We collected these shells on and around Honaz Mountain, southeast of Denizli, Turkey, during our survey earlier last month. I identified them tonite about an hour ago. First I thought they were Z. casius, a species that had been recorded from the general area. But they turned out to be flatter and more keeled than Z. casius (see photo below).
Zonites osmanicus (left) and Z. casius (right).
Zonites osmanicus was described by Riedel in 1987 (Annales Zoologici, 41:1-42). It is endemic to Turkey. In fact, most known Zonites species are endemic to Turkey. They may have originated on some land mass that subsequently got incorporated into the Anatolian Peninsula.