Roussoella bambusicola X. M. Chen, S. Tibpromma & Karun. 2024, sp. nov.

Roussoella bambusicola X.M. Chen, S. Tibpromma & Karun., sp. nov. FIGURE 2 Index Fungorum number: IF902581; Facesoffungi number: FoF 16483 Etymology: From Latin, cola means dwelling on, and Bambusa is the genus name of bamboo. Holotype: GMB-W1009 Saprobic on decaying bamboo culms. Sexual morph: Undetermined. Asexual morph: Stromata raised, ellipsoidal or globe, occasionally irregular, visible as black on the host surface. Conidiomata 170–550 × 120–220 μm (x = 449 × 169.5 μm, n = 15) scattered or gregarious immersed in the stromata, ellipsoidal, dark brown. Conidiomatal wall up to 70 μm wide comprised several layers of cells of textura angularis, with hyaline to dark brown. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 2.5–24 × 2–4.5 μm (x = 12 × 3 μm, n = 40), lining the inner wall layer of the pycnidium, ampulliform or lageniform to subcylindrical, slightly curved, hyaline, smooth-walled. Conidia 4–5.5 × 2.5–3 μm (x = 4.9 × 2.8 μm, n = 40), oblong or ellipsoidal, hyaline to light brown or yellowish brown, aseptate with two guttules, smooth or rough-walled. Culture characters: Conidia germinated on PDA within 24 h. 20 mm diam. after four weeks at 25–27 ° C, rounded, with even margin, white, with raised center, fluffy from above, white at the margin, black at the center, ringlike from below. Mycelium is superficial, branched, septate, white, smooth. Material examined: China, Yunnan Province, Lijiang City, Shigu Town, on dead culms of bamboo, 15 September 2023, X. M. Chen, LS118 (GMB-W1009, holotype), ex-type living culture GMBCC1032; ibid. LS118-1 (GMB-W1010 isotype), ex-isotype living culture GMBCC1034. Notes: Our new strain Roussoella bambusicola forms the sister clade with R. guttulate (MFLUCC 20-0102) with 91% ML, 1 PP statistical support (Figure 1). Based on a pairwise nucleotide comparison of ITS, LSU, tef 1-α, and rpb 2 sequences, R. bambusicola deviates from R. guttulate (MFLUCC 20-0102) by 70/543 bp (12.89%, without gaps) for ITS, 6/876 bp (0.68%) for LSU, 37/935 bp (3.95%) for tef 1-α, and 84/1065 bp (7.88%) for rpb 2. The asexual morph of Roussoella guttulate (MFLUCC 20-0102) is undetermined, so the morphological comparison is unavailable (Zhang et al. 2020). However, the asexual morphic features of Roussoella bambusicola resemble Roussoella in having ampulliform or lageniform to subcylindrical, hyaline conidiogenous cells, and oblong or ellipsoidal, aseptate, hyaline to brown conidia (Liu et al. 2014; Dai et al. 2017; Hyde et al. 2023). Therefore, we introduce our strain as a new species in Roussoella.