• Didymocystis lanceolata Guiart, 1938 accepted as Didymosulcus lanceolatus (Guiart, 1938) Pozdnyakov, 1990
• Didymocystis macrorchis Guiart, 1938 accepted as Didymosulcus macrorchis (Guiart, 1938) Pozdnyakov, 1990
• Didymocystis philobranchia Yamaguti, 1970 accepted as Didymosulcus philobranchia (Yamaguti, 1970) Pozdnyakov, 1990
• Didymocystis reniformis Ariola, 1902
• Didymocystis thynni (Taschenberg, 1879) Dollfus, 1926
• Didymocystis xiphiados (MacCallum & MacCallum, 1916) accepted as Maccallumtrema xiphiados (MacCallum & MacCallum, 1916) Yamaguti, 1970
• Didymosulcus lanceolatus (Guiart, 1938) Pozdnyakov, 1990
• Didymosulcus macrorchis (Guiart, 1938) Pozdnyakov, 1990
• Didymosulcus philobranchia (Yamaguti, 1970) Pozdnyakov, 1990
• Didymosulcus wedli (Ariola, 1902) (uncertain > taxon inquirendum)
• Didymozoon auxis Taschenberg, 1879
• Didymozoon pretiosus Ariola, 1902
• Didymozoon serrani Monticelli, 1889 (uncertain > taxon inquirendum)
• Didymozoon sphyraenae Taschenberg, 1879
• Didymozoon taenioides Monticelli, 1883 (uncertain > taxon inquirendum)
• Oesophagocystis lydiae Pozdnyakov, 1994
• Platocystis alalongae Yamaguti, 1938