''Trebouxia arboricola'' is a symbiotic species of

green alga The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ( ...

in the family

Trebouxiaceae Trebouxiaceae is a family of green algae in the order Trebouxiales. Many species of Trebouxiaceae are found as symbionts associated with terrestrial lichen A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria livin ...

. Described as new to science in 1924, it is usually found in association with different species of

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 ...

and has a broad global distribution.

Taxonomy

The alga was

formally described A species description is a formal scientific description of a newly encountered species, typically articulated through a scientific publication. Its purpose is to provide a clear description of a new species of organism and explain how it differ ...

as a new species in 1924 by the French phycologist André Henri Laurent de Puymaly. The

type specimen In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...

was associated with the

foliose A foliose lichen is a lichen with flat, leaf-like , which are generally not firmly bonded to the substrate on which it grows. It is one of the three most common lichen growth forms, growth forms of lichens. It typically has distinct upper and lo ...

lichen ''

Xanthoria parietina ''Xanthoria parietina'' is a common and widespread lichen-forming fungus in the family Teloschistaceae. Commonly known as the yellow wall lichen, common orange lichen, or maritime sunburst lichen, this foliose lichen, leafy lichen is known f ...

''. ''Trebouxia arboricola'' is 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 ...

of the genus ''

Trebouxia ''Trebouxia'' is a unicellular green alga. It is a photosynthetic organism that can exist in almost all habitats found in polar, tropical, and temperate regions.Erokhina, L. G., Shatilovich, A. V., Kaminskaya, O. P., & Gilichinskii, D. A. (2004 ...

'', which 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 Puymaly in 1924. In a comprehensive

molecular phylogenetics Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

analysis published in 2016, it was discovered that the lichen photobionts ''Trebouxia arboricola'' and ''

Trebouxia gigantea ''Trebouxia'' is a unicellular green alga. It is a photosynthetic organism that can exist in almost all habitats found in polar, tropical, and temperate regions.Erokhina, L. G., Shatilovich, A. V., Kaminskaya, O. P., & Gilichinskii, D. A. (2004) ...

'' constitute a complex

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

encompassing 34 distinct

operational taxonomic unit An operational taxonomic unit (OTU) is an operational definition used to classify groups of closely related individuals. The term was originally introduced in 1963 by Robert R. Sokal and Peter H. A. Sneath in the context of numerical taxonomy, wh ...

s (OTUs). This finding suggests that what is currently known as ''T. arboricola'' and ''T. gigantea'' may actually represent a group of 34 potentially distinct species, each with its unique genetic identity.

Distribution

''Trebouxia arboricola'' has a wide global distribution. It has been reported in the Arctic and Atlantic Islands, including

Iceland Iceland is a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the regi ...

. In Europe, its presence spans across Britain, France, Germany, Romania, Russia (European regions), Spain, Switzerland, Ukraine, and the

Ural Mountains The Ural Mountains ( ),; , ; , or simply the Urals, are a mountain range in Eurasia that runs north–south mostly through Russia, from the coast of the Arctic Ocean to the river Ural (river), Ural and northwestern Kazakhstan.

. In South America, the species is found in Argentina. The Middle East records include Israel, while in South-west Asia, it has been reported from

Uttar Pradesh Uttar Pradesh ( ; UP) is a States and union territories of India, state in North India, northern India. With over 241 million inhabitants, it is the List of states and union territories of India by population, most populated state in In ...

. Its Asian distribution covers China and Taiwan. Under the

synonym A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

''Trebouxia humicola'', the species was recorded in Europe and Asia.

Ecology

In a study of bark-inhabiting lichens from the '' Physcietum adscendentis'' sociological unit (a set of lichen

taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

that commonly associate together), researchers identified ''Trebouxia arboricola'' as the photobiont in several lichen species. This identification was achieved through axenic cultures and sequence comparisons of

internal transcribed spacer Internal transcribed spacer (ITS) is the spacer DNA situated between the small-subunit ribosomal RNA (rRNA) and large-subunit rRNA genes in the chromosome or the corresponding transcribed region in the polycistronic rRNA precursor transcript. ...

DNA. ''Trebouxia arboricola'' was found in association with ''

Lecania cyrtella ''Lecania'' is a genus of lichenized fungi in the family Ramalinaceae. The genus was circumscribed by Abramo Bartolommeo Massalongo in 1853. ''Lecania'' is widely distributed, especially in temperate regions, and contains about 64 species. S ...

'', '' Candelaria concolor'', '' Candelariella'' cf. reflexa, ''

Lecanora ''Lecanora'' is a genus of lichen commonly called rim lichens.Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, Lichens in the genus '' Squamarina'' are also called rim lichens. Members of the genus have roughly c ...

'' species, ''

Lecidella elaeochroma ''Lecidella elaeochroma'' is a species of fungus belonging to the family Lecanoraceae. It has cosmopolitan distribution. References

{{Taxonbar, from=Q1525272 Lecanoraceae Lichen species Taxa named by Erik Acharius Lichens described in 18 ...

