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 : 44

P. sagittifera cfr. combination coccosphere ( Figs 38– 43 )

Both the EPOS and ANT X/3 Antarctic Weddell Sea material encompassed combination coccospheres that involve P. sagittifera cfr. HET and a Turrisphaera species that is not identical to P. sagittifera cfr. HOL, nor the Antarctic Turrisphaera sp. described above.

In the heterococcolithophore component the central area calcification is rarely exposed, yet it appears to display ( Fig. 41 ) the same aspects of asymmetry (i.e. a skewed cross bar and randomly oriented peripheral elements) described above for P. sagittifera cfr. HET ( Fig. 31 ). The calyx is a flaring four-winged rosette ( Figs 41–42 ) in which each individual wing shows a pronounced stepwise reduction in width towards the distal tip. The holococcolithophore part is characterized by a pronounced asymmetry in the flagellar pole holococcolith, and a more slender yet overall symmetrical appearance of coccoliths elsewhere in the periplast. The unilateral flaring of the circum-flagellar holococcoliths immediately distinguishes this form from both Antarctic Turrisphaera sp. ( Figs 33–37 ) and Arctic P. sagittifera HOL ( Figs 23–26 ).

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.

Figs 27–32. Papposphaera sagittifera cfr. HET. TEM whole mounts from the Antarctic (EPOS samples). 27 – complete cell with flagella and a curled up haptonema; 28 – high magnification of calyces (four-winged rosettes) from Fig. 27; 29 – high magnification of calyx from Fig. 30; 30 – complete cell with flagella and a curled up haptonema; 31 – detail of central area calcification from the cell in Fig. 30; 32 – details of rim structure from the cell shown in Fig. 30.

Figs 33–37. Turrisphaera sp. TEM whole mounts from the Antarctic (EPOS samples). 33 – complete cell with flagella and haptonema; 34 – whole cell at higher magnification showing the regular appearance of the tower-shaped holococcoliths; 35–36 – details of holococ- coliths showing the hexagonal crystallite plates; 37 – complete cell.

Figs 23–26. Papposphaera sagittifera HOL (TEM / Figs 23–25; SEM / Fig. 26) from the Arctic (NEW / Figs 23–25; Svalbard / Fig. 26). 23–25 – complete cells showing flagella, haptonema (Fig. 25, arrow) and large numbers of tower-shaped holococcoliths projecting in all directions; 26 – high magnification of the hexagonal crystallite plates.