Unio masoni Conrad, 1834
Conrad, 1834. New Fresh-Water Shells: 34, pl. 5, fig. 2.
Conrad, 1836. Monogr. Fam. Unionidae 1(3): 28, pl. 12, fig. 2.
Conrad, 1853. Proc. Acad. Nat. Sci. 6: 252.

Unio (sec. Elliptio) masoni — Simpson (1900), Simpson (1914)
Elliptio (s.s.) masoni — Frierson (1927), Haas (1969)
Pleurobema (Lexingtonia) masoni — R.I. Johnson (1970)
Fusconaia masoni — Burch (1975), Davis & Fuller (1981), Johnson & Clarke (1983), Turgeon et al. (1988), Williams et al. (1993), ... Graf & Cummings (2021), FMCS (2021), Bolotov et al. (2022), Hopper et al. (2023), Hauck et al. (2023)

Unio pumilis Lea, 1836
‘Lea’ of Authors.
Lea, 1836. Synopsis Fam. Naiades: 20.
Lea, 1838. Synopsis Fam. Naiades: 17.
Lea, 1852. Synopsis Fam. Naiades: 24.
Conrad, 1853. Proc. Acad. Nat. Sci. 6: 255.
(error for Unio pumilus Lea, 1838)

Unio subplanus Conrad, 1837
Conrad, 1837. Monogr. Fam. Unionidae 1(9): 73, pl. 41, fig. 1.
Conrad, 1853. Proc. Acad. Nat. Sci. 6: 258.

Unio (sec. Elliptio) subplanus — Simpson (1900)
Pleurobema (s.s.) subplanum — Simpson (1914)
Lexingtonia subplana — Ortmann (1914), Thiele (1934), Haas (1969), Haas (1969), Burch (1975), ... Turgeon et al. (1998), Graf & Cummings (2007), Cummings & Graf (2010), ITIS (2012), Jones (2015)
Pleurobema (Lexingtonia) subplanum — Frierson (1927)
Pleurobema (Lexingtonia) masoni — R.I. Johnson (1970)
Fusconaia masoni — Williams et al. (2008), Campbell & Lydeard (2012), Williams et al. (2017), Graf & Cummings (2021)
Fusconaia subplana — Bogan (2010)

Unio pumilus Lea, 1838
Lea, 1836. Synopsis Fam. Naiades: 20 [as ‘pumilis’]. [nomen nudum]
Lea, 1838. Trans. Amer. Phil. Soc. 6 [O. 2]: 23, pl. 7, fig. 17.
Type(s): HOLOTYPE USNM_84545, Black Cr., N.C.

Quadrula (sec. Fusconaia) pumila — Simpson (1900), Simpson (1914)
— de Gregorio (1914)
Pleurobema (Lexingtonia) subplanum — Frierson (1927)
Lexingtonia subplana — Haas (1969)
Pleurobema (Lexingtonia) masoni — R.I. Johnson (1970)
Fusconaia masoni — Burch (1975)

Unio utriculus Lea, 1845
Lea, 1845. Proc. Amer. Phil. Soc. 4: 164.
Lea, 1848. Trans. Amer. Phil. Soc. 10 [O. 4]: 69 [43], pl. 1, fig. 3.
Type(s): HOLOTYPE USNM_85172, N.C.

Quadrula (sec. Fusconaia) utriculus — Simpson (1900)
Pleurobema (s.s.) utriculum — Simpson (1914)
Pleurobema (Lexingtonia) utriculum — Frierson (1927)
Lexingtonia utriculus — Haas (1969)
Lexingtonia utricula — Graf & Cummings (2007), Cummings & Graf (2010)
Fusconaia masoni — Graf & Cummings (2021)

Unio merus Lea, 1852
Lea, 1852. Trans. Amer. Phil. Soc. 10 [O. 5]: 260 [16], pl. 15, fig. 10.
Lea, 1852. Proc. Amer. Phil. Soc. 5: 251. [nomen nudum]
Type(s): HOLOTYPE USNM_85698, Abbeville District, S.C.

Unio (sec. Elliptio) merus — Simpson (1900), Simpson (1914)
Elliptio (s.s.) masoni — Frierson (1927), Haas (1969)
Pleurobema (Lexingtonia) masoni — R.I. Johnson (1970)
Fusconaia masoni — Burch (1975)

Unio striatulus Lea, 1857
Lea, 1857. Proc. Acad. Nat. Sci. 9: 86.
Lea, 1862. Jour. Acad. Nat. Sci. 5 [O. 8]: 55 [59], pl. 2, fig. 202.
Type(s): HOLOTYPE USNM_84548, Roanoke R., Weldon, N.C.

Unio (sec. Elliptio) striatulus — Simpson (1900)
Pleurobema (s.s.) striatulum — Simpson (1914)
— Ortmann (1914)
Pleurobema (Lexingtonia) subplanum — Frierson (1927)
Lexingtonia subplana — Haas (1969)
Pleurobema (Lexingtonia) masoni — R.I. Johnson (1970)
Fusconaia masoni — Burch (1975)

Unio castus Lea, 1860
Lea, 1860. Proc. Acad. Nat. Sci. 12: 306.
Lea, 1860. Jour. Acad. Nat. Sci. 4 [O. 8]: 349 [31], pl. 57, fig. 174.
Type(s): HOLOTYPE USNM_84782, S.C.

Unio (sec. Elliptio) merus — Simpson (1900), Simpson (1914)
Unio castus — de Gregorio (1914)
Pleurobema (Lexingtonia) castum — Frierson (1927)
Lexingtonia casta — Haas (1969)
Pleurobema (Lexingtonia) masoni — R.I. Johnson (1970)
Fusconaia masoni — Burch (1975)

Unio brimleyi S.H. Wright, 1897
S.H. Wright, 1897. Nautilus 10(12): 138.
Type(s): LECTOTYPE USNM_149651, Neuse Riv., Raleigh, N.C.

Unio (sec. Elliptio) brimleyi — Simpson (1900)
Unio brimleyi — Simpson (1900)
Pleurobema (s.s.) brimleyi — Simpson (1914)
— Ortmann (1914)
Pleurobema (Lexingtonia) subplanum — Frierson (1927)
Lexingtonia subplana — Haas (1969)
Pleurobema (Lexingtonia) masoni — R.I. Johnson (1970)
Fusconaia masoni — Burch (1975)

Parreysia robsoni Frierson, 1927
‘Lea’ Sowerby, 1866. Conch. Icon. 16: pl. 36, sp. 198 [as ‘Unio pumilus’].
Frierson, 1927. Check List N. Amer. Naiades: 45.
(new name for Unio pumilus Sowerby, 1866)
Type(s): HOLOTYPE BMNH_1965150, Loc._ ?

Parreysia robsoni — Frierson (1927)
Parreysia favidens — Haas (1969)
Fusconaia masoni — Bolotov et al. (2022)

Unio pumilus Sowerby, 1866
‘Lea’ Sowerby, 1866. Conch. Icon. 16: pl. 36, sp. 198.
(reference to Unio pumilus Lea, 1838)
Type(s): BMNH_1965150, Loc._ ?

Quadrula (sec. Fusconaia) pumila — Simpson (1900)
Parreysia robsoni — Frierson (1927)
Parreysia favidens — Haas (1969)
Fusconaia masoni — Bolotov et al. (2022)

Unio castus Simpson, 1900
‘Lea’ Simpson, 1900. Proc. U.S. Nat. Mus. 22: 708.
(reference to Unio castus Lea, 1860)

Elliptio (s.s.) masoni — Frierson (1927), Haas (1969)