Synonyms: Abrothallus ricasolii A. Massal.; Buellia ricasolii (A. Massal.) A. Massal.; Buellia ricasolii var. hysteroides A. Massal.; Catillaria ricasolii (A. Massal.) A. Massal.; Lecidea sparsa Dufour; Melaspilea arthonioides auct. non (Fée) Nyl.; Melaspilea urceolata auct. eur. non (Fr.) Ertz & Diederich; Poetschia arthonioides auct. non (Fée) Stein
Distribution: N - VG (Tretiach & Carvalho 1995), Frl, Ven (Lazzarin 2000), TAA (Nascimbene & al. 2007b), Lomb, Piem (TO 1863), Emil (Gasparo & Tretiach 1996, Fariselli & al. 2020), Lig. C - Tosc (Loppi & Frati 2006, Lazzarin 2000), Marc (Nimis & Tretiach 1999, Frati & al. 2004, Frati & Brunialti 2006), Laz (TSB 26112), Abr (Recchia & al. 1993, Gheza & al. 2021), Sar. S - Camp, Pugl (Nimis & Tretiach 1999), Si.
Description: Thallus crustose, episubstratic, very thin but well-evident, smooth, white to pale grey. Apothecia rounded, 0.5-2 mm across, with a black, flat to moderately convex disc and a thin, at first slightly emergent, but often finally excluded proper margin. Exciple thin, dark brown to almost black; epithecium brown; hymenium colourless, not amyloid; paraphyses simple; hypothecium colourless to very pale brown. Asci elongate-clavate, thickened at apex and with an internal apical beak, K/I-. Ascospores 1-septate, at first hyaline, then brown, 10-18 x 5-11 µm. Photobiont trentepohlioid. Spot tests: thallus K-, C-, KC-, P-. Chemistry: without lichen substances.
Note: a mild-temperate species found on hard bark of deciduous trees (Quercus, Morus, etc.); more widespread in the past, presently declining. Following Ertz & Diederich (2015), I have placed here all Italian records of Melaspilea urceolata and M. arthonioides, which are two different, American species.The species is included in the Italian red list of epiphytic lichens as “Near-threatened” (Nascimbene & al. 2013c).
Growth form: Crustose
Reproductive strategy: mainly sexual
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)