Two unusual new dinoflagellate cyst genera from the Bunde Borehole, Maastrichtian type area, southern Netherlands

Maastrichtian and Danian deposits from the Bunde Borehole in the Maastricht ian type area contain the morphologically unusual dinoflagellate species Sp umadinium felderorum gen. et sp. nov, and Lasagniella herngreenii gen. et s p, nov., both of which have archeopyles formed by the loss of several parap lates. In S. felderorum the paraplates forming the operculum or opercular p ieces appear to be the third and fourth precingulars (3 "-4 ") plus the fir st and second anterior intercalaries (1a-2a). This suggests that Spumadiniu m, although having a wall resembling some cribroperidinioids, is a cladopyx iinean. L. herngreenii is unique in having up to eight wall layers, separat ed and supported by buttresses. The archeopyle is also a combination type b ut formed by loss of one apical (3'), three anterior intercalary (1a-3a) an d three precingular (3 "-5 ") paraplates. Thus, Lasagniella is assignable t o the Peridiniales. The distinctive morphology and restricted ranges of the two genera make them useful stratigraphic markers for the Upper Maastricht ian-Danian. (C) 2000 Elsevier Science B.V. All rights reserved.