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Selenopemphix nephroides

Zonneveld, K.A.F. and Pospelova V. (2015). A determination key for modern dinoflagellate cysts. Palynology 39 (3), 387- 409.

 
ventral view
photographs Karin Zonneveld
cross section
apical view

Field characteristics

Selenopemphix nephroides (Benedek 1972) Benedek et Sarjeant, 1981

Field characteristics:
Large, brownish-pigmented antero-posteriorly compressed cysts. The epicyst is widely conical with slightly concave outline in dorso-ventral optical section and bears a single broad apical boss. The hypocyst is also conical with a truncated posterior end and without antapical horns. The cingulum is wide and well defined by deep indentation. The cingular lists distinctively waves. The sulcus is wide, short, and is also is well indicated by indentation of the autophragm. Two flagellar pores are often reflected by two small depression in the sulcus. The large and intercalary iso- to lati-deltaform archeopyle is shifted from the middle line, and is derived from the loss of the 2a plate.

Dimensions: Cyst body diameter 48-60 μm.
Motile affinity: Protoperidinium subinerme (Paulsen 1904) Loeblich III 1970.
Cyst theca relationship: Wall and Dale, 1968
Stratigraphic range: Middle Eocene-Recent.

Comparison with other species:
This species has a very characteristic cingulum which is extremely wide. As a result of that you will find it almost exclusively in apical view under the light-microscope. It has no thickened wall at the apical or antapical horn. No striae, undulations of margin, other ornamentation is present.

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
Selenopemphix nephroides occurs in temperate to equatorial regionns. Highest relative abundances are observed in mesotrophic to eutrophic environments such as upwelling areas where bottom waters may be anoxic to oxic. Its seasonal abundance is positively correlated to bioproductivity in surface waters in vicinity of the sampling site.
Distribution:
Selenopemphix nephroides is restricted to the coastal sites of temperate to equatorial regions with exception of a few recordings from the equatorial Atlantic Ocean and central North Atlantic Ocean. Highest abundances (up to 14%) occur in the vicinity of upwelling cells off NW Africa and off SW Africa as well as in western Mediterranean Sea, the South China Sea, the Sea of Okhotsk (Northwestern Pacific) and the Bering Sea (North Pacific). It has not been observed in river plume areas.

Environmental parameter range:
SST: -0.8 - 29.8°C (winter - summer) with summer SST > 5.9°C except for 7 sites from a restricted area in the North Pacific. SSS: 27.6 - 39.4 (summer - autumn) apart from three recordings in the Black and Marmara Seas where SSS: 17.5 - 24.0 (summer - winter). [P]: 0.06 - 1.7 μmol/l, [N]: 0.4 - 17.9 μmol/l, chlorophyll-a: 0.07 - 17.4 ml/l, bottom water [O2]: 0 - 7.2 ml/l.
Although Selenopemphix nephroides occurs in oligotrophic regions, highest abundances are in seasonally mesotrophic to eutrophic areas. These regions are mainly upwelling areas with large inter-annual trophic variability being eutrophic conditions during active upwelling or when upwelling filaments cross the sampling site and oligotrophic when upwelling is absent. High relative abundances occur where bottom waters are well ventilated.

Comparison with other records:
Apart from the records in the dataset of this Atlas, Selenopemphix nephroides has been observed in surface sediments of coastal sites of the Persian Gulf, off western India (Arabian Sea), off the Iberian peninsula, estuaries of New England (Atlantic USA), the upwelling area off Peru (eastern Pacific) and coastal sites off southern China (Bradford, 1975; Biebow et al., 1993; Godhe et al., 2000; Marret and Zonneveld, 2003; Pospelova et al., 2004, 2005; Wang et al., 2004c; D'Costa et al., 2008).
In sediment traps off Somalia, cysts are deposited during active upwelling (Zonneveld and Brummer, 2000). Although this holds as well for the Iberian margin, S. nephroides is not exclusively produced during active upwelling but also occurs in other seasons (Ribeiro and Amorim, 2008). In sediment traps off NW Africa and in British Columbia, higher cyst production of this species can be related to higher organic carbon and biogenic silica fluxes as well as active upwelling (Susek et al., 2005; Pospelova et al., 2010; Zonneveld et al., 2010). In Omura Bay this species is produced in autumn-early winter at times of enhanced bioproduction mainly of diatoms (Fujii and Matsuoka, 2006). This suggest that the production of this species might follow its prey abundance.
In arctic sediments the relative abundance of this species has a small but positive correlation with seasonal ice cover duration whereas a clear negative correlation is registered when the whole North Atlantic Ocean is taken into account (Radi and de Vernal, 2008).