Nigrospora gorlenkoana Novobr., Nov. sist. Niz. Rast. 9:180 (1972)

Index Fungorum number: IF 516929; Facesoffungi number: FoF 06595

Pathogenic or saprobic on leaves of Cirsium setosum (Willd.) Besser ex M.Bieb (Asteraceae). Asexual morph: Hyphae smooth, branched, septate, and hyaline. Conidiophores mostly reduced to conidiogenous cells. Conidiogenous cells 6.9–10 × 4.2–8 μm diam. (x̄ = 8.4 × 6 μm , n = 30), monoblastic, solitary, discrete, determinate, doliiform to ampulliform, and pale brown. Conidia 10.3–14  × 13.3–17.2 μm diam. (x̄ = 12.5 × 15.2 μm, n = 50), solitary, globose or oblate, dark brown to black, shiny, sparse, discrete on aerial mycelia, and smooth-walled. Sexual morph: Undetermined.

Culture characteristics – Colonies on PDA reach 9 cm diam. after 5 d at 25 C, circular shaped, entire margined, floccose with aerial mycelium, surface initially white, turning grayish when mature and reverse initially white, turning smoke gray when mature.

Material examined – China, Shandong Peninsula, on living leaves of Cirsium setosum, 07 October 2017, Yuanyuan Hao (JZBH 3230001), living culture JZB 3230001, and KUMCC 19-0222.

Leaf spot symptoms – Leaf spots irregularly scattered and composed of a dark brown circular outer ring with a light brown inner ring, margined by apparently healthy leaf tissues.

Notes – Based on the phylogenetic analysis of combined ITS, TEF, and TUB2 sequence data of Nigrospora species (Figure 1), our strain Nigrospora gorlenkoana (JZB 3230001) clustered with the ex-type strain of N. gorlenkoana (CBS 480.73) with strong bootstrap support and Bayesian probabilities (100% ML, 100% MP, and 1.00 BYPP) (Figure 1). The base pair difference comparison of ITS, TEF, and TUB2 gene regions between our strain (JZB 3230001) and ex-isotype strain of N. gorlenkoana (CBS 480.73) reveals less than 1% difference, and the two specimens share similar morphological characters confirming both strains are conspecific. In contrast to the ex-type strain (CBS 480.73), an equatorial slit on conidia was not observed in our strain (JZB 3230001). Nigrospora gorlenkoana has not frequently been identified as a plant pathogen, and it was previously reported to be isolated from leaves and fruits of Vitis vinifera. This is the first report of Nigrospora gorlenkoana from Cirsium setosum.

Figure 1. Multilocus phylogenetic tree based on the combined ITS, TEF1, and TUB2 sequences alignment generated from a maximum likelihood phylogenetic analysis. Bootstrap support values for ML, MP (> 70%), and posterior probabilities (> 0.9) are given at the nodes (ML/MP/PP). The tree is rooted with Arthrinium malaysianum (CBS 102053) and Arthrinium obovatum (LC 4940). (* indicates the ex-type isolates)

Figure 2. Nigrospora gorlenkoana (JZB 3230001). (a and b) Appearance of leaf spots on the host substrate; (c and d) Upper view (c) and reverse view (d) of culture on PDA; (e) Conidia on aerial mycelia on PDA; (f) Mature conidia; (g–i) Mature conidia attached to conidiogenous cells. Scale bars f, g = 20 μm, h, i = 10 μm.