species Psoronaias crocodilorum (Morelet, 1849): synonymy

Unio testudineus Morelet, 1849

Morelet, 1849. Test. Nov. 1: 28.
LECTOTYPE [AS HOLOTYPE] BMNH_94-3-22-1 (by R.I. Johnson, 1971: 96), flumen Usumacinta, Guatemala.

Unio (sec. Elliptio) testudineus — Simpson (1900)
Unio (Psoronaias) semigranosus var. testudineus — Martens (1900)
Unio (sec. Elliptio) (Group of U. semigranosus) testudineus — Simpson (1914)
Psoronaias semigranosus — Frierson (1927)
Psoronaias testudinea — Haas (1929), Haas (1969)
Psoronaias testudineus — Haas (1930)
Psoronaias testudinarea [sic] — Bogan (2010)
Psoronaias crocodilorum — Cummings et al. (2025)
Psoronaias semigranosa — Nagel (2025)

Unio crocodilorum Morelet, 1849

Morelet, 1849. Test. Nov. 1: 28.
LECTOTYPE [AS HOLOTYPE] BMNH_1893-2-4-2030 (by R.I. Johnson, 1971: 81), River Usumacinta, Central America.

Unio (sec. Elliptio) crocodilarum [sic] — Simpson (1900)
Unio (Psoronaias) crocodilorum — Martens (1900)
Unio (sec. Elliptio) (Group of U. semigranosus) crocodilarum [sic] — Simpson (1914)
Psoronaias crocodilorum — Frierson (1917), Frierson (1927), Haas (1930), Haas (1969), Graf & Cummings (2007), Bogan (2010), Cummings et al. (2025)
Psoronaias crocodilarum [sic] — Haas (1929)
Psoronaias semigranosus — Goodrich & van der Schalie (1937)
Psoronaias semigranosa — Graf & Cummings (2021)

Unio ostreatus Morelet, 1849

Morelet, 1849. Test. Nov. 1: 29.
LECTOTYPE [AS HOLOTYPE] BMNH_94-3-22-2 (by R.I. Johnson, 1971: 90), flumen Usumacinta, Guatemala.

Quadrula (Rotundaria) ostreata — Simpson (1900)
Unio (Psoronaias) ostreatus — Martens (1900)
Quadrula (Rotundaria) (Group of Q. ostreata) ostreata — Simpson (1914)
Psoronaias ostreatus — Frierson (1927), Haas (1930)
Psoronaias ostreata — Haas (1929), Haas (1969), Graf & Cummings (2007), Bogan (2010), Graf & Cummings (2021), Czaja et al. (2023)
Psoronaias crocodilorum — Cummings et al. (2025)

Unio psoricus Morelet, 1851

Morelet, 1851. Test. Nov. 2: 25.
LECTOTYPE [AS HOLOTYPE] BMNH_93-2-4-2033 (by R.I. Johnson, 1971: 81), Rio Usumacinta, Tabasco.

Unio (sec. Elliptio) psoricus — Simpson (1900)
Unio (Psoronaias) psoricus — Martens (1900)
Unio (sec. Elliptio) (Group of U. semigranosus) psoricus — Simpson (1914)
Psoronaias psoricus — Frierson (1917), Haas (1930), Thiele (1934), Morrison (1966)
Psoronaias semigranosus-psoricus — Frierson (1927)
Psoronaias psorica — Haas (1929), Haas (1969), Haas (1969), Bogan (2010)
Psoronaias semigranosus — Goodrich & van der Schalie (1937)
Psoronaias semigranosa — Graf & Cummings (2007), Pfeiffer et al. (2019), Graf & Cummings (2021)
Psoronaias crocodilorum — Cummings et al. (2025)

Unio morini Morelet, 1851

Morelet, 1851. Test. Nov. 2: 25.
LECTOTYPE [AS HOLOTYPE] BMNH_93-2-4-2026 (by R.I. Johnson, 1971: 88), Rio Usumacinta, Guatemala.

Unio (sec. Elliptio) morini — Simpson (1900)
Unio (Psoronaias) morini — Martens (1900)
Unio (sec. Elliptio) (Group of U. semigranosus) morini — Simpson (1914)
Psoronaias morini — Frierson (1927), Haas (1929), Haas (1930), Haas (1969), Graf & Cummings (2007), Bogan (2010)
Psoronaias semigranosus — Goodrich & van der Schalie (1937)
Psoronaias semigranosa — Graf & Cummings (2021)
Psoronaias crocodilorum — Cummings et al. (2025)

Unio corium Reeve, 1864

Reeve, 1864. Conch. Icon. 16: pl. 10, sp. 39.
HOLOTYPE (MONOTYPY) BMNH_1965209, Chiapas, Mexico.

