Didymocyrtidium populnellum Vain., Acta Soc. Fauna Flora fenn. 49 (no. 2): 229 (1921) Fig. 1
Index Fungorum number: IF 384341; Facesoffungi number: FoF 06233
Saprobic on growing stems of unidentified trees. Sexual morph: Ascomata 10–35 µm × 35–45 µm (x̅ = 35.2 × 38.9 µm, n = 10), semi-immersed to superficial on host surface, simple, visible as dark brown to black circle on host surface. Peridium thick-walled, composed of several layers of dark-brown cells of textura angularis. Hamathecium present, with cellular pseudoparaphyses, anastomosing, branching, embedded in mucilaginous matrix, sometimes aparaphysate, covering asci by gelatinous matrix. Asci 25–31 µm × 15–17 µm (x̅ = 28.4 × 16.4 µm, n = 10), bitunicate, fissitunicate, 8-spored, ovoid to saccate, sessile with indistinct ocular chamber, thick-walled. Ascospores 9–10 µm × 3–4 µm (x̅ = 9.2 × 3.9 µm, n = 10), bi-to tri-seriate, or crowded, oval to ellipsoid, hyaline to subhyaline 1-septate, very slightly constricted at the septum, smooth or rough-walled. Asexual morph: Undetermined.
Material examined – FINLAND, Etelä-Häme, Tavastia, Asikkala, on stems of unidentified trees, June 1892, J.P. Norrlin (1866) (S-F216647, holotype).
Economic significance – None is reported.