Obliquaria rubra Rafinesque, 1820
Rafinesque, 1820. Ann. Gén. Sci. Phys. 5 (13): 314 [also as ‘U. rubra’].
Rafinesque, 1864. [in] Binney & Tryon, reprint: 57.
Type(s): LECTOTYPE ANSP_20237, [no locality available - North America].

— Simpson (1900), Simpson (1914)
Quadrula rubra — Vanatta (1915)
Pleurobema obliqua rubrum — Ortmann (1918)
Pleurobema pyramidatum — Ortmann & Walker (1922), Vidrine (1993)
Quadrula (Obliquata) coccinea — Frierson (1927)
Obliquaria rubra — Burch (1975)
Pleurobema rubrum — Cummings & Mayer (1992), IUCN (1996), Cummings & Mayer (1997), Parmalee & Bogan (1998), Turgeon et al. (1998), ... Inoue et al. (2018), Klymus et al. (2020), Graf & Cummings (2021), FMCS (2021), Hopper et al. (2023)
Pleurobema cordatum — Strayer & Jirka (1997)
Pleurobema (Sintoxia) rubrum — Campbell & Lydeard (2012), Burlakova et al. (2012)
Pleurobema sintoxia — Johnson et al. (2024)

Obliquaria rubra var. lineata Rafinesque, 1820
Rafinesque, 1820. Ann. Gén. Sci. Phys. 5 (13): 314.
Rafinesque, 1864. [in] Binney & Tryon, reprint: 57.
(intro'd as intra-sp. of Obliquaria rubra Rafinesque, 1820)

— Vanatta (1915)

Obliquaria rubra var. pallida Rafinesque, 1820
Rafinesque, 1820. Ann. Gén. Sci. Phys. 5 (13): 314.
Rafinesque, 1864. [in] Binney & Tryon, reprint: 57.
(intro'd as intra-sp. of Obliquaria rubra Rafinesque, 1820)

— Vanatta (1915)

Obliquaria (Scalenaria) triangularis Rafinesque, 1820
Rafinesque, 1820. Ann. Gén. Sci. Phys. 5 (13): 309 [also as ‘U. triangularis’].
Rafinesque, 1864. [in] Binney & Tryon, reprint: 53.

— Simpson (1900), Simpson (1914)
Fusconaia subrotunda — Ortmann & Walker (1922)
Quadrula (Obliquata) catilla — Frierson (1927)
Obliquaria triangularis — Burch (1975)

Obliquaria (Scalenaria) triangularis var. nigrescens Rafinesque, 1820
Rafinesque, 1820. Ann. Gén. Sci. Phys. 5 (13): 309.
Rafinesque, 1864. [in] Binney & Tryon, reprint: 53.
(intro'd as intra-sp. of Obliquaria (Scalenaria) triangularis Rafinesque, 1820)

— Vanatta (1915)

Obliquaria (Sintoxia) sintoxia Rafinesque, 1820
Rafinesque, 1819. Jour. Phys. Chim. Hist. Nat. 88: 427 [as ‘U. (Obovaria) syntoxis’]. [nomen nudum]
Rafinesque, 1820. Ann. Gén. Sci. Phys. 5 (13): 310 [also as ‘U. sintoxia’].
Rafinesque, 1864. [in] Binney & Tryon, reprint: 29, 54.
(correct name for Unio (Obovaria) syntoxis Rafinesque, 1819)
Type(s): LECTOTYPE ANSP_20208, Ohio River.

— Simpson (1900), Simpson (1914)
Quadrula sintoxia — Vanatta (1915)
Fusconaia subrotunda — Ortmann & Walker (1922)
Quadrula (Fusconia [sic]) subrotunda — Frierson (1927)
Pleurobema sintoxia — Morrison (1969), Oesch (1984), Cummings & Mayer (1997), Parmalee & Bogan (1998), Turgeon et al. (1998), ... FMCS (2021), Jeratthitikul et al. (2022), Hopper et al. (2023), Johnson et al. (2024), Freeman et al. (2025)
Obliquaria sintoxia — Burch (1975)
Pleurobema cordatum — R.I. Johnson (1980), Strayer & Jirka (1997)
Pleurobema (Sintoxia) sintoxia — Campbell & Lydeard (2012), Campbell & Lydeard (2012), Burlakova et al. (2012)

Unio cardiacea Guérin-Méneville, 1823
Guérin-Méneville, 1823. Icon. Règne Animal Cuvier 2: pl. 28, fig. 7.

