Bivalvia | ... | Unionoidea | Unionidae | Unioninae | Anodontini | Alasmidontina | Utterbackia
47 specimens + 1 Genbank voucher

Say, 1829. New Harm. Dissem. 2(23): 355, sp. 5.
Type(s): UNKNOWN SMF_4301, N. Amerika.
Anodonta imbecillis — Simpson (1900), Ortmann (1909), Ortmann (1909), Ortmann (1910), Ortmann (1912), ... Turgeon et al. (1988), Rosenberg et al. (1994), Howells et al. (1996), Contreras-Arquieta (2000), ITIS (2012)
Unio (Anodonta) imbecillis — Call (1900)
Lastena ohiensis — Utterback (1915)
Anodonta (Lastena) ohiensis — Frierson (1927), Haas (1969)
Utterbackia imbecillis — F.C. Baker (1927), F.C. Baker (1928), Cummings & Mayer (1992), Williams et al. (1993), Vidrine (1993), ... Chen et al. (2025), FMCS (2025), Cummings et al. (2025), Hou et al. (2025), Wang et al. (2025)
Anodonta (Lastena) imbecillis — Haas (1930)
Anodonta imbecilis [sic] — Clench & Turner (1956), Murray & Leonard (1962), Burch (1975), Rosenberg et al. (1997), Adamkewicz et al. (1997)
Anodonta (Utterbackia) imbecilis [sic] — R.I. Johnson (1970), Heard (1975), Kat (1983)
Utterbackia imbecilis [sic] — Hoeh (1990), Lydeard et al. (1996)
Anodonta (Utterbackia) imbecillis — R.I. Johnson (1999)
U. imbecillis — Marshall et al. (2018)
Lea, 1834. Trans. Amer. Phil. Soc. 5 [O. 1]: 46, pl. 6, fig. 16.
Anodonta imbecillis — Simpson (1900), Simpson (1914)
Anodonta incerta — de Gregorio (1914)
Anodonta (Lastena) ohiensis — Frierson (1927), Haas (1969)
Anodonta (Utterbackia) imbecilis [sic] — R.I. Johnson (1970)
Anodonta imbecilis [sic] — Burch (1975)
Utterbackia imbecillis — Parmalee & Bogan (1998), Brim Box & Williams (2000), Williams et al. (2008), Watters et al. (2009)
‘Say’ of Authors.
Lea, 1836. Synopsis Fam. Naiades: 54.
Conrad, 1853. Proc. Acad. Nat. Sci. 6: 264.
Adams & Adams, 1857. Gen. Rec. Moll. 2(31-32): 502.
Say, 1858. [in] Binney, Compl. Writings T. Say: 140.
Lapham, 1860. Proc. Acad. Nat. Sci. 12: 156.
B.H. Wright, 1888. Check List N. Amer. Unionidae etc.: [7].
Pilsbry & Rhoads, 1896. Proc. Acad. Nat. Sci. 48: 506.
Clench & Turner, 1956. Bull. Fla. State Mus. 1: 187.
Murray & Leonard, 1962. Handbk. Unionid Muss. Kansas: 95.
R.I. Johnson, 1970. Bull. MCZ 140(6): 362.
Heard, 1975. Malacologia 15(1): 84.
Kat, 1983. Malacologia 23(2): 362.
Hoeh, 1990. Malac. Review 23: 63.
Lydeard et al., 1996. Philos. Trans. Roy. Soc. London (B, Biol. Sci.) 351: 1595.
Rosenberg et al., 1997. J. Moll. Studies 63: 303.
Adamkewicz et al., 1997. MBE 14(6): 622.
(error for Anodonta imbecillis Say, 1829)
Anodonta imbecillis — Ortmann & Walker (1922)
Utterbackia imbecillis — Watters et al. (2009)

Gould, 1855. Proc. Boston Soc. Nat. Hist. 5: 229.
Type(s): LECTOTYPE BMNH_196465 (by R.I. Johnson, 1964: 88), Comanche Creek, Texas.
Anodonta imbecillis — Simpson (1900), Simpson (1914), Howells et al. (1996)
Anodonta (Lastena) ohiensis-horda — Frierson (1927)
Anodonta (Lastena) ohiensis — Haas (1969)
Anodonta (Utterbackia) imbecilis [sic] — R.I. Johnson (1970)
Anodonta imbecilis [sic] — Burch (1975)
Utterbackia imbecillis — Parmalee & Bogan (1998), Brim Box & Williams (2000), Williams et al. (2008), Watters et al. (2009), Cummings et al. (2025)
Anodonta horda — Contreras-Arquieta (2000)

