Type Species

Dictyococcites danicus Black, 1967

Synonyms

Praenoelaerhabdus Mihajlovic, 1993

Nannoserratolithus Martini & Schiller, 1998

Description

The plug may or may not cover the entire central area distally. Under the light microscope, the tube cycle and the plug cannot be distinguished from each other.

Elliptical Groups

Dictyococcites stavensis Group

Plug completely closed the central area

  • Dictyococcites burnsii Varol, in prep.; >14.0µm
  • Dictyococcites stavensis (Levin & Joerger, 1967) Varol, 1998; 10.0 - 14.0µm
  • Dictyococcites bisectus (Hay, Mohler & Wade, 1966) Bukry & Percival, 1971; 8.0 - 10.0µm
  • Dictyococcites scissurus (Hay, Mohler and Wade, 1966) Varol, 2025; 6.0 - 8.0µm
  • Dictyococcites antarcticus Haq, 1976; 4.0 - 6.0µm
  • Dictyococcites productellus (Bukry, 1975) de Kaenel in de Kaenel & Londeix, 2014; <4.0µm

Dictyococcites pseudolockeri Group

The plug partly closed the central area.

  • Dictyococcites pseudolockeri (Jurasova, 1974) Varol, n. comb.; 10.0 - 14.0µm
  • Dictyococcites filewiczii (Wise & Wiegand in Wise, 1983) de Kaenel, in de Kaenel & Londeix 2014; 8.0 - 10.0µm

Circular Group

Dictyococcites erbae Group

Plug completely closed the central area

  • Dictyococcites erbae (Fornaciari et al., 2010) Varol, n. comb.; 4.0 - 10.0µm
Remarks

Circular to elliptical placoliths comprise single-tiered distal and proximal shields, a single tube cycle that is often entirely, rarely partly closed the central area distally, and a central area with a permanent central cover proximally.

Dictyococcites differ from Noelaerhabdus by lacking a distal process and from Reticulofenestra and Cyclicargolithus by having a permanent central cover and a tube cycle that often completely or rarely partially closes the central area distally. The genus Cribrocentrum also has a permanent central cover, but its tube cycle is confined to the periphery of the central area.

The species of Dictyococcites are distinguished by their size in this study:

  • forms less than 4.0 μm are assigned to Dictyococcites productellus (holotype is 3.2 μm),
  • forms between 4.0 μm and 6.0 μm are assigned to Dictyococcites antarcticus (holotype 5.9 μm),
  • forms between 6.0 μm and 8.0 μm are assigned to Dictyococcites scissurus (holotype 8.0 μm),
  • forms between 8.0 μm and 10.0 μm are assigned to Dictyococcites bisectus (holotype 8.2 μm) and
  • forms greater than 10.0 μm are assigned to Dictyococcites stavensis (holotype 14.0 μm).

An overview of Dictyococcites species is presented in Table 4 in Varol (2025a).

Optical Properties: All components exhibit inclined extinction lines and length-fast (-) elongation. The extinction angle measured on the distal side is typically about 9° on the distal shield, but it can not be measured in the tube cycle due to the oblique orientation of the tube cycle segments. The apparent angle between extinction on the tube cycle is 67°, corresponding to an obliquity angle of 23°.

References

Backman, J. 1980. Miocene-Pliocene nannofossils and sedimentation rates in the Hatton-Rockall Basin, NE Atlantic Ocean. Stockholm Contributions in Geology 36: 1-91.

Bukry, D. 1975b. Coccolith and silicoflagellate stratigraphy, northwestern Pacific Ocean, Deep Sea Drilling Project Leg 32. Initial Reports of the Deep Sea Drilling Project 32: 677-701.

Bukry, D. & Percival, S. F. 1971. New Tertiary calcareous nannofossils. Tulane Studies in Geology and Paleontology 8: 123-146.

de Kaenel, E. & Londeix, L. 2014. Données nouvelles sur la nannoflore de l’Aquitanien stratotypique. In: Londeix, L. (Ed.) Stratotype Aquitanien. Collection Patrimoine géologique, Muséum national d’Histoire naturelle, Paris. 5: 261-267.

Fornaciari, E., Agnini, C., Catanzariti, R., Rio, D., Bolla, E. M. & Valvasoni, E. 2010. Mid- Latitude calcareous nannofossil biostratigraphy and biochronology across the middle to late Eocene transition. Stratigraphy 7(4): 229-264.

Haq, B. U. 1976. Coccoliths in cores from the Bellinghausen abyssal plain and Antarctic continental rise (DSDP Leg 35). Initial Reports of the Deep Sea Drilling Project 35: 557-567.

Hay, W. W., Mohler, H. P. & Wade, M. E. 1966. Calcareous nannofossils from Nal'chik (northwest Caucasus). Eclogae Geologicae Helvetiae 59: 379-399.

Jurasova, F. 1974. Nannoplankton from the Menilitic Formation (Lower Oligocene) at Dolní Te__ice. Vestnik Ustredniho Ustavu Geologickeho. 49: 91-96.

Levin, H. L. & Joerger, A. P. 1967. Calcareous nannoplankton from the Tertiary of Alabama. Micropaleontology 13(2): 163-182.

Martini, E. & Schiller, W. 1998. Calcareous nannoplankton from Sieblos/Rhoen and the Nieuwied Basin (Lower Oligocene). Geologisches Abhandlungen Hessen. 100: 165-172.

Mihajlovic, D. 1993. Praenoelaerhabdus, a new endemic genus of calcareous nannoplankton from the Pannonian Basin. Geologica Carpathica. 44(1): 59-62.

Varol, O. 1998. Palaeogene. In: Bown, P. R. (Ed.), Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series pp. 200-224

Wise, S. W., 1983. Mesozoic and Cenozoic calcareous nannofossils recovered by DSDP Leg 71 in the Falkland Plateau region, Southwest Atlantic Ocean. Initial Reports of the Deep Sea Drilling Project 71, 481-550.