Meliola holarrhenicola Deighton, Sydowia

Natekar, Pratik D., Patil, Anjali P., Patil, Chandrahas R., Bhise, Mahendra R. & Kambhar, Sidanand V., 2024, Two new records of Meliolaceous black mildew fungi from India, Phytotaxa 641 (1), pp. 73-77 : 74

Meliola holarrhenicola Deighton, Sydowia 11 (1–6): 106, 1958 ( Fig. 2 )

MycoBank number: 300626

Colonies amphigenous, thin to sub-dense, scattered, up to 8 mm in diameter on the upper surface, and up to 5 mm on the lower surface, confluent. Hyphae sub-straight, branching opposite, 1% alternate at acute angles, closely reticulate, cells 21–38 × 5.5–7.5 µm. Appressoria alternate, antrorse, straight to curved, 11.5–19 × 7.5–9.5 µm; stalk cells cylindrical to cuneate, 2.5–7.5 × 4–5.5 µm; head cells globose, entire, ovate, 9.5–11.5 × 7.5–9.5 µm. Phialides few, borne on a separate mycelial branch, alternate to opposite, ampulliform, 11.5–18 × 5.5–7.5 µm. Mycelial setae many, scattered to grouped around perithecia, straight to slightly curved, simple, subacute to obtuse at the tip, up to 375 µm long. Perithecia scattered, verrucose, up to 225 µm in diameter; ascospores cylindrical to oblong, 4-septate, slightly constricted at septa, 32–43.5 × 11.5–15 µm.

Material examined:— INDIA. Maharashtra: Akhavane, Sindhudurg, on living leaves of Holarrhena pubescens , 16°60’83.1” N, 73°82’28” E, 158 m, 23 December 2021, Pratik Dilip Natekar-5050, AMH-10586.

Known distribution:— Sierra Leone and India.

Notes:— Meliola holarrhenicola was first reported on Holarrhena africana A. DC. from Sierra Leone, West Africa ( Hansford 1961). However, the present collection on Holarrhena pubescens is a new host record and this taxon was not previously reported in India. Previously, three species of Meliola have been reported on this host plant from India, Meliola holarrhenae Hansf. & Thirum., M. simillima var. major Hansf. and M. holarrhenae-pubescens Jana, S.N. Ghosh & A.K. Das ( Hosagoudar 1996) . The newly reported Meliola holarrhenicola differs from previously reported species on same host in having amphigenous colonies, perithecia up to 225 µm in diameter, and cylindrical to oblong ascospores.

Figures

FIGURE 2. Meliola holarrhenicola; A. Infected leaves. B. Mycelial colony. C. Appressoriate mycelium with phialides. D. Perithecial setae. E. Perithecium. F. Ascospores.