Graphis Adans.
Familles des Plantes, 2: 11, 1763.
Systematics:
Phylum: Ascomycota Caval.-Sm.
Subphylum: Pezizomycotina O.E.Erikss. & Winka
Class: Lecanoromycetes O.E.Erikss. & Winka
Subclass: Ostropomycetidae Reeb, Lutzoni & Cl.Roux
Order: Ostropales Nannf.
Family: Graphidaceae Dumort.
Brief description: Thallus crustose, thin, whitish to grey. Apothecia black, lirelliform, with a slit-like disc at least when young. Proper exciple black, carbonized laterally, poorly developed and not carbonized at base; epithecium brown; hymenium colourless, I-; paraphyses mostly simple, the apical cells hardly swollen; hypothecium pale. Asci up to 8-spored, clavate or cylindrical-clavate, dehiscent by an apical split, K/I-, Graphis-type. Ascospores transversely septate or muriform, the lumina rounded to lens-shaped, hyaline (but sometimes turning brown when overmature), I+ violet. Pycnidia black, more or less immersed. Conidia hyaline, short-bacilliform. Photobiont trentepohlioid. Chemistry: ß-orcinol depsidones in some species; old apothecia of some species with a K+ purple anthraquinone.
Note: The phylogeny of Graphidaceae has been elucidated by Rivas Plata & al. (2013). The large (c. 450 species), mainly tropical genus Graphis was thought to have very few representatives in Europe, the most common and widespread of which was Graphis scripta, an extremely variable lichen: on the same trunk one can often distinguish among several individual, never merging thalli, just on the base of the shape and form of the ascomata. Neuwirth & Aptroot (2011) have proposed a new taxonomy for G. scripta s.lat., recognizing four distinct taxa, G. betulina, G. macrocarpa, G. pulverulenta, and G. scripta s.str. However, a more recent study based on both molecular and morphological characters (Kraichak & al. 2015) showed that, although between six and seven putative species are nested within the complex, these do not fully correspond to the taxa that were recently distinguished based on apothecium morphology, and cannot be circumscribed with the morphological characters that were traditionally used in the classification of the complex. Any formal taxonomic treatment will require additional sampling and evaluation of additional traits that potentially can characterize these clades. Pending a revision of the Italian material, I treat here G. scripta in the broad sense, while the few recent records of the “species” delimited by Neuwirth & Aptroot (2011) are provisionally treated as separate entities. Several tropical species were reported as new to Europe from Portugal by Lepista & Aptroot (2016, 2022). A worlwide key was provided by Lücking & al. (2009). A key to the species of the British Isles is in Aptroot & al. (2023).
Type: Graphis scripta (L.) Ach.
