Morphologic changes in deflandrea from a campanian section, district of Mackenzie, N.W.T., Canada

Abstract

Diverse microfloras from a section of Santonian to Maastrichtian age from the Horton River, N.W.T., contain abundant specimens of species of Deflandrea and other peridinioid forms. The abundance and ranges of these species, particularly in the Campanian, permit establishment of three microfloral divisions. Six new species of Deflandrea are described: D. ditissima, D. decorosa, D. coronata, D. microarma, D. amphiata, D. biapertura. A new genus, Laciniadinium, has been established, with two new species, L. orbiculatum, and L. biconiculum. In the lower part of the section, morphologic changes in three new Deflandrea species suggest that they form a lineage of cyst species. It may be that the lineage has arisen in response to change in environmental conditions.