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Spiniferites cruciformis

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

 
ventral view
Holotype: Wall 1973
Single grain AII49-145IG, 66.5 - 69 cm
Balck Sea
photographs: Karin Zonneveld
cross section
dorsal view

Field characteristics

Spiniferites cruciformis Wall and Dale in Wall et al. 1973

Field characteristics:
Cruciform, moderately dorsoventrally compressed cyst with variable sutural septa that can have perforated flanges projecting laterally from the apices and from the lateral equatorial points..

Dimensions: cyst body: 34 to 56 (width) x 46 to 65 (length) µm; length of processes: 10 to 29 µm.
Motile affinity: unknown
Stratigraphic range: Late Quaternary to Recent.

Comparison with other species: This species is easily recognisable by its cruciform body shape. The shape can however vary from almost oval to extreme cruciform.

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
Spiniferites cruciformis is endemic to the Caspian Sea, Aral Sea, Black Sea and Eastern Mediterranean Sea and occurs in areas affected by river discharge. At these sites [P]: > 0.1 μmol/l and bottom waters are well ventilated.
Distribution:
Spiniferites cruciformis is restricted to the Black Sea, Caspian Sea, Aral Sea, Marmara Sea and eastern Mediterranean Sea where it is exclusively observed in coastal sites. It can form up to 48% of the association. Apart from three sites, the environment is brackish as result of river discharge.

Environmental parameter range:
SST: 1.6 - 26.0°C (winter - summer), SSS: 8.5 - 17.3 (summer - winter) except for three recordings from Eastern Mediterranean sites where SSS: 37.7 - 39.0 (spring - autumn), [P]: 0.10 - 0.14 μmol/l, [N]: 0.05 - 1.0 μmol/l, chlorophyll-a: 0.1 - 8.3 ml/l, bottom waters [O2]: 4.2 - 6.6 ml/l.

Comparison with other records:
Based on recordings of this species in Greek fresh-water lakes, it has been suggested to be a fresh-water species that is transported into the marine realm by rivers (Kouli et al., 2001). It is rarely present in surface sediments of fresh to brackish lakes around the Marmara Sea as well (Mudie pers comm. 2012). Our records do not reject this hypothesis as the species is exclusively recorded from areas that are influenced by fresh water. We however do also not find evidence for this.
The species shows extreme morphological variation in process length and development which is often suggested to be linked to SSS. However although some weak relationship could be determined with downcore salinity concentrations reconstructed from planktonic foraminiferal transfer functions until now no direct unequivocal relationship with present salinity concentrations in surface waters and cyst morphology could be determined (Mudie et al., 2001; Marret pers. comm. 2012)