Buellia bahiana

Buellia bahiana
Scientific classification
Domain:	Eukaryota
Kingdom:	Fungi
Division:	Ascomycota
Class:	Lecanoromycetes
Order:	Caliciales
Family:	Caliciaceae
Genus:	Buellia
Species:	B. bahiana
Binomial name
Buellia bahiana Malme
Synonyms[1]
Hafellia bahiana (Malme) Sheard, 1992

Buellia bahiana (commonly known as bay buttons^[2]) is a crustose-type lichen species that frequently grows on the bark and wood of trees found in coastal and inland forest habitats.^[3][2] This lichen species exhibits a broad geographic distribution, being documented in various pantropical and subtropical regions around the world.^[3] Specific areas where Buellia bahiana has been recorded include parts of Australia, Africa, North America, Central America, South America, and several Pacific Island chains.^[3]

Buellia bahiana has a thin, continuous thallus that can range in texture from membranous to areolate.^[3] The thallus color varies from white to grey-white or pale grey.^[3][2] A prothallus, the dark border around the thallus, is typically only evident when the lichen is growing adjacent to other species.^[3]

The lichen produces abundant, sessile apothecia that are 0.1-0.7 mm wide.^[3] These apothecia have a black, epruinose (lacking a waxy bloom) disc that is plane to slightly convex in shape. The margin of the apothecia is also black and persistent.^[3][2] Microscopically, the proper exciple, the layer beneath the disc, is dark brown to brown, black, but paler internally.^[3]

The epihymenium, the uppermost layer of the hymenium, is 10-15 μm thick and ranges in color from olive to blue-green or dark olive-green. This layer turns violet when exposed to potassium hydroxide (K+ violet).^[3] The hymenium, the spore-bearing layer, is 65-85 μm thick and contains numerous oil droplets dispersed throughout.^[3] The hypothecium, the layer beneath the hymenium, is 35-80 μm thick and dark brown in color.^[3]

The asci, the spore-producing structures, contain 8 ascospores each. The ascospores are 1-septate, meaning they have a single wall dividing them, and measure 13-20 μm long by 5.5-8.0 μm wide. They are often slightly elongated at the ends and have distinct thickenings of the subapical and septum regions of the spore wall. The outer wall of the ascospores is smooth.^[3] Pycnidia, the structures that produce asexual spores, have not been observed on this species.^[3][2]

Chemical analysis via spot test shows that the thallus of Buellia bahiana tests positive for two substances. It reacts K+ red, indicating the presence of norstictic acid as a major component. The thallus also tests P+ yellow or yellow orange, revealing the minor or trace compound connorstictic acid.^[3]

Buellia bahiana is commonly found growing on the bark and wood of trees in coastal and hinterland forests in several regions of Australia, including Western Australia, Queensland, and Tasmania.^[3] This lichen species has a broader pantropical to subtropical distribution.^[3][2]

Beyond its distribution in Australia, this lichen species is also known to occur in various locations across the Pacific region, Central America, North America, and South America.^[3] Specific areas where Buellia bahiana has been documented include Tahiti, Hawaiian Islands, and the New Caledonia.^[3]

In the U.S. state of Georgia, Buellia bahiana is considered a rare species, reported from swamps and bottomland forests.^[2] However, its overall conservation status in other parts of its range is generally unknown.^[4]

Under the Nature Conservation Act 1992 in the state of Queensland, Australia, the conservation status of this lichen species is listed as "Least Concern".^[5][a]