species Quadrula quadrula (Rafinesque, 1820): synonymy

Obliquaria (Quadrula) quadrula Rafinesque, 1820

Rafinesque, 1820. Ann. Gén. Sci. Phys. 5 (13): 307 [also as ‘Unio quadrula’].
Rafinesque, 1864. [in] Binney & Tryon, reprint: 51.
NEOTYPE ANSP_20224 (by Johnson & Baker, 1973: 167), Salt River.

Quadrula quadrula — Utterback (1915), Vanatta (1915), Ortmann & Walker (1922), Ortmann (1924), Ortmann (1925), ... Hou et al. (2025), Chen et al. (2025), Klymus et al. (2025), Campbell & Lydeard (2026), Barraza et al. (2026)
Quadrula (s.s.) quadrula — Frierson (1927), F.C. Baker (1928), Haas (1969)
Quadrula (s.s.) gigantea [sic] — Haas (1930)
Quadrula (s.s.) quadrula quadrula — Haas (1969)
Obliquaria quadrula — Burch (1975)
“Quadrula quadrula” ** — Lydeard et al. (2000), Serb et al. (2003), Reis et al. (2013), Amaro et al. (2017), Gasparini et al. (2020)
Quadrula quedrula [sic] — Contreras-Arquieta (2000)
“Quadrula quadrula” ** — Lydeard et al. (2000), Reis et al. (2013)
Quadrula quadrula quadrula — ITIS (2012)
Q. quadrula — Sheng et al. (2014)

Unio rugosus Barnes, 1823

(homonym of Unio rugosa Poiret, 1801)
Barnes, 1823. Amer. J. Sci. 6 (1-2): 126, pl. 8, fig. 9a-b.

Quadrula quadrula — Ortmann & Walker (1922), Burch (1975), R.I. Johnson (1980), Parmalee & Bogan (1998), Williams et al. (2008), Lopes-Lima et al. (2019)
Quadrula (s.s.) quadrula — Frierson (1927), F.C. Baker (1928)
Quadrula (s.s.) gigantea [sic] — Haas (1930)
Quadrula (s.s.) quadrula quadrula — Haas (1969)
Quadrula fragosa — Watters et al. (2009)

Unio lacrymosus Lea, 1828

Lea, 1828. Trans. Amer. Phil. Soc. 3 [O. 1]: 272 [14], pl. 6, fig. 8.
LECTOTYPE USNM_84165 (by R.I. Johnson, 1974: 80), Cincinnati, Ohio.

Quadrula (sec. Theliderma) lachrymosa [sic] — Simpson (1900)
Unio (s.s.) lachrymosus [sic] — Call (1900)
Quadrula lachrymosus [sic] — Ortmann (1909)
Quadrula lachrymosa [sic] — Ortmann (1909), Ortmann (1910), Ortmann (1910), Ortmann (1912)
Quadrula (sec. Theliderma) (Group of Q. lachrymosa [sic]) lachrymosa [sic] — Simpson (1914)
Quadrula quadrula — Utterback (1915), Vanatta (1915), Ortmann & Walker (1922), Burch (1975), R.I. Johnson (1980), ... Strayer & Jirka (1997), Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009), Lopes-Lima et al. (2019)
Quadrula (s.s.) quadrula — Frierson (1927), F.C. Baker (1928)
Quadrula (s.s.) quadrula quadrula — Haas (1969)

Unio apiculatus Say, 1829

Say, 1829. New Harm. Dissem. 2(20): 309, sp. 8.
Say, 1834. Amer. Conch. 6: pl. 52.
Say, 1858. [in] Binney, Compl. Writings T. Say: 131, 207, 225.
TYPE LOCALITY TYPE_LOCALITY_MP_016, Lake Ponchartrain, near N. Orleans.

Quadrula (sec. Theliderma) apiculata — Simpson (1900)
Quadrula apiculata — Ortmann (1910), R.I. Johnson (1980), Davis & Fuller (1981), Turgeon et al. (1988), Williams et al. (1993), ... Marshall et al. (2018), Pfeiffer et al. (2019), Pfeiffer et al. (2019), Inoue et al. (2020), Hauck et al. (2023)
Quadrula (sec. Theliderma) (Group of Q. lachrymosa [sic]) apiculata — Simpson (1914)
Quadrula (s.s.) quadrula-apiculata — Frierson (1927)
Quadrula (s.s.) quadrula apiculata — Haas (1969)
Quadrula quadrula — Burch (1975), Lopes-Lima et al. (2019), Graf & Cummings (2021), FMCS (2021), Keogh et al. (2024), FMCS (2025), Cummings et al. (2025)

Unio asperrimus Lea, 1831

Lea, 1831. Trans. Amer. Phil. Soc. 4 [O. 1]: 71 [81], pl. 5, fig. 3.
HOLOTYPE USNM_84174, Cincinnati, Ohio.