Quadrula (sec. Fusconaia) pyramidata — Simpson (1900), Simpson (1914)
Quadrula (Obliquata) obliquata — Frierson (1927), Haas (1930), Haas (1969)
Pleurobema cordatum — R.I. Johnson (1980)
Pleurobema rubrum — Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009)

Unio mytiloides Bory de St. Vincent, 1827
Bruguière, 1797. Encycl. Méth. 2: pl. 249, fig. 4a-b [as Unio sp.].
‘Val.’ Bory de St. Vincent, 1827. Encycl. Méth. 2: 151.
Deshayes, 1832. Enc. Méth. 2 (Deuxième partie): 585.
(homonym of Pleurobema mytiloides Rafinesque, 1820)

Quadrula (sec. Fusconaia) pyramidata — Simpson (1900), Simpson (1914)
Quadrula (Obliquata) obliquata — Haas (1969)
Pleurobema rubrum — Parmalee & Bogan (1998), Watters et al. (2009)

Unio obliquus Wood, 1828
Wood, 1828. Suppl. Index Testac.: 3 [as ‘Mya obliqua’].
Wood, 1828. Suppl. Index Testac.: 57, pl. 1, sp. 8.
Wood & Hanley, 1856. Index Testac.: 200, pl. 1, fig. 8.
(misidentified reference to Unio obliqua Lamarck, 1819)

Quadrula (sec. Fusconaia) pyramidata — Simpson (1900), Simpson (1914)
Pleurobema rubrum — Parmalee & Bogan (1998), Watters et al. (2009)

Unio pyramidatus Lea, 1831
Lea, 1831. Trans. Amer. Phil. Soc. 4 [O. 1]: 109 [119], pl. 16, fig. 39.
Type(s): SYNTYPES ANSP_41726, Ohio River.

Quadrula (sec. Fusconaia) pyramidata — Simpson (1900), Simpson (1914)
Quadrula pyramidata — Ortmann (1909)
Quadrula obliqua — Ortmann (1909)
Pleurobema obliqua form pyramidata — Ortmann (1910)
Pleurobema obliquum — Ortmann (1912)
Unio pyramidatus — de Gregorio (1914)
Pleurobema obliquum pyramidatum — Utterback (1915)
Quadrula rubra — Vanatta (1915)
Pleurobema obliqua rubrum — Ortmann (1918)
Pleurobema pyramidatum — Ortmann & Walker (1922), Stansbery (1970), Turgeon et al. (1988), Williams et al. (1993), Vidrine (1993), ITIS (2012)
Pleurobema cordatum pyramidatum — Ortmann (1924), Ortmann (1925), Murray & Leonard (1962), Gordon et al. (1979)
Quadrula (Obliquata) obliquata — Frierson (1927), Haas (1969)
Pleurobema obliquata — Morrison (1969)
Pleurobema cordatum — R.I. Johnson (1980), Strayer & Jirka (1997)
Pleurobema rubrum — Parmalee & Bogan (1998), Turgeon et al. (1998), Williams et al. (2008), Watters et al. (2009)

Unio catillus Conrad, 1836
Conrad, 1836. Monogr. Fam. Unionidae 1(3): 30, pl. 13, fig. 2.
Conrad, 1853. Proc. Acad. Nat. Sci. 6: 246.

Quadrula (sec. Fusconaia) coccinea — Simpson (1900), Simpson (1914)
Pleurobema obliquum catillus — Utterback (1915)
Pleurobema catillus — Utterback (1915), Ortmann & Walker (1922)
Pleurobema obliqua catillus — Ortmann (1918)
Pleurobema cordatum catillus — Ortmann (1924), Ortmann (1925), Murray & Leonard (1962), Gordon et al. (1979)
Quadrula (Obliquata) catilla — Frierson (1927), Haas (1969)
Pleurobema coccineum catillus — F.C. Baker (1928)
Pleurobema cordatum — Burch (1975), R.I. Johnson (1980)
Pleurobema sintoxia — Oesch (1984), Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009)

Unio coccineus Conrad, 1836
‘Hildreth’ Conrad, 1836. Monogr. Fam. Unionidae 1(3): 29, pl. 13, fig. 1.
‘Hildreth’ Conrad, 1853. Proc. Acad. Nat. Sci. 6: 247.
Type(s): FIGURED SYNTYPE USNM_85848, Columbus, Ohio.

