Thyridaria aureobrunnea Boonmee, Huanraluek & K.D. Hyde, sp. nov.

Index Fungorum number: IF 558540; MycoBank number: MB 558540; Facesoffungi number: FoF 09193; Fig. 1

Etymology – The specific epithet ‘aureobrunnea’ refers to the golden brown to chestnut brown ascospores.

Holotype – MFLU 21-0067

Saprobic on decaying wood. Sexual morph Ascomata 248–294.5 µm high, 262–286.5 µm diam. (x̅=330×367 µm, n=4), immersed, erumpent, aggregated, clustered, globose to subglobose, uniloculate, dark brown to black, central ostiole, with minute papilla. Ostiole, papillate, protruding from the center of the ascomata, with a pore-like opening, yellowish around apical pore when wet. Peridium 18×33 µm wide, comprising several layers of dark brown cells of textura angularis. Hamathecium comprising 1–2 µm wide, cylindrical, filamentous, rarely branched, inconspicuously septate, anastomosed, hyaline pseudoparaphyses. Asci 45–61.5 × 7–8.5 µm (x̅= 52 × 7.5 µm, n = 10), 8-spored, bitunicate, cylindric-clavate to clavate, slightly curved, bulbous pedicellate, apically rounded. Ascospores 10.5–13×3.5–4.5 µm (x̅=12×4 µm, n=20), overlapping uni- to bi-seriate, ellipsoid to obovoid, slightly curved, golden brown to chestnut brown, 3-septate, strongly constricted and darkened at the septa, guttulate, smooth-walled. Asexual morph Undetermined.

Culture characteristics – Ascospore germinating on PDA within 24 h and germ tubes produced from each cell of the ascospores. Colonies on PDA reaching 3.5 cm diam. after 2 weeks at room temperature, circular, entire edge, olivaceous brown to brown from the center towards margin, white grey at the margin, dark brown at the reverse with surrounded by white grey at the margin. Mycelium superficial, velvety.

Material examined – THAILAND, Chiang Rai Province, Mae Yao, on decaying wood, 23 September 2019, N. Huanraluek, MY06 (MFLU 21-0067, holotype), ex-type living culture, MFLUCC 21-0090.

GenBank number – ITS=MZ538528, LSU=MZ538562.

Notes – In the BLASTn search of LSU and ITS sequences, Thyridaria aureobrunnea is most similar to T. broussonetiae (CBS 121895 and CBS 141481) with 99.18% and 92.21% similarities, respectively. A combined LSU, ITS and TEF1-α sequence analysis indicates that T. aureobrunnea forms a distinct lineage basal to T. acaciae and T. broussonetiae (type species) with 100% MLBS, 1.00 BYPP support (Fig. 2). Thyridaria aureobrunnea (Fig. 1) can be distinguished from the type species T. broussonetiae in morphological characteristics such as uniloculate ascomata, shapes and size of asci and ascospores (Jaklitsch and Voglmayr 2016). In addition, Thyridaria acaciae is known only as an asexual morph which is produced in culture (Crous et al. 2014b; Jaklitsch and Voglmayr 2016), and thus we cannot compare the morphology. Based on the highly supported distinct lineage and differences in DNA sequences, a new species, Thyridaria aureobrunnea is introduced.

Figure 1 – Thyridaria aureobrunnea (MFLU 21-0067, holotype). a, b Ascomata on woody substrate. c Cross sections of ascoma. d Peridium. e Pseudoparaphyses. f–h Asci. i–k Ascospores. l Germinated ascospore. m, n Culture on PDA from surface and reverse at 1 month. Scale bars: c=50 µm, d, e=20 µm, f–h=10 µm, i–l=5 µm

Figure 2 – Maximum likelihood phylogenetic tree based on a combined LSU, ITS and TEF1-α sequence data of Thyridaria taxa (Thyridariaceae) and related families. Forty-two strains are included in the combined analysis, which comprise a total of 2216 characters. Occultibambusa bambusae (MFLUCC 11-0394 and MFLUCC 13-0855) are selected as the outgroup taxa. The best RAxML tree with a final likelihood value of − 12410.223662 is presented. RAxML analysis yielded 752 distinct alignment patterns and 19.90% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.235389, C=0.270091, G=0.280715, T=0.213806, with substitution rates AC=1.372292, AG=2.751820, AT=1.999735, CG=1.148507, CT=6.478337, GT=1.000000; gamma distribution shape parameter alpha=0.169795. Bootstrap support values for maximum likelihood (MLBS, left) equal to or greater than 70% is given above or below the nodes. Bayesian posterior probabilities (BYPP, right) equal to or greater than 0.95 are given above the nodes. Ex-type strains are in bold and newly generated sequence is in blue