Coccolithophores in Polar Waters: Papposphaera arctica HET and HOL revisited

摘要

It has been generally accepted based on the finding of combination coccospheres in field samples that Turrisphaera arctica and Papposphaera sarion are alternate life-cycle phases of a single species. However, while recently revisiting P. sarion it became evident that the Turrisphaera phase of this species is not identical with T. arctica but rather is an undescribed species of Turrisphaera. The most conspicuous diagnostic feature of T. arctica, an asymmetrical and tilted hypertrophy of the distal tube opening in circum-flagellar coccoliths, was hinted at in the first description of the taxon. However, focus was here on the overall similarity between T. borealis and T. arctica to the extent that the rather conspicuous difference between the two taxa was not clearly recognized by the authors of the taxon, nor by any researcher who has worked on these species since then. We present here material of T. arctica from various Arctic locations (West Greenland, NE Greenland, Svalbard) that completely matches the type material from Resolute Bay, Cornwallis Island. This material additionally comprised (NE Greenland) large numbers of combination coccospheres that clearly indicate that T. arctica shares a life history with an as yet undescribed species of Papposphaera. This allows us to emend the description of T. arctica including also its heterococcolithophore phase, and in this context making use of the combination P. arctica which was established decades ago, yet here with the specific comment that P. sarion is no longer a valid synonym of P. arctica.