Cetrelia monachorum (Zahlbr.) W. L. Culb. & C. F. Culb. Description. Thallus foliose, heteromerous, dorsiventral, loosely attached, forming wavy, wide-spreading, usually orbicular, wide rosettes. Upper surface greenish-grey, lower surface black in the central part to brown at the lobe edges. Lobes broad and round, up to 20 mm wide, with raised margins. Pseudocyphellae on upper surface frequently developing on slightly raised structures, often appearing as accumulation of individuals to form a larger unit, sometimes lacking in the central parts of older thalli; absent from lower surface. Soralia primarily marginal, often rather irregularly shaped, with coarse soredia (35–55 µm). Lower surface wrinkled, with scattered, simple, black rhizines and a rhizine-free zone along the margin. Apothecia lecanorine, with brown disc. Found fertile three times in Italy (Trentino Alto Adige: Val Brenta, 1; Veneto: Cansiglio, 2). Chemistry. Cortex with atranorin (sometimes in low concentrations); medulla with imbricaric acid (major), perlatolic acid (minor or absent), anziaic acid (traces or absent). Distribution in Italy. Central-eastern Alps (155 specimens from 30 sites): Friuli Venezia Giulia (21 specimens from 6 sites), Veneto (75 specimens from 11 sites), Trentino Alto Adige (47 specimens from 8 sites), Lombardia (12 specimens from 5 sites); Northern Apennines (27 specimens from 7 sites): Liguria (5 specimens from 2 sites), Emilia Romagna (2 specimens from 2 sites), Toscana (20 specimens from 3 sites); Sardegna (1 specimen from 1 site). Fig. 2. Habitat. Beech, coniferous or mixed beech-coniferous forests and chestnut groves from the hilly to the montane belt (274–1600 m a. s. l.). Phorophytes. Abies alba, Acer pseudoplatanus, Alnus incana, Castanea sativa, Corylus avellana, Fagus sylvati ca, Fraxinus excelsior, Picea abies, Prunus avium, Quercus cerris, Salix caprea, Salix sp. Literature. Confirmed citations: Friuli Venezia Giulia: Obermayer and Mayrhofer (2007); Veneto: Nascimbene et al. (2021); Trentino Alto Adige: Obermayer and Mayrhofer (2007), Nascimbene (2014), Nascimbene and Marini (2015), Trindade et al. (2021), Nascimbene et al. (2022); Liguria: Ravera et al. (2019); Sardegna: Nascimbene et al. (2021). Remarks. The record of “ C. olivetorum ” by Brackel (2015) should be referred to this species, since the only Cetrelia species found by us in the same site was C. monachorum. Specimens examined. See Suppl. material 1.

Published as part of Gheza, Gabriele, Vallese, Chiara, Di Nuzzo, Luca, Corneti, Simona, Benesperi, Renato, Bianchi, Elisabetta, Canali, Giulia, Del Vecchio, Silvia, Francesconi, Luana, Giordani, Paolo, Nimis, Pier Luigi, Obermayer, Walter, Pistocchi, Chiara, Mayrhofer, Helmut & Nascimbene, Juri, 2025, Towards a better knowledge and conservation of cryptic macrolichens in Italy: a revision of the genus Cetrelia (Parmeliaceae, Lecanorales, lichenized Ascomycota), pp. 231-254 in MycoKeys 120 on pages 231-254, DOI: 10.3897/mycokeys.120.154233