Morphometry of four phenotypes of Stramonita haemastoma (Gastropoda: Muricidae) from the Urindeua river, Pará state, northern Brazil

Evidence of phenotypic variation in the gastropod Stramonita haemastoma (Muricidae) through external features of the shell on individuals collected in the river Urindeua, Amazon estuary, northern Brazil, as subsidies for studies on the phylogeny and population dynamics of the species.