Quadrula (sec. Theliderma) lachrymosa [sic] — Simpson (1900)
Unio (s.s.) lachrymosus [sic] — Call (1900)
Quadrula (sec. Theliderma) (Group of Q. lachrymosa [sic]) lachrymosa [sic] — Simpson (1914)
Unio asperrimus — de Gregorio (1914)
Quadrula quadrula — Utterback (1915), Ortmann & Walker (1922), Burch (1975), R.I. Johnson (1980), Oesch (1984), Vidrine (1993), Howells et al. (1996), Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009), Lopes-Lima et al. (2019)
Quadrula (s.s.) quadrula — Frierson (1927), F.C. Baker (1928)
Quadrula (s.s.) quadrula quadrula — Haas (1969)

Unio asper Lea, 1831

Lea, 1831. Trans. Amer. Phil. Soc. 4 [O. 1]: 85 [95], pl. 9, fig. 15.
UNKNOWN USNM_84212, Claiborne, Ala. R., Alabama.

Quadrula (sec. Theliderma) asper — Simpson (1900)
Quadrula aspera — Ortmann (1912), Utterback (1915)
Quadrula (sec. Theliderma) (Group of Q. lachrymosa [sic]) aspera — Simpson (1914)
Quadrula (s.s.) quadrula-aspera — Frierson (1927)
Quadrula (s.s.) quadrula aspera — Haas (1969)
Quadrula quadrula — Burch (1975), R.I. Johnson (1980), Vidrine (1993), Lopes-Lima et al. (2019)
Quadrula apiculata — Williams et al. (2008)

Unio quadrulus ‘Rafinesque’ of Authors

(reference to Obliquaria (Quadrula) quadrula Rafinesque, 1820)
‘Rafinesque’ of Authors.
Say, 1834. Amer. Conch. 6: pl. 53.
Conrad, 1840. Monogr. Fam. Unionidae 2(13): 112, pl. 62.

Quadrula (sec. Theliderma) lachrymosa [sic] — Simpson (1900)
Quadrula (sec. Theliderma) (Group of Q. lachrymosa [sic]) lachrymosa [sic] — Simpson (1914)
Quadrula quadrula — Utterback (1915), Watters et al. (2009)

Quadrula lachrymosa ‘Lea’ of Authors

(error for Unio lacrymosus Lea, 1828)
‘Lea’ of Authors.
Swainson, 1840. Treat. Malacol.: 378.
Hanley, 1843. Illustr. Descr. Cat. Rec. Bivalve Shells: 177.
Conrad, 1853. Proc. Acad. Nat. Sci. 6: 256.
Adams & Adams, 1857. Gen. Rec. Moll. 2(31-32): 497.
Reeve, 1864. Conch. Icon. 16: pl. 9, sp. 33.
Call, 1895. Trans. Acad. Sci. St. Louis 7: 21.
F.C. Baker, 1898. Bull. Chicago Acad. Sci. 3(1): 83, pl. 25, fig. 1; pl. 12, fig. 2.
Simpson, 1900. Proc. U.S. Nat. Mus. 22: 776.
Call, 1900. Ind. Dept. Geol. Nat. Res. (1899): 489.
Ortmann, 1909. Nautilus 22(10): 100.
Ortmann, 1909. Ann. Carnegie Mus. 5: 199.
Ortmann, 1910. Nautilus 23(11): 140.
Ortmann, 1910. Nautilus 23: 116.
Ortmann, 1912. Ann. Carnegie Mus. 8: 253.
Simpson, 1914. Descr. Cat. Naiades: 839, 841.
Vanatta, 1915. Proc. Acad. Nat. Sci. 67: 556.
Ortmann & Walker, 1922. Occ. Pap. Mus. Zool. Univ. Mich. (112): 14, 16.
Frierson, 1927. Check List N. Amer. Naiades: 47.
F.C. Baker, 1928. Bull. Wisconsin Geol. Nat. Hist. Survey 70(2): 84.
R.I. Johnson, 1980. Bull. MCZ 149(2): 90.
Vidrine, 1993. Histr. Distr. Freshw. Mussels LA: 53.
Strayer & Jirka, 1997. Pearly Mussels NY (26): 98.

