''Enterographa serusiauxii'' is a species of leaf-dwelling lichen in the family Roccellaceae. It is found in

Guadeloupe Guadeloupe (; ; gcf, label=Antillean Creole, Gwadloup, ) is an archipelago and overseas department and region of France in the Caribbean. It consists of six inhabited islands—Basse-Terre, Grande-Terre, Marie-Galante, La Désirade, and the ...

Taxonomy

The lichen was formally described as a new species in 2020 by Elise Lebreton and

André Aptroot André Aptroot (Heemskerk, 1961) is a Dutch mycologist and lichenologist. In 1993 he did his PhD at the University of Utrecht under the supervision of Robbert Gradstein (nl). His dissertation was titled "Systematic studies on pyrenocarpous li ...

. The type specimen was collected in the Littoral de Robin municipality of Trois Rivières,

. Here it was found growing on living leaves of ''

Garcinia humilis ''Garcinia humilis'', known commonly as ''achachairú'' or ''achacha'', is a small, prolifically fruiting tree related to the mangosteen. It grows in the southern part of the Amazon basin in the central area of Bolivia, but has recently been pla ...

'' in a coastal forest. The species had been found decades ago by Father Casimir Le Gallo, who collected many leaf-dwelling lichens that he sent to the National Museum of Natural History, but it was not published and not documented again until its recollection in 2019. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

honours Belgian lichenologist

Emmanuël Sérusiaux Emmanuël Sérusiaux (born 3 October 1953) is a Belgian lichenologist. His career, spanning more than four decades, has combined both lichenology research and political aspects of nature conservation. He spent several periods working as a res ...

, who the authors noted for his "profound interest in foliicolous lichens and in the lichen flora of Guadeloupe".

Description

The lichen has a crustose, pale-cream to off-white thallus that is verrucose (covered with tiny warts). The thallus is up to in diameter and about 0.1 mm thick. The photobiont partner is a green alga of genus '' Trentepohlia''. The apothecia of the lichen are oval to irregularly slit-shaped, and immersed in the thallus. The ascospores number eight per

ascus An ascus (; ) is the sexual spore-bearing cell produced in ascomycete fungi. Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some genera or s ...

, and are

hyaline A hyaline substance is one with a glassy appearance. The word is derived from el, ὑάλινος, translit=hyálinos, lit=transparent, and el, ὕαλος, translit=hýalos, lit=crystal, glass, label=none. Histopathology Hyaline cartilage is ...

, 7 to 9- septate, and typically measure 27–29 by 2.5–3.5

μm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

. The medulla of ''Enterographa serusiauxii'' contains gyrophoric acid, resulting in a positive C+ red chemical spot test.

Habitat and distribution

The lichen is known only from Guadeloupe, where it grows on the living leaves of both ''Garcinia humilis'' and ''

Calophyllum calaba ''Calophyllum bracteatum'' is a species of flowering plant in the Calophyllaceae family. It is found in Sri Lanka where it is known as ගුරු කින (guru kina) by local people. Trunk Bark - young smooth, mature rough, deeply fissured, ...

'' near the coast.

References

{{Taxonbar, from= Q107185397 Roccellaceae Lichen species Lichens of the Caribbean Lichens described in 2020 Taxa named by André Aptroot