceae. It was formally described as a new species in 2014 by lichenologists Ulrik Søchting, Majbrit Søgaard, and Arve Elvebakk. It is predominantly found in the southernmost parts of Chile, with some instances in Antarctica and the Kerguelen Islands. Characterised by its dark reddish-brown to almost purple apothecia, this species of lichen was originally thought to be lichenicolous, meaning it grows on other lichens, particularly Aspicilia species. The later discovery non-lichen-dwelling examples from James Ross Island in the Antarctic Peninsula suggests that it is not exclusively lichenicolous. Its distinctive secondary compound, 7-chlorocatenarin, sets it apart from other lichens in the region.
Sarcogyne brunnea is a species of saxicolous and terricolous, crustose lichen in the family Acarosporaceae. It is found at high altitudes in arid regions of the Andes, growing on volcanic rock and soil. It has an areolate and densely pruinose brown thallus.
