Unio recta Lamarck, 1819
Lamarck, 1819. Hist. Natur. Anim. sans Vert. 6: 74, sp. 19.
Type(s): HOLOTYPE MNHN_MPL_0016, Habite le Lac Erié. Michaud. [Lives in Lake Erie. Michaud].

Lampsilis (sec. Eurynia) rectus — Simpson (1900)
Unio (s.s.) rectus — Call (1900)
Lampsilis recta — Ortmann (1909), Ortmann (1909), Ortmann (1909), Ortmann (1910), R.I. Johnson (1969)
Eurynia (s.s.) recta — Ortmann (1912), Utterback (1916), Ortmann (1918)
Lampsilis (Eurynia) recta — Simpson (1914)
— de Gregorio (1914)
Lampsilis rectus — Vanatta (1915)
Ligumia recta — Ortmann & Walker (1922), Haas (1969), Clarke (1973), Burch (1975), Gordon et al. (1979), ... Graf & Cummings (2021), FMCS (2021), Hnytka et al. (2022), Hopper et al. (2023), Hauck et al. (2023)
Lampsilis (Ligumia) recta — Frierson (1927), Haas (1930)
Ligumia (s.s.) recta — F.C. Baker (1928), Thiele (1934)
Unio rectus — Henderson (1935)
Ligumia recta recta — Haas (1969)

Unio (Eurynia) latissima Rafinesque, 1820
Rafinesque, 1818. Amer. Mon. Mag. 3: 355 [as ‘Potamilus latissimus’]. [nomen nudum]
Rafinesque, 1819. Jour. Phys. Chim. Hist. Nat. 88: 426. [nomen nudum]
Rafinesque, 1820. Ann. Gén. Sci. Phys. 5 (13): 297, pl. 80, figs. 14-15 [also as ‘Ellipto latissima’].
Rafinesque, 1864. [in] Binney & Tryon, reprint: 22, 29, 42.
Type(s): LECTOTYPE ANSP_20212, Ohio River.

Lampsilis (sec. Eurynia) rectus — Simpson (1900)
Lampsilis (Eurynia) recta — Simpson (1914)
Lampsilis rectus — Vanatta (1915)
Ligumia recta latissima — Ortmann & Walker (1922), Ortmann (1924), Ortmann (1925), Murray & Leonard (1962), Haas (1969)
Lampsilis (Ligumia) recta-latissima — Frierson (1927)
Ligumia (s.s.) recta latissima — F.C. Baker (1928)
Ligumia recta — Clarke (1973), Burch (1975), R.I. Johnson (1980), Oesch (1984), Strayer & Jirka (1997), Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009), IUCN (2017)
Ligumia latissima — ITIS (2012)

Unio praelongus Barnes, 1823
Barnes, 1823. Amer. J. Sci. 6 (1-2): 261, pl. 13, fig. 11 [as ‘prælongus’].

Lampsilis (sec. Eurynia) rectus — Simpson (1900)
Lampsilis (Eurynia) recta — Simpson (1914)
Eurynia (s.s.) recta — Utterback (1916)
Lampsilis (Ligumia) recta-latissima — Frierson (1927)
Ligumia (s.s.) recta latissima — F.C. Baker (1928)
Ligumia recta latissima — Haas (1969)
Ligumia recta — Oesch (1984), Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009), IUCN (2017)

Unio sageri Conrad, 1836
Conrad, 1836. Monogr. Fam. Unionidae 1(6): 53, pl. 29, fig. 1.

Lampsilis (sec. Eurynia) rectus — Simpson (1900)
Lampsilis (Eurynia) recta var. sageri — Simpson (1914)
Ligumia recta — Ortmann & Walker (1922), Burch (1975), R.I. Johnson (1980), Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009), IUCN (2017)
Lampsilis (Ligumia) recta — Frierson (1927)
Ligumia (s.s.) recta — F.C. Baker (1928)
Ligumia recta recta — Haas (1969)

Unio arquatus Conrad, 1854
Conrad, 1854. Jour. Acad. Nat. Sci. 2(4): 297, pl. 26, fig. 8.

Lampsilis (sec. Eurynia) rectus — Simpson (1900)
Lampsilis (Eurynia) recta — Simpson (1914)
Ptychobranchus (s.s.) fasciolare-arquatum — Frierson (1927)
Ptychobranchus (s.s.) fasciolaris — Haas (1969)
Ligumia recta — Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009)
Ptychobranchus fasciolaris — Parmalee & Bogan (1998), Watters et al. (2009)

Unio leprosus Miles, 1861
Miles, 1861. Biann. Rept. Geol. Survey Michigan 1: 240.
Type(s): SYNTYPE ANSP_42392, Huron River, Mich.

Lampsilis (Eurynia) recta — Simpson (1914)
Lampsilis (Ligumia) recta-latissima — Frierson (1927)
Ligumia recta latissima — Haas (1969)
Ligumia recta — Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009)

Unio rectoides Whitfield, 1885
Whitfield, 1885. U.S. Geol. Surv. Mon. 9: 250, pl. 32, figs. 1-2.

Unio rectus — Henderson (1935)

Unio angustatus var. cuniculus de Gregorio, 1914
de Gregorio, 1914. Il Nat. Siciliano 2: 52, pl. 10, fig. 1a-d.
(intro'd as intra-sp. of Unio angustatus Lea, 1831)

Unio angustatus var. cuniculus — de Gregorio (1914)
Ligumia recta — Watters et al. (2009)

Unio proelongus Ferussac, 1835
‘Barnes’ Ferussac, 1835. Mag. Zool. 5: 27.
(error for Unio praelongus Barnes, 1823)

Unio rectus Conrad, 1836
Conrad, 1836. Monogr. Fam. Unionidae 1(3): 33, pl. 55.
(reference to Unio recta Lamarck, 1819)

Ligumia recta latissima — Ortmann & Walker (1922)
Ligumia recta — Watters et al. (2009)