A phylum of the Protoctista (See Classification) that contains a group of obligate endoparasites, including the species that causes malaria (q.v.). All apicomplexans contain a vestigial plastid, the apicoplast. This chloroplast-derived organelle is the remnant of a secondary endosymbiosis between an ancestral apicomplexan and a chlorophyte (q.v.).
Subjects: Ecology and Conservation.