Nigrospora osmanthi Mei Wang & L. Cai, in Wang, Liu, Crous & Cai, Persoonia 39: 135 (2017)

Index Fungorum number: IF 820736; Facesoffungi number: FoF 06597

Pathogenic or saprobic on leaves of Rudbeckia hirta L. Asexual morph: Hyphae smooth, branched, septate, hyaline, or pale brown. Conidiophores mostly reduced to conidiogenous cells. Conidiogenous cells 6.8–12.6 × 5.3–7.4 μm diam. (x̄ = 9.3 × 6.3 μm, n = 30), discrete, solitary, monoblastic, determinate, ampulliform to subglobose, straight or curved, hyaline. Conidia 9–11.5  12.5–14.6 μm diam. (x̄ = 10 × 13.2 μm, n = 50), discrete on aerial mycelia, solitary, globose or oblate, dark brown to black, shiny, smooth-walled, and aseptate. Sexual morph: Undetermined.

Culture characteristics – Colonies on PDA reach 9 cm diam. in 5 d at 25 C, circular, entire margined, flat with aerial mycelium, floccose, filiform,
surface initially white, turning dark gray when mature and reverse initially white, and turning leek green when mature.

Material examined – China, Shandong Peninsula, on living leaves of Rudbeckia hirta L., 07 October 2017, Yuanyuan Hao (JZBH 3230011), living culture JZB 3230011, KUMCC 19-0229.

Leaf spot symptoms and characters – Irregularly scattered and free-form shaped leaf spots are composed of the dark brown outer border with a light brown inner core, margined by apparently healthy leaf tissues.

Other materials examined – China, Shandong Peninsula, on living leaves of Cirsium setosum, October 7 2017, Yuanyuan Hao (JZBH 3230008), living culture JZB 3230008, KUMCC 19-0227; China, Shandong Peninsula, on living leaves of Phyllostachys nigra, October 07 2017, Yuanyuan Hao (JZBH 3230009), living culture JZB 3230009, KUMCC 19-0228; China, Shandong Peninsula, on living leaves of Phragmites australis (Cav.) Trin. ex Steud. (Poaceae), October 7 2017, Yuanyuan Hao (JZBH 3230007), living culture JZB 3230007; China, Shandong Peninsula, on living leaves of Rosa chinensis Jacq. (Rosaceae), October 7 2017, Yuanyuan Hao (JZBH 3230005), living culture JZB 3230005, and KUMCC 19-0226.

Notes – Based on the phylogenetic analysis of combined ITS, TEF, and TUB2 sequence data of Nigrospora species (Figure 1), our strains of N. osmanthi (JZB 3230005, JZB 3230006, JZB 3230007, JZB 3230008, JZB 3230009, JZB 3230010, and JZB 3230011) form a strongly supported lineage (100% ML, 99% MP, and 1.00 BYPP) with the ex-type strain N. osmanthi (CGMCC 3.18126) (Figure 1). The base pair comparison shows 100% similarity in all three gene regions of ITS, TEF, and TUB2 between our strain (JZB 3230011) and ex-type strain (CGMCC 3.18126). The two specimens share similar morphological characters except for culture characteristics where our strain (JZB 3230011) has an entire margin and reference strain (CGMCC 3.18126) has a lobate margin. This is the first time N. osmanthi has been isolated from Rudbeckia hirta L., Cirsium setosum, which is a Chinese herb, Phyllostachys nigra, Phragmites australis, which is a perennial grass species found in wetlands, and Rosa chinensis.

Figure 1. Multilocus phylogenetic tree based on the combined ITS, TEF, 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 4. Nigrospora osmanthi (JZB 3230011). (a and b) Appearance of leaf spots on host substrate; (c) Enhanced view of leaf spot on the host substrate; (d and e) Upper view (c) and reverse view (d) of culture on PDA; (f) Colony on PDA; (g–i) Mature conidia attached to conidiogenous cells. Scale bars f = 50 μm, g–i = 10 μm.