Molecular phylogeny and morphology reveal three novel species of Curvularia (Pleosporales, Pleosporaceae) associated with cereal crops and weedy grass hosts

Abstract

The genus Curvularia comprises phytopathogenic, saprobic, epiphytic and endophytic fungal species associated with cereal crops and their wild relatives. Recently, multi-locus phylogenetic studies have been widely implemented for accurate identification of Curvularia, at the species level. Although the genus is taxonomically diverse, the species associated with cereal crops and weeds are poorly known in Sri Lanka. In this study, symptomatic specimens of cereals and associated weedy grass hosts were collected from selected locations in Sri Lanka. The isolates obtained were initially identified based on microscopic characters. The nuclear ribosomal internal transcribed spacers 1 and 2 with 5.8S region (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and translation elongation factor 1-α (TEF1) loci were sequenced and used in multi-locus phylogenetic analyses. Three novel evolutionary lineages were identified, distinct from all the currently accepted species of Curvularia. To accommodate the novel phylogenetic lineages, three novel species of Curvularia are described, namely Curvularia eleusinicola, C. panici-maximi and C. simmonsii. Morphological descriptions and illustrations are provided for the newly described taxa. In addition, host records are updated for recently introduced C. plantarum and C. pseudointermedia. This study highlights the need for extensive collections and molecular identifications of tropical species of hyphomycetous fungi associated with cereals, fibre crops and weeds in order to support effective disease management and surveillance measures.