Prisodon truncatus Schumacher, 1817
Schumacher, 1817. Essai. Nouv. Syst.: 139.

Tetraplodon ambiguus — Simpson (1900), Simpson (1914), Haas (1916)
Castalia (s.s.) ambigua ambigua — Modell (1950)
Castalia ambigua — Simone (2006)

Castalia ambigua Lamarck, 1819
Lamarck, 1819. Hist. Natur. Anim. sans Vert. 6: 67, sp. 1.
Type(s): HOLOTYPE MNHN-IM-2000-27235, Amérique du Sud.

Tetraplodon ambiguus — Simpson (1900), Ihering (1910), Simpson (1914), Haas (1916)
Castalia ambigua — Corsi (1900), F. Baker (1913), Vernhout (1914), Thiele (1934), Morretes (1949), ... Olivera-Hyde et al. (2020), Graf & Cummings (2021), Wu et al. (2021), Breure et al. (2022), Torres et al. (2024)
Castalia (s.s.) ambigua ambigua — Modell (1950)
Castalia ambigua ambigua — Bonetto (1965), Mansur & Valer (1992), Ramírez et al. (2003), Martinez et al. (2004), Lasso et al. (2009)
Castalia inflata — Figueiras (1965)

Unio ambiguus Sowerby & Sowerby, 1821
‘Lamarck’ Sowerby & Sowerby, 1821. Genera of Shells 2: pl. 85, fig. 2.
(reference to Castalia ambigua Lamarck, 1819)

Tetraplodon ambiguus — Simpson (1900), Simpson (1914), Haas (1916)

Tetraplodon pectinatus Wagner, 1827
Spix in Wagner, 1827. Test. Fluv. Brasil.: 32, pl. 25, fig. 3-4.
Type(s): SYNTYPE MNHN_MP_0117, Brazil [described from “Habitat in flumine S. Francisci in Provincia Minarum” [= Minas Gerais].

Tetraplodon ambiguus — Simpson (1900), Haas (1916)
Castalia ambigua — Corsi (1900), Simone (2006)
Tetraplodon pectinatus — Ihering (1910), Simpson (1914)
Castalia pectinata — Ortmann (1921), Morretes (1949), Haas (1969)
Castalia (s.s.) ambigua pectinata — Modell (1950)
Castalia ambigua pectinata — Bonetto (1965)

Castalia ambigua Wood, 1828
Wood, 1828. Suppl. Index Testac.: 3 [as ‘Mya ambigua’].
Wood, 1828. Suppl. Index Testac.: 30, pl. 1, fig. 9.
Wood & Hanley, 1856. Index Testac.: 200, pl. 1, fig. 9.
(reference to Castalia ambigua Lamarck, 1819)

Tetraplodon quadrilaterum — Simpson (1900)

Castalia quadrilatera d’Orbigny, 1835
d’Orbigny, 1835. Mag. Zool. 5(61-62): 42.
d’Orbigny, 1846. Voyage dans l’Amérique Méridionale 5: 599, pl. 73.
Type(s): SYNTYPE SMF_4344, Rio San Miguel, Guarayos, Bolivia.

Tetraplodon quadrilaterum — Simpson (1900)
Tetraplodon quadrilaterus — Ihering (1910), Simpson (1914)
Castalia quadrilatera — F. Baker (1913), Haas (1931), Haas (1969), Quintana (1982)
Castalia (s.s.) quadrilatera quadrilatera — Modell (1950)
Castalia ambigua ambigua — Bonetto (1965), Ramírez et al. (2003)
Castalia ambigua — Simone (2006)

Castalia ambigua Sowerby, 1839
‘Lamarck’ Sowerby, 1839. Conch. Man.: fig. 140.
(reference to Castalia ambigua Lamarck, 1819)

Tetraplodon retusus — Simpson (1900), Simpson (1914)
Tetraplodon cordatus — Ihering (1910)

Castalia acuticosta Hupé, 1857
Hupé, 1857. [in] Castelnau, Anim. Nouv. Rares d’Amer. Sud: 77, pl. 14, fig. 3.
Type(s): HOLOTYPE MNHN_MP_0162, Rio Mondego, (Bresil).

Tetraplodon quadrilaterum — Simpson (1900)
Tetraplodon acuticosta — Ihering (1910)
Tetraplodon quadrilaterus — Simpson (1914)
Castalia acuticosta — Ortmann (1921), Haas (1931), Morretes (1949), Bonetto (1961)
Castalia (s.s.) quadrilatera quadrilatera — Modell (1950)
Castalia ambigua ambigua — Bonetto (1965), Ramírez et al. (2003)
Castalia quadrilatera — Haas (1969), Quintana (1982)
— Mansur (1991)
Castalia ambigua — Simone (2006)

Castalia retusa Hupé, 1857
Hupé, 1857. [in] Castelnau, Anim. Nouv. Rares d’Amer. Sud: 75, pl. 14, fig. 2.
Type(s): POSSIBLE SYNTYPE MNHN_MP_0294, Guyane.

