Roussoella scabrispora (Höhn.) Aptroot

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 : 17-18

Roussoella scabrispora (Höhn.) Aptroot , Nova Hedwigia 60: 368. 1995. FIG. 10

≡ Didymosphaeria scabrispora Höhn., Sber. Akad. Wiss. Wien, Math. Nat 118: 1501. 1909.

Saprobic on decaying bamboo culms or palms branches. Ascostromata 2−2.5 mm diam., immersed under a clypeus, raised, visible as black, dome-shape areas on host surface and becoming tumefied on maturity. Locules 350−500 µm high, 1000−1500 µm diam., solitary to gregarious, subglobose to ellipsoidal, dark brown, with an inconspicuous central ostiole. Peridium 10−15 µm wide, composed of dark brown cells of textura angularis, side wall wide, hyaline to dark brown, 300−500 µm wide, comprising host and fungal tissues. Hamathecium comprising 1−1.5 µm wide, numerous, anastomosing, cellular pseudoparaphyses, branching rough-walled, and embedded in a gelatinous matrix. Asci (165−)197.5−217.5(−228) × 9.5−11.5(−12.5) µm (x = 198.5 × 10.5 µm, n = 20), 8−spored, bitunicate, cylindrical, with a short knob-like pedicel, with an apical chamber. Ascospores (24−)25−29(−32) × (7−)9−10.5 µm (x = 27 × 9.6 µm, n = 30), uni-seriate or overlapping, ellipsoid to broad fusiform, 2-celled, constricted at the septum, narrowly at both ends, with a reticulate spore wall ornamentation.

Specimen examined THAILAND, Chiang Rai Province, Doi Pui , on dead culm of bamboo, 1 Sep 2011, D. Q Dai; DDQ00116 ( MFLU 13−0641 , living culture MFLUCC 11−0624 ) .

Notes: Roussoella scabrispora has distinctive ascospores with a reticulate wall ornamentation. There are only two species in Roussoella that have reticulate spore wall ornamentation, namely R. angustispora and R. scabrispora , with R. angustispora having conspicuously narrower ascospores (24−28 × 6−8 vs. 26.5−35 × 10−12.5 µm) ( Zhou et al. 2003). The ascospores of this collection are slightly smaller (25−29(−32) × (7−)9−10.5 µm vs. 26.5−35 × 10−12.5 µm) than in the protologue ( Hyde 1997). Roussoella scabrispora was phylogenetically closely related with Roussoellopsis species (FIG. 1). This could possibly be a species of Roussoellopsis , however, it did not produce an asexual state in culture and asci are typical of Roussoella .

FIGURE 0. Roussoella scabrispora . a, b. Ascostromata on bamboo culm; c. Section of ascostroma; d, e. Wedge-shaped stromatic region; f. Pseudoparaphyses; g. Apex of ascus; h−l. Asci; m. Germinating ascospore; n−p. Ascospores with reticulate ornamentation; q, r Culture on PDA after 30 days. ─ Scale bars: a = 10 mm; b = 3 mm; c=200 μm; d, e=100 μm; f, g, m−p=10 μm; h−l = 30 μm.