Tetraploa obpyriformis C.F. Liao, K.D. Hyde & Doilom, sp. nov.
Index Fungorum number: IF 559272; MycoBank number: MB 559272; Facesoffungi number: FoF 10586; Fig. 1
Etymology – referring to the obpyriform conidia character of this fungus.
Saprobic on dead stem of Tripidium arundinaceum (Retz.) Welker, Voronts. & E.A. Kellogg. Sexual morph: Undetermined. Asexual morph: Colonies pale brown to black, effuse, superficial on the host substrate. Mycelium pale brown, branched, aseptate. Conidiophores absent. Conidigenous cells monotretic, intercalary, clavate, aseptate, verrucose. Conidia 30–47 × 17–39 µm (x = 36 × 26 µm, n=30), obpyriform, dark green to light brown, verrucose at base, composed of four columns, 2–4-septate in each columns, 1–5 appendages, mostly 4 appendages. Appendages 50–160 µm long (x=98 µm, n=30), 6–10 µm wide at the base, 2–4 µm wide at the apex, divergent, straight or slightly flexuous, smooth-walled, unbranched, gradually tapering to the tip, brown to dark brown, subhyaline at the apex, 4–12-septate, smooth-walled.
Culture characteristics – Colonies on PDA at 25±2 ℃, after 17 days reaching to 40–45 mm, floccose, convex or dome-shaped, mucoid or oil droplets at the center, light gray to dark green and almost glabrous towards the periphery, with a fimbriate margin; reverse blackish green to light brown; no pigment production.
Material examined – China, Yunnan Province, Kunming City, from dead stem of Tripidium arundinaceum (Poaceae), 4 July 2020, C.F. Liao, (KUN–HKAS 107637, holotype), ex-type culture KUMCC 21-0011.
GenBank numbers – ITS: OL473558, LSU: OL473554, SSU: OL473557, β tubulin: OL473558, tef1-α: OL505598.
Notes – In the multigene phylogenetic analyses of ITS, LSU, SSU, β tubulin, and tef1-α our collection (KUMCC 21-0011) grouped with Tetraploa bambusae (KUMCC 21-0844) and an undescribed Tetraploa species (KT 1684) with ML=92% and BI=0.99 statistical support (Fig. 2). A comparison of LSU, ITS, SSU and β tubulin sequences of our isolate showed 0.36%, 5.15%, 0.6% and 5.67% nucleotide differences with T. bambusae and the nucleotide differences between our isolate and Tetraploa sp. (KT 1684) are 0.48%, and 0.7% for LSU and SSU.
Figure 1 – Tetraploa obpyriformis (KUN-HKAS 107637, holotype). a–c Conidia on host substrate. d–h Conidia. i Conidia with conidiogenous cell. j Germinating conidium. k Surface view of colony on PDA. l Reverse view of colony on PDA. Scale bars: d, i, j=20 μm, e–h=50 μm
Figure 2 – Phylogram generated from maximum likelihood analyses based on combined LSU, ITS, SSU, β tubulin and tef1-α sequence data which comprised 3716 characters (LSU=852, ITS=571, SSU=1,336, β tubulin=639, tef1-α=318). The best scoring RAxML tree with a final likelihood value of f − 20,590.306011 is presented. The matrix had 1192 distinct alignment patterns, with 32.10% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.239693, C=0.252943, G=0.275644, T=0.231720; substitution rates AC=2.413323, AG=3.943519, AT=1.709808, CG=1.421703, CT=8.021695, GT=1.0; gamma distribution shape parameter α=0.164747. Bootstrap support for ML and MP equal to or greater than 75% and Bayesian posterior probabilities equal to or greater than 0.95 (the rounding of values to 2 decimal proportions) are labelled at each node. Ex-type strains are in bold, while the new isolates are indicated in blue bold. The tree is rooted to Muritestudina chiangraiensis (MFLUCC 17-2551)