gemmocystis gemmocystis gemmocystis is a genus of apicomplexans. gemmocystis scientific classification domain: eukaryota clade: diaphoretickes clade: sar clade: alveolata phylum: apicomplexa class: conoidasida order: agamococcidiorida family: gemmocystidaeupton & peters 1986 genus: gemmocystisupton & peters 1986 species: g. cylindrus binomial name gemmocystis cylindrusupton & peters 1986 this genus is parasitic on scleractinian corals (agaricia agaricites, dendrogyra cylindrus, diploria strigosa, meandrina meandrites, montastraea cavernosa, porites astreoides, porites porites) and is found in the caribbean. very little is known about the species in this genus. gemmocystis cylindrus was isolated from within the gastrodermal cells of the mesenterial filaments of the coral. only the oocysts and released sporozoites have been described. the parasites were isolated from bleached coral but their role if any in this sign is not known. taxonomy there is one species known in this genus