Ostropomyces pruinosellus Thiyagaraja, Lucking, Ertz & K. D. Hyde

Ostropomyces pruinosellus Thiyagaraja, Lücking, Ertz & K.D. Hyde, in Thiyagaraja et al., Journal of Fungi 7(2):105 (2021) (Fig. 3)

Index Fungorum number: IF 556556; Facesoffungi number: FoF 09512

Saprobic on dead wood of Arabica coffee. Pycnidia with a pruinose appearance on the surface, irregular shape, solitary. Sexual morph: Undetermined. Asexual morph: Pycnidia (excluding neck) 100–300 µm wide, 80–250 μm high (x̅ = 206 × 127 μm, n = 10), immersed, globose to oval, single or clustered under the substrate, with short ostiole. Pycnidial wall 5–35 µm wide (x̅ = 21 μm, n = 20), transverse section shows two layers; outer layer hyaline, thin-walled, densely packed, and inner layer of textura angularis, hyaline, loosely packed. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 5–10 µm wide (x̅ = 5.5 μm, n = 10), hyaline, lining the inside wall. Conidia 5–10 × 2–4 µm (x̅ = 7.5 × 2.7 µm, n = 30), allantoid to filiform, aseptate, hyaline, catenate, guttulate at maturity, conidia connect to form a large branch.

Culture characteristics:— Colonies on PDA reaching 15 mm diam after 4 weeks at room temperature (20–25 ℃). Culture from above, white, circular, with clusters of bumps that secrete brown liquid, towards the edge with irregular white aerial mycelia. Reverse side changes from dark brown in the middle to lighter on both sides.

Material examined:— CHINA. Yunnan Province: Pu’er, on dead wood of coffee, 23 December 2020, Li Lu, MJ-C5 (HKAS 113187); living culture KUMCC 21-0022.

Notes:— Based on ITS and LSU blast results, our isolate is95%similar to Ostropomyces. pruinosellus (NR_172006), and 98% similar to O. pruinosellus (NG_074507). The new strain formed a group together with O. pruinosellus in the combined mtSSU, LSU and ITS phylogenetic analyses with 100% ML, 1.00 BYPP boostrap support and shares similar morphological characteristics (asexual morph) with O. thailandicus. Our new collection differs from O. thailandicus in its allantoid to filiform conidia, and large branched conidial chains, whereas O. thailandicus has filiform conidia with unbranched chains, but similar in having catenate conidia and pruinose on the surface. Comparison of mtSSU, LSU and ITS regions of our new isolate with O. pruinosellus (MFLU 20-0538) reveals 0/6/13 (-/0.69%/2.4%) base pair differences, with O. pruinosellus ( MFLU 21-0115) 4/0/3 (0.55%/0/0.57%) base pair differences and with O. pruinosellus (MFLUCC 21-0112) 10/4/13 (1.36%/0.47%/2.4%) base pair differences. Therefore, we identify our strain as O. pruinosellus based on guidelines of Jeewon & Hyde (2016). Ostropomyces pruinosellus has been reported as sexual morph from unidentified dicotyledonous plant from Thailand (Thiyagaraja et al. 2021, Wei et al. 2021). Thus, this is first report of the asexual morph of O. pruinosellus with a new host record from coffee and new geographical record from China.