“…Anatomical aspects of Argentinean species of Bostryx have been provided in different publications (Hylton Scott 1945, 1954, 1967, Breure 1978. Previous works on B. stelzneri (Doering 1875, 1879, Pfeiffer 1876, Pilsbry 1896[1895-1896, Holmberg 1912, Parodiz 1946, 1948 are based mainly on shell and jaw descriptions, with scarce anatomical information (Hylton Scott 1945, Breure 1978. Because of the high shell intraspecifi c variation, many varieties and forms have been described: Bostryx stelzneri stelzneri (Dohrn, 1875) B. stelzneri peristomatus (Doering, 1879), B. stelzneri conispirus (Doering, 1879), B. stelzneri hector (Holmberg, 1909), B. stelzneri apertus (Hylton Scott, 1948), B. stelzneri hybrida (Parodiz, 1948), B. stelzneri nonogastanus (Parodiz, 1948), B. stelzneri tinogastanus (Parodiz, 1948), and B. stelzneri scaber (Parodiz, 1948).…”