Ampelomyces Ces. ex Schltdl., in Klotzsch, Bot. Ztg. 10: 303 (1852).
Hyperparasitic on Erysiphales or saprobic. Sexual morph: unknown. Asexual morph: Conidiomata pycnidial, scattered, solitary, superficial, uniloculate, globose or elongated to pyriform, pale brown, ostiolate, sometimes papillate. Conidiomata walls thick, composed of pale brown cells, arranged in textura angularis. Conidiophores mostly reduced to conidiogenous cells. Conidiogenous cells enteroblastic, phialidic, determinate, discrete, doliiform to ampulliform, hyaline, smooth-walled, channel and collarette minute, periclinal wall towards apex thickened, formed directly from the pycnidial wall cells. Conidia amerosporous, cylindrical to fusiform, straight to curved, very pale brown, aseptate, thin and smooth-walled, with guttules (Adapted from Sutton, 1980 and Phookamsak et al., 2014).
Type species: Ampelomyces quisqualis Ces.
Notes: Ampelomyces was introduced by Cesati (1852) with A. quisqualis as type species. Ampelomyces is characterized by pycnidial, scattered, solitary, superficial, uniloculate, globose or elongated to pyriform, pale brown conidiomata, discrete, doliiform to ampulliform conidiogenous cells amd amerosporous, cylindrical to fusiform conidia. Ampelomyces has different morphological and cultural characters and species were delineated based on features of pycnidia, cultures and conidial types in isolates of pycnidial mycoparasites from powdery mildews (Clare, 1964; Belsare et al., 1980; Kiss et al., 2004; Phookamsak et al., 2014). Kiss et al. (2004) differentiated Ampelomyces species based on slow and fast-growing cultures and reported that strains from the two types of growth rate were not congeneric and this observation was also supported by phylogenetic analysis based on ITS region. The slow-growing taxa from intracellular pycnidia in powdery mildew mycelia was referred to Ampelomyces sensu stricto and the fast-growing taxa from sessile pycnidia on mildew-infected leaves were reported to be closely related to Phoma species. Example of fast-growing taxa include Ampelomyces heraclei, A. humuli and A. quercinus (Rudakov, 1979; Kiss & Nakasone, 1998; Sullivan & White, 2000; Phookamsak et al., 2014). In the phylogenetic analysis of De Gruyter et al. (2009) based on LSU, SSU, ITS and β-tubulin (TUB) gene region, two strains of A. quisqualis clustered in Phaeosphaeriaceae. Aveskamp et al. (2010) introduced the new combination A. quercinus within Phoma in Didymellaceae based on LSU, SSU, ITS and BTub sequence data. Phookamsak et al. (2014) re-circumscribed Ampelomyces and accepted Ampelomyces as a distinct genus in Phaeosphaeriaceae based on phylogenetic analysis of ITS, LSU, SSU, RPB2 and TEF1 sequence data. The taxonomic placement of Ampelomyces is still doubtful as the strain A. quisqualis in the analysis of Phookamsak et al. (2014) is not the type strain. Ampelomyces is currently a distinct genus in Phaeosphaeriaceae but more taxa with sequence data is needed to confirm this taxonomic placement. Molecular markers available for Ampelomyces include LSU, SSU, ITS and actin (act1) gene.