D. Massemin, S. Clavier & J.-P. Pointier 
Novapex 12(3-4): 109-118, 10 octobre 2011 
Figure 2. A. Eupera viridans (Prime, 1865), Crique Leblond, Sinnamary 4.1 mm; B. Eupera viridans Crique 
Leblond, Sinnamary 3.8 mm; C. Pisidiumpunctiferum (Guppy, 1867), Crique Arataï, Régina 2.9 mm, 
C. Pisidium punctiferum Saut Fracas 3.1 mm. 
umbones, where the concentric striation is less 
évident; 4/ A short periostracum may be présent and 
5/ The hinge is well-developed with latéral teeth in 
both valves (1-1/1-1 ) and small cardinal teeth (2/2). 
Diagnose of the mottled fmgernail clam Eupera 
viridans, was established according to the following 
criteria: 1/ The size can be of about 8 mm when adult 
(Pointier, 2008); 2/ The shell is oblong, compressed 
and inequilateral, the anterior side is shorter and 
rounded, the posterior one is sub abrupt and the basal 
margin is slightly rounded; 3/ The test lias very 
regular and délicate striation, a cream colour with 
irregular dark brown spots, 4/ There is no mention of 
periostracum and 5/ It présents a sub central umbo and 
a cardinal tooth on each valve (Pointier, 2008). 
discussion 
The small freshwater mussels belonging to the 
Sphaeriidae Family are distributed ail over the world 
and the main généra, Pisidium , is cosmopolitan 
(Kuiper, 1983). Pisidium punctiferum was described 
from the Caribbean Island of Trinidad in 1867, under 
the name Cyclas punctifera ; the type locality is a pond 
at Saint Ann's River, near Port of Spain (10°39'00" N / 
61°31’01" W): specimens were collected by the 
government botanist Prestoe and by Guppy [The first 
example was found by Mr. Prestoe, the colonial 
botanist, when we were examining the weeds in a 
pond at St. Ann, near Port of Spain, for Mollusca ]. 
Authors took a spécial care to compare the 
collected specimens to the peaclam Pisidium 
sterkianum Pilsbry, 1897 because this species is 
widely distributed from the Guiana Shield [from 
Venezuela (specimens collected by one of us, JPP, in 
1987 and identified by Kuiper) and Brazil (Agudo- 
Padrôn, 2009; Mansur & Pereira, 2006)] to Argentina 
(Darrigran & Pastorino, 1995; Ituarte, 2007), 
including the Pemvian Amazon (Ituarte, 2004), 
Paraguay and Uruguay (Scarabino & Mansur, 2007). 
Pisidium sterkianum occupies the same type of 