Unio (sec. Elliptio) corium — Simpson (1900)
Unio (Psoronaias) corium — Martens (1900)
Unio corium — Pilsbry (1910)
Unio (sec. Elliptio) (Group of U. semigranosus) corium — Simpson (1914)
Psoronaias semigranosus-corium — Frierson (1927)
Psoronaias semigranosus — Haas (1930), Goodrich & van der Schalie (1937)
Psoronaias semigranosa corium — Haas (1969)
Psoronaias crocodilorum — Cummings et al. (2025)

Unio percompressus Martens, 1887

Martens, 1887. S.-Ber. Ges. Naturf. Freunde zu Berlin 1887: 107.
Martens, 1900. Biol. Centr.-Amer., Moll.: 496, pl. 32, figs. 1-3.
LECTOTYPE ZMB_39463 (by Cummings et al., 2025: 315), Rio de las Salinas, Guatemala.

Quadrula (Rotundaria) percompressa — Simpson (1900)
Unio (Psoronaias) percompressus — Martens (1900)
Quadrula (Rotundaria) (Group of Q. ostreata) percompressa — Simpson (1914)
Psoronaias percompressus — Frierson (1927)
Rotundaria percompressa — Haas (1929)
Amblema (Psorula) percompressa — Haas (1930)
Psorula percompressa — Haas (1969), Graf & Cummings (2007), Bogan (2010), Pfeiffer et al. (2019), Inoue et al. (2020)
Psoronaias percompressa — Graf & Cummings (2021), Czaja et al. (2023), Campbell & Lydeard (2026)
Psorula percompressus — Freeman et al. (2025)
Psoronaias crocodilorum — Cummings et al. (2025)

Unio usumasintae Crosse & Fischer, 1893

(renamed Unio usumacintae Martens, 1900)
Crosse & Fischer, 1893. J. de Conch. 40: 294 [as ‘usumasintæ’].
Fischer & Crosse, 1894. Miss. Sci. Mexique, Rech. Zool. 2(15): 574, pl. 63, fig. 4; pl. 67, fig. 5 [as ‘usumasintæ’].
TYPE LOST XXX_UNKNOWN, in flumine Usumasinta, Provinciæ Peten dictæ, Guatemalæ.

Quadrula (Rotundaria) usumasintæ — Simpson (1900)
Unio (Pleurobema) usumacintæ — Martens (1900)
Quadrula (Rotundaria) (Group of Q. ostreata) usumasintæ — Simpson (1914)
Amblema (Psorula) usumasintae — Haas (1930)
Psorula usumasintae — Graf & Cummings (2007), Bogan (2010), Pfeiffer et al. (2019), Inoue et al. (2020), Freeman et al. (2025)
Psoronaias usumasintae — Graf & Cummings (2021), Czaja et al. (2023), Campbell & Lydeard (2026)
Psoronaias crocodilorum — Cummings et al. (2025)

Unio crocodilorum var. B semipustulata Fischer & Crosse, 1894

(intro'd as intra-sp. of Unio crocodilorum Morelet, 1849)
Fischer & Crosse, 1894. Miss. Sci. Mexique, Rech. Zool. 2(16): 578, pl. 60, fig. 4.
HOLOTYPE BMNH_1893-2-4-2032, River Usumacinta, Guatemala.

Unio (Psoronaias) crocodilorum — Martens (1900)
Psoronaias crocodilorum — Frierson (1927), Haas (1969), Cummings et al. (2025)
Psoronaias crocodilarum [sic] — Haas (1929)

Unio crocodilorum var. G praestricta Fischer & Crosse, 1894

(intro'd as intra-sp. of Unio crocodilorum Morelet, 1849)
Fischer & Crosse, 1894. Miss. Sci. Mexique, Rech. Zool. 2(16): 578, pl. 60, fig. 5.
HOLOTYPE BMNH_1893-2-4-2031, River Usumacinta, Guatemala.

