A new species of Peritrichida found in Biomphalaria schrammi (Crosse, 1864) is described. This new species is characterized by a reticular central area of the adhesive disc and a horseshoe-shaped macronucleus, a 80.0 ± 7 μm-diameter celular body and a 41.4 ± 2.9 μm adhesive disc; it shows 19-32 (27±3) 13.1 ± 1.1 μm - long denticle, and 8 ± 1 6.6 ± 1.1 μm - long radial pins per denticle, being different from other already described Trichodina. This is the first report of simbiontic interaction among trichodinid and molluscs of the genus Biomphalaria in Brazil.