''Allographa pedunculata'' is a species of script lichen in the family

Graphidaceae The Graphidaceae are a family of lichen-forming fungi in the order Graphidales. The family contains nearly a hundred genera and more than 2000 species. Although the family has a cosmopolitan distribution, most Graphidaceae species occur in tropic ...

, discovered in the

Galápagos Islands The Galápagos Islands () are an archipelago of volcanic islands in the Eastern Pacific, located around the equator, west of the mainland of South America. They form the Galápagos Province of the Republic of Ecuador, with a population of sli ...

. The species is characterized by its distinctly stalked and contains

norstictic acid Norstictic acid is a depsidone produced as a secondary metabolites in lichens. The compound contains both an aldehyde carbonyl group and an adjacent hydroxyl In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical fo ...

. It is similar to other species in the '' Graphis nuda''

species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

but has the longest in the group.

Taxonomy

The lichen was first formally described by lichenologists Frank Bungartz and

André Aptroot André Aptroot ( Heemskerk, 1961) is a Dutch mycologist and lichenologist. His primary research focus is on biodiversity, particularly tropical lichens, encompassing systematics, floristic surveys, and taxonomic reviews. A prolific research ...

in 2010, as a member of the genus '' Graphis''. The species is part of the '' Graphis nuda'' group and is closely related to '' Graphis emersa'', another species containing

Robert Lücking Robert Lücking (born 1964) is a German lichenologist, known for his extensive research on foliicolous lichens (lichens that live on leaves) and his significant contributions to the taxonomy, ecology, and biodiversity of fungi and lichens. He e ...

and Klaus Kalb transferred the taxon to the genus ''

Allographa ''Allographa'' is a genus of script lichens in the family Graphidaceae. It has nearly 200 species. Formally circumscription (taxonomy), circumscribed in 1824 by François Fulgis Chevallier, ''Allographa'' was formerly included in ''Graphis (liche ...

'' in 2018.

Description

The thallus of ''Allographa pedunculata'' is thin and continuous, either forming a thin film encrusting bryophytes and plant debris, or granular to granular , over rock. The thallus surface is smooth and shiny, pale creamy white to brownish, and not . Its

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 ...

are typically distinctly and conspicuously stalked, rarely , and . The lirellae are very broad and short, and never branched. The are thick, entire, and black, only basally more or less covered by a thin thallus layer. 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 ...

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 clear. The are hyaline to pale gray, brownish with age, and measure 22–27 by (80)130–210

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 ...

; they are transversely

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

with (11)16–22 cells. The lichen contains

, which causes a K+ (yellow turning red) (red crystals) and P+ (yellow) spot test reactions. It is C−.

Habitat and distribution

''Allographa pedunculata'' is currently known from a single collection site on a sheltered and shaded

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

cliff at the top of Cerro Gavilán in Santiago Island. The species prefers rock substrates and is found in a distinct habitat compared to its close relative, '' Graphis cleistomma'', which has been found encrusting

bryophyte Bryophytes () are a group of embryophyte, land plants (embryophytes), sometimes treated as a taxonomic Division (taxonomy), division referred to as Bryophyta ''Sensu#Common qualifiers, sensu lato'', that contains three groups of non-vascular pla ...

s and plant debris.

References

{{Taxonbar, from=Q107479218, from2=Q107709257 pedunculata Lichen species Lichens described in 2010 Lichens of the Galápagos Islands Taxa named by André Aptroot Species known from a single specimen Taxa named by Frank Bungartz