Calophoma petasitis Tibpromma, Camporesi & K.D. Hyde, in Tibpromma et al., Fungal Diversity 83: 74 (2017)
Index Fungorum number: IF 552695; Facesofungi number: FoF 2775
Etymology: Named after the host genus.
Holotype: MFLU 15-1489
Saprobic on dead stem of Petasites sp. Sexual morph: Ascomata 573–661 μm high × 437–508 μm diam. (x̄ = 624 × 494 μm, n = 5), superficial, flattened at the base, solitary, black subglobose, solitary or aggregated, ostiolate. Peridium 20–50 μm wide, comprising 1–2 layers, the outer layer heavily encrusted with pigments and often longitudinally striate on the surface pigmentation and the inner layer comprising thick-walled, hyaline cells of textura angularis. Hamathecium comprising few, 0.6–1.5 μm wide, septate, guttulate pseudoparaphyses. Asci 60–92 × 9–12 μm (x̄ = 81 × 10 μm, n = 10), 8-spored, bitunicate, cylindrical, slightly curved, with short, furcate pedicel. Ascospores 14–16 × 4–6 μm (x̄ = 15 × 6 μm, n = 20), overlapping 1–2-seriate, 2-celled, hyaline, 1-septate, guttulate, enlarged at the first cell, constricted at the septum, conical at the ends, smooth-walled, lacking a mucilaginous sheath. Asexual morph Undetermined.
Culture characteristics: Colonies on MEA reaching 7 cm diam. after 7 days at 16 °C, edge entire, brown to black mycelium, raised, producing fruiting bodies on media.
Material examined: ITALY, Province of Forlı`-Cesena, near Campigna—Santa Sofia, dead stem of Petasites sp. (Asteraceae), 9 June 2014, Erio Camporesi, IT1920 (MFLU 15-1489, holotype; ex-type living culture, MFLUCC 15-0076); Ibid. (HKAS 94594 bis, paratype).
GenBank Numbers LSU:KY496729, ITS:KY496749, SSU:KY501117, RPB2:KY514407.
Notes: Calophoma petasitis is introduced as a new species with the first report of a sexual morph for this genus. The sexual morph of C. petasitis is characterized by subglobose ascomata and smooth-walled, guttulate, hyaline ascospores lacking a mucilaginous sheath. Multigene phylogenetic analyses support the position of the new taxon in Calophoma and its establishment as a new species. Calophoma petasitisi clearly segregates from other known species. We attempted to induce the asexual morph of this species on WA media and found that they produce ascomata on media (Tibpromma et al. 2017).