n = 61
| Scientific Name | Author | Valid Name | Family | English Name |
|---|---|---|---|---|
| Thyasira alleni | Carrozza, 1981 | Thyasira alleni | Thyasiridae | |
| Thyasira anassa | Oliver, 2015 | Thyasira anassa | Thyasiridae | |
| Thyasira atlantica | Payne & Allen, 1991 | Thyasira atlantica | Thyasiridae | |
| Thyasira barbarensis | (Dall, 1890) | Thyasira barbarensis | Thyasiridae | |
| Thyasira biplicata | (Philippi, 1836) | Thyasira biplicata | Thyasiridae | |
| Thyasira bisecta | Conrad, 1849 | Conchocele bisecta | Thyasiridae | Giant cleftclam |
| Thyasira brevis | Verrill & Bush, 1898 | Thyasira brevis | Thyasiridae | |
| Thyasira conia | Dall & Simpson, 1901 | Thyasira conia | Thyasiridae | |
| Thyasira croulinensis | Jeffreys, 1874 | Axinulus croulinensis | Thyasiridae | |
| Thyasira cumingii | (Fischer, 1861) | Thyasira cumingii | Thyasiridae | |
| Thyasira cycladia | (Wood, 1848) | Axinulus cycladius | Thyasiridae | |
| Thyasira cygnus | Dall, 1916 | Thyasira cygnus | Thyasiridae | |
| Thyasira dearborni | Nicol, 1965 | Parathyasira dearborni | Thyasiridae | |
| Thyasira debilis | (Thiele, 1912) | Thyasira debilis | Thyasiridae | |
| Thyasira disjuncta | (Gabb, 1866) | Conchocele disjuncta | Thyasiridae | |
| Thyasira dunbari | Lubinsky, 1976 | Parathyasira dunbari | Thyasiridae | |
| Thyasira elliptica | Verrill & Bush, 1898 | Thyasira elliptica | Thyasiridae | |
| Thyasira equalis | (Verrill & Bush, 1898) | Parathyasira equalis | Thyasiridae | Equal cleftclam |
| Thyasira eumyaria | Sars, 1870 | Thyasira eumyaria | Thyasiridae | |
| Thyasira falklandica | Smith, 1885 | Thyasira falklandica | Thyasiridae | |
| Thyasira ferruginea | Winckworth, 1932 | Mendicula ferruginosa | Thyasiridae | Rusty axinopsid |
| Thyasira ferruginosa | Forbes, 1844 | Mendicula ferruginosa | Thyasiridae | Rusty axinopsid |
| Thyasira flexuosa | (Montagu, 1803) | Thyasira flexuosa | Thyasiridae | Flexuose cleftclam |
| Thyasira flexusa | (Montagu,) | Thyasira flexuosa | Thyasiridae | Flexuose cleftclam |
| Thyasira fuegiensis | (Dall, 1890) | Thyasira fuegiensis | Thyasiridae | |
| Thyasira gouldi | (Philippi, 1845) | Thyasira gouldii | Thyasiridae | |
| Thyasira gouldii | (Philippi, 1845) | Thyasira gouldii | Thyasiridae | |
| Thyasira grandis | Verrill & Smith, 1885 | Thyasira grandis | Thyasiridae | |
| Thyasira granulosa | Monterosato, 1874 | Thyasira granulosa | Thyasiridae | Granulose cleftclam |
| Thyasira inaequalis | (Verrill & Bush, 1898) | Thyasira flexuosa | Thyasiridae | Flexuose cleftclam |
| Thyasira incrassatus | (Jeffreys, 1876) | Thyasira incrassatus | Thyasiridae | |
| Thyasira inequalis | (Verrill & Bush, 1898) | Thyasira flexuosa | Thyasiridae | Flexuose cleftclam |
| Thyasira insignis | (Verrill & Bush, 1898) | Thyasira flexuosa | Thyasiridae | Flexuose cleftclam |
| Thyasira magellanica | Dall, 1901 | Thyasira magellanica | Thyasiridae | |
| Thyasira miyadii | Habe, 1951 | Thyasira miyadii | Thyasiridae | |
| Thyasira oblonga | (Monterosato, 1878) | Thyasira oblonga | Thyasiridae | |
| Thyasira obsoleta | (Verrill & Bush, 1898) | Thyasira obsoleta | Thyasiridae | |
| Thyasira ovoidea | Dall, 1889 | Thyasira ovoidea | Thyasiridae | |
| Thyasira peregrina | (Iredale, 1930) | Thyasira peregrina | Thyasiridae | |
| Thyasira perplicata | Salas, 1996 | Thyasira perplicata | Thyasiridae | |
| Thyasira plana | (Verrill & Bush, 1898) | Thyasira flexuosa | Thyasiridae | Flexuose cleftclam |
| Thyasira planata | (Jeffreys, 1882) | Thyasira planata | Thyasiridae | |
| Thyasira plicata | (Verrill, 1885) | Thyasira perplicata | Thyasiridae | |
| Thyasira polygona | Jeffreys, 1863 | Thyasira trisinuata | Thyasiridae | Atlantic cleftclam |
| Thyasira pygmaea | Verrill & Bush, 1898 | Thyasira pygmaea | Thyasiridae | |
| Thyasira pyriformis | Dall, 1886 | Thyasira grandis | Thyasiridae | |
| Thyasira rotunda | Jeffreys, 1881 | Thyasira rotunda | Thyasiridae | Rotund cleftclam |
| Thyasira sarsi | Philippi, 1845 | Thyasira sarsii | Thyasiridae | |
| Thyasira sarsii | (Philippi, 1845) | Thyasira sarsii | Thyasiridae | |
| Thyasira simplex | Verrill & Bush, 1898 | Thyasira simplex | Thyasiridae | Simple cleftclam |
| Thyasira southwardae | Oliver & Holmes, 2006 | Thyasira southwardae | Thyasiridae | |
| Thyasira striata | (Sturany, 1896) | Thyasira striata | Thyasiridae | |
| Thyasira subequatoria | Payne & Allen, 1991 | Thyasira subequatoria | Thyasiridae | |
| Thyasira subovata | Jeffreys, 1881 | Thyasira subovata | Thyasiridae | |
| Thyasira subtrigona | (Jeffreys, 1858) | Thyasira subtrigona | Thyasiridae | |
| Thyasira succisa | (Jeffreys, 1876) | Thyasira succisa | Thyasiridae | Cut-off cleftclam |
| Thyasira tokunagai | Kuroda & Habe, 1951 | Thyasira tokunagai | Thyasiridae | |
| Thyasira tortuosa | Jeffreys, 1881 | Thyasira tortuosa | Thyasiridae | |
| Thyasira tricarinata | Dall, 1916 | Thyasira tricarinata | Thyasiridae | |
| Thyasira trisinuata | (d'Orbigny, 1842) | Thyasira trisinuata | Thyasiridae | Atlantic cleftclam |
| Thyasira waikanae | Fleming, 1950 | Thyasira waikanae | Thyasiridae |