Pseudocercospora morigena A. Singh, P.N. Singh & N.K. Dubey, 2023

Singh, Archana, Singh, Paras Nath, Kharwar, Ravindra Nath & Dubey, Nawal Kishore, 2023, Morphology and phylogeny of Pseudocercospora morigena sp. nov. on Morus alba from Vindhya Range, India, Phytotaxa 584 (1), pp. 41-51 : 45-47

Pseudocercospora morigena A. Singh, P.N. Singh & N.K. Dubey sp. nov. ( FIGURE 1–4 )

Mycobank: MB840310

Etymology: The species epithet “ morigena ” refers to plant host genus Morus , from which this fungus was isolated.

Culture characteristics: Conidia germinating on potato dextrose agar (PDA). Colonies slow growing, velvety, grayish black, reaching 12–14 mm diam. in 28 days at 27°C, margin circular, reverse black, raising centrally with dense cottony mycelium and hard texture. Asexual and sexual spores were not formed.

Leaf spots hypogenous later amphigenous, 1–3 mm, angular, vein limited, discrete, later coalescing; in early stage it appears as pale brown spots on lower surface, later it turns blackish brown on both leaf surfaces. Caespituli hypophyllous, later amphiphyllous, dark brown, erumpent. Mycelium internal and external; superficial hyphae usually emerging through stomata, simple or branched, decumbent bearing solitary conidiophores, 1.5–4 µm wide, septate, thin-walled, smooth, pale olivaceous. Stromata substomatal, few cells to well developed, made up of oval to round 3–5 µm wide pseudoparenchymatous cells, median to dark brown. Conidiophores 35–50 × 3–5 µm (x = 36×3, n=30) fasciculate, unbranched or rarely branched, geniculate, 2–5 septate, light brown. Conidiogenous cells polyblastic, integrated, cicatrized. Conidia 20–65 × 3–4 µm (x = 33×3, n=30) solitary, pale olivaceous, straight to curved, cylindrical to subcylindrical, 1–8 septate, base obclavate to obconico truncate, tip subacute to obtuse.

Type. India, Uttar Pradesh, Sonebhadra, leaf spots on Morus alba L. ( Moraceae ) 15 Oct, 2020, Archana Singh, AMH-10304 (Holotype), BHU Herb no. AS/20/91 (Isotype), NFCCI 4877 (ex-type living culture), ITS, ACT and TEF sequences GenBank MW534553 , MW507305 , MW507304 .

Figures

FIGURE 1. Molecular Phylogenetic analysis of Pseudocercospora morigena sp. nov. (AMH-10304 holotype, NFCCI-4877 ex type): Maximum likelihood tree from concatenated ITS, ACT and TEF-α.Numbers on the branches are bootstrap values for Maximum likelihood (ML) and Mega 5 Maximum Parsimony and Bayesian posterior probability; ML/MP/PP.

FIGURE 2. a. Habitat of the host plant (Morus alba), b–c. Symptoms on upper and lower leaf surfaces, d–e. Reverse and front view of culture, f. Leaf spot on host surface, g. Transverse section through infection spot showing fungal colonies on lower surfaces (showing arrow). Scale bar f= 1 mm, g= 50 µm.

FIGURE 3. Pseudocercospora morigena sp.nov. (AMH-10304, holotype) a–l. Conidia, m. Tip of conidiophores showing geniculation, n–o. Solitary conidiophores arising from superficial hyphae, p–r. Fascicles of conidiophores. Scale bars: a–r =20µm.

FIGURE 4. Scanning electron micrographs showing fascicles of conidiophores arising from stomata of leaf of the host plant. Scale bars: a= 10 µm, b= 20µm