Set number: 427

  • Helicosphaera recta 1541 1
  • Helicosphaera recta 1542 2
    10µm
Helicosphaerella recta, Late Oligocene, DSDP Leg 25, Site 242, Mozambique Channel (Davie Ridge), Indian Ocean

Set number: 426

  • Helicosphaera recta 1512 1
  • Helicosphaera recta 1513 2
  • Helicosphaera recta 1511 3
    10µm
Helicosphaerella recta, Late Oligocene, Offshore Libya
Final Epithet
Helicosphaerella recta (Haq, 1966) Aubry, Liu, de Vargas, & Probert in Aubry & Bord, 2009
Basionym

Helicosphaera seminulum recta Haq, 1966

Synonyms

Helicosphaera recta (Haq, 1966) Jafar & Martini, 1975

Description

Sub-rectangular helicolith has an asymmetrical blanket (Type II, Helicosphaerella recta type), truncated flange termination and a central area with traverse conjunct bar with relatively small pores at both sides.

Remarks

Helicosphaerella recta is distinguished from Helicosphaerella truncata (Bramlette & Wilcoxon,1967) Aubry, Liu, de Vargas, & Probert in Aubry & Bord (2009) by having smaller central pores.

Helicosphaerella recta is distinguished from Helicosphaerella robinsoniae (Bown & Dunkley Jones, 2012) Varol, n. comb. by having a conjunct bar rather than a disjunct bar.

Helicosphaerella recta was described from Upper Eocene sediments but considered to be caved in here from Oligocene to Early Miocene sediments.

References

Bown, P. R. & Dunkley Jones, T. 2012. Calcareous nannofossils from the Paleogene equatorial Pacific (IODP Expedition 320 Sites U1331-1334). Journal of Nannoplankton Research 32(2): 3-51.

Bramlette, M. N., Wilcoxon, J. A., 1967. Middle Tertiary calcareous nannoplankton of the Cipero section, Trinidad, W.I. Tulane Studies in Geology and Paleontology 5, 93-131.

Haq, B. U., 1966. Electron microscope studies on some upper Eocene calcareous nannoplankton from Syria. Stockholm Contributions in Geology 15, 23-37.

Jafar, S. A., Martini, E., 1975, On the validity of the calcareous nannoplankton genus Helicosphaera. Senckenbergiana Lethaea 56, 381-397.