Conference Agenda

Recently published whole-genome analyses of the two closely related parasites, Plasmodium ovale curtisi and P. ovale wallikeri, which cause human ovale malaria, provide compelling evidence that the nuclear genomes of these two organisms do not recombine and are therefore perfectly dimorphic at all loci examined. The same pattern is observed when comparing the two 4.3 kb mitochondrial genomes. Here, we present an analysis of new sequencing data from the tufa locus, encoded in the plastid-derived apicoplast organelle, that provides evidence that this third parasite genome is also dimorphic and co-segregates with specific dimorphs of the nuclear and mitochondrial genomes. These findings, together with other recent studies, support full species status for the two causative agents of ovale malaria in humans, necessitating a revision of the nomenclature used up until now. We propose redefining the original species name Plasmodium ovale Stephens by designating a neotype from Kenya for what was previously referred to as ‘P. ovale curtisi’. A new species, Plasmodium wallikeri sp. n., is also described using a type specimen from West Africa. Morphological descriptions will be provided and sequence information defined for three genetic loci that distinguish these two species at nuclear, mitochondrial and apicoplast genome levels, respectively.