Quadrula (sec. Fusconaia) coccinea — Simpson (1900), Simpson (1914)
Quadrula coccinea — Ortmann (1909), Ortmann (1909)
Pleurobema obliqua var. coccinea — Ortmann (1910)
Pleurobema coccineum — Ortmann (1912), Utterback (1915), F.C. Baker (1928), Turgeon et al. (1988), Cummings & Mayer (1992), Williams et al. (1993), Graf & Ó Foighil (2000), Graf (2002), ITIS (2012)
Pleurobema obliquum coccineum — Utterback (1915)
Pleurobema obliqua coccineum — Ortmann (1918)
Quadrula (Obliquata) coccinea — Frierson (1927)
Pleurobema cordatum coccineum — Murray & Leonard (1962), Gordon et al. (1979)
Quadrula (Obliquata) coccinea coccinea — Haas (1969)
Pleurobema cordatum — Mathiak (1979), R.I. Johnson (1980), Strayer & Jirka (1997)
Pleurobema cordatum f. coccineum — Mackie et al. (1980)
Pleurobema sintoxia — Oesch (1984), Parmalee & Bogan (1998), Turgeon et al. (1998), Williams et al. (2008), Watters et al. (2009), IUCN (2012), Zieritz et al. (2015)

Unio coccineus Lea, 1838
“Dr. Hildreth’s Letter” Lea, 1836. Synopsis Fam. Naiades: 34. [nomen nudum]
Lea, 1838. Trans. Amer. Phil. Soc. 6 [O. 2]: 12, pl. 5, fig. 12.
(homonym of Unio coccineus Conrad, 1836)
Type(s): FIGURED SYNTYPE USNM_85848, Columbus, Ohio.

Quadrula (sec. Fusconaia) coccinea — Simpson (1900), Simpson (1914)
Unio (s.s.) coccineus — Call (1900)
Unio coccineus — de Gregorio (1914)
Quadrula (Obliquata) catilla — Frierson (1927)
Pleurobema coccineum — F.C. Baker (1928), Graf & Cummings (2006), Hoeh et al. (2009)
Pleurobema cordatum — R.I. Johnson (1980)

Unio cuneus Conrad, 1838
Conrad, 1838. Monogr. Fam. Unionidae 2(11): back cover.
Conrad, 1840. Monogr. Fam. Unionidae 2(12): 105, pl. 58, fig. 1.
Type(s): HOLOTYPE (MONOTYPY) ANSP_41645, Arkansas River.

Quadrula (sec. Fusconaia) cuneus — Simpson (1900), Simpson (1914)
Quadrula (Obliquata) coccinea-cunea — Frierson (1927)
Quadrula (Obliquata) coccinea cunea — Haas (1969)
Pleurobema cordatum — R.I. Johnson (1980)
Pleurobema pyramidatum — Vidrine (1993)
Pleurobema sintoxia — Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009)

Unio solidus Lea, 1838
Lea, 1836. Synopsis Fam. Naiades: 20. [nomen nudum]
Lea, 1838. Trans. Amer. Phil. Soc. 6 [O. 2]: 13, pl. 5, fig. 13.

Quadrula (sec. Fusconaia) solida — Simpson (1900), Simpson (1914)
Unio (s.s.) solidus — Call (1900)
Pleurobema obliquum catillus — Utterback (1915)
Pleurobema catillus — Utterback (1915), Ortmann & Walker (1922)
Pleurobema obliqua catillus — Ortmann (1918)
Pleurobema cordatum catillus — Ortmann (1925), Murray & Leonard (1962)
Quadrula (Obliquata) catilla — Frierson (1927), Haas (1969)
Pleurobema coccineum solida — F.C. Baker (1928)
Pleurobema sintoxia — Morrison (1969), Oesch (1984), Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009)
Pleurobema cordatum — Burch (1975), R.I. Johnson (1980), Strayer & Jirka (1997)

Unio cardiacea Deshayes, 1839
‘Guérin’ Deshayes, 1839. Traité Élém. Conchyl.: 19, pl. 31, figs. 1-2.
(reference to Unio cardiacea Guérin-Méneville, 1823)

Quadrula (sec. Fusconaia) solida — Simpson (1900), Simpson (1914)
Quadrula (Obliquata) catilla — Haas (1969)
Pleurobema sintoxia — Parmalee & Bogan (1998), Watters et al. (2009)

Unio fulgidus Lea, 1845
Lea, 1845. Proc. Amer. Phil. Soc. 4: 164.
Lea, 1848. Trans. Amer. Phil. Soc. 10 [O. 4]: 73 [47], pl. 4, fig. 10.
Type(s): FIGURED SYNTYPE USNM_84649, Alexandria, La.