'', in addition to ''Xanthoria parietina''. The study also suggested the existence of a free-living population of ''Trebouxia arboricola'', based on its frequent occurrence as a photobiont in

pioneer Pioneer commonly refers to a person who is among the first at something that is new to a community. A pioneer as a settler is among the first settling at a place that is new to the settler community. A historic example are American pioneers, perso ...

lichens growing on smooth bark. Additionally, it was observed that the photobionts from ''Xanthoria parietina'' were morphologically and genetically distinct from those in '' Physcia adscendens'' and '' Phaeophyscia orbicularis''. In a 2013 study, researchers found that ''Xanthoria parietina'' from various locations in France and Switzerland associates with diverse genotypes of ''

Trebouxia decolorans ''Trebouxia decolorans'' is a widespread and common symbiotic species of green alga that is found in association with different species of lichen-forming fungi. Some lichens in which it is the partner are ''Xanthoria parietina'' and '' Anaptyc ...

'', while

saxicolous This glossary of mycology is a list of definitions of terms and concepts relevant to mycology, the study of fungi. Terms in common with other fields, if repeated here, generally focus on their mycology-specific meaning. Related terms can be found ...

(rock-dwelling) specimens specifically associate with ''Trebouxia arboricola''.

Oribatid mites Oribatida (formerly Cryptostigmata), also known as oribatid mites, moss mites or beetle mites, are an order of mites, in the "chewing Acariformes" clade Sarcoptiformes. They range in size from . There are currently 12,000 species that have been i ...

inhabiting the lichen ''Xanthoria parietina'' were found in one study to aid in the dispersal of the lichen's photobiont, ''Trebouxia arboricola'', through their faeces, suggesting a potential method for the vegetative dispersal of this alga. ''Trebouxia arboricola'' was studied as part of the first investigation of aerophytic (i.e., deriving moisture and nutrients from the air and rain)

cryptogam A cryptogam (scientific name ''Cryptogamae'') is a plant, in the broad sense of the word, or a plant-like organism that share similar characteristics, such as being multicellular, photosynthetic, and primarily immobile, that reproduces via sp ...

s on monuments in

Bulgaria Bulgaria, officially the Republic of Bulgaria, is a country in Southeast Europe. It is situated on the eastern portion of the Balkans directly south of the Danube river and west of the Black Sea. Bulgaria is bordered by Greece and Turkey t ...

. In

Koprivshtitsa Koprivshtitsa (, pronounced , from the Bulgarian word , ''kopriva'', meaning "Urtica, nettle") is a List of cities and towns in Bulgaria, historic town in the Koprivshtitsa Municipality in Sofia Province, central Bulgaria, lying on the Topolnit ...

, the alga was found in both free-living and lichenised states on

granite Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly coo ...

monuments, alongside other green algae like '' Apatococcus lobatus''.

Culture Culture ( ) is a concept that encompasses the social behavior, institutions, and Social norm, norms found in human societies, as well as the knowledge, beliefs, arts, laws, Social norm, customs, capabilities, Attitude (psychology), attitudes ...

studies confirmed the presence of ''T. arboricola'', providing the first documented evidence of its occurrence in Bulgaria in a free-living (non-lichenised) state.

Preservation and longevity

Research on the ''Xanthoria parietina'' and ''Trebouxia arboricola'' showed that both organisms die off after about 3 years of room temperature storage, evident from colour changes and a decrease in

chlorophyll Chlorophyll is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words (, "pale green") and (, "leaf"). Chlorophyll allows plants to absorb energy ...

fluorescence Fluorescence is one of two kinds of photoluminescence, the emission of light by a substance that has absorbed light or other electromagnetic radiation. When exposed to ultraviolet radiation, many substances will glow (fluoresce) with colore ...

in ''Trebouxia'' cells. When stored

desiccated Desiccation is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container. ...

at , both the fungus and ''T. arboricola'' remained viable for up to 13 years, showing the effectiveness of

cryopreservation Cryopreservation or cryoconservation is a process where biological material - cells, tissues, or organs - are frozen to preserve the material for an extended period of time. At low temperatures (typically or using liquid nitrogen) any cell ...

for long-term storage of viable lichen thalli, including ''T. arboricola'', for experimental studies. The predominance of ''Trebouxia arboricola'' in areas with different levels of

carbon monoxide Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...

(CO) in

Peninsular Malaysia Peninsular Malaysia, historically known as Malaya and also known as West Malaysia or the Malaysian Peninsula, is the western part of Malaysia that comprises the southern part of the Malay Peninsula on Mainland Southeast Asia and the list of isla ...

suggests that this species is resilient to

air pollution Air pollution is the presence of substances in the Atmosphere of Earth, air that are harmful to humans, other living beings or the environment. Pollutants can be Gas, gases like Ground-level ozone, ozone or nitrogen oxides or small particles li ...

. Its widespread presence and ability to thrive in varying CO concentrations make it a potential candidate for monitoring air quality, as changes in its

population density Population density (in agriculture: Standing stock (disambiguation), standing stock or plant density) is a measurement of population per unit land area. It is mostly applied to humans, but sometimes to other living organisms too. It is a key geog ...

could indicate alterations in air pollution levels.

References

{{Taxonbar, from=Q69688543 Trebouxiales Lichen photobiont Protists described in 1927 Chlorophyta species