Tetraplodon retusus — Simpson (1900), Ihering (1910), Simpson (1914)
Castalia retusa — Haas (1931), Haas (1969), Mansur (1991)
Castalia (s.s.) quadrilatera retusa — Modell (1950)
Castalia ambigua ambigua — Bonetto (1965), Ramírez et al. (2003)
Castalia ambigua — Simone (2006)

Castalia turgida Hupé, 1857
Hupé, 1857. [in] Castelnau, Anim. Nouv. Rares d’Amer. Sud: 76, pl. 14, fig. 1.

Tetraplodon ambiguus — Simpson (1900), Simpson (1914), Haas (1916)
Tetraplodon turgidus — Ihering (1910)
Castalia turgida — Morretes (1949)
Castalia (s.s.) quadrilatera quadrilatera — Modell (1950)
Castalia ambigua ambigua — Bonetto (1965), Ramírez et al. (2003)
Castalia ambigua — Haas (1969), Simone (2006)

Castalia carolinensis Sowerby, 1869
Sowerby, 1869. Conch. Icon. 17: pl. 2, sp. 6.
Type(s): HOLOTYPE BMNH_1841-4-6-149, South Carolina.

Tetraplodon ambiguus — Simpson (1900), Simpson (1914), Haas (1916)
Tetraplodon retusus — Ihering (1910)
Castalia (s.s.) quadrilatera retusa — Modell (1950)
Castalia ambigua — Haas (1969), Simone (2006)

Castalia hanleyana Sowerby, 1869
Sowerby, 1869. Conch. Icon. 17: pl. 1, sp. 5.
Type(s): HOLOTYPE BMNH_1900-3-19-5, Hab._?

Tetraplodon ambiguus — Simpson (1900), Simpson (1914), Haas (1916)
Tetraplodon hanleyanus — Ihering (1910)
Castalia hanleyana — Ortmann (1921), Haas (1931), Morretes (1949)
Castalia (s.s.) quadrilatera quadrilatera — Modell (1950)
Castalia ambigua ambigua — Bonetto (1965), Ramírez et al. (2003)
Castalia ambigua — Haas (1969), Simone (2006)

Castalia cordata Strobel, 1874
Strobel, 1874. Bibliotheca Malacologica 4: 75.
(misidentified reference to Castalia cordata Swainson, 1840)

Tetraplodon ambiguus — Simpson (1900), Simpson (1914), Haas (1916)
Castalia ambigua — Haas (1969), Simone (2006)

Castalia ambigua Ihering, 1890
‘Lamarck’ Ihering, 1890. Arch. Naturg. 56(1): 162.
(reference to Castalia ambigua Lamarck, 1819)

Castalia pectinata — Ortmann (1921)

Castalia ambigua var. kuesteri Ihering, 1893
Ihering, 1893. Arch. Naturg. 59(1): 88 [as ‘küsteri’].
(intro'd as intra-sp. of Castalia ambigua Lamarck, 1819)

Castalia (s.s.) quadrilatera küsteri — Modell (1950)
Castalia ambigua — Simone (2006)

Tetraplodon baro Ihering, 1910
Ihering, 1910. Abh. Senckenb. Naturf. Ges. 32: 127.
Type(s): HOLOTYPE SMF_3789, Amazonas.

Tetraplodon baro — Ihering (1910), Simpson (1914)
Castalia baro — Ortmann (1921), Haas (1931), Morretes (1949), Haas (1969)
Castalia (s.s.) quadrilatera küsteri — Modell (1950)
Castalia ambigua ambigua — Bonetto (1965), Ramírez et al. (2003)
Castalia ambigua — Simone (2006)

Tetraplodon juruanus Ihering, 1910
Ihering, 1904. Rev. Mus. Paul. 6: 460 [as ‘T. ambiguus’].
Ihering, 1910. Abh. Senckenb. Naturf. Ges. 32: 126.
Type(s): TYPE SMF_3790, Rio Juruá, Brasilien.

Tetraplodon juruanus — Ihering (1910), Simpson (1914)
Castalia juruana — Haas (1931), Morretes (1949)
Castalia juruanus — Haas (1932)
Castalia (s.s.) ambigua crosseana — Modell (1950)
Castalia ambigua ambigua — Bonetto (1965), Mansur & Valer (1992), Ramírez et al. (2003)
Castalia quadrilatera — Haas (1969)
Castalia ambigua — Simone (2006)

Chevronais colombiana Olsson & Wurtz, 1951
Olsson & Wurtz, 1951. Notulae Naturae (239): 6, text fig. 3-6.
Type(s): HOLOTYPE (ORIG. DESIG.) ANSP_187181, Rio Caqueta, above Tres Esquinas, Colombia.

