Microdochium chuxiongense H. Yu, W.Q. Zou & D.X. Tang, 2022

Tang, De-Xiang, Zou, Wei-Qiu, Wang, Yao-Ming, Huang, Ou & Yu, Hong, 2022, Morphology and phylogeny of Microdochium chuxiongense sp. nov., a fungus from Southwest China, Phytotaxa 555 (2), pp. 147-158 : 151

Microdochium chuxiongense H. Yu, W.Q. Zou & D.X. Tang , sp. nov. ( Figure 2 )

MycoBank:— MB 844086

Etymology:— Referring to Chuxiong City where was this species collected.

Typus:— The Zixi Mountains , Chuxiong City, Yunnan Province, China (25°04′19.88′′ N, 110°54′60.46′′ E, alt. 2300 m), on pileus of Bondarzewia sp. , 22 September 2020, Hong Yu (YHH 20400, holotype; YFCC 8794 , ex-holotype living culture) .

Asexual morph:— Mycelium immersed and superficial, hyphae hyaline, branched, smooth, septate, 2–3 μm wide (x̅=3 µm, n =30). Conidiophores cylindrical, straight, septate, 8–15 × 2–3 μm (x̅=11 × 2 µm, n =10), and borned from the hyphae. Conidiogenous cells sparse, solitary, clavate, occasionally curved or swollen, hyaline, smooth, septate, 27–74 × 2–3 μm (x̅=50 × 2 µm, n =20). Conidia single or multiple, long oval, shuttle or sickle, straight or curved, 0(–3)-septate, 4–12 × 2–5 μm (x̅=7 × 3 µm, n =30). Chlamydospores were produced directly from mycelium, single, round or palmate, 9–11 × 10 μm (x̅=10 × 10 µm, n =10). Sexual morph were not found.

Culture characteristics:— The colony was on PDA medium fast-growing, 55–60 mm (x̅= 58 mm, n =3) in diameter after 7 days. The center has obvious milky white aerial mycelium bulge, and the edge mycelium was smooth, back light yellow. The colony was 78–82 mm (x̅= 80 mm, n =3) in diameter after 14 days, with pale aerial mycelium cottony, forming an obvious black circle in centre, back dark brown.

Know distribution:— The Zixi Mountains, Chuxiong City, Yunnan Province, China.

Notes:— This study reported that M. chuxiongense was isolated from pileus of Bondarzewia sp. , and was different from the host reported by previous studies. Phylogenetic analysis based on four genes showed that M. chuxiongense was formed a separate clade with M. indocalami and M. maculosum , it was a sister with M. indocalami , with strongly being supported by BI posterior probabilities (PP = 83%) and ML boostrap proportions (BP = 82%). The sequence length was 3255 bp for M. indocalami and M. chuxiongense , the gap sites of M. indocalami was 293 bp, and M. chuxiongense was 759 bp, their conserved sites were 2385 bp, and variable sites were 106 bp, 73% similar to M. indocalami and M. chuxiongense .

M. chuxiongense was very similar to M. indocalami in the colony, conidiophores and conidiogenous cells and conidia. However, it differed in the colony forming an obvious black circle in centre ( Huang et al. 2020) ( Table 2 ). Moreover, the shape of conidiophores differs from M. chuxiongense and M. indocalami . M. chuxiongense was cylindrical, straight, septate, 8–15 × 2–3 μm, M. indocalami was straight or slightly curved, septate, aggregated in the aerial mycelium ( Table 2 ). In addition, the size and shape of conidiogenous cells also differ from two species, conidiogenous cells of M. indocalami was terminal or intercalary, denticulate, straight or bent, 11–28 × 2–3 μm. Nevertheless, M. chuxiongense was sparse, occasionally curved or swollen, 27–74 × 2–3 μm ( Table 2 ). The size, shape and septate of conidia reported for M. indocalami (13–16 × 4–6 μm, cylindrical, clavate to obovoid, base usually flattened, 1–3-septate) were different from M. chuxiongense (4–12 × 2–5 μm, single or multiple, long oval, shuttle or sickle, straight or curved, 0–3-septate) ( Table 2 ). Importantly, chlamydospores were observed in M. chuxiongense , and yet M. indocalami was not observed.

Figures

FIGURE 2. Morphology of Microdochium chuxiongense. a. The host Bondarzewia sp.. b–e. Colonies on PDA at 25°C in 7 days. f–i. Conidiogenous cells and conidia. J. Conidiogenous cells. k–n. Conidiogenous cells and conidia. o. Conidia. p–q: Chlamydospores. Scale bars: a–e. 2 cm; f. 10 μm; g–h. 20 μm; i–o. 10 μm; p–q. 5 μm.