The Echinoderes coulli-group is characterized by the presence of an enlarged nephridiopore composed of two regions apparently related to increase the osmoregulation efficiency. Representatives of this group are often intertidal species living in habitats with daily salinity changes, including mangroves. In the present study, two new species potentially belonging to this group are described from a lowly polluted mangrove in French Guiana (western Atlantic Ocean). Echinoderes angelae sp. nov. possesses spines in middorsal position on segment 4 and sublateral position on segments 6–7, plus tubes in lateroventral position on segments 5 and 8 and in laterodorsal position on segment 10. Besides, this species has modified type 2 glandular cell outlets throughout different positions on segments 2, 4–8 and 10 and large sensory spots on segment 1 with a transversal row of conspicuously elongated hairs at the posterior part of the papillae area. Echinoderes guianensis sp. nov. has spines in middorsal position on segment 4, lateroventral position on segment 6 and sublateral position on segment 7, plus tubes in lateroventral position on segment 5 and laterodorsal position on segment 10. Also, it lacks modified type 2 glandular cell outlets and large sensory spots with a posterior, transversal row of elongated hairs. These diagnostic features allow the distinction of the new species from the remaining congeners of the E. coulli-group. In addition, the presence of epibionts in some of the examined specimens is discussed.