Quaternariella obscura Thomsen 1980

• Main Authors: Thomsen, Helge A., Østergaard, Jette B.
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2015
• Subjects: Biodiversity; Taxonomy; Chromista; Haptophyta; Coccolithophyceae; Coccosphaerales; Calyptrosphaeraceae; Quaternariella; Quaternariella obscura; Antarc*; Antarctica; Greenland
• Online Access: https://doi.org/10.5281/zenodo.12637798; http://treatment.plazi.org/id/2462E075FFAAA664666CFB65FA5914F6

Quaternariella obscura Thomsen 1980d (Figs 21–33) This taxon was described based on material from West Greenland (Arctic Station). The main diagnostic feature is packages of rhombohedral crystallites (typically in groups of four) evenly distributed over the entire cell surface. The coccolith base plate scale is circular and rimmed and has a diameter of approx. 0.6 µm (Thomsen 1980d). Evidence is also available documenting the presence of small non mineralized under layer scales (Thomsen 1980d; loc. cit. Fig. 6). Most probably there is a cluster of four crystallites in the centre of each scale. Here we illustrate additional material from the type locality (Figs 21–22) and also document the occurrence of this taxon in NE Greenland (NEW / Figs 23–27) as well as from Antarctica (EPOS / Figs 28–29). Irrespective of the origin of the material the general appearance is very similar. Numerical details have been accounted for in Table 3. We provide here for the first time evidence for the existence of different life cycle phases in Q. obscura (Figs 30–33). We found three combination cells in the Arctic that display typical Q. obscura holococcoliths in one half of the cell whereas the other half carries heterococcoliths that bear resemblance to e.g. Papposphaera spp. (Figs 30, 32). The contours of the individual heterococcolith can be traced and we can additionally account for at least some details of the rim calcification. In the combination cells (Figs 30, 32) the heterococcolith rims have fallen apart into the individual elements. This probably is due to the very delicate structure of the rim. The heterococcolith central area is oval and measures 0.47–0.61 × 0.82–0.96 µm which is within the size range typical for species of Papposphaera . Unfortunately we were not able to resolve the exact structure of the central area calcification, although Fig. 33 shows that it seems to consist of a heap of irregularly placed elements. The rim consists of a proximal/inner cycle of rod shaped elements aligned end-to-end (Figs 30, ...