Rhytidhysteron xiaokongense G.C. Ren & K.D. Hyde, 2022

Ren, Guang-Cong, Wanasinghe, Dhanushka N., Jeewon, Rajesh, Monkai, Jutamart, Mortimer, Peter E., Hyde, Kevin D., Xu, Jian-Chu & Gui, Heng, 2022, Taxonomy and phylogeny of the novel rhytidhysteron-like collections in the Greater Mekong Subregion, MycoKeys 86, pp. 65-85 : 65

Rhytidhysteron xiaokongense G.C. Ren & K.D. Hyde sp. nov.

Figure 2

Etymology.

The species epithet reflects the location where the species was collected.

Holotype.

HKAS 112728.

Diagnosis.

Similar to R. hysterinum and R. rufulum , but differs in some conidial features.

Description.

Saprobic on woody litter of Prunus sp. Sexual morph Undetermined. Asexual morph Conidiomata 448-464 × 324-422 µm (x̄ = 454 × 378 μm, n = 5), solitary, scattered, semi-immersed in the host, black, unilocular, subglobose to ampulliform. Ostioles 178-227 × 166-234 µm (x̄ = 205 × 198 μm, n = 6), central, short papillate. Conidiomata wall 30-40 μm thick, 4-6 layers, reddish-brown to dark brown cells of textura angularis. Conidiogenous cells 5-8 × 3-6 µm (x̄ = 6.8 × 4.5 μm, n = 10), subglobose or ellipsoidal, hyaline, smooth, forming in a single layer over the entire inner surface of the wall, discrete, producing a single conidium at the apex. Conidia 20-25 × 8-10 μm (x̄ = 22 × 9 μm, n = 20), hyaline to yellowish-brown when immature, becoming brown to dark brown at maturity, oblong to ellipsoidal, with rounded ends, straight to slightly curved, aseptate when immature, becoming 1-septate when mature, with granular appearance, slightly constricted at septa.

Habitat and distribution.

Known to inhabit woody litter of Prunus sp. (Yunnan, China) (this study).

Material examined.

China, Yunnan Province, Kunming city, Xiaokong Mountain (25.171311°N, 102.703690°E), on dead wood of Prunus sp. ( Rosaceae ), 21-Dec-2019, G.C. Ren, KM18 (HKAS 112728, holotype), ex-type living culture KUMCC 20-0160; KM17 (HKAS 112727, paratype), ex-paratype living culture KUMCC 20-0158 .

Notes.

Rhytidhysteron xiaokongense is similar to R. hysterinum and R. rufulum in having black, unilocular, subglobose conidiomata and dark brown, 1-septate conidia. However, some of the conidia features in these species are different: R. xiaokongense has oblong to ellipsoidal conidia with rounded ends, whereas the conidia of R. rufulum and R. hysterinum have a truncated base with a pore in the middle of the septum ( Samuels and Müller 1979). In the phylogenetic analyses, R. xiaokongense is distinct from R. rufulum and R. hysterinum and is more closely related to R. thailandicum . Rhytidhysteron xiaokongense has 1-septate, dark brown, oblong to ellipsoidal conidia, while R. thailandicum has globose to subglobose, hyaline conidia ( Thambugala et al. 2016). The sequence data from both mycelium and fruiting bodies confirms that single spore isolation was successfully performed.

Figures

Figure 2. Rhytidhysteron xiaokongense (HKAS 112728, holotype) a, b conidiomata on natural wood surface c sections through conidioma d ostiolar neck e conidioma wall f-h conidiogenous cells and developing conidia i-m conidia n germinated conidium o, p culture characters on PDA (o = above, p = reverse). Scale bars: 100 μm (c, d); 50 μm (e); 15 μm (f-h); 10 μm (i-m); 20 μm (n); 25 mm (o, p).