Quadrula (sec. Fusconaia) solida — Simpson (1900), Simpson (1914)
Pleurobema catillus — Utterback (1915)
Quadrula (Obliquata) catilla — Frierson (1927), Haas (1969)
Pleurobema cordatum — R.I. Johnson (1980)
Pleurobema sintoxia — Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009)

Unio obliquus Lapham, 1860
‘Lamarck’ of Authors.
Lapham, 1860. Proc. Acad. Nat. Sci. 12: 156.
Baker, 1905. Trans. Acad. Sci. St. Louis 15: 256.
Ortmann, 1919. Mem. Carnegie Mus. 8(1): 73. [in part]
(misidentified reference to Unio obliqua Lamarck, 1819)

Pleurobema coccineum solida — F.C. Baker (1928)

Unio catilus B.H. Wright, 1888
‘Conrad’ of Authors.
B.H. Wright, 1888. Check List N. Amer. Unionidae etc.: [2].
Ortmann, 1924. Amer. Midl. Nat. 9(1): 38.
(error for Unio catillus Conrad, 1836)

Quadrula (sec. Fusconaia) coccinea — Simpson (1900), Simpson (1914)
Pleurobema sintoxia — Parmalee & Bogan (1998), Watters et al. (2009)

Unio cuneus Call, 1895
Call, 1895. Trans. Acad. Sci. St. Louis 7: 14.
(reference to Unio cuneus Conrad, 1838)

Quadrula (sec. Fusconaia) coccinea — Simpson (1900), Simpson (1914)

Quadrula (sec. Fusconaia) coccinea var. paupercula Simpson, 1900
Simpson, 1900. Proc. U.S. Nat. Mus. 22: 789.
(intro'd as intra-sp. of Unio coccineus Conrad, 1836; homonym of Unio pauperculus Lea, 1861; renamed Quadrula (sec. Fusconaia) coccinea var. magnalacustris Simpson, 1914)

Quadrula (sec. Fusconaia) coccinea var. paupercula — Simpson (1900)
Quadrula (sec. Fusconaia) coccinea var. magnalacustris — Simpson (1914)
Pleurobema coccineum paupercula — Ortmann & Walker (1922)
Quadrula (Obliquata) coccinea-magnalacustris — Frierson (1927)
Quadrula (Obliquata) coccinea magnalacustris — Haas (1969)
Pleurobema cordatum — R.I. Johnson (1980), Strayer & Jirka (1997)
Pleurobema sintoxia — Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009), IUCN (2012)

Pleurobema missouriensis Marsh, 1901
Marsh, 1901. Nautilus 15(7): 74.
Walker, 1915. Nautilus 28(12): 140, pl. 5, figs. 1-2.
Type(s): FIGURED SYNTYPE UMMZ_113527, Black River, Poplar Bluff, Butler Co., Missouri.

Pleurobema (s.s.) missouriense — Simpson (1914)
Pleurobema missourense [sic] — Utterback (1915)
Quadrula (Obliquata) missouriensis — Frierson (1927), Haas (1969)
Fusconaia subrotunda — R.I. Johnson (1980)
Pleurobema sintoxia — Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009)

Quadrula (sec. Fusconaia) coccinea var. magnalacustris Simpson, 1914
Simpson, 1914. Descr. Cat. Naiades: 884.
(intro'd as intra-sp. of Unio coccineus Conrad, 1836; new name for Quadrula (sec. Fusconaia) coccinea var. paupercula Simpson, 1900)
Type(s): LECTOTYPE USNM_133834, Niagara Riv., 3 mi above Falls.

Quadrula (sec. Fusconaia) coccinea var. magnalacustris — Simpson (1914)
Pleurobema coccineum paupercula — Ortmann & Walker (1922)
Quadrula (Obliquata) coccinea-magnalacustris — Frierson (1927)
Quadrula (Obliquata) coccinea magnalacustris — Haas (1969)
Pleurobema cordatum — R.I. Johnson (1980)
Pleurobema sintoxia — Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009)

Pleurobema coccineum var. mississippiensis F.C. Baker, 1928
F.C. Baker, 1928. Bull. Wisconsin Geol. Nat. Hist. Survey 70(2): 121, pl. 53, figs. 1-5.
(intro'd as intra-sp. of Unio coccineus Conrad, 1836)
Type(s): HOLOTYPE (ORIG. DESIG.) INHS_82273, Lake Pepin, Wisconsin.

