Pontosphaera

Pontosphaera syracusana Lohmann, 1902

Crassapontosphaera Boudreaux & Hay, 1969

Koczyia Boudreaux & Hay, 1969

An elliptical cribrilith discolith displaying the optical properties characteristic of Pontosphaeraceae.

Structural features of Pontosphaera:

• The proximal plate is typically perforated, with pores arranged randomly, in concentric cycles, or in combination; in rare cases, it may be radial or non-perforated.
• The outer wall consists of dextrally imbricated segments.
• The inner wall is composed of tangentially arranged segments extending over the proximal plate’s distal surface, varying in thickness.

Morphological variations for species identification in Pontosphaera:

• Wall height
• The extension of the inner wall segments over the proximal plate forms the distal cover. The distal cover varies in height and interference colour:
  • Very low, as in Pontosphaera wondersii and Pontosphaera trena (the interference colour of the distal cover is distinctly weaker than that of the wall).
  • Moderately high, as in Pontosphaera sparsiforata and Pontosphaera vigintiforata (the interference colour of the distal cover is considerably different from that of the wall).
  • Equal to the wall height, as in Pontosphaera multipora (interference colour of the distal cover and wall are similar).
• Perforation characteristics
  • Presence or absence of perforations on the proximal plate (e.g., absent in Pontosphaera jonesii).

• Arrangement of perforations:
  • Random, as in Pontosphaera lowei.
  • Concentric cycles, as in Pontosphaera callosa (with variations in the number of cycles, such as a single complete cycle in Pontosphaera sparsiforata).
  • Lateral arrangement, as in Pontosphaera lepida.
• Pore size and variability
  • Large pores, as in Pontosphaera rorsa.
  • Tiny pores, as in Pontosphaera syracusana.
  • Variable pore sizes, as in Pontosphaera desuetoidea

Boudreaux, J. E. & Hay, W. W. 1969. Calcareous nannoplankton and biostratigraphy of the late Pliocene-Pleistocene-Recent sediments in the Submarex cores. Revista Española de Micropaleontología 1(3): 249-292.

Lohmann, H. 1902. Die Coccolithophoridae, eine Monographie der Coccolithen bildenden Flagellaten, zugleich ein Beitrag zur Kenntnis des Mittelmeerauftriebs. Archiv für Protistenkunde. 1: 89-165.