Quadrula quadrula — Utterback (1915), Murray & Leonard (1962), Oesch (1984), Vidrine (1993), Parmalee & Bogan (1998), Watters et al. (2009)

Unio rumphianus Lea, 1852

Lea, 1852. Trans. Amer. Phil. Soc. 10 [O. 5]: 276 [32], pl. 22, fig. 34.
Lea, 1852. Proc. Amer. Phil. Soc. 5: 252. [nomen nudum]
HOLOTYPE USNM_84189, West Georgia.

Quadrula (sec. Theliderma) rumphiana — Simpson (1900)
Quadrula (sec. Theliderma) (Group of Q. lachrymosa [sic]) rumphiana — Simpson (1914)
Quadrula (s.s.) quadrula-rumphiana — Frierson (1927)
Quadrula (s.s.) quadrula rumphiana — Haas (1969)
Quadrula quadrula — Burch (1975), Lopes-Lima et al. (2019), Graf & Cummings (2021), FMCS (2021), FMCS (2025)
Quadrula rumphiana — Turgeon et al. (1988), Williams et al. (1993), Turgeon et al. (1998), Lydeard et al. (1999), Serb et al. (2003), ... Haag (2012), Williams et al. (2017), Inoue et al. (2018), Burlakova et al. (2019), Hauck et al. (2023)
Quadrula quadrula rumphiana — Keogh et al. (2024)

Unio blandianus Lea, 1857

Lea, 1857. Proc. Acad. Nat. Sci. 8: 263.
Lea, 1857. Proc. Acad. Nat. Sci. 9: 31.
Lea, 1858. Jour. Acad. Nat. Sci. 4 [O. 6]: 65, pl. 11, fig. 47.
HOLOTYPE USNM_84190, Othcaloosa Cr., Ga.

Quadrula (sec. Theliderma) rumphiana — Simpson (1900)
Quadrula (sec. Theliderma) (Group of Q. lachrymosa [sic]) rumphiana — Simpson (1914)
Quadrula (s.s.) quadrula-rumphiana — Frierson (1927)
Quadrula (s.s.) quadrula rumphiana — Haas (1969)
Quadrula quadrula — Burch (1975), Lopes-Lima et al. (2019)
Quadrula rumphiana — Williams et al. (2008)

Unio forsheyi Lea, 1859

Lea, 1859. Proc. Acad. Nat. Sci. 11: 155.
Lea, 1860. Jour. Acad. Nat. Sci. 4 [O. 8]: 357 [39], pl. 60, fig. 182.
LECTOTYPE [AS HOLOTYPE] USNM_84169 (by R.I. Johnson, 1974: 59), Texas.

Quadrula (sec. Theliderma) forsheyi — Simpson (1900)
Quadrula forsheyi — Ortmann (1910)
Quadrula (sec. Theliderma) (Group of Q. lachrymosa [sic]) forsheyi — Simpson (1914)
Quadrula (s.s.) quadrula-forsheyi — Frierson (1927)
Quadrula (s.s.) quadrula forsheyi — Haas (1969)
Quadrula quadrula — Burch (1975), Howells et al. (1996), Lopes-Lima et al. (2019), Cummings et al. (2025)
Quadrula apiculata — Williams et al. (2008)

Unio speciosus Lea, 1862

Lea, 1862. Proc. Acad. Nat. Sci. 14: 168.
Lea, 1862. Jour. Acad. Nat. Sci. 5 [O. 9]: 207 [29], pl. 31, fig. 276.
LECTOTYPE [AS HOLOTYPE] USNM_84172 (by R.I. Johnson, 1974: 134), Leon Co., Texas.

Quadrula (sec. Theliderma) speciosa — Simpson (1900)
Quadrula speciosa — Ortmann (1910)
Quadrula (sec. Theliderma) (Group of Q. lachrymosa [sic]) speciosa — Simpson (1914)
Quadrula (s.s.) quadrula-speciosa — Frierson (1927)
Quadrula (s.s.) quadrula speciosa — Haas (1969)
Quadrula quadrula — Burch (1975), Cummings et al. (2025)
Quadrula apiculata — R.I. Johnson (1999)

Unio quadratus Reeve, 1864

(error for Obliquaria (Quadrula) quadrula Rafinesque, 1820)
‘Rafinesque’ Reeve, 1864. Conch. Icon. 16: pl. 6, sp. 24.

Quadrula (sec. Theliderma) lachrymosa [sic] — Simpson (1900)
Quadrula (sec. Theliderma) (Group of Q. lachrymosa [sic]) lachrymosa [sic] — Simpson (1914)
Quadrula (s.s.) quadrula — Frierson (1927)
Quadrula (s.s.) quadrula quadrula — Haas (1969)
Quadrula quadrula — Parmalee & Bogan (1998), Watters et al. (2009)

Unio turgidus Reeve, 1864

(misidentified reference to Unio turgidus Lea, 1838)
‘Lea’ Reeve, 1864. Conch. Icon. 16: pl. 3, sp. 10.

