The phylogenetic relationships amongst Hammondia, Neospora
and Toxoplasma were investigated by DNA sequence
comparisons of the D2/D3 domain of the large subunit ribosomal DNA
and the internal transcribed spacer 1. The results
obtained allow us to reject the hypothesis that N. caninum and
H. heydorni are the same species and show that Hammondia
hammondi is probably the sister taxon to Toxoplasma gondii.