REGISTROS DE MOLUSCOS GASTROPODA NO MÉDIO RIO XINGU - PARÁ

Abstract

This study records some mollusk species from the Gastropod associated with rapids in the main channel of the middle Xingu River. The samples were gathered along marginal shores of the River, in sand-rock substrates. Based on the total length and width of the shell, their frequency distribution were built and the regression of these two parameters was made. Of the 185 specimens collected, 44 was of Pomacea canaliculata (Lamarck, 1804), (13,0-82,0mm); 65 of Doryssa heathi (Baker, 1914), (20,0-47,0mm); 30 Doryssa starksi (Baker, 1913), (15,2-66,0mm) and 46 of Doryssa sp. nov. sensu Simone, 2007 (6,0-23,7mm). The linear regression equations were calculated for the 3 species of Doryssa. The invasion of the alien gastropod species Melanoides tuberculatus in the nearby tributaries of the Xingu River, and its high competitive advantage in relation to the local species, could be lead to the extinction of these Amazon mollusk species.