Nodulosphaeria modesta (Desm.) Munk ex L. Holm, in Holm, Symb. bot. upsal. 14(no. 3): 80 (1957)

Sphaeria modesta Desm., Ann. Mag. nat. Hist., Ser. 1: 1786 (1840)

Saprobic on dead stems. Sexual state: Ascomata 130–200 µm high, 150–250 µm diam., scattered, solitary to gregarious, immersed, erumpent to superficial, base not easy to remove from the substrate, visible as small, black dots on the host surface, uniloculate, coriaceous, globose to subglobose, setose, covered by hyphae, dark brown to black, ostiole central, with blunt brown hairs around the ostiole, papillate. Peridium 7–10 μm wide, thin-walled, of equal thickness, composed of two layers of pseudoparenchymatous cells, outer layer comprising 2–3 cell layers of dark brown to black, thickened cells, arranged in a textura angularis, inner layer comprising 3–5 cell layers of thin-walled cells, hyaline, flattened cells, arranged in textura angularis to textura prismatica. Hamathecium composed of numerous, 2–3 μm wide, filamentous, broad cellular pseudoparaphyses, with distinct septa, embedded in a mucilaginous matrix, anastomosing at the apex. Asci 60–70 × 13–17 μm ( = 67 × 15 µm, n = 20), 8-spored, bitunicate, fissitunicate, cylindrical to cylindric-clavate, subsessile to short pedicellate, apically rounded, with well-developed ocular chamber. Ascospores 29–40 × 5–6 µm ( = 35 × 6 µm, n = 40), partially overlapping 1–2 seriate, phragmosporous, cylindrical with slightly narrow ends, initially hyaline to subhyaline with small guttules, becoming yellowish-brown to brown at maturity, 4-septate, slightly curved, constricted at the septa, smooth-walled, with small, globose appendages, without a refractive sphere near the apices, enlarged at the second cell below the apex. Asexual state: Unknown.

Material examined: ITALY, Forlì-Cesena, Montevescovo, on dead stem, 8 February 2012, E. Camporesi (MFLU 14-0304), living culture = MFLUCC 11-0461 = MUCL.

Notes: Based on the morphological comparison, our isolate is similar to Nodulosphaeria modesta due to its small ascomata covered by hairs and short, broad setae at the papilla apex, the asci are bitunicate and clavate and the ascospores are cylindrical, brown, 4-septate with narrow with narrow apices, and an enlarged cell at the second cell below the apex. The multigene phylogenetic analysis indicates that Nodulosphaeria belongs to Phaeosphaeriaceae (Fig. 1, 2).

Fig. 1 Nodulosphaeria modesta (MFLU 12-2214). a Ascomata on host substrate. b Close up of ascoma. c−d Section of ascoma. e Close up of the peridium. f Hamathecium of dense long cellular pseudoparaphyses. g−j Asci with short, broad pedicel bearing 8 spores. k−n Mature and immature ascospores. Scale bars: c = 100 μm, e = 20 μm, d, f, g, h, i, j, k, l, m, n, o = 10 μm.