Quadrula (sec. Theliderma) asper — Simpson (1900)
Quadrula (sec. Theliderma) (Group of Q. lachrymosa [sic]) aspera — Simpson (1914)

Unio lunulatus Pratt, 1876

(correct name for Unio unul atus Pratt, 1876)
Pratt, 1876. Proc. Davenport Acad. Nat. Sci. 1: 168, pl. 31, fig. 1a-b [as ‘unul atus’; corrected in Errata].

Quadrula (sec. Theliderma) lachrymosa [sic] var. lunulata — Simpson (1900)
Tritogonia nobilis — Simpson (1914)
Quadrula (s.s.) quadrula — Frierson (1927)
Quadrula (s.s.) quadrula quadrula — Haas (1969)
Quadrula quadrula — Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009), Lopes-Lima et al. (2019)

Quadrula quadrula contraryensis Utterback, 1915

(intro'd as intra-sp. of Obliquaria (Quadrula) quadrula Rafinesque, 1820)
Utterback, 1915. Amer. Midl. Nat. 4(4): 138, pl. 18, figs. 47a-b.
NEOTYPE CM_61.6892 (by Parodiz & Tripp, 1988: 118), Lake Contrary, St. Joseph, Buchanan Co., Missouri.

Quadrula quadrula contraryensis — Utterback (1915)
Quadrula quadrula — Burch (1975), R.I. Johnson (1980), Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009), Lopes-Lima et al. (2019)

Quadrula (Quadrula) quadrula bullocki F.C. Baker, 1928

(intro'd as intra-sp. of Obliquaria (Quadrula) quadrula Rafinesque, 1820)
F.C. Baker, 1928. Bull. Wisconsin Geol. Nat. Hist. Survey 70(2): 87, pl. 46, figs. 1-3.
HOLOTYPE (ORIG. DESIG.) UMMZ_209203, Fox River, nr. De Pere, Wisc.

Quadrula (s.s.) quadrula bullocki — F.C. Baker (1928)
Quadrula quadrula — Clarke (1973), Burch (1975), R.I. Johnson (1980), Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009), Lopes-Lima et al. (2019)

Unio dombeyanus Barnes, 1828

(misidentified reference to Unio dombeyana Valenciennes, 1827)
Barnes, 1828. Amer. J. Sci. 13(2): 360.

Quadrula (s.s.) quadrula — Frierson (1927)

Unio asperimus Ravenel, 1834

(error for Unio asperrimus Lea, 1831)
‘Lea’ Ravenel, 1834. Cat. Rec. Shells: 5.

Unio asper Jay, 1839

(reference to Unio asper Lea, 1831)
‘Lea’ Jay, 1839. Cat. Rec. Shells: 55.

Unio nobilis Conrad, 1854

(misidentified reference to Unio nobilis Conrad, 1854)
Conrad, 1854. Jour. Acad. Nat. Sci. 2(4): 297, pl. 27, figs. 2. [in part]

Quadrula (sec. Theliderma) apiculata — Simpson (1900)
Quadrula (sec. Theliderma) (Group of Q. lachrymosa [sic]) apiculata — Simpson (1914)
Quadrula nobilis — Utterback (1915)
Quadrula quadrula — Burch (1975), R.I. Johnson (1980), Howells et al. (1996)
Quadrula apiculata — Vidrine (1993), Parmalee & Bogan (1998)

Unio unul atus Pratt, 1876

(incorrect original spelling of Unio lunulatus Pratt, 1876)
Pratt, 1876. Proc. Davenport Acad. Nat. Sci. 1: 168.

Quadrula quadrula — Lopes-Lima et al. (2019)

Quadrula (s.s.) gigantea Haas, 1930

(error for Obliquaria (Quadrula) quadrula Rafinesque, 1820)
‘Raf.’ Haas, 1930. Senckenbergiana 12(6): 327.

Quadrula contrayensis R.I. Johnson, 1969

(error for Quadrula quadrula contraryensis Utterback, 1915)
‘Utterback’ R.I. Johnson, 1969. Nautilus 82(4): 132.

Quadrula quadrula — Parmalee & Bogan (1998)

Quadrula quedrula Contreras-Arquieta, 2000

(error for Obliquaria (Quadrula) quadrula Rafinesque, 1820)
‘Rafinesque’ Contreras-Arquieta, 2000. Mexicoa 2(1): 44.