Roussoella chiangraina Phookamsak, J.K. Liu & K.D. Hyde, 2014

Liu, Jian-Kui, Phookamsak, Rungtiwa, Dai, Dong-Qin, Tanaka, Kazuaki, Jones, Gareth, Xu, Jian-Chu, Chukeatirote, Ekachai & Hyde, Kevin D., 2014, Roussoellaceae, a new pleosporalean family to accommodate the genera Neoroussoella gen. nov., Roussoella and Roussoellopsis, Phytotaxa 181 (1), pp. 1-33 : 12-13

Roussoella chiangraina Phookamsak, J.K. Liu & K.D. Hyde , sp. nov. FIG. 5

Index Fungorum : IF550662

Etymology. Named after the city from where this fungus was collected, Chiangrai.

Saprobic on decaying bamboo culms or palms branches. Ascostromata 100–125 µm high, 650–750 µm diam,,immersed under a clypeus, raised, visible as black dome-shaped on host surface, uni-biloculate. Locules 65–125.5 μm high, 300–400 μm diam, subglobose to lenticularis with a flattened base, solitary to clustered, coriaceous, black, centrally ostiolate. Peridium 7.5–23 μm wide, composed of 3–4 layers of textura angularis, thin-walled, brown to dark brown. Hamathecium comprising 1.5–2 μm wide, numerous, anastomosing, broadly cellular pseudoparaphyses, branching at the apex, rough-walled, and embedded in a gelatinous matrix. Asci 70.5–90 × 5–6.5 μm (x = 78 × 5.5 μm, n = 20), 8−spored, bitunicate, cylindrical, short pedicellate, apically rounded with an ocular chamber (1–1.5 μm). Ascospores 8–11.5 × 3–4 μm (x = 9.5 × 3.5 μm, n = 30), uni-seriate or overlapping, ellipsoidal to fusiform, 2-celled, constricted at the septum, pale brown to brown, rough-walled, longitudinally ribbed. Ascospores germinated within 12 hours, initially from one cell, hyaline hyphae. Asexual morph produced on bamboo pieces on WA cultures after 2 months. Conidiomata 178–334 μm high, 180–300 μm diam, superficial, pycnidium, globose to irregular shape, flatten at the basal of pycnidium, scattered or gregarious, clustered to solitary, non ostiolate. Pycnidial wall 5–15 µm wide, composed of 4–5 layers of cells of textura angularis, 2–3 outer layers, thin-walled, dark brown to black, 1–2 inner layers, thin-walled, hyaline. Conidiophores arising from the basal cavity around conidiomata, unbranched, aseptate. Conidiogenous cells (1.5–)3–14(–19.5) × 1–2 µm (x = 5.5 ×1.6 μm, n = 20), annellidic, unbranched, ampulliform or lageniform, cylindrical or cylindric-clavate, hyaline, aseptate, thin-walled,. Conidia (3–)3.5–4(–4.5) × 1.5–2(–2.5) μm (x = 4 × 2 μm, n = 30), subglobose to oblong or ellipsoidal, initially hyaline, becoming brown to yellowish brown, aseptate with two guttules, rough-walled, verrucose.

Specimen examined. THAILAND, Chiang Rai, Muang District, Huai Mae Sai Waterfall , on dead branch of bamboo, 10 Mar 2010, R . Phookamsak, RP 0027 (holotype MFLU 11−0148 , ex-type living culture MFLUCC 10−0556 ) .

Notes: Roussoella chiangraina shares superficially similar morphology with R. neopustulans and R. siamensis ; however R. chiangraina has slightly smaller ascospores than the latter two species (8–11 × 3–4 µm vs. 10–12.5 × 3.5–5 µm).All phylogenetic reconstructions strongly suggested this species is phylogenetically distinct from R. neopustulans and R. siamensis ( FIGS. 1, 2). In addition, this fungus formed a “ Cytoplea ”-like asexual morph in culture; it has much smaller conidia (3.5–4.5 × 2–2.5 μm vs. 7–10(–13) × 4–5(–6) μm) compared with Cytoplea hysterioides (asexual morph of R. hysterioides ) and smooth walls, which is usually with minutely warty in C. hysterioides . The asexual morphs are not known for R. neopustulans and R. siamensis .

Figures

FIGURE. 5 Roussoella chiangraina (MFLU 11−0148). a. Ascostromata on host surface; b. Section through astrostroma; c. Section through peridium; d. Ascospores; e. Pseudoparaphyses; f−i. Asci; j−n. Ascospores; o. Germinating ascospore; p. Conidiomata produced on bamboo pieces after two months; q. Section through conidiomata; r. Pycnidial wall; s−t. Conidiogenous cells; u-ac. Conidia; ─ Scale bars: a, b = 200 μm; q = 100 μm; c−i, r = 20 μm; d, s, t, u = 10 μm; j−o = 5 μm; v−ac = 2μm.