A molecular characterization of Cercospora species pathogenic to water hyacinth and emendation of C-piaropi

Phylogenetic relationships among isolates of Cercospora species pathogenic to water hyacinth, collected from several geographic regions of the world, were examined by using partial DNA sequences from three protein-coding gene s: elongation factor-la, P-tubulin, and histone H3. In cladograms from indi vidual, as well as from combined datasets for 14 isolates, two statisticall y well supported clades were found: a major clade that included isolates fr om Brazil, Venezuela, Mexico, Florida (USA), South Africa, and Zambia; and a minor clade restricted to isolates from Texas (USA). Shape and dimensions of conidia were unreliable criteria for taxonomic differentiation of most isolates that composed the two clades. In addition, the ex-type culture of C. rodmanii did not show differences in DNA sequence in relation to the oth er isolates grouped in the major clade, including some that had conidial si ze and morphology fitting the description of C. piaropi. Therefore, the sep aration of these species not only did not have strong phenotypic support, b ut also did not have support from the phylogenetic analysis. Consequently, the description of C. piaropi is emended herein to include C. rodmanii as a synonym.