''Xanthocarpia feracissima'' is a species of saxicolous,

crustose lichen Crustose lichens are lichens that form a crust which strongly adheres to the Substrate (biology), substrate (soil, rock, tree bark, etc.), making separation from the substrate impossible without destruction. The basic structure of crustose lichen ...

in the family

Teloschistaceae The Teloschistaceae are a large family of mostly lichen-forming fungi belonging to the class Lecanoromycetes in the division Ascomycota. The family, estimated to contain over 1800 species, was extensively revised in 2013, including the creation o ...

. It was first formally described as a new species in 1953 by Swedish lichenologist

Adolf Hugo Magnusson Adolf Hugo Magnusson (1 March 188514 July 1964) was a Swedish naturalist who specialized in lichenology. He was a school teacher in Gothenburg from 1909 to 1948, but spent his spare time on the study of lichens. He described about 900 new taxa, ...

, as a member of the genus ''

Caloplaca ''Caloplaca'' is a lichen genus comprising a number of distinct species. Members of the genus are commonly called firedot lichen, jewel lichen.Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, gold lichens, "ora ...

''. The

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

was collected in 1939 by

John Walter Thomson John Walter Thomson Jr. (1913–2009) was a Scottish-born American botanist and lichenologist, sometimes referred to as the "Dean of North American Lichens". Biography When he was eight years old, Thomson moved with his family to the U.S.A. In ...

Lake Koshkonong, Wisconsin Lake Koshkonong is a census-designated place (CDP) in the towns of Koshkonong, Wisconsin, Koshkonong and Sumner, Jefferson County, Wisconsin, Sumner, Jefferson County, Wisconsin, Jefferson County, Wisconsin, United States. The population was 1,239 ...

. In the original description, Magnusson notes a similarity to the lichen now known as '' Gyalolechia flavovirescens'', but distinguishes the new species by its lack of a visible

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 wer ...

, the sordid-reddish color of its , and the "unusually narrow"

septa The Southeastern Pennsylvania Transportation Authority (SEPTA) is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly 4 million people in five coun ...

of the spores. Patrik Frödén, Ulf Arup, and Ulrik Søchting transferred the

taxon In biology, a taxon (back-formation from ''taxonomy''; plural 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 nam ...

to ''

Xanthocarpia ''Xanthocarpia'' is a genus of mostly crustose lichens in the family Teloschistaceae. It has 12 species with a largely Northern Hemisphere distribution. Taxonomy The genus was originally circumscription (taxonomy), circumscribed in 1859 by Abra ...

'' in 2013, following

molecular phylogenetic 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 of the family Teloschistaceae. The lichen occurs in the eastern United States and Canada. In North America, a

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

for the species is "sidewalk firedot lichen". It is very common on cement and mortar, particularly on sidewalks that are not commonly used. Despite the nearly imperceptible thallus, the tiny apothecia can grow so profusely so as discolor large areas of sidewalks yellow. The ability of ''Xanthocarpia feracissima'' to grow on rock surfaces, however, has led to instances where the species has damaged

marble Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or Dolomite (mineral), dolomite. Marble is typically not Foliation (geology), foliated (layered), although there are exceptions. In geology, the ...

; in one documented case of the restoration of a statue, the lichen penetrated up to into the stone along larger cracks and beneath loose surface crystals, leading to crumbling of the marble surface.

References

{{Taxonbar, from=Q108478483 Teloschistales Lichen species Lichens described in 1953 Lichens of Eastern Canada Lichens of the United States Taxa named by Adolf Hugo Magnusson