Soloacrosporiella acaciae Crous & M.J. Wingf., Persoonia 34: 183 (2015)

Index Fungorum Number: IF 812421; MycoBank Number: MB 812421; Facesoffungi Number: FoF 12484

Etymology – Name reflects the host genus Acacia, from which the species was isolated.

Mycelium consisting of hyaline, smooth, septate, branched, 1.5 µm diam hyphae. Setae erect, solitary, flexuous, distributed throughout the colony, foot cell swollen or T-cell lacking rhizoids, stipe brown, smooth, uniformly 2–2.5 µm diam, up to 300 µm long, multiseptate, apex obtusely rounded. Conidiophores erect, solitary, arising from superficial hyphae, subcylindrical, pale brown, smooth, straight to flexuous, 15–80 × 2–3 µm. Conidiogenous cells integrated, terminal or intercalary, proliferating sympodially, subcylindrical, pale brown, smooth, 5–20 × 1.5–2 µm; loci slightly thickened and darkened, 0.5–1 µm diam. Conidia in branched chains, pale brown, smooth, guttulate, fusoid-ellipsoid to subcylindrical. Ramoconidia fusoid-ellipsoid, 1(–3)-septate, base obtusely rounded, apex with 1–3 sympodial loci that are slightly thickened and darkened, 0.5–1 µm diam, 17–25 × 2.5–4 µm. Conidia in chains of up to 20, acropetal in development, fusoid-ellipsoid, 1-septate, frequently slightly constricted at septum, loci thickened and darkened, 0.5–1 µm diam, (5–)10–13(–15) × (2–)2.5–3 µm.

Culture characteristics — Colonies spreading, reaching 40 mm diam after 1 mo at 25 °C, lacking aerial mycelium with smooth margin. On PDA surface honey, reverse isabelline in centre, honey in outer region. On OA centre honey, outer region rosy vinaceous due to diffuse pigment. On MEA surface greyish rose, reverse salmon to ochreous.

Typus – Malaysia, Sabah, on seed pods of Acacia mangium (Leguminosae), May 2014, M.J. Wingfield (holotype CBS H-22223, culture ex-type CPC 24871 = CBS 139894;

GenBank Accession Numbers – ITS: KR476729, LSU: KR476764

Notes — Soloacrosporiella is morphologically similar to Soloacrospora, but differs in that it has a much more complex arrangement of conidia, occurring in branched chains with ramoconidia and terminal conidia. Furthermore, conidiogenous loci and conidial hila are slightly thickened and darkened, features which are absent in Soloacrospora (Castañeda Ruiz et al. 1997). Phylogenetically, it is allied to the genus Neocladophialophora (Crous et al. 2014c), but is morphologically distinct in that its colonies produce numerous brown setae, produces well-defined conidiophores and ramoconidia, which are absent in Neocladophialophora.


Figure 1 – Soloacrosporiella acaciae. Symptomatic leaf of Acacia mangium; setae, conidiophores and conidial chains. Scale bars = 10 µm.