Microdochium australe Z. X. Zhang, & X. G. Zhang, 2024

Zhang, Zhao-Xue, Shang, Yu-Xin, Zhang, Meng-Yuan, Zhang, Jin-Jia, Geng, Yun, Xia, Ji-Wen & Zhang, Xiu-Guo, 2024, Phylogenomics, taxonomy and morphological characters of the Microdochiaceae (Xylariales, Sordariomycetes), MycoKeys 106, pp. 303-325 : 303-325

Microdochium australe Z. X. Zhang, & X. G. Zhang sp. nov.

Fig. 5

Type.

China, Hainan Province, Jianfengling National Forest Park, on diseased leaves of Phragmites australis , 13 October 2023, Z. X. Zhang ( HMAS 352973, holotype), ex-holotype culture SAUCC 6322-5 - 1.

Etymology.

Referring to the species name of the host plant Phragmites australis .

Description.

Endogenic on diseased leaves of Phragmites australis . Mycelia are superficial and immersed, 3–3.3 µm wide, branched, membranous and hyaline. Sporodochia black, aggregative or solitary. Conidiophores are indistinct and often reduced to conidiogenous cells. Conidiogenous cells are straight or slightly curved, 15.4–23.5 × 2.8–4 µm, terminal, hyaline, septate, ampulliform or obpyriform, smooth. Conidia are solitary, hyaline, straight to slight curved, oblong to ellipsoid, 11.3–16.1 × 2.5–3.7 µm, multi-guttulate, (2) 3 - septate, apex rounded, base usually flattened. Sexual morphs were not observed, chlamydospores were not observed, see Fig. 5 .

Culture characteristics.

Cultures incubated on PDA at 25 ° C in darkness, reaching 73–76 mm diam., had a growth rate of 5.2–5.4 mm / day after 14 days, with moderate aerial mycelia, milky white to grey-white, with regular margin, and sporodochia are observed, reverses black to brown in the centre, with grey-white and regular margin.

Additional material studied.

China, Hainan Province, Jianfengling National Forest Park, on saprophytic leaves, 13 October 2023, Z. X. Zhang ( HSAUP 6151-1), living culture SAUCC 6151-1.

Notes.

Phylogenetic analyses showed that Microdochium australe sp. nov. formed an independent clade closely related to Microdochium bambusae and Microdochium indocalami (Fig. 1 ). Mi. australe was distinguished from Mi. bambusae ( SAUCC 1862-1) by 47 / 503, 2 / 836, 56 / 848 and 17 / 710 base pair differences, from Mi. bambusae and Mi. indocalami (SAUCC 1016) by 52 / 503, 2 / 848, 44 / 840 and 17 / 708 base pairs in ITS, LSU, RPB 2 and TUB 2 sequences, respectively. Morphologically, Mi. australe (11.3–16.1 × 2.5–3.7 µm, (2) 3 - septate) differs from Mi. bambusae (13.0–17 × 2.5–3.5 μm, aseptate) and Mi. indocalami in conidia (13–15.5 × 3.5–5.5 μm, 3 - septate), and, therefore, we described this fungus as a novel species.

Figures

Figure 1. A maximum likelihood tree was constructed using a combined dataset of ITS, LSU, RPB 2, and TUB 2 sequence data. Branch support values, shown as ML / BIPP, are indicated above the nodes: MLBV ≥ 70 % on the left and BIPP ≥ 0.90 on the right. Ex-type cultures are denoted in bold and marked with an asterisk (*). Strains from the current study are highlighted in red. The tree was rooted with Cryptostroma corticale (CBS 218.52). The scale bar at the bottom center represents 0.05 substitutions per site.

Figure 5. Microdochium australe (HMAS 352973, holotype) a a leaf of Phragmites australis b, c colonies on PDA from above and below after 14 days d colony overview e, f conidiogenous cells and conidia g, h conidia. Scale bars: 10 μm (e – h).