apicystis apicystis apicystis is a genus of parasitic alveolates of the phylum apicomplexa. apicystis scientific classification domain: eukaryota (unranked): sar (unranked): alveolata phylum: apicomplexa class: conoidasida subclass: gregarinasina order: neogregarinorida family: lipotrophidae genus: apicystis species apicystis bombi taxonomy there is one species currently recognised in this genus. history this species in this genus was first described by liu in 1974 as a species in the genus mattesia. in 1996, lipa and triggiani transferred this organism, to a new genus apicystis on the basis of morphology and life cycle. description the species in this genus are spread by the orofaecal route. oocysts are ingested. within the intestine these develop into sporozoites. the sporozoites penetrate the gut wall and invade the haemocoele subsequently taking up residence in the fat body. host records this genus infects a number of hosts apis mellifera bombus dahlbomii bombus ephippiatus bombus hortorum bombus pratorum bombus ruderatus bombus terrestris bombus vagans bombus impatiens bombus griseocollis bombus bimaculatus