Sporidesmium guttulatum W.P. Wang, H.W. Shen, K. D. Hyde & Z.L. Luo, in Liu, Gu, Gou, Liu, Chen, Wu & Liu, MycoKeys 123: 183 (2025)

Index Fungorum number: IF902435; MycoBank number: MB902435; Facesoffungi number: FoF16119

Etymology – Referring to guttulate conidia of this fungus.

Holotype – HKAS 131397

Saprobic on submerged decaying wood. Asexual morph: Colonies effuse, hairy, scattered or in small groups, olivaceous to brown. Mycelium mostly immersed, composed of branched, septate, hyaline to pale brown, smooth hyphae. Conidiophores 26–55 × 3.4–5 µm (x̅ = 40 × 4 µm, n = 20), macronematous, mononematous, solitary, cylindrical, straight or slightly flexuous, 1–3-septate, smooth-walled, olivaceous to brown, truncate at apex, swollen at the base. Conidiogenous cells 12– 20 × 3–4.8 µm ( x̅ = 15.4 × 3.9 µm, n = 20), monoblastic, integrated, terminal, determinate, cylindrical, smooth-walled, olivaceous to brown. Conidia 44–84 × 8.7–12 µm (x̅ = 64 × 10.1 µm, n = 20), acrogenous, solitary, dry, olivaceous to pale brown, paler at the apex, obclavate, tapering gradually towards the apex, smooth-walled, straight or slightly curved, 6–14-distoseptate, guttulate, most with a mucilaginous sheath over the apex to middle, truncate basal with a 2–3.1 µm wide conspicuous darkened scar. Sexual morph: Undetermined.

Culture characteristics – Conidia germinating on PDA within 24 h, and germ tubes produced at the apex and middle. Colonies on PDA reaching 5 mm diameter after 4 weeks at room temperature. Mycelium damp, dense, colonies on the surface of PDA, surface smooth, dry, irregular edges, accumulate in the middle, brown to dark brown. Reverse smooth, brown.

Material examined – China, Yunnan Province, Wenshan Zhuang and Miao Autonomous Prefecture, Bamei Town, on submerged decaying wood, 7 February 2022, W.P. Wang, S-3481 (HKAS 131397, holotype), ex-type living cultures CGMCC 3.27021 = KUNCC 23–13374.

Notes – In the phylogenetic analysis, Sporidesmium guttulatum is sister to S. nujiangense with 89% ML/ 1.00 PP support (Fig. 2). Sporidesmium guttulatum shares the similar sized, septate conidiophores with S. nujiangense, however, it differs from S. nujiangense in having guttulate and longer (44–84 vs. 54–69 µm) conidia (Bao et al. 2021). Comparison of ITS and LSU nucleotides sequences between S. guttulatum (CGMCC 3.27021) and S. nujiangense (DLUCC 983) indicates that 3.74% (17/454 bp, four gaps) and 2.25% (18/801 bp) difference, respectively.

Figure 1 – Sporidesmium guttulatum (HKAS 131397, holotype). a Colonies on the substratum. b−e Conidiophores. f Conidiophore with conidium. g–l Conidia. m Germinating conidium. n, o Colonies on PDA from surface and reverse. Scale bars: b–m = 15 µm.

Figure 2 – RAxML tree based on analysis of Sporidesmium that combined LSU, ITS, SSU, rpb2, and tef1-α dataset. The combined analyses include 81 strains with 4172characters including gaps (LSU: 822 bp, ITS: 525 bp, SSU: 916 bp, rpb2: 974 bp and tef1-α: 888 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 Sordaria fimicola (CBS 508.50). 6620 The new collections are indicated in red. Ex-type strains are indicated with “T” after the strain number.