Kirschsteiniothelia acutisporum S. Wang, Q. Zhao & K.D. Hyde sp. nov.

MycoBank number: MB 559759; Facesoffungi number: FoF 11799; Fig. 1

Etymology – Named after the acute conidia

Holotype – MFLU 21-0127

Saprobicon decaying plant substrates. Sexual morph: Not observed. Asexual morph: Colonies effuse, scattered, dark brown to black, hairy, glistening. Mycelium partly superficial, partly immersed in the substratum, composed of brown, septate, branched hyphae. Conidiophores macronematous, mononematous, solitary, cylindrical, straight or slightly flexuous, dark brown, slightly tapering towards the apex, 8–12 septate, truncate at the apex, 180–260 µm (x̄ = 230 µm, n = 10) long, 7–12.5 μm (x̄ =9 µm, n = 10) wide. Conidiogenous cells integrated, terminal, monoblastic, cylindrical and\, brown, calyciform. Conidia acrogenous, solitary, obclavate to obspathulate, tapering to the apex, rostrate, 7–12-euseptate, mid to dark brown, becoming pale brown to pale towards the apex, truncate at the base, 75–120 µm (x̄ = 92 µm, n = 15) long, 10.5–19.5 μm (x̄ = 15 µm, n = 15) wide.

Material examined – Thailand, Chiang Mai Province, saprobic on decaying wood at the Mushroom Research Center (MRC), August 2020, Song Wang, SW231 (MFLU 21-0127, holotype).

GenBank numbers – ON980758 (LSU); ON980754 (SSU); OP120780 (ITS); OP009582 (rpb2)

Notes – Kirschsteiniothelia acutisporum shares similar characteristics with K. fluminicola in having macronematous, unbranched, cylindrical, septate, conidiophores and solitary, obclavate, septate, conidia. However, Kirschsteiniothelia acutisporum differs from K. fluminicola in having a gelatinous rounded sheath at the apex of shorter and thinner conidia (33–43 × 7.5–8.5 μm vs 47.5–86.5 × 8–10 μm). Kirschsteiniothelia acutisporum phylogenetically creates an independent branch with 100ML/100MP/1.00BYPP support (Fig. 2).

Figure 1 – Kirschsteiniothelia acutisporum (MFLU 21-0127, holotype) A–C Colonies on dead wood. D,E Conidiophore with conidia. F,G Conidiogenous cells and conidia. H Conidiogenous cell. I–M Conidia. N Germinating conidium. Scale bars: A = 100 μm, B = 200 μm, C–E = 100 μm, F,G= 50 μm, H = 20 μm, I–N = 50 μm.

Figure 2 – Phylogram generated from maximum likelihood analysis based on combined LSU, SSU, ITS sequence data. Forty-six taxa were included in the combined analyses, which comprised 2,104 characters (LSU=1–788 bp, SSU=789–1,632 bp, ITS=1,633–2,104 bp), including alignment gaps. Among them, 1,191 characters were constant, 239 characters were singleton sites, and 674 characters were parsimony informative. The best scoring RA×ML tree is presented. Bootstrap support values for ML and MP≥75% and BYPP≥0.95 are given above the nodes. Pseudorobillarda eucalypti (MFLUCC 12–0422) and P. phragmitis (CBS 398.61) were used as the outgroup taxa. The newly generated sequences are indicated in red. The ex-type strains are indicated in bold