''Lichina'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

lichen A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...

-forming

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

in the family

Lichinaceae The Lichinaceae are a family of ascomycete fungi. Most species are lichenized with cyanobacteria, and have a distribution largely in temperate regions. Taxonomy The family was circumscribed in 1854 by Finnish lichenologist William Nylander. H ...

. The genus contains four marine species. These cyanolichens include species such as '' L. pygmaea'' or '' L. confinis'', in which the associated cyanobiont has been assigned to the genus '' Rivularia''. Furthermore, evidence of a high specificity of each

mycobiont A lichen ( , ) is a hybrid colony of algae or cyanobacteria living symbiotically among filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualistic relationship.

towards particular cyanobiont lineages in both species has been detected.

Taxonomy

''Lichina'' was

circumscribed In geometry, a circumscribed circle for a set of points is a circle passing through each of them. Such a circle is said to ''circumscribe'' the points or a polygon formed from them; such a polygon is said to be ''inscribed'' in the circle. * Circum ...

by the Swedish botanist

Carl Adolph Agardh Carl Adolph Agardh (23 January 1785 in Båstad, Sweden – 28 January 1859 in Karlstad) was a Swedish botanist specializing in algae, who was eventually appointed bishop of Karlstad. Biography In 1807 he was appointed teacher of mathematics ...

in 1817. He assigned ''Lichina pygmaea'' as the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

. This lichen was originally described by

John Lightfoot John Lightfoot (29 March 1602 – 6 December 1675) was an English churchman, rabbinical scholar, Vice-Chancellor of the University of Cambridge and Master of St Catharine's College, Cambridge. Life He was born in Stoke-on-Trent, the son of ...

in 1777 as ''Fucus pygmaea'' in his work '' Flora Scotica''.

Description

''Lichina'' species form characteristic black fruiting

thalli Thallus (: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. A thallus usually names the entir ...

associated with cyanobacteria. They often create distinguishable bands in the

intertidal The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various sp ...

and

supralittoral The supralittoral zone, also known as the splash zone, spray zone or the supratidal zone, sometimes also referred to as the white zone, is the area above the spring high tide line, on coastlines and estuaries, that is regularly splashed, but not s ...

zones of rocky coastal areas in

temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...

and cold regions of both hemispheres. The thalli are typically dwarf-, with branches that can be rounded or flattened depending on the species and growth conditions.

Habitat, distribution, and ecology

''Lichina'' species are found in maritime habitats worldwide. Three species (''L. pygmaea'', ''L. confinis'', and ''L. canariensis'') occur in the Northern Hemisphere, while ''L. intermedia'' is restricted to the Southern Hemisphere. They typically grow on rocky shores, with different species occupying distinct zones based on their tolerance to submersion and sea spray. ''Lichina'' species play important roles in rocky coastal ecosystems. They are often associated with diverse bacterial communities and can form

biofilm A biofilm is a Syntrophy, syntrophic Microbial consortium, community of microorganisms in which cell (biology), cells cell adhesion, stick to each other and often also to a surface. These adherent cells become embedded within a slimy ext ...

s on rock surfaces. The genus shows varying levels of

genetic diversity Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It ranges widely, from the number of species to differences within species, and can be correlated to the span of survival for a species. It is d ...

, with ''L. intermedia'' showing particularly high intraspecific variation.

Evolutionary history and biogeography

Molecular A molecule is a group of two or more atoms that are held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemistry, ...

studies suggest that the diversification of the genus ''Lichina'' began between 22.8 and 84.65 million years ago. The current geographic distribution of ''Lichina'' species is believed to be the result of

long-distance dispersal Biological dispersal refers to both the movement of individuals (animals, plants, fungi, bacteria, etc.) from their birth site to their breeding site ('natal dispersal') and the movement from one breeding site to another ('breeding dispersal' ...

events across ocean basins, rather than ancient

vicariance Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...

Species

The following species are recognized in the genus ''Lichina'': *'' Lichina canariensis'' *'' Lichina confinis'' *'' Lichina intermedia'' *'' Lichina pygmaea'' Recent

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

studies have led to a reevaluation of the genus ''Lichina''. Several species previously included in the genus, such as ''L. antarctica'', ''L. minutissima'', ''L. tasmanica'', and ''L. willeyi'', are now considered to be phylogenetically distinct from the core ''Lichina'' group. These species, along with others like ''L. rosulans'' and ''L. polycarpa'', are typically non-marine and form pycnoascocarps, characteristics that set them apart from the four recognised marine ''Lichina'' species. As a result, they are likely to be reclassified into different genera in future taxonomic revisions. Additionally, some species like ''L. antarctica'' and ''L. macrospora'' require further phylogenetic evaluation to determine their taxonomic placement.

References

{{Taxonbar, from=Q3285184 Lichinomycetes Lichinomycetes genera Lichen genera Taxa described in 1817 Taxa named by Carl Adolph Agardh