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Buellia stellulata
Species of fungus From Wikipedia, the free encyclopedia
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Buellia stellulata, commonly known as the disc lichen[1]) is a species of crustose lichen that is widely distributed throughout the Northern Hemisphere.[2]
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Morphology
Summarize
Perspective
Thallus
The thallus 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.[3][4]
Medulla
The medulla is white and lacks calcium oxalate.[3]
Apothecia
The apothecia 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 apothecia, the proper exciple appears narrow and lacks differentiation, resembling the aethalea-type. The inner excipular hyphae are narrow, hyaline, and often prosoplectenchymatous, exhibiting structural and orientational similarities to the paraphyses. 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.[4][3]
Epihymenium
The epihymenium is brown, with pigmentation continuous with the outer exciple.[3]
Hymenium
The hymenium is hyaline and not inspersed with oil droplets. The paraphyses are simple to moderately branched, with apically swollen tips containing a brown pigment cap.[3]
Asci and ascospores
The asci are clavate, Bacidia-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-[9.9]-11.1(-13) x (4.5-)4.8-[5.5]-6.1(-7) μm. The proper septum is narrow and does not thicken during spore ontogeny (Buellia-type). The spore ornamentation is microrugulate.[3]
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Chemistry
The lichen contains the secondary metabolites atranorin, 2'-O-methylperlatolic acid,[a] and confluentic acid. Spot tests are K+ yellow (sometimes weak), P− or + faintly yellow, C−, KC−, and CK−. UV fluorescence is − (dark).[3]
Substrate and ecology
Buellia stellulata, an epilithic lichen, thrives on siliceous rock surfaces (typically HCl−) and is commonly found in coastal regions. However, its habitat is not restricted solely to seashore environments.[3]
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.[3][2]
See also
Notes and references
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