Smut fungi on Trachypogon spicatus in Africa: Sporisorium trachypogonis-spicati and Tilletia afrotrachypogonis, sp. nov

Two smut fungi infecting the crinkle-awn grass Trachypogon spicatus (Poaceae) in Africa are characterized morphologically, illustrated, and linked to DNA barcodes (rDNA ITS, 28S). Sporisorium trachypogonis-spicati is reported for the first time from Benin, South Africa, and Togo, far from the previously known localities in the Democratic Republic of the Congo and Zimbabwe. This species is morphologically similar and closely related but genetically divergent to Sporisorium trachypogonicola, which infects Trachypogon spicatus in the Americas. Tilletia afrotrachypogonis is described as a new species from Togo and is also known from southeastern Africa (Malawi, Zambia). This species is morphologically almost identical to but genetically distinct from Tilletia trachypogonis, which infects Trachypogon spicatus in Mexico. The phylogenetic sister relationship, phenotype, and ecological similarity for the two species pairs Sporisorium trachypogonis-spicati/S. trachypogonicola and Tilletia afrotrachypogonis/T. trachypogonis, but occurrence in different geographic areas (Africa and the Americas/North America, respectively), suggest a common ancestral species, allopatric speciation, and duplication, i.e. speciation on the same host species.