Two new species of canaliculate rudists (Dictyoptychidae) from southeastern turkey

Two new species of canaliculate rudist genus Dictyoptychus Douvillé: Dictyoptychus quadrizonalis n. sp. and Dictyoptychus vanensis n. sp., are described from the Maastrichtian limestone block of the ophiolitic unit of the Geva?-Van area, southeastern Turkey. The new species are mainly characterized by the complex structure of the canal layer of the lower valve, and also they seem to be most primitive species of Dictyoptychus and transitional between Dictyoptychus Douvillé and its presumed ancestor, Eodictyoptychus Skelton and El-Asa'ad. Many specimens of the Dictyoptychus paronai (Kühn), allows us to first determination of the upper valve shape and to study also of the lower valve canal layer.