Triplosphaeria acuta

Triplosphaeria acuta Kaz. Tanaka & K. Hiray.

Index Fungorum number: IF515263

Etymology: In reference to the large-sized ascospores.

Holotype: HHUF 29387

Sexual morph: Ascomata 250–300 μm high, 900–1000 μm diam (including the rim), with single locule of 420–530 μm diam, scattered to sometimes clustered, immersed below the epidermis, globose to subglobose, glabrous. Beak none or short, with hyaline sparse periphyses-like hyphae, filled with pseudoparaphyses tips. Ascomatal wall at sides 170–270 μm wide and rim-like, composed of vertically orientated rectangular to polygonal 5–13 × 3.5–8 μm hyaline cells; near the epidermis composed of polygonal to subglobose brown cells of 3–10 μm diam; at the base flattened and poorly developed. Pseudoparaphyses narrowly cellular, numerous, 1–2.5 μm wide, guttulate, branched and anastomosed, with thin septa at 7 to 20 μm intervals. Asci 95–133 × 14.5–21 μm (x̄ = 113 × 18 μm, n = 50), fissitunicate, numerous, basal and somewhat lateral, clavate to cylindrical, rounded at the apex, short-stalked (7–25 μm long), with (4–)8 biseriate ascospores. Ascospores (32.5–)34–45(–48.5) × (6–)7–9(–10) μm (x̄ = 38.9 × 7.9 μm, n = 120), L/W 4.2–5.9 (x̄ = 5.0, n = 120), narrowly fusiform with acute ends, straight or slightly curved, 1-septate, submedian (0.50–0.54 x̄ = 0.52, n = 94), constricted at the septum, hyaline, up to 4 guttules in each cell or without guttules, smooth, with an inconspicuous sheath of 3–7 μm wide. (Descriptions from Tanaka et al. 2009)

Culture characteristics: Colonies on PDA attaining 2.6–2.8 cm diam, velvety in appearance, olive (2E4), with whitish entire margin of 2 mm; reverse dark green (29F6); no pigment produced. On RSA, a Tetraploa-like asexual morph with 3 setose appendages is formed. Conidiophores absent. Conidiogenous cells monoblastic. Conidia consist of a conidial body and 3 setose appendages, solitary. Conidial body 41–55 × 17–23(–27.5) μm (x̄ = 48.3 × 19.3 μm, n = 61), L/W = 2.2–3.2 (x̄ = 2.5, n = 61), 5–6-pseudoseptate, pale brown, smooth, narrowly ovate or ovate. Appendages 12–66 μm long (x̄ = 27.4 μm, n = 65), 3–4 μm wide, 1–6-septate, pale brown at the base and almost hyaline at the apex, smooth, unbranched, slightly curved.

Material examined: JAPAN, Aomori, Nishimeya, Ookawa, on culms of Sasa kurikensis, 23 July 2002, S. Hatakeyama, HHUF29330 holotype designated here, living culture KTC 870 (= JCM 13172 = MAFF 239682).

Note: This fungus is clearly distinguishable from other species of Triplosphaeria by its largest asci and ascospores.

Freshwater distribution: Japan (Tanaka et al. 2009)