Pleurobema coccineum mississippiensis — F.C. Baker (1928)
— Haas (1969)
Pleurobema cordatum — R.I. Johnson (1980)
Pleurobema sintoxia — Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009)

Unio (Obovaria) syntoxis Rafinesque, 1819
Rafinesque, 1819. Jour. Phys. Chim. Hist. Nat. 88: 427. [nomen nudum]
Rafinesque, 1864. [in] Binney & Tryon, reprint: 29.
(incorrect original spelling of Obliquaria (Sintoxia) sintoxia Rafinesque, 1820)

Fusconaia subrotunda — Haas (1969)

Unio caridacea Conrad, 1836
‘Guérin’ Conrad, 1836. Monogr. Fam. Unionidae 1(5): 41.
(error for Unio cardiacea Guérin-Méneville, 1823)

Unio mytiloides Conrad, 1836
‘Rafinesque’ Conrad, 1836. Monogr. Fam. Unionidae 1(4): 41, pl. 20.
(misidentified reference to Pleurobema mytiloides Rafinesque, 1820)

Quadrula (sec. Fusconaia) pyramidata — Simpson (1900), Simpson (1914)
Quadrula (Obliquata) obliquata — Frierson (1927)

Unio gouldianus Jay, 1839
Ward in Jay, 1839. Cat. Rec. Shells: 24. [nomen nudum]

Quadrula (sec. Fusconaia) coccinea — Simpson (1900), Simpson (1914)
Unio (s.s.) coccineus — Call (1900)
Quadrula (Fusconia [sic]) antrosa — Frierson (1927)
Fusconaia antrosa — Haas (1969)
Pleurobema cordatum — R.I. Johnson (1980)
Pleurobema sintoxia — Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009)

Unio coccineus Jay, 1850
Jay, 1850. Cat. Rec. Shells: 66.
(reference to Unio coccineus Conrad, 1836)

Unio obovalis Conrad, 1853
‘Rafinesque’ Conrad, 1853. Proc. Acad. Nat. Sci. 6: 253.
(misidentified reference to Obovaria obovalis Rafinesque, 1820)

Quadrula (sec. Fusconaia) solida — Simpson (1900), Simpson (1914)
Pleurobema sintoxia — Parmalee & Bogan (1998), Watters et al. (2009)

Unio ruber Conrad, 1853
‘Rafinesque’ Conrad, 1853. Proc. Acad. Nat. Sci. 6: 257.
(reference to Obliquaria rubra Rafinesque, 1820)

Quadrula (sec. Fusconaia) pyramidata — Simpson (1900), Simpson (1914)
Quadrula (Obliquata) obliquata — Frierson (1927), Haas (1969)
Pleurobema rubrum — Parmalee & Bogan (1998), Watters et al. (2009)

Unio mytiloides Lapham, 1860
‘Raf.’ Lapham, 1860. Proc. Acad. Nat. Sci. 12: 156.
(misidentified reference to Pleurobema mytiloides Rafinesque, 1820)

Pleurobema coccineum catillus — F.C. Baker (1928)

Unio cardidiacea Lea, 1870
‘Conrad’ Lea, 1870. Synopsis Fam. Naiades: 39.
(error for Unio caridacea Conrad, 1836)

Unio pyramidatus Call, 1885
Call, 1885. unknown publication: 46.
(reference to Unio pyramidatus Lea, 1831)

Pleurobema coccineum catillus — F.C. Baker (1928)

Quadrula kirtlandiana Simpson, 1900
‘Conrad’ Simpson, 1900. Proc. U.S. Nat. Mus. 22: 791. [in part]
‘Conrad’ Simpson, 1914. Descr. Cat. Naiades: 891. [in part]
(misidentified reference to Unio kirtlandianus Lea, 1834)

Pleurobema coccineum — F.C. Baker (1928)

Quadrula pyramidata Simpson, 1900
‘Lea’ Simpson, 1900. Proc. U.S. Nat. Mus. 22: 789. [in part]
Chadwick, 1906. unknown publication: 97.
‘Lea’ Simpson, 1914. Descr. Cat. Naiades: 889. [in part]
(reference to Unio pyramidatus Lea, 1831)

Pleurobema coccineum solida — F.C. Baker (1928)

Pleurobema missourense Utterback, 1915
‘Marsh’ Utterback, 1915. Amer. Midl. Nat. 4(5): 195.
(error for Pleurobema missouriensis Marsh, 1901)

Unio mytilloides Frierson, 1927
‘Lea, 1829’ Frierson, 1927. Check List N. Amer. Naiades: 52.
(misidentified reference to Pleurobema mytiloides Rafinesque, 1820; error for Pleurobema mytiloides Rafinesque, 1820)

Pleurobema rubrum — Parmalee & Bogan (1998), Watters et al. (2009)