The life cycle of Haemogregarina bigemina (Adeleina : Haemogregarinidae) in South African hosts

Haemogregarina bigemina Laveran et Mesnil, 1901 was examined in marine fish es and the gnathiid isopod, Gnathia africana Barnard, 1914 in South Africa. Its development in fishes was similar to that described previously for thi s species. Gnathiids taken from fishes with IL bigemina, and prepared seque ntially over 28 days post feeding (d.p.f.), contained stages of syzygy, imm ature and mature oocysts, sporozoites and merozoites of at least three type s. Sporozoites, often five in number, formed from each oocyst from 9 d.p.f. First-generation merozoites appeared in small numbers at I I d.p.f., arisi ng from small, rounded meronts. Mature, second-generation merozoites appear ed in large clusters within gut tissue at 18 d.p.f. They were presumed to a rise from fan-shaped meronts, First observed at 11 d.p.f. Third-generation merozoites were the shortest, and resulted from binary Fission of meronts, derived from second-generation merozoites. Gnathiids taken from sponges wit hin rock pools contained only gamonts and immature oocysts. It is concluded that the development of 11. bigemina in its arthropod host illustrates an affinity with Hemolivia and one species of Hepatozoon. However, the absence of sporokinetes and sporocysts also distances it from these genera, and fr om Karyolysus. Furthermore, H. bigemina produces fewer sporozoites than Cyr ilia and Desseria, although, as in Desseria, Haemogregarina (sensu stricto) and Babesiosoma, post-sporogonic production of merozoites occurs in the in vertebrate host. The presence of intraerythrocytic binary fission in its Fi sh host means that H. bigemina is not a Desseria. Overall it most closely r esembles Haemogregarina (sensu stricto) in its development, although the ma tch is not exact.