Molecular phylogeny and morphology reveal two new graminicolous species, Bipolaris adikaramae sp. nov and B . petchii sp. nov., with new records of fungi from cultivated rice and weedy grass hosts

Phytopathogenic fungi in the genus Bipolaris are typically associated with poaceous hosts including major cereal crops. Morphological identification alone is often insufficient for species discrimination due to overlapping microscopic characters. Thus, molecular phylogenetic analyses have been utilised for accurate species identification and to establish evolutionary relationships within the genus. Although there are 138 species epithets of Bipolaris listed in the Index Fungorum , only 46 species have been identified and accurately placed within the genus based on ex-type derived DNA sequence data, with only four Bipolaris species reported from Sri Lanka. During this study, diseased and dead plant specimens of weedy grasses and cultivated rice were collected from several collection sites in Sri Lanka and associated fungal species were isolated. Morphological characters together with phylogenetic inference from the analyses of three loci, internal transcribed spacers 1 and 2 with 5.8S region (ITS), glyceraldehyde-3-phosphate dehydrogenase ( GAPDH ) and translation elongation factor 1-α ( TEF1 ), supported the introduction of two novel species namely Bipolaris adikaramae from Panicum maximum and B . petchii from Ischaemum sp. Morphological descriptions and illustrations are provided for the newly described taxa. In addition, B . shoemakeri from Echinochloa sp. and Oryza sativa and B . sivanesaniana from O . sativa were identified as novel records from Sri Lanka. This study suggests the need for extensive surveys of crops and associated weedy hosts in order to accurately assess the diversity of emerging species of phytopathogenic and opportunistic graminicolous fungi.