Arctic coccolithophorids: two species of Turrisphaera gen. nov. from West Greenland, Alaska, and the Northwest Passage

Abstract

TURRISPHAERA gen. nov. is characterized by an unusual type of calcification in which small hexagonal crystallites, shaped like perforated plates or rings, are reticulately arranged within an organic matrix responsible for the tubular or tower-like coccolith morphology. T. borealis sp. nov., the type species which is described, was found living in very cold water (-1.degree. C) in the middle of the Northwest Passage as well as near the adjacent oceans at each end where the sea temperature is higher. In the coldest locality (Resolute Bay), typical T. borealis, though present, was outnumbered by deviants described here as a 2nd species, T. arctica sp. nov., perhaps alternatively interpretable as locally induced growth-forms. Comparisons with other living and fossil taxa indicate fewer points of resemblance between Turrisphaera and other known coccolithophorids than between it and several species of the wholly unmineralized genus Chrysochromulina. Finally, the geographical distribution suggests that in this particular case the Northwest Passage could be a significant migration route from the Pacific to the Atlantic Ocean.