Bambusicola didymospora Phookamsak, D.Q. Dai & K.D. Hyde, sp. nov. Index Fungorum number: IF552021
Etymology: The epithet Bdidymospora^ refers to the didymosporous ascospores and conidia.
Holotype: MFLU 11–0149
Saprobic on dead bamboo culms, as raised, black, domeshaped stractures, on host surface. Sexual morph: Ascostromata 90–155 μm high, 310–400 μm diam., solitary, scattered to gregarious, immersed in host cortex, with red pigment in the ostiole, with flattened base, convex or domeshaped, uni-loculate, rarely bi-loculate, with centrally located ostiole. Peridium 16–33 μm wide, thin- to thick-walled, of unequal thickness, poorly developed at the base, composed of several layers of dark brown to black, pseudoparenchymatous cells, intermixed with host cells, arranged in a textura angularis, coriaceous. Hamathecium of dense, 0.5–1.5 μm wide, filamentous, indistinct, septate, cellular pseudoparaphyses, not constricted at the septum, slightly rough-walled, anastomosing at the apex, embedded in a hyaline gelatinous matrix. Asci 55–85 × 9–13 μm (x = 71 × 11.2 μm, n = 20), 8-spored, bitunicate, fissitunicate, cylindric-clavate to clavate, short pedicellate, apically rounded, with an ocular chamber. Ascospores 17–23 × 4.5–6 μm (x = 20.7 × 5.6 μm, n = 25), overlapping bi-seriate, hyaline, fusiform, with rounded to acute ends, 1-septate, constricted at the septum, upper cell larger than lower cell, smooth-walled, guttulate, surrounded by a mucilaginous sheath. Asexual morph: Coelomycetous, produced in culture after 4 months. Conidiomata 90–210 μm high, 95–180 μm diam., pycnidial, solitary, semi-immersed to embedded in agar, visible as raised, black dots, ovoid to obpyriform, or irregular in shape, uniloculate, ostiolate, covered by vegetative hyphae. Wall of conidiomata thin-walled, composed of a few layers of orangish brown to dark brown, pseudoparenchymatous cells, arranged in textura angularis. Conidiophores reduced to conidiogenous cells. Conidiogenous cells (2–)5–8×1–3 μm (x = 5.5 × 2 μm, n= 30), enteroblastic, phialidic, determinate, discrete, cylindrical to ampulliform, hyaline, aseptate, apically attenuated, with distinct periclinal thickening, smooth-walled. Conidia (9.5–)10–13(−15) × 4–5 μm (x = 12.5 × 4.5 μm, n = 30), pale brown, oblong to ellipsoidal, rounded apex, with truncate base, 1-septate, slightly constricted at the septum, smooth-walled.
Culture characters: Colonies on MEA 26–30 mm diam. after 2 weeks at 25–30 °C, under 12 h light/12 h dark, circular, dense, flat, slightly raised, dull with entire edge, fluffy to floccose, with regular edge; white at the margin, becoming greyish at the center with red droplets; reverse white to cream at the margin, greenish-grey at middle, pale yellowish to reddish, slightly radiating with pale yellowish concentric ring; non-pigmented, forming black pycnidia at the margin.
Material examined: THAILAND, Chiang Rai, Muang District, Huai Mae Sai Waterfall, on dead culms of bamboo, 10 March 2010, R. Phookamsak, RP0028 (MFLU 11–0149, holotype), ex-type living culture, MFLUCC 10–0557, KUMCC; Phang-Nga Province, Amphoe Mueang Phangnga, Tambon Tham Nam Phut, forest, 8°26′24″N 98°32′15″ E, on dead culms of bamboo, 5 December 2014, Kevin D. Hyde DDQ00288 (MFLU 16–0882, paratype), living cultures, MFLUCC 15–0189, MUCL 55886.
Notes: Bambusicola didymospora is similar to B. massarinia D.Q. Dai & K.D. Hyde, B. bambusae D.Q. Dai & K.D. Hyde, B. loculata D.Q. Dai & K.D. Hyde and B. pustulata D.Q. Dai & K.D. Hyde in having didymosporous, fusiform ascospores with rounded ends. However, B. didymospora differs from B. massarinia in its asexual morph. Bambusicola didymospora forms oblong to ellipsoidal, brown to reddish brown conidia, with phialidic conidiogenous cells, while B. massarinia forms cylindrical, pale brown conidia with many guttules; phialidic conidiogenous cells were not observed (Dai et al. 2012). Bambusicola didymospora differs from B. loculata in having scattered ascostromata, while B. loculata forms multi-loculate ascostromata (Dai et al. 2015). Bambusicola didymospora differs from B. bambusae and B. pustulata in having immersed ascostromata strongly raised from host surface, black, dome-shaped, however, in B. bambusae and B. pustulata darken only at the slightly raised cracks (Dai et al. 2012).
FIG 9. Bambusicola didymospora (MFLU 11–0149, holotype). a Appearance of ascostromata on host surface; b Vertical section through ascoma; c Peridium; d Pseudoparaphyses; e–h Asci; i–l Ascospores; m Ascospore stained in Indian ink; n Ascospore germination on WA; o, p Culture characteristics (upper and lower sides); q, r Conidiomata produced on culture colony; s–v Conidiogenous cells producing conidia; w–aa Conidia. Scale bars: b = 100 μm, c, r = 50 μm, d, e–h, n = 20 μm, i–m = 10 μm, s–aa = 5 μm