Lea, 1857. Proc. Acad. Nat. Sci. 9: 102 [as ‘henryiana’].
Lea, 1860. Jour. Acad. Nat. Sci. 4 [O. 8]: 373 [55], pl. 66, fig. 198.
(error for Anodonta henryiana Lea, 1857)
Type(s): LECTOTYPE USNM_86692 (by R.I. Johnson, 1974: 69), Matamoras, Mexico.
Anodonta henryana — Simpson (1900), Ortmann (1912), Simpson (1914), Heard (1975), Contreras-Arquieta (2000)
Anodonta (s.s.) henryana — Martens (1900)
Anodonta (Lastena) ohiensis — Frierson (1927), Haas (1969)
Utterbackia henryana — F.C. Baker (1927)
Anodonta (Utterbackia) imbecilis [sic] — R.I. Johnson (1970)
Anodonta imbecilis [sic] — Burch (1975)
Utterbackia imbecillis — Bieler (2021), Cummings et al. (2025)
Lea, 1857. Proc. Acad. Nat. Sci. 9: 102.
Anodonta henryana — Simpson (1900), Simpson (1914)
Anodonta (Lastena) ohiensis — Haas (1969)
Utterbackia imbecillis — Brim Box & Williams (2000), Watters et al. (2009), Bieler (2021)
de Gregorio, 1914. Il Nat. Siciliano 2: 64, pl. 11, figs. 3a-e.
Anodonta phalena — de Gregorio (1914)
Utterbackia imbecillis — Williams et al. (2008), Watters et al. (2009)
‘Rafinesque’ of Authors.
Utterback, 1915. Amer. Midl. Nat. 4(6): 260, pl. 23, figs. 74a-b.
Ortmann, 1919. Mem. Carnegie Mus. 8(1): 162, pl. 11, fig. 4.
Thiele, 1934. Handb. Syst. Weichtierk. 3: 832 [1267].
Modell, 1945. Jena. Z. Med. Naturw. 78: 84.
(misidentified reference to Anodonta (Lastena) ohiensis Rafinesque, 1820)
Anodonta imbecillis — Ortmann & Walker (1922), R.I. Johnson (1980)
Utterbackia imbecillis — F.C. Baker (1928), Vidrine (1993), Parmalee & Bogan (1998), Watters et al. (2009)

F.C. Baker, 1927. Amer. Midl. Nat. 10(7): 222.
F.C. Baker, 1928. Bull. Wisconsin Geol. Nat. Hist. Survey 70(2): 175, pl. 103, figs. 12-14.
(intro'd as intra-sp. of Anodonta imbecillis Say, 1829)
Type(s): HOLOTYPE (ORIG. DESIG.) UMMZ_209141, Sturgeon Bay, Wisc.
Utterbackia imbecillis fusca — F.C. Baker (1927), F.C. Baker (1928)
Anodonta (Utterbackia) imbecilis [sic] — R.I. Johnson (1970)
Anodonta imbecillis — R.I. Johnson (1980)
Utterbackia imbecillis — Parmalee & Bogan (1998), Williams et al. (2008), Watters et al. (2009)
‘Sow.’ Paetel, 1890. Cat. Conch.-Samml. 3: 180.
(error for Anodon horda Gould, 1855)
Anodonta imbecillis — Simpson (1900), Simpson (1914)
Anodonta (Lastena) ohiensis — Haas (1969)
Utterbackia imbecillis — Parmalee & Bogan (1998), Watters et al. (2009)
‘Gould’ Call, 1895. Trans. Acad. Sci. St. Louis 7: 63.
(error for Anodon horda Gould, 1855)
Anodonta imbecillis — Simpson (1900), Ortmann (1909), Ortmann (1909), Ortmann (1910), Ortmann (1912), ... Turgeon et al. (1988), Rosenberg et al. (1994), Howells et al. (1996), Contreras-Arquieta (2000), ITIS (2012)
Anodonta henryana — Simpson (1900), Ortmann (1912), Simpson (1914), Heard (1975), Contreras-Arquieta (2000)
Anodonta (s.s.) henryana — Martens (1900)
Unio (Anodonta) imbecillis — Call (1900)
Anodonta incerta — de Gregorio (1914)
Anodonta phalena — de Gregorio (1914)
Lastena ohiensis — Utterback (1915), Modell (1945)
Anodonta (Lastena) ohiensis — Frierson (1927), Haas (1969)
Anodonta (Lastena) ohiensis-horda — Frierson (1927)
Utterbackia imbecillis — F.C. Baker (1927), F.C. Baker (1928), Cummings & Mayer (1992), Williams et al. (1993), Vidrine (1993), ... Chen et al. (2025), FMCS (2025), Cummings et al. (2025), Hou et al. (2025), Wang et al. (2025)
Utterbackia imbecillis fusca — F.C. Baker (1927), F.C. Baker (1928)
Utterbackia henryana — F.C. Baker (1927)
Anodonta (Lastena) imbecillis — Haas (1930)
Anodonta ohiensis — Thiele (1934)
Anodonta imbecilis [sic] — Clench & Turner (1956), Murray & Leonard (1962), Burch (1975), Rosenberg et al. (1997), Adamkewicz et al. (1997)
Anodonta (Utterbackia) imbecilis [sic] — R.I. Johnson (1970), Heard (1975), Kat (1983)
Utterbackia imbecilis [sic] — Hoeh (1990), Lydeard et al. (1996)
Anodonta (Utterbackia) imbecillis — R.I. Johnson (1999)
Anodonta horda — Contreras-Arquieta (2000)
U. imbecillis — Marshall et al. (2018)