Rugonectria microconidia Z.Q. Zeng & W.Y. Zhuang

Zeng, Zhao-Qing & Zhuang, Wen-Ying, 2019, The genera Rugonectria and Thelonectria (Hypocreales, Nectriaceae) in China, MycoKeys 55, pp. 101-120 : 101

Rugonectria microconidia Z.Q. Zeng & W.Y. Zhuang sp. nov. Figure 2

Holotype.

CHINA. Hunan, Yizhang, Mangshan, (24°57'56.58"N, 112°57'34.63"E), alt. 700 m, on mossy bark, 26 October 2015, Z.Q. Zeng, X.C. Wang, K. Chen, Y.B. Zhang 10266 (HMAS 254521); ex-type culture: HMAS 247232.

Sequences.

ACT (MF669044), ITS (MF669050), LSU (MF669052) and RPB1 (MF669056).

Etymology.

The specific epithet refers to the microconidia produced in culture.

Description.

Mycelium not visible around ascomata or on natural substrata. Ascomata superficial, gregarious, with basal stroma, pyriform to subglobose, non-papillate, yellow to orange, often with a darker red ostiolar area when dry, turning dark red in KOH, becoming slightly yellow in LA, 421-549 × 333-470 μm (n = 8). Perithecial surface warted, 30-93 µm thick, of textura globulosa to textura angularis, cells 10-27 × 8-18 µm, walls 1.5-2.5 µm thick. Perithecial wall of two layers, 45-70 µm thick, outer layer 25-45 µm thick, of textura globulosa to textura angularis; inner layer 7-25 µm thick, of textura prismatica. Asci unitunicate, clavate, 8-spored, 93-130 × (11 –)15– 25 µm (112.6 ± 12.6 × 18.9 ± 3.2 μm). Ascospores ellipsoid to broadly ellipsoid, 1-septate, striate, uniseriate or biseriate above and uniseriate below, hyaline, 20-28 × 8-12 µm (24.0 ± 2.0 × 10.1 ± 0.9 μm). Colony on PDA 42 mm diameter after 7 d under daylight at 25 °C, surface velvety, with white aerial mycelium, producing pale pinkish pigment in medium. Colony on SNA reaches 40 mm diameter after 7 d under daylight at 25 °C, surface with sparse whitish aerial mycelium. Conidiophores simply branched, 18-50 × 2-3 μm. Microconidia allantoid to rod shaped, slightly curved, 0(1-2)-septate, 3 –14(– 18) × 1.2 –2.5(– 3) μm (6.7 ± 3.1 × 1.6 ± 0.4 μm).

Habitat.

On mossy bark.

Distribution.

Asia (China).

Notes.

The non-papillate perithecia with warted surface, clavate asci with ellipsoidal to broadly ellipsoidal, uniseptate, striate ascospores, as well as our molecular data, suggest that this species belongs to Rugonectria ( Chaverri et al. 2011). Amongst the known species of the genus, R. microconidia is morphologically most similar to the type species, R. rugulosa , in having gregarious, warted, orange perithecia often with a dark red ostiole when dry ( Samuels et al. 1990; Samuels and Brayford 1994). The newly described species differs in having asci that are 93-130 × (11 –)15– 25 µm and larger than those of R. rugulosa that are (53 –)64–83(– 95) × (7.5 –)11.3–15.5(– 17) µm. In addition, the ascospores of R. microconidia are also larger, 20-28 × 8-12 µm, while those of R. rugulosa are (10 –)13.5–18(– 24) × (3.3 –)4.7–6.7(– 10) µm. Unlike R. microconidia , R. rugulosa does not produce macroconidia in culture ( Samuels et al. 1990; Samuels and Brayford 1994). Sequence comparisons reveal that there are 21 bp, 21 bp, 12 bp and 22 bp divergences in the ACT, ITS, LSU and RPB1 regions, respectively, between R. microconidia and R. rugulosa (YH1001). Both morphological and molecular data suggest that these species are distinct.

Figures

Figure 2. Rugonectria microconidia a-d ascomata on natural substratum e colony on PDA f colony on SNA g, h median section through perithecium i-k asci with ascospores l-o ascospores p-s conidiophores and conidia t, u conidiogenous cells and conidia v, w microconidia. Scale bars: 0.5 mm (a-d); 50 μm (g, h); 10 μm (i-w).