Papposphaera sagittifera

Thomsen, Helge A., Østergaard, Jette B. & Heldal, Mikal, 2016, Coccolithophores in Polar Waters: HOL Revisited Papposphaera sagittifera HET and, Acta Protozoologica 55 (1), pp. 33-50 : 45

P. sagittifera cfr. HOL ( Figs 44–48)

The holococcolithophore component of the combi- nation coccospheres illustrated in Figs 38–43 was also abundantly present in the holococcolithophore phase in the EPOS and ANT X/3 samples from the Weddell Sea ( Figs 44–48). The keystone feature of this species is the pronounced asymmetry in the circum-flagellar holoco- ccoliths where one side of the distal end of the tower is drawn out into a long lip-like structure that is offset from the tower itself at an angle of up to 55 degrees. Coccoliths elsewhere are fairly narrow and symmetrical and with a pronounced distal flaring. Cell dimensions in the Antarctic specimens range between 4–6 µm. The circum-flagellar holococcoliths typically reach 3 µm in length whereas those found elsewhere tend to be ca. 1 µm long. The hexagonal plates are of standard ‘ Turrisphaera ’ size. When measuring 37 individual plates from Fig. 48 the mean value is 0.11 ± 0.014 µm and the overall range 0.06–0.14 µm. A central hole in the hexagonal plates is a typical feature of these cells. No underlayer scales have so far been observed.

Figures

Figs 38–43. Papposphaera sagittifera cfr. TEM combination coccospheres from Antarctica (EPOS / Figs 39, 42–43; ANT X/3 / Figs 38, 40–41). 38 – complete cell with flagella and haptonema; 39 – cell with just a few P. sagittefera cfr. HET coccoliths and ‘Turrisphaera’ holococcoliths that are highly asymmetrical at the anterior pole; 40 – detail of holococcoliths from the cell shown in Fig. 38; 41 – higher magnification of anterior cell end of the cell shown in Fig. 38 to show details of the calyces and the central area calcification; 42–43 – details of coccoliths from the cell shown in Fig. 39.