Apatemon is a genus of trematodes (class Trematoda) within the family Strigeidae and order Diplostomida. The genus was first described by L. Szidat in 1928. These flatworms have a cosmopolitan distribution and include several recognized species, such as Apatemon gracilis (Rudolphi, 1819), Apatemon annuligerum, Apatemon barbusi, Apatemon cobitidis, Apatemon fuligulae, Apatemon hypseleotris, Apatemon jamiesoni, Apatemon pellucidus, Apatemon somateriae, Apatemon tilapiae, and Apatemon fuhrmanni.[1][2][3][4][5][6]
The life cycle of Apatemon species is complex and involves multiple hosts. Gastropods, such as Potamopyrgus antipodarum, serve as the first intermediate host, where sporocysts develop primarily in the mantle, digestive gland, and basal visceral mass. Second intermediate hosts include small freshwater fishes, such as Galaxias auratus, where metacercariae may encyst in various locations including the body cavity, orbit, and vitreous humour. The final hosts are typically birds, such as ducks (e.g., Anas superciliosa), in which the adult flukes inhabit the upper small intestine.[1][4]