The Silicoflagellates from the diatomitic and argillaceous layers of a Miocenic outcrop from Sierra Columbares (Murcia, Spain) are described. The following species have been
determined: Dictyocha triacantha, D. fibula, D. messanensis, D. rhombica, D. brachyacantha,
D. staurodon, D. crux, D. speculum, D.. culum , D. pseudofibula, Mesocena elliptica crenulata, M. elliptica minoriformis, M. circulus, Cannopilussp. Of these, a clear
predominance of speculum been observed: in some samples this species constitutes more than 80 % of the total number of individuals of silicoflagellates. D. Speculum
shows a great variability, and different species have been considered: D. binoculus, D.
triommata, and D. Ornamentus, all interpreted as synonimous of D. Speculum
