Pseudocercospora opuntiae is newly described from Opuntia spp. from Mexico, where it
causes a serious disease of this host. Although P. opuntiae is morphologically similar to other
members of the genus with pigmented conidia and conidiophores, and unthickened, not
darkened conidiogenous scars, DNA sequence data of the ITS region revealed that it clusters
distant from other species of Pseudocercospora within Mycosphaerella. These data support the
assumption that Pseudocercospora is paraphyletic within Mycosphaerella.