Sporidesmium filiforme W.P. Wang, H.W. Shen, K.D. Hyde & Z.L. Luo, in Liu, Gu, Gou, Liu, Chen, Wu & Liu, MycoKeys 123: 182 (2025)
Index Fungorum number: IF902436; MycoBank number: MB902436; Facesoffungi number: FoF16120
Etymology – Referring to the filiform conidial appendages of this species.
Holotype – HKAS 130435
Saprobic on submerged decaying wood. Asexual morph: Colonies effuse, hairy, scattered, sparkling. Mycelium mostly immersed, composed of branched, septate, hyaline to pale brown, smooth hyphae. Conidiophores 22–54 × 3.5–4.9 µm (x̅ = 33.8 × 4.2 µm, n = 10), macronematous, mononematous, solitary, cylindrical, straight, 1–3-septate, smooth-walled, brown, truncate at the apex. Conidiogenous cells 12–16 × 3.6–4.9 µm (x̅ = 14 × 4.1 µm, n = 10), monoblastic, integrated, terminal, determinate, cylindrical, smooth-walled, brown. Conidia (33–) 53–100 × 5.8–9.5 µm (x̅ = 78 × 7.7 µm, n = 20), acrogenous, solitary or occasionally catenate, dry, pale brown to olivaceous, obclavate, smooth-walled, straight, mostly 10-distoseptate, with a up to 140 µm long, filiform, hyaline to subhyaline apical appendage, truncate base with a conspicuous darkened scar. Conidial secession schizolytic. Sexual morph: Undetermined.
Culture characteristics – Conidia germinating on PDA within 24 h, and germ tubes produced at the apex and the base. Colonies on PDA reaching 20 mm diameter after 6 weeks at room temperature. Mycelium dry, dense, colonies on the surface of PDA, with rough surface, irregular edges, slightly protuberance in the center, uneven surface, yellow to reddish brown. Reverse yellow to 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-3826 (HKAS 130435, holotype).
Notes – Phylogenetic analysis showed that Sporidesmium filiforme clustered with S. guizhouense with 100% ML/ 1.00 PP support (Fig. 2). However, S. filiforme differs from S. guizhouense in having elongated and narrow conidia with filiform appendages, but without mucilaginous sheath (Liu et al. 2019). The LSU and ITS sequences data of S. filiforme (HKAS 130435) differ from S. guizhouense (CGMCC 3.19605) by 4.99% (40/801 bp) and 16.43% (81/493 bp, 42 gaps), respectively. We therefore identified S. filiforme as a new species.
Figure 1 – Sporidesmium filiforme (HKAS 130435, holotype). a Colonies on the substratum. b, c Conidiophores. d–k conidia. l Germinating conidium. m, n Colonies on PDA from surface and reverse. Scale bars: b = 10 µm, c 15 µm, d–f, k, l = 20 µm, g–j = 30 µm
Figure 59 – 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). The new collections are indicated in red. Ex-type strains are indicated with “T” after the strain number.