Unio retusa Lamarck, 1819
Lamarck, 1819, Hist. Natur. Anim. sans Vert. 6: 72, sp. 9.
Type(s): HOLOTYPE MNHN_MPL_0043, Habite les rivières de la Nouvelle Ecosse. A. Michaud. [Lives in the rivers of Nova Scotia. A. Michaud."].

Unio retusa — Lamarck (1819), Ferussac (1835)
Unio retusus — Menke (1828), Menke (1830), Conrad (1836), Hanley (1843), Küster (1852), Conrad (1853), Sowerby (1868), Call (1895)
Unio torsa — Lea (1834)
Margarita (Unio) retusus — Lea (1836)
Obovaria torsus — Agassiz (1852)
Margaron (Unio) retusus — Lea (1852), Lea (1870)
Unio (Obovaria) torsus — Mörch (1853)
Unio (Limnium sec. Obovaria) retusus — Fischer (1887)
Obovaria (s.s.) retusa — Simpson (1900), Simpson (1914), Ortmann (1918), Ortmann (1924), Ortmann (1925), Frierson (1927), Haas (1930), Thiele (1934), Haas (1969), Haas (1969)
Unio (s.s.) retusus — Call (1900)
Obovaria retusa — Ortmann (1909), Ortmann (1909), Ortmann (1910), Ortmann (1912), Vanatta (1915), Ortmann & Walker (1922), R.I. Johnson (1969), Stansbery (1970), Burch (1975), R.I. Johnson (1980), Turgeon et al. (1988), Cummings & Mayer (1992), Williams et al. (1993), IUCN (1996), Parmalee & Bogan (1998), Turgeon et al. (1998), Lydeard et al. (1999), Graf (2002), Cicerello & Schuster (2003), Graf & Cummings (2007), Williams et al. (2008), Watters et al. (2009), Cummings & Graf (2010), Bogan (2010), Haag (2012), ITIS (2012), Inoue et al. (2013), Williams et al. (2017), Watters (2018), Graf & Cummings (2021)

Unio obtusa Cuvier, 1817
‘Desh.’ Cuvier, 1817, Règne Animal 2: pl. 92, pl. 1.

Unio obtusa — Cuvier (1817)
Margaron (Unio) retusus — Lea (1852), Lea (1870)
Unio retusus — Conrad (1853), Sowerby (1868), Call (1895)

Obovaria torsa Rafinesque, 1820
Rafinesque, 1819, Jour. Phys. Chim. Hist. Nat. 88: 427 [as ‘U. (Obovaria) torsa’]. [nomen nudum]
Rafinesque, 1820, Ann. Gén. Sci. Phys. 5 (13): 311, pl. 82, figs. 1-3.
Rafinesque, 1864, [in] Binney & Tryon, reprint: 29, 54.
Type(s): NEOTYPE ANSP_20256, Kentucky River.

Obovaria torsa — Rafinesque (1820), Simpson (1900), Simpson (1914)
Unio (Obovaria) torsa — Rafinesque (1819)
Unio torsus — Lea (1829), Ravenel (1834), Jay (1835)
Unio torsa — Lea (1834)
Unio retusa — Ferussac (1835)
Unio retusus — Conrad (1836), Hanley (1843), Küster (1852), Conrad (1853), Sowerby (1868), Call (1895)
Margarita (Unio) retusus — Lea (1836)
Unio (s.s.) torsa — Swainson (1840)
Obovaria torsus — Agassiz (1852)
Margaron (Unio) retusus — Lea (1852), Lea (1870)
Unio (Obovaria) torsus — Mörch (1853), Adams & Adams (1857)
Obovaria retusa — Vanatta (1915), Ortmann & Walker (1922), Burch (1975), Parmalee & Bogan (1998), Graf & Cummings (2007), Williams et al. (2008), Watters et al. (2009)
Obovaria (s.s.) retusa — Frierson (1927), Haas (1969)

Obovaria torsa var. marginata Rafinesque, 1820
Rafinesque, 1820, Ann. Gén. Sci. Phys. 5 (13): 311.
Rafinesque, 1864, [in] Binney & Tryon, reprint: 54.
(intro'd as intra-sp. of Obovaria torsa Rafinesque, 1820)

Obovaria torsa var. marginata — Rafinesque (1820)

Unio incurvis Say, 1829
Say, 1829, New Harm. Dissem. 2(19): 293.

Unio incurvis — Say (1829)
Margaron (Unio) retusus — Lea (1870)
Obovaria (s.s.) retusa — Frierson (1927), Haas (1969)

Unio torsus Potiez & Michaud, 1844
‘Rafinesque’ Potiez & Michaud, 1844, Galérie Moll. at. Mus. Douai 2: 149, pl. 57, figs. 1-2.
(reference to Obovaria torsa Rafinesque, 1820)

Unio torsus — Potiez & Michaud (1844)
Margaron (Unio) retusus — Lea (1852)
Obovaria (s.s.) retusa — Simpson (1900), Simpson (1914)
Obovaria retusa — Watters et al. (2009)

Unio cordatus Küster, 1852
‘Rafinesque’ Küster, 1852, Conchyl. Cab. 9(2): 57, pl. 13, fig. 1.
(misidentified reference to Obovaria cordata Rafinesque, 1820)

Unio cordatus — Küster (1852)
Margaron (Unio) retusus — Lea (1852), Lea (1870)
Quadrula (sec. Fusconaia) obliqua — Simpson (1900)

Unio jorsus de Gregorio, 1914
‘Rafinesque’ de Gregorio, 1914, Il Nat. Siciliano 2: 43, 56.
(error for Obovaria torsa Rafinesque, 1820)

Unio jorsus — de Gregorio (1914)