Atractium yunnanense H. Zheng & Z. F. Yu, 2024

Zheng, Hua, Dai, Xinwen, Li, Haiyan & Yu, Zefen, 2024, Two new species of Nectriaceae (Hypocreales, Sordariomycetes) from Yunnan, China, MycoKeys 108, pp. 269-285 : 269-285

Atractium yunnanense H. Zheng & Z. F. Yu sp. nov.

Fig. 2

Etymology.

Refers to the Yunnan province where the holotype was collected.

Type.

China • Yunnan province, Huize county; isolated from soil in karst rocky desertification area; Oct 2020; Z. F. Yu, preserved by lyophilization (a metabolically inactive state) in State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan ( YMF 1.06524 , holotype); ex-type living culture: CGMCC 3.20977 , other living cultures: GDMCC 3.734 ; JCM 39337 .

Description.

Sexual morph not observed. Asexual morph on CMA. Hyphae 1.5–3 μm wide, pale olivaceous-green, occasionally branched, septate, smooth-walled. Conidiophores sometimes aggregated into synnemata, nonstromatic, macronematous, mononematous, cylindrical or subulate, straight or flexuous, stipes branched once or twice, monochasial, monoverticillate or irregularly biverticillate, with 1 - septate at base. Conidiogenous cells monophialidic, hyaline, with conspicuous periclinal thickening. Conidia pale olivaceous-green, solitary, smooth-walled, clavate to oblong-ellipsoidal, slightly curved, with a rounded apical cell, and somewhat conical basal cell, lacking a differentiated foot, 0–3 (– 4) - septate: 0–1 - septate conidia accounting for 8 %, 43–65 × 4.5–5.5 μm; 2–3 - septate conidia mostly abundant, accounting for 90 %, 40.5–67.5 × 4–5.5 μm; 4 - septate conidia rare, accounting for 2 %, 50.5–57 × 5–5.5 μm. Chlamydospores 5.5–7.5 × 7–8.5 μm, ellipsoidal, pale olivaceous-green, terminal or intercalary, solitary or in chain.

Culture characteristics.

Colonies growing on PDA and CMA after 20 days of incubation at 28 ° C. Colony on PDA slow-growing, surface thick, rosy buff to white, reverse white, raised, aerial hyphae abundance, reaching 30–33 mm diam., entire margin. Colonies on CMA flat, surface white, reverse translucent to pale white, aerial hyphae sparsely developed, reaching 40–42 mm diam.

Additional materials examined.

China • Yunnan province, Huize county ; isolated from soils in karst rocky desertification area; Oct 2020; Z. F. Yu; living cultures H 77 , H 102 .

Notes.

Phylogenetically, the three strains of Atractium yunnanense ( YMF 1.06524, H 77 and H 102) clustered together in a single clade with a high statistical support (BP / BS = 1.00 / 100) (Fig. 1 ). The clade containing A. yunnanense and A. crassum makes a sister clade to A. stilbaster . Morphologically, A. yunnanense is similar to A. crassum in having clavate to oblong-ellipsoidal and slightly curved conidia. However, the 2–3 - septate conidia are most common in A. yunnanense , whereas A. crassum has most 3–5 - septate conidia and no aseptate conidia ( Gräfenhan et al. 2011). In addition, the chlamydospores of A. crassum are larger and rounder than A. yunnanense (7–12 μm diam. vs. 5.5–7.5 × 7–8.5 μm diam.). In a comparison of ITS, LSU and tub 2 sequences, A. yunnanense (type strain YMF 1.06524) has 97 % (546 / 564 bp, 3 gaps), 98 % (857 / 876 bp, 4 gaps) and 95 % (403 / 419 bp, 3 gaps) similarity to A. crassum ( CBS 180.31), respectively. Moreover, the type species A. stilbaster can be morphologically distinguished from A. yunnanense in having smaller conidia, 20–40 × 1.5–2.5 μm vs. 40.5–67.5 × 4–5.5 μm ( Seifert 1985).

Figures

Figure 1. Phylogenetic tree inferred from a Maximum likelihood analysis based on a concatenated alignment of ITS, LSU, rpb 2 and tub 2 sequences of some representing species in Nectriaceae. The Bayesian posterior probabilities (BP) ≥ 0.9 and RAxML bootstrap support values (BS) ≥ 75 % were shown at the nodes (BP / BS). Strains obtained in this study are shown in blue font. Ex-type strains are marked by a T after the strain number. The tree was rooted to Sarocladium summerbellii (CBS 430.70).

Figure 2. Atractium yunnanense (YMF 1.06524, holotype) A colony on PDA after 14 days of inoculation at 28 ° C B colony on CMA after 3 days of inoculation at 28 ° C C conidiophores D conidia E chlamydospores. Scale bars: 1.9 cm (A, B); 10 µm (C – E).