Abrothallus De Not., Abrothallus: 1 (1845).
Vegetative hyphae immersed, K/ILugol+ violet [IMelzer+ blue]. Sexual morph: Ascomata black, globose to slightly appressed, mainly epruinose, only a few ascomata slightly green pruinose. Epihymenial layer of dark brown granules, K+ greenish to emerald greenish, N+ violet. Hymenium hyaline, upper part K+ greenish. Hypothecium brown below the hymenium, turns gradually lighter towards the base, hypothecial cells rectangular. Asci clavate, bitunicate, 8-spored. Interascal filaments irregularly dichotomously branched. Ascospores 2-celled, asymmetric, verruculose. Asexual morph: Undetermined (Adapted from Suija et al. 2018).
Type species: Abrothallus bertianus De Not.
Notes: Abrothallus was introduced by De Notaris with A. bertianus as type species. Abrothallus is characterized by globose to slightly appressed, mainly epruinose ascomata, clavate, bitunicate, 8-spored asci and 2-celled, asymmetric, verruculose ascospores. De Notaris (1846; 1849) at first described Abrothallus as lichenized but he pointed out that the genus might be parasitic. Montagne (1851) agreed that Abrothallus was a lichenized fungus and this was confirmed by the microscopic examination of Tulasne (1852) and Lindsay (1857). The asexual morph was initially described under the epithet Vouauxiomyces (Hawksworth and Dyko 1979; Pérez-Ortega et al. 2011; Suija et al. 2018) but this generic name was not considered based on one fungus one name rule. Species delineation in Abrothallus is problematic as very often specimen under the same name growing on the same host have different morphological features and this problem is common for species growing on hosts of the lichen family Parmeliaceae (Diederich 2004; Ihlen and Wedin 2008; Suija et al. 2018). Pérez-Ortega et al. (2011) recognized the connection between Abrothallus and its anamorph Vouauxiomyces by Denaturing Gradient Gel Electrophoresis (DGGE). Suija et al. (2018) re-examined the original specimen of De Notaris (1846, 1849), Sommerfelt (1826) and Kotte (1909), provided the new combination A. santessonii and illustrated the sexual morph of the genus. Several authors added new species in Abrothallus (Cole and Hawksworth 2001; Etayo 2002; Hafellner et al. 2008; Pérez-Ortega et al. 2010; Diederich 2011; Suija et al. 2015; Etayo 2017; Flakus et al. 2019). Abrothallus is morphologically and phylogenetically a distinct genus in Lichenoconiaceae. Molecular markers available for Abrothallus include ITS, LSU, SSU, RPB2 and TEF-1.