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 Maastrichtian type area contain the morphologically unusual dinoflagellate species Spumadinium felderorum gen. et sp. nov, and Lasagniella herngreenii gen. et sp, nov., both of which have archeopyles formed by the loss of several paraplates. In S. felderorum the paraplates forming the operculum or opercular pieces appear to be the third and fourth precingulars (3 "-4 ") plus the first and second anterior intercalaries (1a-2a). This suggests that Spumadinium, although having a wall resembling some cribroperidinioids, is a cladopyxiinean. L. herngreenii is unique in having up to eight wall layers, separated and supported by buttresses. The archeopyle is also a combination type but formed by loss of one apical (3'), three anterior intercalary (1a-3a) and three precingular (3 "-5 ") paraplates. Thus, Lasagniella is assignable to the Peridiniales. The distinctive morphology and restricted ranges of the two genera make them useful stratigraphic markers for the Upper Maastrichtian-Danian. (C) 2000 Elsevier Science B.V. All rights reserved.