''Chrysothrix insulizans'' is a species of leprose lichen in the family

Chrysotrichaceae Chrysotrichaceae is a family of lichenized fungi in the order Arthoniales. Member of this family have a widespread distribution, but are especially prevalent in tropical areas. "Chrysothrichaceae" and "Chrysothricaceae" are alternative spellings ...

. It is a distinctive species of lichen characterized by its bright yellow-green to yellow-orange coloring and unique growth patterns. Most collections have been found growing on rocks, although a few have been recorded growing on bark.

Taxonomy

''Chrysothrix insulizans'' was first discovered in

Missouri Missouri is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it is bordered by eight states (tied for the most with Tennessee ...

's Shannon County. Found within the Ozark National Scenic Riverway's Prairie Hollow Gorge Natural Area, 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 on a shaded

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...

face under a massive overhang on a west-facing slope. The lichen was formally described as a new species in 2008 by lichenologists Richard C. Harris and Douglas Ladd. The species name ''insulizans'' ("island-forming") reflects the lichen's tendency to form isolated, soralium-like patches. The new species was distinct from its closest relatives due to its thin, often discontinuous thallus, and unique chemical composition.

Description

''Chrysothrix insulizans'' has a

crustose Crustose is a habit of some types of algae and lichens in which the organism grows tightly appressed to a substrate, forming a biological layer. ''Crustose'' adheres very closely to the substrates at all points. ''Crustose'' is found on rocks and ...

, leprose thallus that is thin to moderately thick and brightly colored. The unstratified and adherent thallus forms small, round or irregular soralium-like colonies, which can expand into larger continuous patches. The are and spherical, with diameters between 20 and 50

μm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

. Both and , typical reproductive structures in lichens, are not observed in this species. The lichen's is , measuring between 9–14 μm across. On a chemical level, it tests positive for calycin and possibly leprapinic acid. ''

Chrysothrix galapagoana ''Chrysothrix'' is a genus of lichen-forming fungi in the family Chrysothricaceae. They are commonly called gold dust lichens or sulfur dust lichens,Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, because they ...

'', found in the Galapagos Islands, is somewhat similar to ''Chrysothrix insulizans'', and also produces calycin. It is distinguished by its larger granules (typically 170–250 μm in diameter), the presence of a distinctly pseudo-areolate thallus, and the lack of an unidentified secondary substance. ''

Chrysothrix bergeri ''Chrysothrix bergeri'' is a species of crustose lichen in the family Chrysotrichaceae. It is found in the southeastern United States and the Caribbean, where it grows as a bright yellow, powdery crust on the bark and wood of mostly hardwoods. T ...

'' is lookalike with similar secondary chemistry and distribution, but it is distinguished from ''C. insulizans'' by its continuous thallus and corticolous substrate preference.

Habitat and distribution

''Chrysothrix insulizans'' can be found primarily on non-

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines. In zoology ''Calcareous'' is used as an adje ...

rocks, in both shaded and exposed situations. It is most prevalent in the southeastern United States and the Ozarks region. The species is frequently collected from

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

, but can also be found on

granite Granite () is a coarse-grained (phaneritic) 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 cools and solidifies undergro ...

, and cherty

dolomites The Dolomites ( it, Dolomiti ; Ladin: ''Dolomites''; german: Dolomiten ; vec, Dołomiti : fur, Dolomitis), also known as the Dolomite Mountains, Dolomite Alps or Dolomitic Alps, are a mountain range located in northeastern Italy. They form par ...

. While initially thought to only inhabit rocks, some specimens have been found on bark, indicating broader substrate preferences than originally assumed. These findings, especially those from

Maine Maine () is a state in the New England and Northeastern regions of the United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Canadian provinces of New Brunswick and Quebec to the northeast and north ...

and

Michigan Michigan () is a state in the Great Lakes region of the upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the 10th-largest state by population, the 11th-largest by area, and the ...

, suggest there may be another distinct

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 ...

related to ''Chrysothrix insulizans'', which could require

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

methods for definitive classification.

References

{{Taxonbar, from=Q21246298 insulizans Lichen species Lichens described in 2008 Lichens of the Northeastern United States Taxa named by Richard Clinton Harris