Original Description: Unio granosa Bruguiére, J.G. 1792. Sur une nouvelle espéce de Mulette. Journal d’Histoire Naturelle 1:103-109. p. 107, pl. 6, figs. 3-4.
Type Locality: Riviéres de la Guyane. [=Rivers of Guyana.]
Holotype: Location unknown.
- Unio granosa Bruguiére, 1792
- Bruguiére, 1792:107.
Unio granosus Bruguiére, 1792
- Hanley 1842:182; 1843:182, pl. 23, fig. 21; Catlow & Reeve 1845:59; H. & A. Adams 1857:496; Drouet 1859:86.
Margarita (Unio) granosus (Bruguiére, 1792)
- Lea 1836:17; 1838:16.
Margaron (Unio) granosus (Bruguiére, 1792)
- Lea 1852:23; 1870:34.
Diplodon (Diplodon) granosus granosus (Bruguiére, 1792)
- Haas 1931:30; 1969:525.
Diplodon granosus (Bruguiére, 1792)
- Parodiz 1968:6.
Description: “Shell of medium size, subsolid, elongate-rhomboid to long elliptical, inflated;…
Range: Essequibo, Caura, and Orinoco rivers, Venezuela and Guyana.
Comments: This species has been misunderstood for many years. Simpson (1900:879) has included Unio multistriatus Lea, U. pfeifferi Dunker, U. psammactinus Phillippi, U. famelicus Gould, and U. niloticus Sowerby in the synonomy of Diplodon granosus. which is incorrect. I have examined the types of most of these species and they are not synonymous with D. granosus. Haas (1931:31) also did not understand this species and his synonomy reflects many of the ideas of Simpson.
Unio niloticus Sowerby (found only in the Nile River Africa) and U. famelicus Gould (known from Walla Walla Washington, although stated by Simpson to be an error in location) are definitely not the same as D. granosus.
Specimens Examined: INHS 14950 (1). trib. to Rio Yuruari, ca. 20 km ESE El Manteco, Bolivar, Venezuela. 9 January 1994. K.S. Cummings, C.A. Mayer & G.B. Mottesi. INHS 14954 (17). Rio Guanare, El Miamo, Bolivar, Venezuela. 11 January 1994. K.S. Cummings, C.A. Mayer, G.B. Mottesi, M.H. Sabaj, C.A. Laird & J.W. Armbruster. USNM 428118 (1 female). A small creek, tributary to the Cuyuni, Kamaria, British Guiana [=Guyana]. 22 July 1925. J.P.E. Morrison. FSM 29407 (1). Tributary of Rio Erebato (Rio Caura – Rio Orinoco Dr.), 35 km SSW intersection of Rio Caura and Rio Erebato [Distrito Cedeno] County, Bolivar, Venezuela. 24 March 1981. R. Franz.