Phylogenetic assessment and taxonomic revision of Scytalidium (Helotiales, Leotiomycetes) Tong, Shuo-Qiu Yang, Yi-Fan Li, Peng Wu, Yong-Jun Sun, Bing-Da Zhang, Zhi-Yuan IMA Fungus 2025 2025-10-14 16 e 164608 e 164608 S. Q. Tong & Zhi. Y. Zhang S. Q. Tong & Zhi. Y. Zhang 2025 Leotiomycetes Chaetomiaceae Scytalidium Fungi Helotiales Ascomycota species guizhouense sp. nov.   Fig. 4   Type.   CHINA• Guizhou, Guiyang, Huaxi District, Shiban Town,  26.46°N, 106.65°E, soil,  8 July 2022, Shuo-Qiu Tong( holotype  HMAS354097, dried culture; ex-type  CGMCC3.28992, ibid., SQT 08 and SQT 09).   Etymology. The epithet refers to the type location.   Description.  Culture characteristics(14 days at 25 ° C): Colony on PDAattaining 48–55 mmdiam., flat, margin lobate edge, ash gray (1 B 2) to dull green (30 E 3). Reverse ash gray (1 B 2) to jade green (27 E 3). Colony on SNAattaining 20–26 mmdiam., flat, margin radially striate with lobate edge, white (1 A 1). Reverse white (1 A 1).  Myceliumconsisting of hyaline, smooth-walled, branched, septate, 1–2.5 μm diam hyphae. Conidiophoreserect, hyaline, smooth, solitary, terminal, lateral, subcylindrical, straight to flexuous, unbranched, 0–2 - septate, reduced to conidiogenous cells, 12.5–43 × 1–3 μm. Conidiasolitary, catenate, hyaline, smooth-walled, oblong or ellipsoidal to globose, subcylindrical to cylindrical, not constricted at septa, segments 6.5–12 × 5–7 μm (avg. 8.9 × 5.9 μm, n = 30). Chlamydospore-likecells dark brown, oblong or ellipsoidal to subglobose, ellipsoidal, 0–1 - septate, thick-walled, smooth, solitary or catenate, 7.5–13 × 4.5–6.5 μm (avg. 10.5 × 5.4 μm, n = 30). Fertile hyphae borne laterally on simple conidiophores, fragmenting into arthroconidia. Arthroconidiahyaline to brown, smooth, cuboidal to oblong or cylindrical, 3–7.5 × 2–3 µm (avg. 5.3 × 2.7 μm, n = 30). Sexual morphunknown.   Figure 4.   Scytalidium guizhouense(from holotype  HMAS354097) a, b upper and reverse views of cultures on PDAand SNAafter 14 d at 25 ° C c conidia and conidiophores d, f arthroconidia e chlamydospore-like cells g arthroconidia and chlamydospore-like cells. Scale bars: 10 μm (c – f); 20 μm (g).   Geographical distribution.  Guizhou Province, China.   GenBank numbers. SQT 08 – SQT 09, ITS: PV 890023– PV 890024, LSU: PV 890030– PV 890031.   Notes. Phylogenetic analysis showed that two new isolates (   CGMCC3.28992and SQT 09) clustered in a single subclade with strong support (100 / 1) (Figs 1, 2). Morphologically,  S. guizhouensediffers from other species in  Scytalidiumby its production of conidia, arthroconidia, and chlamydospore-like cells, and an unknown sexual morph (see notes of key).  Scytalidium guizhouensewas isolated from soil in a pepper cultivation area and is likely to have a saprophytic lifestyle. 5841306304 soil 2022-07-08 HMAS, CGMCC Shuo-Qiu Tong China Guiyang 26.46 Shiban Town 745 106.65 Huaxi District HMAS 354097, CGMCC 3.28992 1 Guizhou holotype