Roussoellopsis I. Hino & Katum., J. Jap. Bot.

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 : 23-25

Roussoellopsis I. Hino & Katum., J. Jap. Bot. 40: 86. 1965.

Type species. Roussoellopsis japonica (I. Hino & Katum.) I. Hino & Katum.

Saprobic on decaying bamboo culms. Ascostromata immersed under a clypeus or epidermis raised, visible as black, dome-shaped on host surface, solitary to gregarious, centrally ostiolate, multiloculate, cells of ascostromata of brown-walled textura angularis. Peridium composed of 2–3 layers of cells of textura angularis, light brown to brown thin-walled, flattened at the base. Hamathecium comprising numerous, anastomosing, hyphae-like, cellular pseudoparaphyses, branching at the apex, often constricted at the septum, and embedded in a gelatinous matrix.

FIGURE. Neoroussoella bambusae a. Ascostromata on host surface; b. Section through ascostroma; c. Section of peridium ; d. Pseudoparaphyses; e−h. Asci; i−l. Ascospores; m. Germinating ascospore; n−o. Culture characteristics; p. Conidiomata produced on bamboo pieces after two months; q. Section through conidiomata; r. Pycnidial wall; s−t. Conidiogenous cells; u−x. Conidia ; ─ Scale bars: q = 200 μm; b = 100 μm; c, r, s = 20 μm; d−h, m = 10 μm; i−l, t, u = 5 μm; v−x = 2 μm.

Asci 8–spored, bitunicate, fissitunicate, clavate, short to long pedicellate with shallow ocular chamber. Ascospores uni-biseriate, fusiform, thick-walled, 2-celled, constricted at the septum, hyaline, pale brown or yellowish brown. Asexual state Melanconiopsis or “Neomelanconium”-like. Conidiomata pycnothyrial, superficial to semi-immersed, subglobose, dark-brown to black, unilocular or multilocular, if unilocular, locules separated by vertical columns of lightly pigmented pseudoparenchyma; Peridium comprising several brown to dark brown layers with cells of textura angularis. Conidiophores reduced to annellidic conidiogenous cells, hyaline, cylindrical, smooth, formed from cells lining the inner most layer of the pycnidium. Conidia almost globose, black, aseptate, thick-walled surrounded by an entire gelatinous material.

Notes: Roussoellopsis was introduced by Hino and Katumoto (1965), typified by Ro. japonica (I. Hino & Katum.) I. Hino & Katum , and currently comprises three species, with all being transferred from Didymosphaeria by Hino and Katumoto (1965). Roussoellopsis is similar to Roussoella , but differs in having clavate asci and large fusiform ascospores which are strongly constricted at the submedian septum. In addition, Roussoellopsis has Melanconiopsis or “Neomelanconium”-like asexual morphs with annellidic conidiogenous cells, and aseptate, almost globose, black, thick-walled conidia ( Tanaka et al. 2009).