Rhytidhysteron neorufulum

Rhytidhysteron neorufulum Thambug. & K.D. Hyde 2016

Index Fungorum number: IF 551865

Saprobic on decaying wood of Tectona grandis. Sexual morph Hysterothecia 1400–2100 μm long, 350–500 μm high, 600–1000 μm diam. (x̅ = 1780 × 400 × 700 μm, n = 5), superficial, black, solitary to aggregated, coriaceous, smooth, elliptical or irregular in shape, elongated with a longitudinal slit. Exciple 75–115μm (x̅ = 90, n = 20) wide, composed of several layers of brown to dark brown, thick-walled cells of textura angularis. Hamathecium 2–3.5 μm wide, dense, septate pseudoparaphyses, constricted at the septum, filiform, pale-yellow pigmented, forming epithecium above the asci and enclosed in a gelatinous matrix. Asci 190–260 × 13–18 μm (x̅ = 230 × 16 μm, n = 10), 8-spored, bitunicate, clavate to cylindrical, with a short furcate pedicel, apically rounded, without a distinct ocular chamber. Ascospores 36–44 × 11–17 μm (x̅ = 41 × 13 μm, n = 30), uni-seriate, yellowish to brown, with 1–3-septa, ellipsoidal to fusiform, slightly rounded or pointed at both ends, constricted at the central septum, with granular appearance. Asexual morph Undetermined.

Material examined: Thailand, Tak Province, Mogro District, Amphoe Umphang, on dead woods of Tectona grandis (Lamiaceae), 20-Aug-2019, G.C. Ren, T203 (HKAS 115534), living culture MFLUCC 21-0035.

Notes: Rhytidhysteron neorufulum was introduced by Thambugala et al. (2016) based on both morphological and phylogenetic analyses of a combined dataset of LSU, SSU and tef1-α sequence data. Thambugala et al. (2016) accounted R. neorufulum (MFLUCC 13-0216) from decaying woody stems and twigs in Thailand. Our new collection shares similar morphology to that of the type description of Rhytidhysteron neorufulum (MFLUCC 13-0216) in having superficial, coriaceous, elliptical or irregular, elongated hysterothecia with a longitudinal slit, bitunicate, cylindrical, short furcate pedicel asci and yellowish to brown, ellipsoidal to fusiform ascospores with 1–3-septa (Thambugala et al. 2016). However, our new collection has larger asci (190–260 × 13–18 μm vs 185–220 × 9.5–13 μm) and ascospores (36–44 × 11–17 μm vs 19–31 × 8–13 μm) in comparison to the type of Rhytidhysteron neorufulum (MFLUCC 13-0216). The multi-gene phylogenetic analysis based on combined SSU, LSU, ITS, and tef1-α sequence data showed that our collection is related to Rhytidhysteron neorufulum.