Unio (Psoronaias) crocodilorum — Martens (1900)
Psoronaias crocodilorum — Frierson (1927), Haas (1969), Cummings et al. (2025)

Unio pigerrimus Crosse & Fischer, 1894

Crosse & Fischer, 1894. J. de Conch. 41: 293.
Fischer & Crosse, 1894. Miss. Sci. Mexique, Rech. Zool. 2(16): 582, pl. 65, figs. 1-1a.
LECTOTYPE MNHN-IM-2000-1761 (by Cummings et al., 2025: 316), Mexique.

Unio (sec. Elliptio) pigerrimus — Simpson (1900)
Unio (Psoronaias) psoricus var. pigerrimus — Martens (1900)
Unio (sec. Elliptio) (Group of U. pigerrimus) pigerrimus — Simpson (1914)
Elliptio (Barynaias) pigerrimus — Frierson (1927), Haas (1929)
Elliptio (sec. Barynaias) pigerrima — Thiele (1934)
Barynaias pigerrimus — Morrison (1966), Haas (1969), Czaja et al. (2023)
Barynaias pigerrima — Graf & Cummings (2007), Bogan (2010), Graf & Cummings (2021)
Psoronaias crocodilorum — Cummings et al. (2025)

Quadrula rudis Simpson, 1900

Simpson, 1900. Proc. Acad. Nat. Sci. 52: 82, pl. 3, fig. 2.
Simpson, 1914. Descr. Cat. Naiades: 910.
HOLOTYPE (MONOTYPY) USNM_84210, Rio Taxtunilha, (tributary to the Rio de la Pasion), Guatemala.

Quadrula rudis — Simpson (1900)
Unio (Psoronaias) crocodilorum var. rudis — Martens (1900)
Quadrula (Rotundaria) (Group of Q. ostreata) rudis — Simpson (1914)
Psoronaias rudis — Frierson (1927)
Rotundaria rudis — Haas (1929)
Amblema (Psorula) rudis — Haas (1930)
Amblema (sec. Psorula) rudis — Thiele (1934)
Psoronaias semigranosus — Goodrich & van der Schalie (1937)
Psorula rudis — Haas (1969), Graf & Cummings (2007), Bogan (2010), Pfeiffer et al. (2019), Inoue et al. (2020), Freeman et al. (2025)
Psoronaias semigranosa — Graf & Cummings (2021)
Psoronaias crocodilorum — Cummings et al. (2025)

Unio usumacintae Martens, 1900

(new name for Unio usumasintae Crosse & Fischer, 1893)
Crosse & Fischer, 1893. J. de Conch. 40: 294 [as ‘usumasintæ’].
Martens, 1900. Biol. Centr.-Amer., Moll.: 500 [as ‘usumacintæ’].

Unio (Pleurobema) usumacintæ — Martens (1900)
Psoronaias usumacintae — Frierson (1927)
Rotundaria usumacintae — Haas (1929)
Psorula usumacintae — Haas (1969)
Psoronaias crocodilorum — Cummings et al. (2025)

Unio crocodilarum ‘Morelet’ of Authors

(error for Unio crocodilorum Morelet, 1849)
‘Morelet’ of Authors.
Simpson, 1900. Proc. U.S. Nat. Mus. 22: 702.
Simpson, 1914. Descr. Cat. Naiades: 591.
Haas, 1929. Senckenbergiana 11: 332.

Psoronaias crocodilorum — Cummings et al. (2025)

Quadrula (Rotundaria) quadrata Simpson, 1914

Simpson, 1914. Descr. Cat. Naiades: 911.
LECTOTYPE USNM_128996 (by R.I. Johnson, 1975: 18), Usumacinta River, Guatemala.

Quadrula (Rotundaria) (Group of Q. ostreata) quadrata — Simpson (1914)
Psoronaias quadrata — Frierson (1927), Graf & Cummings (2021), Nagel (2025)
Rotundaria quadrata — Haas (1929)
Amblema (Psorula) quadrata — Haas (1930)
Psorula quadrata — Haas (1969), Graf & Cummings (2007), Bogan (2010)
Psoronaias crocodilorum — Cummings et al. (2025)

Quadrula (Rotundaria) profunda Simpson, 1914

Simpson, 1914. Descr. Cat. Naiades: 907.
HOLOTYPE (MONOTYPY) USNM_128987, Usumacinta River, Guatemala.

