Apiognomonia errabunda (Roberge ex Desm.) Höhn., Ann Mycol. 16(1/2): 51 (1918)

Index Fungorum number: IF 264192, MycoBank number: MB 264192, Facesofungi number: FoF 07116, Fig. 1

Saprobic or parasitic on the host plant. Sexual morph: see Sogonov et al. (2007). Asexual morph: Conidiomata 900–1000 µm diam., 450–500 µm high, black, stromatic, pycnidial, solitary, deeply immersed when young, becoming erumpent at maturity, dehiscing by an irregular break
in the apical wall, multilocular, convoluted, with locules 200–450 µm diam., 200–400 µm high, ovoid to subglobose, thick-walled, glabrous, smooth-walled. Conidiomatal wall 85–180 µm wide, composed of relatively thick-walled, hyaline cells of textura angularis to textura intricata in the upper part, and thin-walled, hyaline cells of textura angularis in the basal and lateral part. Conidiophores arising from the inner layer cells of the conidiomata, hyaline, cylindrical, branched at the base, septate, smooth-walled. Conidiogenous cells 10–20×2–5 µm hyaline, enteroblastic, annellidic, ampulliform to subcylindrical, integrated or discrete, indeterminate, thick- and smooth-walled, tapered towards apex, with several indistinct percurrent proliferations (Fig. 24i, j, k, l). Conidia 10–15×3–5 µm (x̄ =12×4 µm; n=50), hyaline, fusiform to oval or cylindrical, rounded at both ends, straight or slightly curved, unicellular, smooth, guttulate.

Culture characters – colonies on MEA, reaching to 90 mm diam. after 14 d at 25 °C, forming concentric circles, white, fattened, with dense, filamentous, aerial, fluffy hyphae on the surface; margin entire, circular; reverse pale brown; colonies on PDA, reaching 30–40 mm diam. after 14 d at 25 °C, without forming concentric circles, whitish, plane to slightly convex, velutinous to felty, dense in the middle zone, becoming sparse in the marginal zone; margin entire to undulate; reverse whitish to pale brown with age.

Material examined – Italy, Province of Forlì-Cesena, Passo la Calla, on a dead branch of Fagus sylvatica (Fagaceae), 5 April 2016, Erio Camporesi, IT2571 (MFLU 16-1148), living culture MFLUCC 16-1318=ICMP 21528=KUMCC 16-0073, (KUN, HKAS 93598)

Notes – Conidia of strain (MFLUCC 16-1318) share a similar form (fusiform to oval or cylindrical) and dimension (av. 12.7 × 3.8, Sogonov et al. 2007) to those asexual morphs of Apiognomonia errabunda. Phylogenetic tree reconstruction based on the combined genes of LSU, ITS, rpb2 and tef1 sequence dataset of Apiognomonia and related genera shows that MFLUCC 16-1318 clustered with the epitype strain (CBS 775.79) of A. errabunda. Therefore, it is identified as the asexual morph of A. errabunda, and a detailed description and plate are provided.

Fig. 1. Apiognomonia errabunda (MFLU 16-1148). a Herbarium specimen. b–c Appearance of orange to yellowish conidiomata on the host. d–e Vertical section of conidiomata. f, g, h Section of peridium. i–m Conidiophores, conidiogenous cells and developing conidia. n Germinating conidium. o–p Conidia. q–r Culture on MEA. Scale bars b–d=500 µm, e=100 µm, f=20 µm, g–h=50 µm, i–m=10 µm, n=20 µm, o–p=5 mm, q