Three new organic-walled dinoflagellate cysts from the Upper Cretaceous deposits in the western External Rif, northwestern Morocco: Taxonomy and stratigraphic distribution

Abstract

Three new species of organic-walled dinoflagellate cysts (dinocysts) have been spotted during our palynological investigations in the Upper Cretaceous deposits from the western External Rif Chain, northwestern Morocco. They have been previously mentioned and figured under different names, but have not been formally described. In this paper, the formal descriptions of these new species are presented, based on several specimens observed within rich, diverse and well-preserved upper Campanian dinocyst assemblages from the Sekada, Tattofte and Bou Lila sections. Canningia wilsonii sp. nov. is a holocavate cyst, characterized by having densely packed pillars, supporting a finely reticulate ectophragm on the mid-dorsal surface to coarsely reticulate elsewhere, mainly in the periphery. Impagidinium sekadensis sp. nov. is distinguished by the combination of a smooth central body wall, rigid and well-developed sutural septa, narrow longitudinal apical plates (1′, 4′) which are rarely separated (partially) by a discontinuous sutural septum, a strongly leavorotatore cingulum and a narrow sulcus with a differentiated posterior sulcal (ps) plate. Nematosphaeropsis lilaensis sp. nov. differs from the published species of Nematosphaeropsis by having a smooth central body wall and numerous sutural (gonal and intergonal) processes that are flexible, hollow and joined proximally by low and discontinuous sutural ridges and distally by pairs of thin penitabular trabeculae. The taxonomic synonyms and stratigraphic ranges of the new species, as well as their comparison with published dinoflagellate taxa, which morphologically resemble them, are given and discussed.