The generic position of Planorbis (Gyraulus) intermixtus Mousson, 1874, and Planorbis presbensis Sturany, 1894 (Gastropoda, Basommatophora)

The two planorbid species described as Planorbis (Gyraulus) intermixtus Mousson, 1874, from Samava/Euphrates and as Planorbis presbensis Sturany, 1894, from Lake Presba, Makedonia, usually considered to belong to the genus Gyraulus Charpentier, 1837, turned out to be members of Planorbis O.F. Müller, 1774. Their anatomical characters are described and compared with those of Planorbis planorbis (L.) and P. carinatus O.F. Müller. For the conchologically aberrant P. presbensis a new subgenus, Crassiplanorbis, is established. The two species studied thus have to be named Planorbis (Planorbis) intermixtus Mousson, 1874, and Planorbis (Crassiplanorbis) presbensis Sturany, 1894.