''Buellia stellulata'', commonly known as the disc lichendisc lichen
-

Encyclopedia of Life The Encyclopedia of Life (EOL) is a free, online encyclopedia intended to document all of the 1.9 million living species known to science. It aggregates content to form "pages" for every known species. Content is compiled from existing trusted ...

(eol.org)) is a species of

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 ...

that is widely distributed throughout the

Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...

.Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.

Morphology

Thallus

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 ...

is crustose, areolate, and thin to moderately thickened, often forming a continuous layer. The prothallus is conspicuous and black, strongly developed in most specimens, growing between the areoles to form a hypothallus. The thallus surface is usually white to whitish gray, rarely dark gray, and can be dull or slightly shiny. The thallus is epruinose and phenocorticate, and lacks

soredia Soredia are common reproduction, reproductive structures of lichens. Lichens asexual reproduction, reproduce asexually by employing simple fragmentation and production of soredia and isidia. Soredia are powdery propagules composed of fungus, fung ...

Medulla

The

medulla Medulla (Latin for "marrow") 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 ...

is white and lacks

calcium oxalate Calcium oxalate (in archaic terminology, oxalate of lime) is a calcium salt of oxalic acid with the chemical formula or . It forms hydrates , where ''n'' varies from 1 to 3. Anhydrous and all hydrated forms are colorless or white. The monohydr ...

Apothecia

The

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 ...

exhibit a lecideine structure, with a diameter ranging from (0.2-)0.3-0.4(-0.5) mm. They are typically immersed to adnate, occasionally found in a sessile form. The margin may appear black or masked by grayish remnants of necrotic thalline material, forming a thin and usually persistent boundary, occasionally excluded as they mature. The disc is characterized by a black, epruinose surface, typically flat but occasionally developing a slight convexity over time. Within the

, the proper exciple appears narrow and lacks differentiation, resembling the aethalea-type. The inner excipular

hyphae A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one o ...

are narrow,

hyaline A hyaline substance is one with a glassy appearance. The word is derived from , and . Histopathology Hyaline cartilage is named after its glassy appearance on fresh gross pathology. On light microscopy of H&E stained slides, the extracellula ...

, and often prosoplectenchymatous, exhibiting structural and orientational similarities to the

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 ...

. The hypothecium is characterized by a deep reddish-brown color, described as leptoclinos-brown with a textura intricata. Outer excipular hyphae are arranged parallelly, moderately swollen (textura oblita), and heavily carbonized, displaying a range of brown shades and aeruginose pigments. 1861: ''A manual of British lichens, description of all the species and varieties, five plates, with figures of the spores of one hundred and thirty species, illustrative of the genera.'' - Darlington. 1-309 pp. attick Rec. # 33113
(Recent Literature on Lichens - Mattick No.)(PDF file)
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Epihymenium

The epihymenium is brown, with pigmentation continuous with the outer exciple.

Hymenium

The

hymenium The hymenium is the tissue layer on the hymenophore of a fungal fruiting body where the cells develop into basidia or asci, which produce spores. In some species all of the cells of the hymenium develop into basidia or asci, while in oth ...

is hyaline and not inspersed with oil droplets. The paraphyses are simple to moderately branched, with apically swollen tips containing a brown pigment cap.

Asci and ascospores

The asci are clavate,

Bacidia ''Bacidia'' is a genus of lichen-forming fungi in the family Ramalinaceae. Taxonomy The genus was circumscribed by Giuseppe De Notaris in 1846. Description ''Bacidia'' is characterised by its crustose (crust-like) growth form. The main body ...

-type, and 8-spored. The ascospores soon become brown, 1-septate, oblong to ellipsoid, usually not constricted, with obtuse ends, and not curved, measuring (8-)8.7- .911.1(-13) x (4.5-)4.8- .56.1(-7)

μm The micrometre (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 unit of length in the International System ...

. The proper septum is narrow and does not thicken during spore ontogeny (Buellia-type). The spore ornamentation is microrugulate.

Chemistry

The lichen contains the secondary metabolites

atranorin Atranorin is a chemical substance produced by some species of lichen. It is a secondary metabolite belonging to a group of compounds known as depsides. Atranorin has analgesic, anti-inflammatory, antibacterial, antifungal, cytotoxic, antioxidant, ...

, 2'-O-methylperlatolic acid, and confluentic acid. Spot tests are K+ yellow (sometimes weak), P- or + faintly yellow, C-, KC-, and CK-. UV fluorescence is -(dark).

Substrate and ecology

''Buellia stellulata'', an

epilithic Lithophytes are plants that grow in or on rocks. They can be classified as either epilithic (or epipetric) or endolithic; epilithic lithophytes grow on the surfaces of rocks, while endolithic lithophytes grow in the crevices of rocks (and are als ...

lichen, thrives on

siliceous rock Siliceous rocks are sedimentary rocks that have silica (SiO2) as the principal constituent. The most common siliceous rock is chert; other types include diatomite. They commonly form from silica-secreting organisms such as radiolarians, diatoms, o ...

surfaces (typically HCl-) and is commonly found in coastal regions. However, its habitat is not restricted solely to seashore environments.

Distribution

''Buellia stellulata'' exhibits a broad distribution across the Northern Hemisphere. Within the Sonoran region, this species is notably present in coastal areas spanning from southern California to Baja California and Baja California Sur.

Notes and references

Note

References

{{Taxonbar, from=Q10437400 stellulata Lichen species Lichens of Mexico Lichens of the United States Taxa named by Thomas Taylor (botanist)