Unio subtentus Say, 1825
Say, 1825. Jour. Acad. Nat. Sci. 5(3-4): 130.
Say, 1831. Amer. Conch. 2: pl. 15.
Say, 1858. [in] Binney, Compl. Writings T. Say: 118.

Medionidus subtentus — Simpson (1900)
Ptychobranchus subtentus — Ortmann (1912), Thiele (1934), Bogan (2010), Williams et al. (2017), Klymus et al. (2020), Graf & Cummings (2021), FMCS (2021), Hopper et al. (2023), FMCS (2025)
Ptychobranchus subtentum — Simpson (1914), Ortmann (1924), Ortmann (1925), Stansbery (1970), Burch (1975), ... ITIS (2012), Haag (2012), Roe (2013), Jones (2015), Huang et al. (2019)
Unio subteritus [sic] — de Gregorio (1914)
Ellipsaria subtenta — Ortmann (1918)
Ptychobranchus (Subtentus) subtentum — Frierson (1927), Haas (1969)
Ptychobranchus (Subtentus) subtentus — Haas (1969)

Unio subteritus [sic] var. purchreornatus de Gregorio, 1914
de Gregorio, 1914. Il Nat. Siciliano 2: 61, pl. 9, figs. 2a-d.
(intro'd as intra-sp. of Unio subtentus Say, 1825)

Unio subteritus [sic] var. purchreornatus — de Gregorio (1914)
Ptychobranchus subtentum — Parmalee & Bogan (1998), Williams et al. (2008)

Unio subteritus de Gregorio, 1914
‘Say’ de Gregorio, 1914. Il Nat. Siciliano 2: 61.
(error for Unio subtentus Say, 1825)

Unio subtontus de Gregorio, 1914
‘Say’ de Gregorio, 1914. Il Nat. Siciliano 2: pl. 9, caption.
(error for Unio subtentus Say, 1825)

Unio subtontus [sic] var. puchreornatus de Gregorio, 1914
de Gregorio, 1914. Il Nat. Siciliano 2: pl. 9, caption.
(error for Unio subteritus [sic] var. purchreornatus de Gregorio, 1914)

Unio subteritus [sic] var. purcheornatus Parmalee & Bogan, 1998
‘de Gregorio’ Parmalee & Bogan, 1998. The Freshwater Mussels of Tennessee: 204.
‘de Gregorio’ Williams et al., 2008. Freshw. Mussels AL and Mobile Basin: 629.
(error for Unio subteritus [sic] var. purchreornatus de Gregorio, 1914)