Pleosporales » Roussoellaceae » Roussoella

Roussoella aquatica

Roussoella aquatica W. Dong, H. Zhang & K.D. Hyde

Index Fungorum number: IF557933, Facesoffungi number: FoF09276

Holotype: MFLU 18-1169

Etymology: referring to aquatic habitat of this fungus


Saprobic on submerged wood. Sexual morph: Undetermined. Asexual morph: Stromata immersed under an epidermis, becoming raised at maturity, 1–2 locules. Locules 150–180 μm high, 210–240 μm diam., immersed in the stromata, conical or hemispherical, flattened at the base, dark brown to black, ostiolate. Peridium 10–30 μm thick, comprising 3–5 layers of brown, thick-walled cells of textura angularis. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 3–4 × 1.5–2 μm, enteroblastic, annellidic, integrated, determinate, ampulliform, hyaline, smoothwalled. Conidia 2.7–3.5 × 2–2.5 μm ( = 3.2 × 2.2 μm, n = 30), ellipsoidal, aseptate, straight, rounded at both ends, brown to greenish brown, smooth-walled. (Description from Dong et al. 2020)


Material examined: CHINA, Yunnan Province, Dehong, on submerged wood in a stream, 25 November 2017, G.N. Wang, H1A-1 (MFLU 18-1169, holotype), ex-type living culture MFLUCC 18-1040; ibid., H1A-2 (HKAS 101739, isotype), ex-type living culture KUMCC 18-0091.


Notes: Roussoella aquatica is similar to R. tuberculata D.Q. Dai & K.D. Hyde in having ellipsoidal, aseptate, brown conidia. However, the latter has small, roughened tubercules sparsely covering the conidia (Dai et al. 2017), while R. aquatica has smooth-walled conidia. Additionally, R. aquatica has smaller conidia than R. tuberculata (2.7–3.5 × 2–2.5 μm vs. 8.5–10 × 4.5–5.5 μm). The ellipsoidal, brown, aseptate conidia of R. aquatica are also similar to R. chiangraina Phook. et al, but the latter has obvious verrucose conidia (Liu et al. 2014; Wijayawardene et al. 2016), and molecular evidence shows them to be different species. (Notes from Dong et al. 2020)


Freshwater distribution: China (Dong et al. 2020)