Rhytidhysteron hongheense Wanas., in Wanasinghe et al., Journal of Fungi 7(3, no. 180): 27 (2021)

Index Fungorum number: IF 837992; MycoBank number: MB 837992; Facesoffungi number: FoF 14168; Fig. 1

Saprobic on the dead twigs of Prunus pseudocerasus Lindl. Sexual morph: Hystherothecia 1000–2000 µm long×300–500 high×500–1,000 µm diam. (x=1680×420×740 µm, n=10), solitary or gregarious, sessile, slightly erumpent. Receptacle cupulate black, flat or slightly concave, with a slightly dentate margin. Excipulum 60–105 µm (x=75.4, n=20) wide, with the ecto-excipulum narrow-layered, deep, and thick-walled, with black cells of textura globulosa to textura angularis. Hamathecium 2–5 µm wide (x=4.1 µm, n=20), numerous, propoloid, pseudoparaphyses, reddish-orange pigmented. Asci 180–285×9–18 µm (x=212.3×12 µm, n=50), 8-spored, bitunicate, fisitunicate, long cylindrical, short pedicellate, rounded at apex. Ascospores 18–40 × 8.7–13.8 µm (x=28.1×11.1 µm, n=30), overlapping uniseriate, hyaline to light brown when young, dark brown at maturity, one-septate, ellipsoid, 3-septate, rarely muriform, guttulate. Asexual morph: Undetermined.

Culture characteristics – Colonies on PDA reached 40 mm in diameter after 7 days at 20 °C in the dark. Initially, the colony was white, circular, smooth, with an undulated edge, with floccose. After 4 weeks, it became greenish-grey and slightly raised at the centre and pale brown towards margin, dark brown from the reverse side. The hyphae were septate, branched, hyaline, thin, and smooth-walled.

Material examined – China, Sichuan Province, Jianyang City, Xingfucun, on decaying twigs of Prunus pseudocerasus (Rosaceae), N30° 28′ 37, E104° 20′ 58, 18 April 2021, Y. Chen, XFC14 (HUEST 21.0018), living culture UESTCC 21.0018.

Hosts and distribution – On decaying wood of Dodonaea Mill in Yunnan, China (Wanasinghe et al. 2021), on decaying twigs of Prunus pseudocerasus Lindl in Sichuan, China.

GenBank numbers – ITS: OL741380, LSU: OL741320, SSU: OL741383, tef1-α: ON411270

Notes – The combined ITS, LSU, SSU and tef1-α sequences analysis (Fig. 2) of our isolate (UESTCC 21.0018) show that our strain clusters with the type strain of R. hongheense (KUMCC 20-0222). Our collection is similar to R. hongheense (Wanasinghe et al. 2021) and we identified our strain as Rhytidhysteron hongheense. This is the first report of Rhytidhysteron hongheense on Prunus pseudocerasus.

Figure 1 – Rhytidhysteron hongheense (HUEST 21.0018). a, b Hysterothecia on decaying wood. c Horizontal section of hysterothecium. d Vertical section through hysterothecium. e Wall of the hysterothecium. f Pseudoparaphyses. g–k Asci. l–q Ascospores. Scale bars: d=100 µm, e–f=20 µm, g–q=10 µm

Figure 2 – The best scoring RAxML tree with a combined dataset of ITS, LSU, SSU and tef1-α sequence data of species of Rhytidhysteron. The topology and clade stability of the combined gene analyses was compared to the single gene analyses and no significant differences. The tree is rooted with Gloniopsis calami (MFLUCC 15-0739). The matrix had 850 distinct alignment patterns with 31.32% undetermined characters and gaps. Estimated base frequencies were as follows; A=0.239, C=0.250, G=0.276, T=0.235; substitution rates AC=1.213710, AG=2.120204, AT=1.148572, CG=1.118178, CT=5.920120, GT=1.0; gamma distribution shape parameter α=0.212865 and final likelihood value of − 13,078. Extype strains are in bold and newly generated sequences are in blue bold. Bootstrap support for ML≥75% and BI≥0.95 are given at the nodes. The scale bar presents the expected number of nucleotide substitutions per site