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 off of, 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.
The Lichinaceae are a family of ascomycete fungi. Most species are lichenized with cyanobacteria, and have a distribution largely in temperate regions.
Verrucariaceae is a family of lichens and a few non-lichenised fungi in the order Verrucariales. The lichens have a wide variety of thallus forms, from crustose (crust-like) to foliose (bushy) and squamulose (scaly). Most of them grow on land, some in freshwater and a few in the sea. Many are free-living but there are some species that are parasites on other lichens, while one marine species always lives together with a leafy green alga.
Cryptothecia rubrocincta is a species of lichen in the fungal family Arthoniaceae. The species is distributed in subtropical and tropical locations throughout the southeastern United States, as well as Central and South America, and has been collected infrequently in a few locales in Africa. The body of the lichen forms continuous, circular crust-like patches on dead wood, readily recognizable by the prominent red pigment. The older, central region is covered with red, spherical to cylindrical granules. Moving outwards from the center, zones of color may be distinguished, the first gray-green, the second white, and finally a bright red cottony rim. The red and green colors of this unmistakable woodland lichen give the appearance of a Christmas wreath, suggestive of its common North American name, the Christmas (wreath) lichen. The red pigment, called chiodectonic acid, is one of several chemicals the lichen produces to help tolerate inhospitable growing conditions.
Pilophorus acicularis, commonly known as the nail lichen or the devil's matchstick lichen, is a species of matchstick lichen in the family Cladoniaceae.
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. 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.
Lichen morphology describes the external appearance and structures of a lichen. These can vary considerably from species to species. Lichen growth forms are used to group lichens by "vegetative" thallus types, and forms of "non-vegetative" reproductive parts. Some lichen thalli have the aspect of leaves ; others cover the substrate like a crust, others such as the genus Ramalina adopt shrubby forms, and there are gelatinous lichens such as the genus Collema.
Heppia is a genus of olive, brownish, gray, or blackish squamulose, crustose, or peltate like lichens. Heppia was once the type genus of the family Heppiaceae, but that family was folded into synonymy with Lichinaceae.
Peltigera vainioi is a species of lichen in the family Peltigeraceae. It is found in high-elevation locations in South America. It is a somewhat unusual species in its genus, characterized by a single holdfast that attaches to its substrate, and pores in its cortex.
Sagiolechia phaeospora is a species of crustose lichen in the family Sagiolechiaceae. It is found in the alpine tundra of Alaska.
Parmelia barrenoae is a species of foliose lichen in the large family Parmeliaceae. It was formally described as a new species in 2005. Before this, it was lumped together as one of several lichens in the Parmelia sulcata group—a species complex of genetically distinct lookalikes. Parmelia barrenoae is widely distributed, occurring in Europe, western North America, Africa, and Asia.
Lepraria santosii is a species of crustose lichen in the family Stereocaulaceae. It occurs in Tenerife, in the Canary Islands.
Bacidina flavoleprosa is a species of saxicolous (rock-dwelling), leprose (powdery) lichen in the family Ramalinaceae. It is found in a single locality in the Czech Republic.
Inoderma sorediatum is a species of crustose lichen in the family Arthoniaceae. It is only known to occur on the bark of trees in Poland's Białowieża National Park. It is differentiated from other species in genus Inoderma by the form of its thallus, which is entirely made of powdery, granular soredia, as well as by the presence of a unique combination of lichen products.
Septotrapelia multiseptata is a species of bryophilous (moss-dwelling) lichen in the family Byssolomataceae. Found in South Korea, it was formally described as a new species in 2014 by lichenologists André Aptroot and Kwang-Hee Moon. The type specimens were collected by the first author from Mabok-san mountain at altitudes between 200 and 500 m ; there, the lichen was overgrowing mosses that were growing on siliceous rock. It has a thin mottled greyish and olive green thallus covering areas of up to about 15 cm (6 in). The thallus lacks a cortex; rather, it comprises small, irregularly shaped areoles on a somewhat gelatinous crust. The photobiont partner of the lichen is an myrmecioid green alga, which measures 2–4 μm in diameter. Ascospores of the lichen have a long ellipsoid shape, and measure 17–20 by 6.5–7.5 μm. The species epithet multiseptata refers to the 5 or 6 septa that divide the ascospores into chambers.
Verrucaria simplex is a species of saxicolous (rock-dwelling), crustose lichen in the family Verrucariaceae. Found in Europe and Asia, it was described as new to science in 1988 by lichenologist Patrick McCarthy. The type specimen was collected by Brian Coppins from Morpeth, Northumberland; there, it was found growing on a fragment of mortar-cement lying on the floor of a woodland. The lichen was later reported from the Czech Republic, and Korea.
Porina howeana is a species of saxicolous (rock-dwelling) crustose lichen in the family Trichotheliaceae. Found on Lord Howe Island, Australia, it was formally described as a new species in 1997 by lichenologist Patrick M. McCarthy. The type specimen was collected by the author from east of Dawsons Point Ridge on Max Nicholls Track, where it was growing on shaded basalt.
Porina mariae is a species of saxicolous (rock-dwelling) crustose lichen in the family Trichotheliaceae. Found on Lord Howe Island, Australia, it was formally described as a new species in 1997 by lichenologist Patrick M. McCarthy. The type specimen was collected by the author on the track from Smoking Tree Ridge to Boat Harbour, where it was growing on deeply shaded basalt. The species epithet honours the author's wife, Marie Meaney-McCarthy, "in recognition of her unwavering encouragement and support".
Dictyonema album is a species of basidiolichen in the family Hygrophoraceae. It is found in Mauritius, where it grows as an epiphyte on shrubs.
Dictyonema ramificans is a basidiolichen species in the family Hygrophoraceae. Discovered in 2010 in the Galapagos Islands, it was formally described as a new species in 2017 by lichenologists Manuela Dal-Forno, Alba Yanez-Ayabaca, and Robert Lücking. Its species epithet is derived from the branching pattern of the fibrils that form a net-like structure, giving it an arachnoid (cobweb-like) appearance. This species has only been found in the humid zone of Santa Cruz Island, growing exclusively on bryophytes. While it is similar to other Dictyonema species, it differs in its unique fibril branching pattern and erect arachnoid structure.
