Neoroussoella chromolaenae Z. H. Htet, A. Mapook & K. D. Hyde, 2024

Htet, Zin Hnin, Hyde, Kevin D., Alotibi, Fatimah O., Chethana, Thilini K. W. & Mapook, Ausana, 2024, Multigene phylogeny, taxonomy, and potential biological properties of Pseudoroussoella and Neoroussoella species (Roussoellaceae, Dothideomycetes) from Asteraceae weeds in northern Thailand, MycoKeys 111, pp. 129-146 : 129-146

Neoroussoella chromolaenae Z. H. Htet, A. Mapook & K. D. Hyde sp. nov.

Fig. 2

Etymology.

Name reflects the host plant Chromolaena odorata , from which this species was isolated.

Holotype.

MFLU 24-0264 .

Description.

Saprobic on the dead stems of Chromolaena odorata ( Asteraceae ). Sexual morph: Undetermined. Asexual morph: Coelomycetous. Conidiomata 70–150 × 120–150 µm (av. 85 × 138 µm, n = 5), pycnidial, solitary, uniloculate, immersed, ostiolate. Ostiole papillate. Peridium 10–20 µm wide, comprising 2–3 layers of brown cells of textura angularis. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 3–5 × 2–3.5 µm (av. 3 × 3 µm, n = 10), phialidic, ampulliform to cylindrical, hyaline. Conidia 3–6 × 2–4 μm (av. 4.4 × 3.1 μm, n = 20), hyaline, oblong to slightly ellipsoid, aseptate, with small guttules.

Culture characteristics.

Conidia germinating on MEA within 24 hours, reaching 22 mm after 10 days at 27 ° C, irregular, curled margin, brown in the middle and becoming pale brown on the outer parts of the culture, wrinkled on the surface; wrinkle, pale brown to brown in reverse.

Material examined.

Thailand • Chiang Rai Province, Doi Pui , 19°48'51"N, 99°52'1"E, on dead stems of Chromolaena odorata ( Asteraceae ), 14 March 2023, Zin Hnin Htet (CO-DP-3, MFLU 24-0264 , holotype); ex-type culture MFLUCC 24-0274 .

Notes.

In a megablast search of GenBank, the closest match for the ITS sequence of our isolate was fungal sp. isolate NFC- 3 (MG 189955) with 99.47 % similarity. The closest match for the LSU region was N. solani CBS 141288 ( MH 878207 ) with 100 % similarity, and the closest match for the SSU region was N. bambusae strain GMB 1295 ( OM 764650 ) with 93.99 % similarity. Additionally, the closet matches for the tef 1 - α and rpb 2 gene regions were Neoroussoella entadae strain MFLUCC 18-0243 ( MK 360065 ) and N. entadae strain MFLUCC 17-0920 ( MK 434898 ) with 99.45 % and 99.77 % similarities, respectively.

Based on the multi-locus phylogeny (Fig. 1 ), our isolate ( MFLUCC 24-0274 ) formed a separate branch from N. entadae with 100 % ML and 1.00 BYPP. A comparative analysis of base pair differences between Neoroussoella chromolaenae ( MFLUCC 24-0274 ) and Neoroussoella entadae ( MFLUCC 18-0243 ) revealed variations in ITS (0.6 % - 3 / 476), LSU (0.1 % - 1 / 838), SSU (1.9 % - 14 / 717), tef 1 - α (0.5 % - 5 / 902), and rpb 2 (2.0 % - 18 / 885) without gaps, respectively. Morphologically, our collection is similar to N. entadae ( MFLUCC 17–0920 ) in having solitary, unilocular, ostiolate, phialidic, ampulliform to cylindrical, hyaline conidiogenous cells, and oblong to ellipsoidal, hyaline conidia ( Jayasiri et al. 2019). However, our species differs from N. entadae ( MFLUCC 17–0920 ) in having smaller conidiomata (70–150 × 120–150 µm vs. 127–192 × 161–190 µm), slightly wider conidiogenous cells (2–3.5 µm vs. 0.7–1.8 µm) and larger conidia size (3–6 × 2–4 μm vs. 3–4 × 1.7–1.9 μm). Therefore, N. chromolaenae is described here as a new species based on phylogeny and morphological evidence. Synopsis of the asexual morph of Neoroussoella species is also provided in Table 3 .

Figures

Figure 1. Phylogram generated from maximum likelihood analysis based on the combined dataset of LSU, SSU, ITS, tef 1 - α and rpb 2 sequence data. Bootstrap support values for ML equal to or greater than 75 % and BYPP equal to or greater than 0.90 are given at the nodes. Newly generated sequences are in blue and type species are in bold.

Figure 2. Neoroussoella chromolaenae (MFLU 24-0264, holotype) a, b Conidiomata on the substrate c a section through conidioma d ostiole e peridium f conidia and conidiogenous cells g – i conidia j germinating conidia k culture on the MEA. Scale bars: 500 µm (a, b); 100 µm (c); 20 µm (d, e); 10 µm (e – j).