The paleoecological significance of new species of Limbicysta (Acritarcha) from the upper Albian of the Canadian Arctic Islands

Abstract

Limbicysta octopediformis and Limbicysta quadriformis are new acritarch species from the upper Albian Bastion Ridge and Strand Fiord formations of the Sverdrup Basin, Canadian Arctic Islands. They are similar to the type species, Limbicysta pediformis Marshall, but have eight asymmetric or four symmetric process tips versus the four asymmetric and one symmetric process tips of L. pediformis. They are distinguished from other species of Limbicysta by their single wall layer, lack of longitudinal folds, and degree of compression. Like other species of Limbicysta, both new species are found associated with indicators of brackish-water paleoenvironments—in this example, assemblages dominated by terrestrial palynomorphs and with a low diversity of dinoflagellate cysts dominated by Nyktericysta spp. and acritarchs. The presence of Limbicysta in large numbers indicates stressed nearshore marine environments, probably brackish water. This study extends the age range of Limbicysta considerably (late Pliensbachian to early Santonian), and the geographic occurrence from the Southern Hemisphere into the Northern Hemisphere. The affinities of the genus are uncertain.