- Hysterothylacium aduncum (Rudolphi, 1802) Deardorff & Overstreet, 1981
- Hysterothylacium incurvum (Rudolphi, 1819) Deardorff & Overstreet, 1980
- Hysterothylacium magnum (Smedley, 1934) Deardorff & Overstreet, 1981
- Hysterothylacium reliquens (Norris & Overstreet, 1975) Deardorff & Overstreet, 1981
- Thynnascaris aduncum Rudolphi, 1802 accepted as Hysterothylacium aduncum (Rudolphi, 1802) Deardorff & Overstreet, 1981
- Thynnascaris thynnascans (uncertain)