''Rexiella'' is a

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 ...

genus in the family

Cladoniaceae The Cladoniaceae are a family of lichen-forming fungi in the order Lecanorales, comprising about 560 species distributed amongst 18 genera. This family is one of the largest among lichen-forming fungi and is globally distributed, from Arctic t ...

. The genus, originally circumscribed with the name ''Rexia'' by authors Soili Stenroos, Raquel Pino-Bodas, and Teuvo Ahti in 2018, was created to contain the species ''Cladonia sullivanii'', first formally described in 1882 by Swiss botanist

Johannes Müller Argoviensis Johann Müller (9 May 1828 – 28 January 1896) was a Swiss botanist who was a specialist in lichens. He published under the name Johannes Müller Argoviensis to distinguish himself from other naturalists with similar names. Biography Müller ...

. After publication of the new genus, it was discovered that the name was

illegitimate Legitimacy, in traditional Western common law, is the status of a child born to parents who are legally married to each other, and of a child conceived before the parents obtain a legal divorce. Conversely, ''illegitimacy'', also known as ''b ...

, because an earlier

homonym In linguistics, homonyms are words which are either; '' homographs''—words that mean different things, but have the same spelling (regardless of pronunciation), or '' homophones''—words that mean different things, but have the same pronunciat ...

had been published; the generic name '' Rexia'' had already been created in 2006 to contain the cyanobacterial species ''Rexia erecta''. The new name ''Rexiella'' was therefore proposed in 2019. Both the original name ''Rexia'' and the replacement name ''Rexiella'' honour the Australian lichenologist Rex Filson, who published

monograph A monograph is generally a long-form work on one (usually scholarly) subject, or one aspect of a subject, typically created by a single author or artist (or, sometimes, by two or more authors). Traditionally it is in written form and published a ...

s on the genera '' Cladia'' and '' Heterodea''. ''Rexiella'' differs from ''Cladia'' by the presence of thick

pseudopodetia A podetium (plural: podetia) is the upright secondary thallus in ''Cladonia'' lichens. It is a hollow Stipe (mycology), stalk extending from the . Podetia can be pointed stalks, Club (weapon), club like, cupped, or branched in shape and may or may ...

with black to white, tightly packed, and loosely woven medulla. The genus produces the secondary compounds

usnic acid Usnic acid is a naturally occurring dibenzofuran derivative found in several lichen species with the formula C18H16O7. It was first isolated by German scientist W. Knop in 1844 and first synthesized between 1933 and 1937 by Frank H. Curd and Al ...

and divaricatic acid. ''Rexiella sullivanii'' is found in Australia, New Zealand, and South America.

References

Cladoniaceae Monotypic Lecanorales genera Taxa described in 2019 Taxa named by Teuvo Ahti Lichen genera {{Lecanorales-stub