CHILINA-MEGASTOMA HYLTON SCOTT, 1958 (PULMONATA, BASOMMATOPHORA) - A STUDY ON TOPOTYPIC SPECIMENS

This is a contribution to the knowledge of Chilina megastoma Hylton Sc ott, 1958 (Pulmonata: Basommatophora: Chilinidae), based on the study of topotypic specimens. This species is endemic to the Iguazu Falls, a frontier region between Argentina and Brazil. C. megastoma is known o nly from a brief original description, which was based exclusively on the shell morphology of a single specimen. The relevant results includ e the following: the radula is formed by 40-50 transverse rows of teet h in ''chevron'' arrangement; the central tooth is bicuspid with a red uced or rudimentary third cusp; the first lateral is tricuspid with a wide and short base, and the remaining laterals and marginals (40-44) each have four cusps and a long attachment base, which is bent in the marginals. The secondary or accessory seminal receptacle, in the femal e genital system, is strongly reduced and does not seems to be functio nal. The penis is as long as the penis sheath, and the penis sheath is two or three times longer than the prepuce.