Stigmatodiscus enigmaticus Voglmayr & Jaklitsch, in Voglmayr, Gardiennet & Jaklitsch, Fungal Diversity 80: 278 (2016)

Index Fungorum number: IF815328;

Saprobic on twigs of Acer monspessulanum. Asexual morph: not observed. Sexual morph: Ascomata 350–400 μm diam., dark brown to black, apothecioid, embedded in cortex of dead twigs, initially covered by bark, later becoming exposed through irregular cracks. Subhymenium thin, 14–16 μm height from base of ascomata and composed of tightly packed hyaline hyphae. Pseudoparaphyses 70–80 μm long, 1–2 μm wide. Asci (100–)115–120(–125) × (30–)35–40(–50) μm (n=20), bitunicate, broadly fusiform to ellipsoid, almost sessile, with a distinct apical chamber, containing 8 irregularly bi- to triseriate ascospores. Ascospores (45–)50–55(–58) × (12–)14–16(–18) μm (n=30), brown, asymmetric, at first 1-septate, developing 2 additional distosepta constricted at the septa, surrounded by gelatinous sheath, dark brown, the contents granular.

Material examined – Italy, Province of Forlì-Cesena, Rocca delle Caminate – Predappio, on twigs of Acer monspessulanum (Sapindaceae), 1 March 2017, E. Camporesi, IT425 (MFLU 17-0716).

GenBank Numbers – ITS: MT965719

Known distribution (based on molecular data) – Austria, Croatia, Czech Republic, France, Greece, Italy, Morava and Spain (Voglmayr & Amengual 2018).

Known hosts (based on molecular data) – Acer sp., Carpinus sp., Cistus sp., Globularia sp., Quercus sp., Olea sp., Pistacia sp., Pinus sp., Populus sp. and Tamarix sp. (Voglmayr & Amengual 2018).

Notes – A fungal strain obtained from twigs of Acer monspessulanum was identified as Stigmatodiscus enigmaticus, with support from both morphology and phylogeny. The new strain clustered with the type of S. enigmaticus (L69), in the combined ITS, SSU, TEF1-α, RPB2 and β-TUB phylogeny. Stigmatodiscus enigmaticus was recorded from Acer monspessulanum in the Czech Republic, France and Slovenia (Voglmayr et al. 2016). This is the first record of S. enigmaticus from Acer monspessulanum in Italy.

Stigmatodiscus enigmaticus (MFLU 17-0716, new host record). a, b Appearance of ascomata erumpent from bark. c Vertical section of apothecioid ascomata. d Peridium. e Subhymenium and base of pseudoparaphyses. f Pseudoparaphyses. g–i Asci. j–m Ascospores. Scale bars: c = 50 µm, d = 20 µm, e = 5 µm, f = 20 µm, e = 5 µm, g–i = 50 µm, j–m = 20 µm.