Freshwater Molluscan Shells / African unionaceans
Africa has species from several unionacean families, including four European species (Margaritifera auricularia, Psilunio littoralis, Anodonta cygnaea, and A. anatina) in small areas of northern Africa. Pan-African species diversity is reflected in the following table for unionacean mollusca in northern Africa, the Congo basin, and southern Africa.
Genus northern Africa
Van Damme, 1984)
(Pilsbry and Bequaert,
1927) species ;
Unio 1 ; 2 1 Parreysia 9 Grandidiera 11 ; 4 Caelatura 2 19 2 Pseudarcula 1 Psilunio 1 Anodonta 2 Aspatheria 3 19 ; 3 1 Spathiopsis 3 ; 3 31 ; 9 2 Mutela 3 29 ; 11 1 Iridina 12 ; 1 Pseudospatha 3 ; 1 Etheria 1 1 1 Totals 16 ; 5 135 ; 29 8
The species counts are imprecise. All three authors was aware that some earlier workers tended to be "splitters"--naming new species for every population encountered. Several species existed in more than one region; for example, all three authors identified Etheria elliptica in the regions they covered. On the other hand, species living in isolated or inaccessible habitats can be overlooked, and although Pilsbry and Bequaert did cover areas outside the Congo basin, it is likely some river systems were not included.
This family is present only in Africa, but is probably related to the South American Mycetopodidae (Banarescu, 1990). Genera include the following;
Unknown Spathopsis species, West Africa. Hinge teeth are lacking in these bivalves.
Mutela hargeri hargeri (E. A. Smith, 1908) African lakes.
Iridina (Cameronia) spekei
(S. Woodward, 1858), and
hinge teeth; LakeTanganyika.
The black and white images below are from Pilsbry and Bequaert, (1927), courtesy American Museum of Natural History.
(E. A. Smith, 1880)
Mutela dubia (Gmelin, 1757)
Mutela (chelidinopsis) hirundo
(E. v. Martens, 1881)
Genera of the family Unionidae present in Africa include
Anodonta, including species anatina and cygnaea, and
Pilsbry and Bequaert (1927) provisionally included
Caelatura aegyptiaca Cailliaud, (1827), Ouagadougou, Africa. x3.
Grandidieria burtoni (Woodward, 1859)
(H. Adams, 1866)
Etheriidae "River oysters" live attached to rocks in deep and rapidly moving water. One variable African species.
Etheria eliptica Lamark, 1807 form tubifera. Throughout Congo
Basin, but only in rapids. Widely used by native peoples for food, and
as a source of lime by early Belgian settlers (Pilsbry and Bequaert, 1927).
Extremely variable in shape and ornamentation.
Other African freshwater bivalves
Images from Pilsbry and Bequaert, (1927) courtesy American Museum of Natural History.
Iphigenia rostrata Roemer,
1869. 60 mm.
Egeria tenuicula langi
Pilsbry and Bequaert,
1927. 45 mm
(Boettger, 1818) Large
heavy triangular clams may
grow to over 120 mm in size.