Prisodon obliquus Schumacher, 1817
Schumacher, 1816. Overs. Dansk. Vid. Selsk. Forhandl. Kjobehhaven 1816: 7. [nomen nudum]
Schumacher, 1817. Essai. Nouv. Syst.: 139, pl. 11, fig. 2.

Prisodon (s.s.) obliquus — Simpson (1900), Simpson (1914), Thiele (1934), Graf & Cummings (2007)
Prisodon obliquus — F. Baker (1913), Haas (1916), Haas (1931), Parodiz & Bonetto (1963), Haas (1969), ... Guerra et al. (2019), Mansur et al. (2020), Pfeiffer et al. (2021), Graf & Cummings (2021), Breure et al. (2022)

Hyria avicularis Lamarck, 1819
Lamarck, 1819. Hist. Natur. Anim. sans Vert. 6: 82, sp. 1, var. [a]. [in part]
Type(s): UNKNOWN MNHN_MPL_0019, La variété [b] vient du cabinet de Lisbonne. Je la crois du Brésil . The [b] variety comes from the cabinet of Lisbon. Brazil I think]. “Figured holotype is in the Geneva Museum (Johnson 1952:65).

Prisodon (s.s.) obliquus — Simpson (1900), Simpson (1914)
Prisodon obliquus — Haas (1916), Haas (1969), Simone (2006)
Paxyodon syrmathophorus [sic] — Ramírez et al. (2003)

Hyria intermedia Gray, 1825
Gray, 1825. Ann. Phil. 9: 138.

Diplodon furcatum Wagner, 1827
Spix in Wagner, 1827. Test. Fluv. Brasil.: pl. 27, figs. 1-2.

Prisodon (s.s.) obliquus — Simpson (1900), Simpson (1914)
Prisodon obliquus — Haas (1916), Haas (1969), Simone (2006)

Unio caudatus Wagner, 1827
Wagner, 1827. Test. Fluv. Brasil.: 35, pl. 27, figs. 1-2.

Prisodon (s.s.) obliquus — Simpson (1900), Simpson (1914)
Prisodon obliquus — Haas (1969), Simone (2006)

Hyria elongata Swainson, 1841
Gray, 1825. Ann. Phil. 9: 138 [as ‘elongatum’]. [nomen nudum]
Swainson, 1840. Treat. Malacol.: 284, 380. [nomen nudum]
Swainson, 1841. Ex. Conch.: 29, pl. 24.

Prisodon (s.s.) obliquus — Simpson (1900), Simpson (1914)
Prisodon obliquus — Haas (1916), Haas (1969), Simone (2006)

Unio macropterus Dunker, 1846
Dunker, 1846. Z. Malak. 3: 109.

Diplodon macropterus — Simpson (1900), Simpson (1914)
Physunio (s.s.) superbus — Haas (1920), Haas (1969)
Prisodon obliquus — Haas (1931), Parodiz (1968), Simone (2006), Pfeiffer et al. (2021)
Physunio superbus — Brandt (1974)

Hyria castelnaudii Hupé, 1857
Hupé, 1857. [in] Castelnau, Anim. Nouv. Rares d’Amer. Sud: 81, pl. 16, fig. 1.

Prisodon (s.s.) castelnaudi — Simpson (1900), Simpson (1914)
Prisodon obliquus castelnaui [sic] — Ihering (1910)
Prisodon castelnaudi — Ortmann (1921), Morretes (1949)
Prisodon obliquus — Haas (1931), Haas (1969), Simone (2006)

Unio ortonii Lea, 1868
Lea, 1868. Proc. Acad. Nat. Sci. 20: 161.
Lea, 1868. Jour. Acad. Nat. Sci. 6 [O. 12]: 321, pl. 52, fig. 134.
Type(s): HOLOTYPE (MONOTYPY) USNM_703563, River Napo, Ecuador.

Prisodon (Hyriana) ortonii — Simpson (1900), Simpson (1914)
Prisodon obliquus — Haas (1931), Haas (1969), Simone (2006), Breure et al. (2022)

Hyria recta Sowerby, 1869
Sowerby, 1869. Conch. Icon. 17: pl. 5, sp. 10.

Prisodon (s.s.) rectus — Simpson (1900)
Prisodon (s.s.) recta — Simpson (1914)
Prisodon rectus — Morretes (1949), Haas (1969)
Prisodon obliquus — Simone (2006)

Diptodon [sic] fuscatum Lea, 1836
‘Spix’ Lea, 1836. Synopsis Fam. Naiades: 11.
(error for Diplodon furcatum Wagner, 1827)

Prisodon obliquus castelnaui Lea, 1870
‘Hupé’ Lea, 1870. Synopsis Fam. Naiades: 25 [as ‘Hyria castelnauii’].
‘Hupé’ Ihering, 1910. Abh. Senckenb. Naturf. Ges. 32: 135.
(error for Hyria castelnaudii Hupé, 1857)

Prisodon audatus Simone, 2006
‘Wagner’ Simone, 2006. Land. Freshw. Moll. Brazil.: 251.
(error for Unio caudatus Wagner, 1827)

Prisodon obliquus — Simone (2006)