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Impagidinium sphaericum

Zonneveld, K.A.F. and Pospelova V. (2015). A determination key for modern dinoflagellate cysts. Palynology 39 (3), 387- 407.

 
dorsal view
photo: Karin Zonneveld
cross section
photo: Karin Zonneveld
ventral view
photo: Karin Zonneveld

Field Characteristics

Impagidinium sphaericum (Wall 1967) Lentin et Williams 1981

Field characteristics:
Proximochorate cyst of spherical to polyhedral shape with a pronounced apical protuberance and a microgranulate wall surface. Tabulation is well expressed all over the cyst body by low, slightly undulate sutural septa. Archeopyle is precingular (type P).

Dimensions: Cyst body: 40 x 58 µm; height of septa: 3 µm.
Motile affinity: Probably a cyst of Gonyaulax spp.
Stratigraphic range: Upper Miocene to Recent.

Comparison with other species:
Very characteristic for this species are its septa that contain holes and/or ruptures. If you focus on their distal parts you see that their width is not equal. Especially on the triple junctions the lateral sides of the septa are often disconnected. The wall is granulated. The archeopyle is often visible.

Geographic Distribution

Geographic distribution based on :
Zonneveld et al., 2013. Atlas of modern dinoflagellate cyst distribution based on 2405 datapoints. Review of Palaeobotany and Palynology, v. 191, 1-197
Impagidinium spahericum has a cosmopolitan distribution and can be observed from coastal to open oceanic sites in all climatic zones. It is restricted to regions with low upper water productivity, well ventilated bottom waters and high phosphate and nitrate concentrations. It can be observed in full-marine environments as well as regions where salinity can be seasonally reduced due to melting of ice.
Distribution:
Impagidinium sphaericum has a cosmopolitan distribution and can be observed in all studied regions from the arctic/antarctic to the equator, and from the coast to the central oceans. However, its distribution is restricted to environments with low upper water chlorophyll-a concentrations and well ventilated bottom waters. Highest abundances (up to 65%) occur in the Atlantic sector of the southern Ocean and the northern North Atlantic Ocean in the vicinity of the sub-polar frontal systems as well as in the central South Atlantic Ocean.

Environmental parameters:
SST: -2.1 - 29.4°C (spring - spring), SSS: 17.4 - 39.4 (summer - autumn), [P]: 0.06 - 1.88 μmol/l, [N]: 0.04 - 26.5 μmol/l, chlorophyll-a: 0.05 - 3.56 ml/l, bottom water [O2]: > 1.7 ml/l except for one recording.
Impagidinium sphaericum can be observed in regions where salinities are seasonally reduced due to melting of ice.

Comparison with other records:
Apart from the distribution covered in this Atlas I. sphaericum has been documented from the South China Sea, Iberian upwelling area and the Peruvian upwelling area (Marret and Zonneveld, 2003; Sprangers et al., 2004). Relative abundances decrease with increasing duration of seasonal sea ice cover which may last several months (de Vernal et al., 1998; Radi and de Vernal, 2008; Solignac et al., 2009). The only sediment trap study reporting this species from the upwelling area off NW Africa records no seasonality in cyst production nor any relationship to characteristic upper water conditions (Zonneveld et al., 2010).