Kirschsteiniothelia distoseptata W.P. Wang, H.W. Shen, K.D. Hyde & Z.L. Luo, in Wang, Hyde, Bao, Wanasinghe, Lin, Shen, Lu, Zhang, Su, Li, Al-Otibi, Yang & Luo, Mycosphere 15(1): 6534 (2024)

Index Fungorum number: IF902421; MycoBank number: MB902421; Facesoffungi number: FoF16094

Etymology – Referring to the distoseptate conidia of the species.

Holotype – HKAS 131382

Saprobic on submerged decaying wood. Asexual morph: Colonies effuse, hairy, scattered or gathered, dark brown. Mycelium mostly immersed, composed of pale brown, septate, unbranched hyphae. Conidiophores 60–140 (–250) × 2.9–3.9 µm (x̅ = 119 × 3.5 µm, n = 20), macronematous, mononematous, erect, smooth, pale brown to brown, septate, unbranched, subcylindrical, straight or flexuous at the base, truncate at the apex, and darker at the apex connect to conidia. Conidiogenous cells 11–23 (–30) × (1.9–) 3.3–4.5 µm (x̅ = 18 × 3.8 µm, n = 20), monoblastic, terminal, integrated, subcylindrical, pale brown to brown, with a black thickened scar at the connection with the conidia, percurrent proliferating. Conidia 24–35 × 4.9–6.7 µm (x̅ = 28.7 × 5.9 µm, n = 10), acrogenous, solitary or occasionally catenate, dry, obclavate, tapering to the apex, 3–4-distoseptate when mature, smooth, straight or slightly curved, pale brown to brown or olive green, rounded apical sometimes with a rounded, gelatinous sheath, thickened scar and truncate at the base. Conidial secession schizolytic. Sexual morph: Undetermined.

Culture characteristics – Conidia germinating on the potato dextrose agar (PDA) within 12 h, and germ tubes produced from the apex. Colonies on PDA reaching 25 mm diameter after 3 weeks at room temperature. Mycelium dry, dense, colonies on the surface of PDA, with regular edges, flat surface, velvety, brown to dark green, the lower layer is dark green. Reverse dark green, smooth.

Material examined – China, Yunnan Province, Wenshan Zhuang and Miao Autonomous Prefecture, Bamei Town, on submerged decaying wood, 28 February 2023, W.P. Wang, S-4436 (HKAS 131382, holotype), ex-type living cultures CGMCC 3.25402 = KUNCC 23–14619.

Notes – Kirschsteiniothelia distoseptata resembles K. submersa in having solitary or occasionally catenate, obclavate, apically rounded, distoseptate conidia with thickened scars and truncate base (Su et al. 2016). However, the phylogenetic analysis showed that K. distoseptata is closely related to K. sichuanensis (Fig. 2). Kirschsteiniothelia distoseptata is different from K. sichuanensis in having distoseptate conidia with a rounded, gelatinous sheath at the apex, and sometimes occasionally catenate. Furthermore, conidia of K. distoseptata are comparatively smaller than K. sichuanensis (24–35 × 4.9–6.7 vs. 34–54 × 8–14 µm) (Jin et al. 2024). The LSU and ITS sequences data of K. distoseptata (CGMCC 3.25402) differ from K. sichuanensis (MFLU 21–0130) by 0.54% (4/738 bp) and 14.24% (85/597 bp, 13 gaps), respectively.

Figure 3 – Kirschsteiniothelia distoseptata (HKAS 131382, holotype). a Colonies on the substratum. b−d Conidiophores. e–i Conidiophores with conidia. j Germinating conidium. k, l Colony on PDA from surface and reverse. Scale bars: b–d, j = 15 µm, e–i = 30 µm.

Figure 2 – RAxML tree based on analysis of Kirschsteiniotheliaceae that combined LSU, ITS, and SSU dataset. The combined analyses include 68 strains with 2133 characters, including gaps (LSU: 803 bp, ITS: 491 bp, and SSU: 839 bp). Bootstrap support values for maximum likelihood (ML) greater than 75% and Bayesian posterior probabilities greater than 0.95 are indicated above branches as ML/PP. The tree is rooted with Pseudorobillarda eucalypti (MFLUCC 12–0417) and P. phragmitis (CBS 398.61). The new collections are indicated in red. Ex-type strains are indicated with “T” after the strain number