Figure 2

Amblyosporidae life cycles. 1. Diplokaryotic meront 2. Primary (autoinfective) diplokaryotic mitospore 3. Within-host transmission or vertical transmission (not Hyalinocysta) 4. Secondary (environmental) diplokaryotic spore (Culicosporella only) 5. Horizontal transmission 4a. Nuclear dissociation and karyokinesis (Culicospora and Edhazardia only) 4b. Formation of sporophorous vesicle (not Culicospora) 5. Meiosis and karyokinesis 6. Nuclear division to form plasmodia 7. Monokaryotic sporogony (abortive in Culicosporella and Edhazardia) 8. Monokaryotic meiospore 9. Transmission to intermediate host 10. Monokaryotic meront 11. Primary monokaryotic mitospore 12. Within-host transmission 13. Secondary monokaryotic mitospore (not Culicosporella) 14. Transmission to determinate host 15. Gametogenesis 16. Plasmogamy In the sexual Amblyospora, Duboscqia, Hyalinocysta and Parathelohania species, monokaryotic meiospores infect an intermediate host. Monokaryotic mitospores released by the intermediate host then infect the determinate host, where they differentiate into gametes and undergo plasmogamy to form diplokaryotic cells. In Edhazardia aedis and Culicosporella lunata, meiosis is abortive and any meiospores produced are non-functional while in Culicospora magna, meiosis is completely absent. E. aedis and C. magna produce monokaryotic mitospores by nuclear dissociation, eliminating meiosis. These monokaryotic spores are functionally equivalent to the spores produced by the intermediate host of Amblyospora, capable of infecting the determinate host and of undergoing gametogenesis and plasmogamy. In C. lunata, diplokaryotic mitospores are produced for horizontal transmission between larval hosts, eliminating both gametogenesis and plasmogamy.