Myxospora poaceicola Y.P. Chen, Z.H. Lu & Maharachch., 2023

Chen, Yanpeng, Lu, Zhenghua, Faraj, Turki Kh. & Maharachchikumbura, Sajeewa S. N., 2023, Myxospora poaceicola sp. nov. (Stachybotryaceae, Hypocreales), a novel myrothecium-like fungus from Digitaria sanguinalis (Poaceae), Phytotaxa 625 (3), pp. 280-288 : 283-285

Myxospora poaceicola Y.P. Chen, Z.H. Lu & Maharachch. , sp. nov. FIGURE 2

MycoBank number: MB 850687

Etymology: The name reflects the hosts belonging to the family Poaceae , from which this fungus was isolated.

Holotype: HUEST 23.0116 .

Saprobic on stems and leaves of Poaceae . Asexual morph: Conidiamata on host surface scattered, 823–1,455 μm long × 35–51 μm wide (x̅ = 1,016 × 41 μm, n = 15), synnematous, solitary, upright or curved, with white to pale brown stems consisting of parallel, longitudinal, closely compacted hyphae, terminating with a black head composed of conidiogenous cells and conidia. Conidiophores septate, bunched forming synnemata, hyaline to pale brown. Conidiogenous cells 6–13 × 1–2 μm (x̅ = 9 × 1.6 μm, n=30), phialidic, cylindrical, and hyaline, tapering at the top. Conidia 6–8 × 2–4 μm (x̅ = 7 × 3 μm, n=30), aseptate, short cylindrical, smooth and pale brown. Sexual morph: undetermined.

Culture characteristics: Conidia germinated on PDA within 12 h at 25°C in darkness. Mycelium septate, hyaline to white. Colonies 45 mm in diam. after 5 days, white, sparse, and dense on the front; on the reverse side, light brown on the central area, gradually fading to white towards the outside.

Materials examined: CHINA. Sichuan Province: Chengdu City, Baiyungou, elevation 990 m, 30°47′35″ N, 103°23′49″ E, from decaying stems and leaves of Digitaria sanguinalis ( Poaceae ), 2021 Sep 27, Z. H. Lu & Y. P. Chen, BY41.2 (holotype HUEST 23.0116), ex-type culture UESTCC 23.0116; ibid., Yaan City, Zhougong Mountain, 29°56′36″ N, 103°2′31″ E, elevation 1,042.6 m, from decaying stems of an unidentified Poaceae plant, 2022 Nov 16, Y. P. Chen & P. W. Su, ZGS77.1, ( HUEST 23.0212), living culture UESTCC 23.0212.

Notes: In the phylogenetic tree ( FIGURE 1 ), Myxospora poaceicola formed a sister clade with M. graminicola and M. masonii . In terms of morphology, they differ in the length of synnemata and the width of conidia. The synnemata of M. poaceicola (823–1,455 μm) are comparatively longer than those reported for M. masonii (150–900 μm) and M. graminicola (80–220 μm) ( Lombard et al. 2016). In addition, the conidia of M. poaceicola (2–4 μm) are wider than those of M. masonii (1.5–2.5 μm) and M. graminicola (2–3 μm). The corresponding length-to-width ratios of the conidia range from 3 to 2 ( M. poaceicola ), 3 to 3.6 ( M. masonii ) and 2.5 to 2.3 ( M. graminicola ), respectively. BLASTn analyses for six barcode sequences of M. poaceicola ( UESTCC 23.0116) showed that the closest hits are M. graminicola CBS 116538 using ITS (99% identity, no gap), CAL (95% identity, no gap) and RPB 2 (98% identity, no gap), M. masonii CBS 174.73 using LSU (99% identity, 2 gaps) and TUB 2 (99% identity, no gap), and M. crassiseta CBS 121141 using TEF 1 (84% identity, 21 gaps). Based on the distinct difference in morphology and protein-coding genes, we proposed our new collections as a new species of Myxospora .

Figures

FIGURE 1. The phylogram of the genus Myxospora from ML analysis based on the concatenated dataset (ITS-LSU-TEF1-RPB2-TUB2- CAL). The tree is rooted with Dimorphiseta terrestris (CBS 127345). Support values of ML-UFBoot and MP-UFBoot ≥ 95 and Bayesian posterior probabilities ≥ 0.95 were displayed at the nodes as ML/MP/PP. Support values below 95 and 0.95 were indicated by a hyphen (-). Newly collected taxa were shown in red. Strains from type materials are in bold.

FIGURE 2. Myxospora poaceicola (HUEST 23.0116, holotype). a. Natural substrates of Phragmites australis. b. Synnemata on the host surface. c, d. Close-up of Synnemata. e, g. Conidiophores. f. Conidiogenous cells and conidia. h. Conidia. i, j. Colony on PDA (front and back views) after 5 days at 25 °C in darkness. Scale bars: d = 100 µm. e–h = 10 µm.