Chaetomium subaffine X. Wei Wang & Houbraken

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Chaetomium subaffine Sergeeva ex X. Wei Wang & Houbraken, in Wang, Han, Bai, Luo, Bensch, Meijer, Kraak, Han, Sun, Crous & Houbraken, Stud. Mycol. 101: 167 (2022) Fig. 22 Description. Associated with decaying twigs in the cave environment. Sexual morph on PDA: Ascomata 200–400 × 150–350 μm, obovate or ovate, ostiolate, usually covered by thick aerial hyphae, olivaceous or umber to dark-brick in reflected light owing to ascomatal hairs. Terminal hairs verrucose, brown, erect to flexuous or slightly undulate, usually unbranched, 2–4 μm near the base, tapering towards the tips. Lateral hairs similar. Asci 8 - spored, fasciculate, fusiform or clavate, spore-bearing part 42–63 × 7–17 μm (x ̄ = 52.86 × 11.76, n = 30), evanescent. Ascospores 9–12 × 8–10 μm (x ̄ = 11.28 × 9.19, n = 90), biseriate, hyaline to olivaceous brown with age, limoniform, some globose, verruculose, thick-walled, biapiculate, bilaterally flattened, with an apical germ pore. Asexual morph: Undetermined. Culture characteristics. Colony on PDA attaining 60 mm after 15 days at room temperature (25 ± 2 ° C), circular, folded, white to light yellow, with slightly entire edge, sporulated within 30 days. Reverse yellow to yellow brown. Odor absent. Material examined. CHINA • Yunnan Province, Qujing City, Malong District, Wangjiazhuang Street, Y 008, Longyangxian Cave, associated with decaying twigs on the floor of the cave, 25.434721°N, 103.509524°E, elev. ca 1920.43 m, 29 April 2024, Xiangfu Liu and Xuemei Chen, QJ 2 C 2 (GMB -W 1252), living culture GMBCC 2271. Known distribution. China (Wang et al. 2016 b; Farr and Rossman 2026), Netherlands (Wang et al. 2016 b), and Russia (Wang et al. 2016 b, 2022). Known hosts or substrata. Castanea mollissima (Farr and Rossman 2026), Glycine max (Farr and Rossman 2026), Homo sapiens (Wang et al. 2016 b), Morus alba (Farr and Rossman 2026), unknown plant stem (Wang et al. 2016 b), seed and dead stem of cereal (Wang et al. 2022). Notes. Chaetomium subaffine was first described by Sergeeva (1961), but, lacking a Latin description, it was considered invalid. Then, Wang et al. (2022) reintroduced the species. In the phylogenetic analyses of the combined ITS, LSU, rpb 2, and tub 2 data, our isolates clustered with Chaetomium subaffine (CBS 637.91 (ex-type), and 22 N 617) within the Chaetomium clade, with 100 % ML and 1.00 PP support (Fig. 20). Nucleotide comparisons between our strain (GMBCC 2271) and C. subaffine (CBS 637.91, ex-type) showed 1.73 % (10 / 578 bp, 1 gap) differences in ITS, 1.65 % (10 / 607 bp, 1 gap) differences in LSU, 2.19 % (11 / 503 bp, without gap) differences in rpb 2, and 0.99 % (7 / 704 bp, without gap) differences in tub 2. Morphologically, the new isolate (GMBCC 2271) resembles C. subaffine, with obovate or ovate ascomata usually covered by thick aerial hyphae, brown, erect to flexuous or slightly undulate terminal hairs, and brown, limoniform, biapiculate, bilaterally flattened ascospores (Wang et al. 2016 b). Therefore, based on both morphology and phylogeny, we report Chaetomium subaffine as a new substrate record from a cave in Yunnan, China.

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