D. Massemin, S. Clavier & J.-P. Pointier 
Novapex 12(3-4): 109-118, 10 octobre 2011 
Appendix 1 
In French Guiana, Bivalvia of brackish waters, as oysters, can be observed up to more than 50km inside lands 
and are therefore considered by the authors to be continental species; size is expressed for adult shells. 
Drawing by the authors (DM). 
1 1.1 
Hinge dysodont 
(absence of tooth) 2 
1.2 
Hinge heterodont 
(cardinal and latéral teeth présents and dissimilar) 3 
2 2.1 
Shell extended, widened and rounded 
behind, end not sharp (mytiliform); internai 
surface entirely pearly; in brackish water; 
shell attached by a byssus to hard substratum 
size of 10 to 20 mm Dreissenidae 
Mytilopsis leucophaeata ( Fig. 1) 
2.2 
Shell oval to variable-shaped, 
kept closely; internai surface 
entirely pearly; in brackish water 
size more than 9 mm Ostreidae 
Crassostrea rhizophorae (Fig. 2) 
3 3.1 
Shell circular to suboval; 
in treshwater: size less than 8mm 4 (Sphaeriidae) 
3.2 
Shell rectangular to subtrigonal; 
in freshwater; size up to 40 mm 5 (Hyriidae) 
3.3 
Shell subtriangular clam-shaped; 
in hrackish water: size up to 10mm 7 (Corbiculidae) 
4 4.1 
4.2 
The iirnbo is central 8 (Pisidium) 
The umbo is subcentral 9 ( Eupera ) 
5 5.1 
Shell subtrigonal; 
cardinal teeth well developed; 
test concentrically sculptured; 
up to 45 mm Castci 1 ici sulccita (Fig. 3) 
5.2 
Shell rectangular; 
cardinal teeth not well developed__6 
6 6.1 
Tessellata sculpture; 
muscle scar rounded at the posterior end; 
size np to 40mm Diplodon yronosus (Fig. 4) 
6.2 
Concentric sculpture; 
muscle scar angulated at the posterior end; 
size up to 60mm Diplodon voltzi (fig.5) 
7 
Palliai sinus well developed; 
size more than 20 mm__ Polymesoda aequilatera (Fig. 6) 
8 8.1 
Shell oval and compressed; 
test matt and diaphanous; whitish, slightly tinted 
with fuscous patches; 
surface finely concentrically striated and covered with 
granular points; 
latéral teeth similar in both valves; 
minute species (3-5mm)__ Pisidium punctiferum (Fig. 7) 
8.2 
Shell inequilateral and rounded; 
117 