Quadrula (Rotundaria) (Group of Q. ostreata) profunda — Simpson (1914)
Psoronaias profunda — Frierson (1927), Graf & Cummings (2021), Czaja et al. (2023), Nagel (2025), Campbell & Lydeard (2026)
Rotundaria profunda — Haas (1929)
Amblema (Psorula) profunda — Haas (1930)
Psorula profunda — Haas (1969), Graf & Cummings (2007), Bogan (2010), Pfeiffer et al. (2019), Inoue et al. (2020), Freeman et al. (2025)
Psoronaias crocodilorum — Cummings et al. (2025)

Psoronaias martensi Frierson, 1927

Martens, 1900. Biol. Centr.-Amer., Moll.: 494, pl. 31, figs. 1-2 [as ‘Unio psoricus’].
Frierson, 1927. Check List N. Amer. Naiades: 64, sp. 279.
LECTOTYPE [AS TYPE] ZMB/MOLL_39466 (by R.I. Johnson, 1972: 146), N. Guatemala: Rio de las Salinas.

Psoronaias martensi — Frierson (1927), Haas (1930), Haas (1969), Graf & Cummings (2007), Bogan (2010), Graf & Cummings (2021)
Psoronaias crocodilorum — Cummings et al. (2025)

Rotundaria salinarum Haas, 1929

Haas, 1929. Senckenbergiana 11: 339, figs. 20-21.
HOLOTYPE (ORIG. DESIG.) SMF_3487, Rio de las Salinas, N. Guatemala.

Rotundaria salinarum — Haas (1929)
Amblema (Psorula) salinarum — Haas (1930), Haas (1969)
Psorula salinarum — Haas (1969), Graf & Cummings (2007), Bogan (2010)
Psoronaias salinarum — Graf & Cummings (2021), Nagel (2025)
Psoronaias crocodilorum — Cummings et al. (2025)

Psoronaias semigranosa ‘von dem Busch in Philippi’ of Authors

(misidentified reference to Unio semigranosus von dem Busch in Philippi, 1843)
‘von dem Busch in Philippi’ of Authors.
Pfeiffer et al., 2019. Zool. Scripta 48: 108.
Pfeiffer et al., 2019. MPE 137: 116.
Inoue et al., 2020. Zootaxa 4816(4): 460.
Smith et al., 2020. Cladistics 36: 507.
Freeman et al., 2025. Malacologia 67(1/2): 256, Table 1.
Campbell & Lydeard, 2026. Malacologia 68(1/2): 289.

Psoronaias crocodilorum — Cummings et al. (2025)

Unio crocolilorum Lea, 1852

(error for Unio crocodilorum Morelet, 1849)
‘Morelet’ Lea, 1852. Synopsis Fam. Naiades: 39.

Unio testidineus Lea, 1852

(error for Unio testudineus Morelet, 1849)
‘Morelet’ Lea, 1852. Synopsis Fam. Naiades: 40.

Unio semigranosus Reeve, 1864

(misidentified reference to Unio semigranosus von dem Busch in Philippi, 1843)
‘Philippi’ Reeve, 1864. Conch. Icon. 16: pl. 10, sp. 36; errata.
FIGURED SPECIMEN BMNH_196496, Mexico.

Unio (sec. Elliptio) testudineus — Simpson (1900)
Unio (Psoronaias) semigranosus var. testudineus — Martens (1900)
Unio (sec. Elliptio) (Group of U. semigranosus) testudineus — Simpson (1914)

Unio pliciferus Reeve, 1864

(misidentified reference to Unio pliciferus Lea, 1838; error for Unio crocodilorum Morelet, 1849)
‘Lea’ Reeve, 1864. Conch. Icon. 16: pl. 10, sp. 37; errata [changed to ‘U. crocodilorum Morelet’].

Unio (Psoronaias) crocodilorum — Martens (1900)
Unio (sec. Elliptio) crocodilarum [sic] — Simpson (1900)
Unio (sec. Elliptio) (Group of U. semigranosus) crocodilarum [sic] — Simpson (1914)
Psoronaias crocodilorum — Frierson (1927)

Unio psoricus Martens, 1900

(reference to Unio psoricus Morelet, 1851)
Martens, 1900. Biol. Centr.-Amer., Moll.: 494, pl. 31, figs. 1-2.

Psoronaias martensi — Frierson (1927), Haas (1969)

Psoronaias testudinarea Bogan, 2010

(error for Unio testudineus Morelet, 1849)
‘Morelet’ Bogan, 2010. FADA: [web].