''Calogaya pusilla'' is a species of

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),

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 (biology), family of mostly lichen-forming fungi belonging to the class (taxonomy), class Lecanoromycetes in the division (botany), division Ascomycota. The family has a cosmopolitan distribution, althoug ...

. ''Calogaya pusilla'' is common in Europe, and has been recorded from a few locations in the United States. Its typical habitat is on vertical,

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

rock surfaces. It also occurs on walls with mortar.

Taxonomy

It was originally

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 ...

in 1852 by Italian lichenologist

Abramo Bartolommeo Massalongo Abramo Bartolommeo Massalongo (13 May 1824 – 25 May 1860) was an Italian paleobotanist and lichenologist. He was born in Tregnago in the Province of Verona and took a great interest in botany as a young man. Massalongo joined the faculty of med ...

, who placed it in genus ''

Physcia ''Physcia'' is a genus of lichen-forming fungi in the family Physciaceae. The widely distributed genus contains about 80 species. The genus is cosmopolitan distribution, cosmopolitan, and has been extensively studied in various regions in the p ...

''. 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 collected in

Veneto Veneto, officially the Region of Veneto, is one of the 20 regions of Italy, located in the Northeast Italy, north-east of the country. It is the fourth most populous region in Italy, with a population of 4,851,851 as of 2025. Venice is t ...

, Italy. It has undergone several changes of genus in its taxonomic history, including transfers to '' Caloplaca'', '' Placodium'', and '' Teloschistes''. In 2013, it was placed in the newly

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 ...

genus '' Calogaya''.

Description

''Calogaya pusilla'' is a small but visually striking lichen that forms neat,

rosette Rosette is the French diminutive of ''rose''. It may refer to: Flower shaped designs * Rosette (award), a mark awarded by an organisation * Rosette (design), a small flower design *hence, various flower-shaped or rotational symmetric forms: ** R ...

-shaped growths measuring 1–3 centimetres in diameter. The

thallus Thallus (: 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. A thallus usually names the entir ...

(main body of the lichen) appears yellow to orange, occasionally with a pinkish tint, and grows closely attached to its substrate. Around the edge, the lichen forms short, broad, flattened about 2 mm long and 1.5 mm wide. These lobes are typically convex and swollen, giving them a plump appearance, and may be divided by small furrows. A distinctive feature of this species is the frequent presence of a white, powdery coating () on the surface of the lobes. The central area of the lichen consists of convex that are often obscured by numerous

apothecia An ascocarp, or ascoma (: ascomata), 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. As ...

(fruiting bodies). These -shaped apothecia can reach up to 1.0 mm in diameter and are typically densely crowded in the central portion of the lichen. When young, each apothecium has a flat, orange to brownish-orange disc surrounded by a noticeable yellow to orange rim (). As the apothecium matures, the disc becomes convex and the rim becomes less prominent. Under the microscope, the spore-producing structures reveal further identifying features. The tips of the sterile filaments (

paraphyses Paraphyses are erect sterile filament-like support structures occurring among the reproductive apparatuses of fungi, ferns, bryophytes and some thallophytes. The singular form of the word is paraphysis. In certain fungi, they are part of the f ...

) within the apothecia are swollen, measuring 6–8

micrometre The micrometre (English in the Commonwealth of Nations, Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a uni ...

s (μm) in diameter. The spores () are

ellipsoid An ellipsoid is a surface that can be obtained from a sphere by deforming it by means of directional Scaling (geometry), scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a Surface (mathemat ...

al, measuring 10–15 μm long by 5–7 (occasionally 8) μm wide, with a cross-wall (

septum In biology, a septum (Latin language, Latin for ''something that encloses''; septa) is a wall, dividing a Body cavity, cavity or structure into smaller ones. A cavity or structure divided in this way may be referred to as septate. Examples Hum ...

) that is 2–4 μm thick, occupying approximately one-fourth to one-fifth of the spore's length. When tested with

potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which utili ...

solution ( K), both the thallus and apothecia turn purple, which is a key chemical characteristic for identifying this species.

References

{{Taxonbar , from1=Q25412987 , from2=Q107482572 , from3=Q108239175 , from4=Q108423194 , from5=Q107693178 , from6=Q21254414 Teloschistales Lichen species Lichens described in 1852 Lichens of Europe Lichens of the United States Taxa named by Abramo Bartolommeo Massalongo