Arthrinium euphorbiae M.B. Ellis, Mycol. Pap. 103: 6 (1965) (Fig 2)

MycoBank number: MB 326463; Index Fungorum number: IF 326463; Facesoffungi number: FoF 10729;

Saprobic on dead culms of bamboo. Sexual morph: Not observed. Asexual morph: Conidiomata 70 µm length × 65 µm diam, on the natural substrate, superficial, gregarious, scattered, irregular, dark brown to black, the fruiting bodies are raised on the surface of the plant body. With a small spore stalk, brown. Conidiophores 5–50 × 1–5 μm ( = 32 × 3 μm, n=20) arise singly or in loose groups; erect, straight, or somewhat flexuous; occasionally branched; septate; and scarcely swollen at the tip, with meristematic apices capable of producing conidia in basipetal succession. Conidiogenus cells 1–10 × 1–5 μm ( = 3 × 2 μm, n=15) erect, aggregated in clusters on hyphae, hyaline to pale brown, smooth, doliiform to clavate or lageniform. Conidia 10–40 × 10–25 μm ( =25 × 21 μm, n = 40 ), solitary, oval to broadly round or irregularly round, brown to medium brown, guttulate to roughened, granular, with finely pale slit at the outer edge.

Culture characteristics – Conidia germinated on PDA within 12 hours at 25°C.  Colonies on PDA reach 6–8 cm diam after 7 days at 25°C. Colonies circular, medium dense, flattened, white radial, margin undulate. Reverse white, becoming tawny from the center.

Material examined – China, Guangdong Province, Shaoguan City, Renhua County, Danxia Mountain, isolated from a dead twig of Bamboo plant, E 113°44′22″, N 25°2′39″ 17 November 2020, H.J. Zhao & Y.R. Xiong. (ZHKU 22-0001); living cultures, ZHKUCC 22-0001.

Known host and distributionAbies alba, Poland (Mulenko et al. 2008); Ammophila sp., United Kingdom (Dennis & R.W.G 1986); Bambusa sp., Bangladesh (Wang et al. 2018, Yan et al. 2019); Elettaria cardamomum, Tanzania (Ebbels & Allen 1979); Euphorbia sp., Zambia (Ellis 1965, 1971); Miscanthus floridulus Hong Kong (Lu et al. 2000, Wong & Hyde 2001, Zhuang 2001); Neolitsea scrobiculata, India (Saravanan & Vittal 2007); Pennisetum purpureum, Hong Kong (Lu et al. 2000, Wong & Hyde 2001, Zhuang 2001); Persea mechrantha, India (Saravanan & Vittal 2007).

Notes – In the present study, a single isolate (ZHKUCC 22-0001) forms a clade with A. euphorbiae (IMI 285638b) in our multi-gene phylogenetic analysis (Fig 1). The strain ZHKUCC 22-0001, isolated and described in this study, is morphologically similar to A. euphorbiae (Ellis 1965). The two A. euphorbiae strains (ZHKUCC 22-0001 and IMI 285638b) had all base pairs the same in the ITS, LSU, tef1-α, β-tubulin regions. The two isolates were different only by colony colour. Based on this trivial difference in morphological and molecular data, we introduced A. euphorbiae isolate (ZHKUCC 22-0001) as a new host record from bamboo.

FIGURE 2. Arthrinium euphorbiae (ZHKUCC 22-0001). (a,b) Conidiomata on the host surface. (c-e) Conidia, Conidiophores and conidiogenous cells. (f) Conidia. (g) Germinated conidium. (h-i) Culture on PDA from above and below. Scale bars: c–g = 10 μm.