Pseudocercospora rauvolfiicola A. Singh, P.N. Singh and N.K. Dubey, 2022

Singh, Archana, Singh, Paras Nath & Dubey, Nawal Kishore, 2022, Morphology and Phylogeny of a new species Pseudocercospora rauvolfiicola on medicinal plant Rauvolfia serpentina from Sonebhadra Forest, Uttar Pradesh, India, Phytotaxa 545 (2), pp. 128-138 : 131

Pseudocercospora rauvolfiicola A. Singh, P.N. Singh and N.K. Dubey sp. nov. Fig 1–4

MycoBank: MB 834637

Etymology. Name refers to Rauvolfia , the host genus from where the fungus was isolated.

Culture characteristics – Colonies after 21 days at 27 ° C on Oat Agar (OA) blackish grey, velvety, mycelium sparse, sulcate, reverse blackish grey reaching 30 mm diameter. On Potato Dextrose Agar (PDA) erumpent in centre, margin lobed, grayish black, velvety, reverse black, upto 16 mm.

Pathogen on Rauvolfia serpentina Leaf spots dark blackish brown with yellowish encircling area on the upper leaf surfaces, grayish brown on lower surfaces, circular to irregular. Caespituli hypophyllous, substomatal. Mycelium internal, branched. Asexual morph: Stromata substomatal, pseudoparenchymatous, light yellowish brown to light brown, globular, few cells to 13 µm filling stomatal opening, Conidiophores 14–35.5 × 2–3 µm (x̅= 24×3, n=40) macronematous, mononematous, olivaceous brown to light brown, paler towards the tip, fasciculate in divergent fascicles (up to 14), smooth, 0–3 septate, branched, straight to curved, geniculate, sub cylindrical. Conidiogenous cells polyblastic, integrated, terminal, pale olivaceous, smooth, geniculate, scar unthickened. Conidia 9.5–56.5 × 2–3.5 µm (x̅= 36×3 µm, n =40), solitary to branched in chains, acropleurogenous, holoblastic, pale brown, subcylindrical to obclavate, apex obtuse to subacute, base obconico truncate, ramoconidium present, straight to curved, 1–5 septate, hilum unthickened.

Type. India, Uttar Pradesh, Sonebhadra, leaf spots on Rauvolfia serpentina (L.) Benth.ex Kurz ( Apocynaceae ), 15 Dec. 2019, Archana Singh , AMH-10139 (Holotype), BHUAS/19/23 (Isotype), NFCCI 4586 (ex-type living culture), ITS, LSU, ACT and TEF sequences GenBank MT068200.1, MT102882.1, MW496125 , MW496126 .

Figures

FIGURE 1. a Habit of the host plant (Rauvolfia serpentina (L.) Benth.ex Kurz. b–c Symptoms on upper and lower surfaces of leaf. d Transverse Section through infection spots of leaf showing fungal colonies on lower surfaces. e Fungal culture on Potato dextrose Agar. f Fungal culture on Oatmeal Agar.

FIGURE 2. Pseudocercospora rauvolfiicola sp.nov. (Holotype AMH: 10139) a–p Conidia. q–s Fascicles of conidiophores. Scale bars: 20 µm.

FIGURE 3. Scanning Electron Micrographs a–b Fascicles of conidiophores arising from stomata of leaf of the host plant. c Conidia attached to conidiophores (showing arrow). d Fascicle of conidiophores showing conidiogenous cells (showing arrow). Scale bars: a–c= 10 µm, d=2µm.

FIGURE 4. Molecular Phylogenetic analysis of Pseudocercospora crotalariigena sp. nov. (AMH:10041 Holotype; NFCCI:4441 ex type): Batesian tree from LSU, ITS, ACT and TEF1α. Numbers on the branches are bootstrap values for Mega 5 Maximum likelihood (ML) and Mega 5 maximum parsimony and Bayesian posterior probability (PP). Pallidocercospora heimii and Coremiopassalora eucalypti are out groups.