''Pyxine cocoes'', commonly known as the buttoned rosette lichen, is a widely distributed species of

foliose lichen Foliose lichen is one of the morphological classes of lichens, which are complex organisms that arise from the symbiotic relationship between fungi and a photosynthetic partner, typically algae. This partnership allows lichen to live in dive ...

in the family

Caliciaceae The Caliciaceae are a family of mostly lichen-forming fungi belonging to the class Lecanoromycetes in the division Ascomycota. Although the family has had its classification changed several times throughout its taxonomic history, the use of mo ...

Taxonomy

It was first described as a new species by Swedish botanist

Olof Swartz Olof Peter Swartz (21 September 1760 – 19 September 1818) was a Swedish botanist and taxonomist. He is best known for his taxonomic work and studies into pteridophytes. Biography Olof Swartz attended the University of Uppsala where he s ...

in 1788. He called it ''Lichen cocoës'', following the lead of

Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his Nobility#Ennoblement, ennoblement in 1761 as Carl von Linné#Blunt, Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalise ...

who, in his influential 1753 work '' Species Plantarum'', placed all lichens in the

eponym An eponym is a person, a place, or a thing after whom or which someone or something is, or is believed to be, named. The adjectives which are derived from the word eponym include ''eponymous'' and ''eponymic''. Usage of the word The term ''epon ...

ous genus ''Lichen''. Finnish lichenologist

William Nylander William Andrew Michael Junior Nylander Altelius (born 1 May 1996) is a Canadian-born Swedish professional ice hockey right winger for the Toronto Maple Leafs of the National Hockey League (NHL). Nylander was selected by the Maple Leafs in th ...

transferred it to the genus ''

Pyxine ''Pyxine'' is a genus of foliose lichens in the family Caliciaceae. The genus has a widespread distribution in tropical regions. The presence or absence of the compound lichexanthone is a character Character or Characters may refer to: Arts ...

'' in 1853. It is commonly known as the buttoned rosette lichen in North America.

Description

''Pyxine cocoes'' has a pale grayish-green

thallus Thallus (plural: 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. Many of these organisms ...

comprising radiating lobes that are typically less than 1 mm wide. These lobes are closely attached to the surface of the substrate, have granular

soredia Soredia are common reproductive structures of lichens. Lichens reproduce asexually by employing simple fragmentation and production of soredia and isidia. Soredia are powdery propagules composed of fungal hyphae wrapped around cyanobacteria or ...

that protrude through the

cortex Cortex or cortical may refer to: Biology * Cortex (anatomy), the outermost layer of an organ ** Cerebral cortex, the outer layer of the vertebrate cerebrum, part of which is the ''forebrain'' *** Motor cortex, the regions of the cerebral cortex i ...

in irregularly shaped regions called soralia. The

medulla Medulla or Medullary may refer to: Science * Medulla oblongata, a part of the brain stem * Renal medulla, a part of the kidney * Adrenal medulla, a part of the adrenal gland * Medulla of ovary, a stroma in the center of the ovary * Medulla of t ...

is white, while the

apothecia An ascocarp, or ascoma (), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascocarps are mos ...

are black with black margins in mature specimens. They are 1–5 mm wide, flat, and disc-shaped. The tissue making up base of the apothecia is brownish red.

Ascospore An ascus (; ) is the sexual spore-bearing cell produced in ascomycete fungi. Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some genera or ...

s measure 15–22 by 6–8 μm. The lichen contains

lichexanthone Lichexanthone is an organic compound in the structural class of chemicals known as xanthones. Lichexanthone was first isolated and identified by Japanese chemists from a species of leafy lichen in the 1940s. The compound is known to occur in ma ...

, a

xanthone Xanthone is an organic compound with the molecular formula O 6H4sub>2CO. It is a white solid. In 1939, xanthone was introduced as an insecticide and it currently finds uses as ovicide for codling moth eggs and as a larvicide. Xanthone is also ...

compound that is found in about 20 ''Pyxine'' species.

Habitat and distribution

''Pyxine cocoes'' grows on bark and rocks. The lichen has been reported from Asia (Japan and the Philippines), East Africa, North America, Central America, and South America, Hawaii, and Australia. In Australia, it is present only in coastal locations that are seasonally humid, and both wet and warm. In this continent, it is common on tree trunks growing on coral

cay A cay ( ), also spelled caye or key, is a small, low-elevation, sandy island on the surface of a coral reef. Cays occur in tropical environments throughout the Pacific, Atlantic, and Indian Oceans, including in the Caribbean and on the Great ...

s; these trunks are often used as bird perches, which accumulate bird droppings. Lichenologist Roderick W. Rogers suggests that the lichen could be nitrophilic, which would explain this growth habitat, as well as its tendency to prefer habitats that are at least partially

urbanized ''Urbanized'' is a documentary film directed by Gary Hustwit and released on 26 October 2011. It is considered the third of a three-part series on design known as the Design Trilogy; the first being ''Helvetica'', about the typeface, and the seco ...

. In North America, it distribution extends as far north to

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

in the United States.

Biomonitoring studies

Studies conducted in India suggest that ''Pyxine cocoes'' is a candidate for

biomonitoring In analytical chemistry, biomonitoring is the measurement of the body burden of toxic chemical compounds, elements, or their metabolites, in biological substances. Often, these measurements are done in blood and urine. Biomonitoring is performed ...

of local air pollution. It bioaccumulates toxic heavy metals that it acquires from the air and retains the pollutants in the thallus, which can then be sampled and assayed to determine their concentration.

Human uses

''Pyxine cocoes'' is used in

Papua New Guinea Papua New Guinea (abbreviated PNG; , ; tpi, Papua Niugini; ho, Papua Niu Gini), officially the Independent State of Papua New Guinea ( tpi, Independen Stet bilong Papua Niugini; ho, Independen Stet bilong Papua Niu Gini), is a country i ...

as a component of a

traditional medicine Traditional medicine (also known as indigenous medicine or folk medicine) comprises medical aspects of traditional knowledge that developed over generations within the folk beliefs of various societies, including indigenous peoples, before the ...

-based remedy for inflammatory conditions. In a chemical analysis of the lichen, the

triterpene Triterpenes are a class of chemical compounds composed of three terpene units with the molecular formula C30H48; they may also be thought of as consisting of six isoprene units. Animals, plants and fungi all produce triterpenes, including squa ...

compound 6,22-hopanediol was identified. This compound, commonly known as zeorin, is a

hopanoid Hopanoids are a diverse subclass of triterpenoids with the same hydrocarbon skeleton as the compound hopane. This group of pentacyclic molecules therefore refers to simple hopenes, hopanols and hopanes, but also to extensively functionalized deriv ...

with potent

inhibitory An inhibitory postsynaptic potential (IPSP) is a kind of synaptic potential that makes a postsynaptic neuron less likely to generate an action potential.Purves et al. Neuroscience. 4th ed. Sunderland (MA): Sinauer Associates, Incorporated; 2008. ...

activity against the enzyme

protein tyrosine phosphatase Protein tyrosine phosphatases (EC 3.1.3.48, systematic name protein-tyrosine-phosphate phosphohydrolase) are a group of enzymes that remove phosphate groups from phosphorylated tyrosine residues on proteins: : proteintyrosine phosphate + H2O = ...

References

{{Taxonbar, from=Q10647700 Caliciales Lichen species Lichens described in 1788 Lichens of Africa Lichens of Asia Lichens of Australia Lichens of Central America Lichens of New Guinea Lichens of North America Lichens of South America Taxa named by Olof Swartz