Muyocopron yunnanensis L. Lu, K.D. Hyde & Tibpromma, sp. nov.

Index Fungorum number: IF 900169; Mycobank number: MB 900169; Facesoffungi number: FoF 13910; Fig. 1

Etymology – The specific epithet refers to the location, Yunnan, from where the holotype was collected.

Holotype – MHZU 22-0124

Saprobic on dead wood of unknown host. Sexual morph Ascomata 60–90 µm high × 180–400 µm wide (x̄=75×255 µm, n=10), superficial, solitary or scattered, conspicuous at the surface, appearing as irregular or circular, flattened, yellowish-green and surrounded by one black bands spots, covering the host, without a subiculum, short ostiole. Peridium 17–22 µm wide, thick-walled; outer layer comprising brown to black, pseudoparenchymatous cells, inner layer comprising light brown cells of textura angularis. Hamathecium comprises numerous, dense, 1.5–2 µm wide, filiform, filamentous, branched, septate pseudoparaphyses. Asci 45–80×25–35 μm (x̄=56×29 μm, n=20), 8-spored, bitunicate, obovoid or pyriform, hyaline, with ocular chamber when young. Ascospores 18–22×10–12 µm (x̄=19×11 µm, n=20), overlapping 1–2 seriate or crowded, oval to ellipsoid, or ovoid, hyaline, aseptate, smooth-walled, with oil guttules when immature. Asexual morph Not observed.

Culture characteristics – Ascospores germinated within 12 h on PDA. Colonies on PDA, 35 mm diam. after two weeks, colonies medium dense, circular, flatted, entire edge, colony from above, white to cream; from below, yellowish at margin, light brown at centre.

Material examined – China, Yunnan Province, Jinghong City, on an unidentified dead wood, 14 September 2021, Li Lu, JH6 (MHZU 22-0124, holotype), ex-type ZHKUCC 22-0216, ZHKUCC 22-0217.

GenBank numbers – ITS: OQ064500; LSU: OQ064502; SSU: OQ064504 (ZHKUCC 22-0216), ITS: OQ064501; LSU: OQ064503; SSU: OQ064505 (ZHKUCC 22-0217).

Notes – Muyocopron yunnanensis is morphologically similar to characteristics of Muyocopron species, in having superficial, circular, flattened ascomata, bitunicate, 8-spored asci, and oval to obovoid, hyaline ascospores (Spegazzini 1881; Mapook et al. 2016). In multigene phylogeny, M. yunnanensis formed a distinct clade in Muyocopron with 0.90 BYPP values (Fig. 2). Based on the blast results of sequence, ITS 91.7% was similar to M. laterale (MK487741), LSU 98.5% was similar to M. coloratum (MK487710), but M. laterale and M. coloratum were reported as asexual from leaf spot of Alloteropsis semialata and Cattleya sp. in Australia respectively, thus, it is unable to compare morphology with M. yunnanensis (Hernández-Restrepo et al. 2019), while SSU was similar to M. dipterocarpi up to 99% (KU726969). Muyocopron yunnanensis and M. dipterocarpi have similar shapes and sizes of ascospore (hyaline, oval to ellipsoid, or ovoid, 18–22×10–12 µm vs. hyaline, oval to obovoid, (12–)15–18×(6–)7–9(–11), but they differ in that M. yunnanensis having yellowish-green and surrounded by one black bands spots on the substrate and obovoid or pyriform, without pedicellate asci, while M. dipterocarpi is brown to dark brown spots on the substrate and saccate or broadly obpyriform and pedicellate asci. Therefore, we introduce M. yunnanensis as a new species in Muyocopron.

Figure 1 – Muyocopron yunnanensis (MHZU 22-0124, holotype). a, b Appearance of ascomata on host. c, d Section of ascomata. e Section of peridium. f Hamathecium. g–i Asci. j–m Ascospores. n Germinated ascospore. o, p Culture on PDA from above and reverse. Scale bars: c, d=30 μm, e, f, j–n=10 μm, g–i=20 μm

Figure 2 – Phylogram generated from maximum likelihood analysis based on combined ITS, LSU and SSU sequence data. Related sequences were obtained from Kandawatte et al. (2021). Seventy-eight strains are included in the combined sequence analysis, which comprises 2483 characters with gaps. Lophium mytilinum (AFTOL-ID 1609) and Mytilinidion rhenanum (EB 0341) were used as the outgroup taxa. The tree topology of the ML analysis was similar to the BYPP. The best-scoring RAxML tree with a final likelihood value of − 21,247.317842 is presented. The matrix had 1250 distinct alignment patterns, with 31.45% of undetermined characters or gaps. Estimated base frequencies were as follows; A=0.243361, C=0.241210, G=0.293208, T=0.222222; substitution rates AC=1.761418, AG=3.375009, AT=1.973830, CG=1.330507, CT=7.087473, GT=1.000000; gamma distribution shape parameter α=0.248188. Bootstrap support values for ML equal to or greater than 60% and BYPP equal to or greater than 0.90 are given above the nodes. Newly generated sequences are in blue and type strains are in bold