Xalocoa
| Xalocoa | |
|---|---|
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Lecanoromycetes |
| Order: | Graphidales |
| Family: | Graphidaceae |
| Genus: | Xalocoa Kraichak, Lücking & Lumbsch (2013) |
| Species: | X. ocellata
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| Binomial name | |
| Xalocoa ocellata (Fr.) Kraichak, Lücking & Lumbsch (2013)
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| Synonyms[1] | |
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List
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Xalocoa is a single-species fungal genus in the family Graphidaceae.[2] It contains the single species Xalocoa ocellata, a lichen. This bark-dwelling species forms thin grey-white crusts with unusually large, eye-like spots that can reach up to 4 millimetres across. It has a nearly worldwide distribution in areas with Mediterranean-type climates and was first scientifically described in 1831 based on specimens collected from France.
Taxonomy
[edit]The genus Xalocoa was circumscribed in 2013 by the lichenologists Ekaphan Kraichak, Robert Lücking, and H. Thorsten Lumbsch. It contains Xalocoa ocellata,[3] a corticolous (bark-dwelling), crustose lichen that was originally described by Elias Magnus Fries in 1831 (as Parmelia ocellata).[4] The type specimen was collected from France.[3]
Xalocoa belongs to the subfamily Graphidoidae, and tribe Thelotremateae in the Graphidaceae. The genus is characterized by its greyish-white thallus covered by an epinecral layer, large apothecioid ascomata with exposed discs and thick, entire thalline margins, as well as a thin, reduced, uncarbonised proper exciple that lacks lateral paraphyses. The genus features a non-inspersed hymenium, pale brown, non-amyloid ascospores, bacilliform conidia, and contains the norstictic acid chemosyndrome. The genus name Xalocoa originates from the Catalan term xaloc, which signifies the sirocco, a warm wind that comes from the Sahara and affects Mediterranean regions. The species epithet pays tribute to Xavier Llimona, a Catalan researcher known for his work on Mediterranean lichens and his contributions to the taxonomy of the genus Diploschistes.[3]
Description
[edit]Xalocoa ocellata forms a thin, grey-white crust (the thallus) that is covered by an epinecral layer – a delicate, often slightly powdery film of dead fungal cells that helps the surface shed water. Its reproductive bodies (apothecia) are unusually large for the family, reaching up to about 4 mm across. Each apothecium is lecanorine: the round, exposed disc sits in a thick rim of thallus-derived tissue (the thalline margin), so the fruiting bodies look like tiny greyish eye-spots set into the crust. Beneath the margin lies a very thin, uncarbonised proper exciple (the cup-shaped tissue that lines the disc), and the spore-bearing layer (hymenium) is clear rather than shot through with oil droplets (non-inspersed).[3]
Microscopically, the asci produce eight pale-brown, multi-chambered (muriform) ascospores that lack any starch reaction (non-amyloid). The spores measure roughly 25–45 μm long and 10–15 μm wide and are divided by both transverse and longitudinal partitions (septa), giving them a brick-like appearance. Asexual reproduction is by slender, rod-shaped (bacilliform) conidia. Chemical spot tests detect norstictic acid, a secondary metabolite that often gives the medulla a yellow to red reaction with potassium hydroxide solution (the K test). Together, the large lecanorine apothecia, absence of lateral paraphyses, muriform spores and norstictic-acid chemistry distinguish Xalocoa from superficially similar genera in the family Graphidaceae.[3]
Habitat and distribution
[edit]Xalocoa ocellata has a nearly cosmopolitan distribution, occurring in areas with a Mediterranean climate.[3] It has been recorded from Yunnan and Sichuan provinces in China.[5]
References
[edit]- ^ "Synonymy. Current Name: Xalocoa ocellata (Fr.) Kraichak, Lücking & Lumbsch, Aust. Syst. Bot. 26(6): 472 (2014) [2013]". Species Fungorum. Retrieved 26 June 2025.
- ^ "Xalocoa". Catalogue of Life. Species 2000: Leiden, the Netherlands. Retrieved 26 June 2025.
- ^ a b c d e f Kraichak, Ekaphan; Parnmen, Sittiporn; Lücking, Robert; Lumbsch, H. Thorsten (2013). "Gintarasia and Xalocoa, two new genera to accommodate temperate to subtropical species in the predominantly tropical Graphidaceae (Ostropales, Ascomycota)". Australian Systematic Botany. 26 (6): 466. doi:10.1071/sb13038.
- ^ Fries, E.M. (1831). Lichenographia Europaea Reformata (in Latin). Lundin: E. Mauritium. p. 190.
- ^ Jia, Ze-Feng; Li, Min; Fu, Yu-Ru; Pu, Jing (2022). "Notes on lichenized fungi of chroodiscoid Thelotremataceae from China". Mycotaxon. 136 (4): 831–840. doi:10.5248/136.831.