Thelonectria beijingensis Z.Q. Zeng, J. Luo & W.Y. Zhuang, 2013

Zeng, Zhao-Qing & Zhuang, Wen-Ying, 2013, Four new taxa of Ilyonectria and Thelonectria (Nectriaceae) revealed by morphology and combined ITS and - tubulin sequence data, Phytotaxa 85 (1), pp. 15-25 : 18

Thelonectria beijingensis Z.Q. Zeng, J. Luo & W.Y. Zhuang , sp. nov.

FIG. 1

MycoBank MB564936

Etymology. The specific epithet refers to the locality of the fungus.

Diagnosis. Differing from Thelonectria sinensis in having a thinner perithecial wall, relatively large ascospores, and producing microconidia in culture.

Ascomata perithecial, solitary to gregarious up to 10 in a group, with a well-developed stroma that is erumpent through bark, superficial, subglobose to globose, 320–391 µm high, 305–385 µm diam. (n = 10), not collapsing when dry, orange red to red when fresh and red when dry, turning dark red in 3% KOH and orange in lactic acid, surface slightly roughened. Ascomatal wall 22–38 µm thick, of two layers: outer layer 14–27 µm thick, of textura epidermoidea mixed with textura intricata in the upper portion, of textura angularis near the base, cells mostly lacking a definite shape, axis of cells near the apical portion somewhat perpendicular to perithecial surface, 5.4–11 × 2.4–4.9 µm, walls 0.8–1.2 µm thick; inner layer 8–11 µm thick, of textura prismatica, cells flattened, 8–19 × 2.2–3.8 µm, walls 0.5–0.8 µm thick. Asci subcylindrical, 8- spored, with an apical ring, 82–104 × 5.5–8.5 µm. Ascospores fusiform-ellipsoid, uniseptate, not constricted at septum, hyaline, smooth, uniseriate, 13–17 × 4–7 µm.

In culture, colony reaching 22 mm in diam. after 7 days on PDA at 25°C under daylight, surface velvety, aerial mycelium brown to purplish, reverse dark vinaceous. Conidiophores unbranched to sparsely branched, septate, 22–59 × 2.2–3.5 µm, arising from agar surface throughout colony. Microconidia ellipsoid to rodshaped, straight or slightly curved, hyaline, nonseptate, 5.4–14 × 2.2–4.1 µm. Macroconidia subfusoid to cylindrical, with rounded ends, curved, hyaline, 0–3-septate; 0-septate: 41–51 × 3.2–5.4 µm, 1-septate: 32–46 × 2.7–4 m, 2-septate: 43–51 × 3.2–4 µm, 3-septate: 41–54 × 3.2– 4.9 µm. Chlamydospores absent.

Holotype. CHINA. Beijing, on bark of an unidentified tree, 1 Sept 2010, L. Cai 7604, HMAS 188498 !, ex type culture HMAS 188566 .

Notes. Among the existing species of the genus, Thelonectria beijingensis is most similar to T. sinensis in cylindrical asci, fusiform-ellipsoid ascospores, and brown to purplish colonies on PDA. The latter fungus differs by having a thicker perithecial wall (32–55 µm thick), relatively small ascospores (10–16 × 3.2–5.8 µm), and not producing microconidia in culture ( Luo and Zhuang 2010). It is also similar to T. discophora and T. lucida in having red perithecia, and cylindrical asci with an apical ring. Thelonectria discophora differs in perithecia with smooth surface and seated on a minute stroma, possessing distinct palisade cells in the outermost perithecial wall, with axes of cells perpendicular to perithecial surface; wider asci (72–95 × 7–10 µm); pale brown, spinulose, wider ascospores (12–17 × 5–8 µm); and the absence of microconidia ( Brayford et al. 2004) . Thelonectria lucida differs in having larger perithecia (430–480 µm in diam.) with a smooth instead of slightly roughened surface and thinner walls (20–30 µm thick), a distinct palisade layer of cells in the outer perithecial wall, with axes of cells perpendicular to outer surface, shorter and wider asci (63–72 × 6.5–10 µm), pale brown and spinulose ascospores, 3–8-septate instead of 0–3-septate and larger macroconidia (60–90 × 5–10 µm), white to tan instead of purple to brown colony, and the absence of microconidia ( Brayford et al. 2004) . Our sequence analysis supports the separation of T. beijingensis from its morphologically similar species ( FIG. 3 ).

Figures

FIGURE 1. Thelonectria beijingensis (holotype). A. Median section of an ascoma; B. Colony on PDA; C. Conidiophores and macroconidia; D Asci with ascospores; E. Microconidia; F, G. Macroconidia.

FIGURE 3. One of thirty-six equally most parsimonious trees inferred from combined ITS and β-tubulin partial sequences. Abbreviations: Neo. = Neonectria, I. = Ilyonectria, T. = Thelonectria, N. = Nectria. Tree length = 1169, CI = 0.6296, HI = 0.3704, CI excluding uninformative characters = 0.5856, HI excluding uninformative characters = 0.4144, RI = 0.8426, Rescaled consistency index = 0.5305. Bootstrap values ≥50% from 1000 replicates are noted above internodes. Asterisks indicate sequences of ITS and β- tubulin gene were from different strains as shown in TABLE 1.