Chevronais colombiana — Olsson & Wurtz (1951)
Castalia ambigua ambigua — Bonetto (1965), Ramírez et al. (2003)
Chevronaias [sic] colombiana — Haas (1969), Haas (1969)
Castalia ambigua — Simone (2006)

Castalia castelnauii of Authors, unknown year
‘Hupé’ of Authors.
(misidentified reference to Hyria castelnaudii Hupé, 1857)

Tetraplodon humilis of Authors, unknown year
Marshall, in USNM coll. of Authors.
Type(s): MANUSCRIPT NAME USNM_362400, Lake Rogagua, Western Bolivia.

Prisodon trigonum Schumacher, 1816
Schumacher, 1816. Overs. Dansk. Vid. Selsk. Forhandl. Kjobehhaven 1816: 7. [nomen nudum]

Tetraplodon pectinatus Wagner, 1827
Spix in Wagner, 1827. Test. Fluv. Brasil.: 32, pl. 25, fig. 3. [in part]
(reference to Tetraplodon pectinatus Wagner, 1827)

Tetraplodon ambiguus — Simpson (1900), Simpson (1914)
Tetraplodon pectinatus — Ihering (1910)

Unio ambiguus Küster, 1861
‘Lamarck’ Küster, 1861. Conchyl. Cab. 9(2): 165, pl. 48, fig. 1.
(reference to Castalia ambigua Lamarck, 1819)

Tetraplodon baro — Ihering (1910), Simpson (1914)
Tetraplodon ambiguus — Haas (1916)
Castalia (s.s.) quadrilatera küsteri — Modell (1950)

Castalia acuticostata Sowerby, 1869
‘Hupé’ Sowerby, 1869. Conch. Icon. 17: pl. 3, sp. 12.
(error for Castalia acuticosta Hupé, 1857)

Castalia ambigua — Simone (2006)

Castalia ambigua Sowerby, 1869
‘Lamarck’ Sowerby, 1869. Conch. Icon. 17: pl. 1, sp. 1, figs. 1a-c.
(reference to Castalia ambigua Lamarck, 1819)

Tetraplodon ambiguus — Simpson (1900), Haas (1916)
Tetraplodon baro — Ihering (1910), Simpson (1914)
Castalia baro — Ortmann (1921), Haas (1931)

Castalia lateriquadrata Sowerby, 1869
‘d’Orbigny’ Sowerby, 1869. Conch. Icon. 17: pl. 2, sp. 10.
(error for Castalia quadrilatera d’Orbigny, 1835)

Tetraplodon quadrilaterum — Simpson (1900)
Tetraplodon lateriquadratus — Ihering (1910)
Castalia lateriquadrata — Haas (1949)
Castalia (s.s.) quadrilatera quadrilatera — Modell (1950)
Castalia quadrilatera — Haas (1969), Quintana (1982)
Castalia ambigua ambigua — Ramírez et al. (2003)
Castalia ambigua — Simone (2006)

Castalia latiquadrata Sowerby, 1869
‘d’Orbigny’ Sowerby, 1869. Conch. Icon. 17: index.
(error for Castalia lateriquadrata Sowerby, 1869)

Tetraplodon quadrilaterum — Simpson (1900)
Tetraplodon quadrilaterus — Simpson (1914)
Castalia latiquadrata — Haas (1931)
Castalia (s.s.) quadrilatera quadrilatera — Modell (1950)
Castalia ambigua ambigua — Bonetto (1965)

Castalia lateriiquadrata Haas, 1969
‘Sowerby’ Haas, 1969. Das Tierreich 88: 535.
(error for Castalia lateriquadrata Sowerby, 1869)

Castalia acuaticosta Ramírez et al., 2003
‘Hupe’ Ramírez et al., 2003. Rev. Biol. Trop. 51: 273.
(error for Castalia acuticosta Hupé, 1857)

Castalia cuadrilatera Ramírez et al., 2003
‘d’Orbigny’ Ramírez et al., 2003. Rev. Biol. Trop. 51: 273.
(error for Castalia quadrilatera d’Orbigny, 1835)

Castalia ambigua — Simone (2006)

Castalia lateriquacrata Simone, 2006
‘auctt.’ Simone, 2006. Land. Freshw. Moll. Brazil.: 252.
(error for Castalia lateriquadrata Sowerby, 1869)

Castalia ambigua — Simone (2006)