Sphenolithus abies

Sphenolithus abies Deflandre, 1953 (nom. nud) Invalid
Sphenolithus abies Deflandre in Deflandre & Fert, 1954 [no holotype was designated]

Sphenolithus verensis Backman, 1978

The pointed dome shape Sphenolithus Deflandre in Grassé (1952) is taller than wider and has three cycles of segments (proximal, lateral and apical).

The longitudinal extinction line is evident at 0° and always greater than the lateral extinction line. Entirely birefringent species at side and plan views.

The three cycles can be better seen in well-preserved specimens at 45° with the help of the gypsum plate.

The biconical clustered apical cycle with axial c-axis is not forming a true apical spine.

The hollow frustum shape proximal cycle is creating a conical proximal cavity. The opposite side of the proximal cycle is better seen at 45° and displays an axial c-axis.

Sphenolithus abies is difficult to identify consistently from Sphenolithus moriformis (Brönnimann & Stradner, 1960) Bramlette & Wilcoxon, 1967, particularly at plan view. The shallower dome shape Sphenolithus moriformis has a longer lateral extinction line than the longitudinal extinction line.

Sphenolithus apoxis Bergen & de Kaenel in Bergen et al., 2017 has a bouquet shape cluster apical cycle whereas Sphenolithus abies has a biconical apical cycle best seen at 45°.

Sphenolithus abies differs from Sphenolithus alatus Varol, in prep. by having a relatively larger apical cycle, lateral cycle with radial to sub-radial segment and relatively shallower proximal cavity.

Backman, J., 1978. Late Miocene - Early Pliocene nannofossil biochronology and biogeography in the Vera Basin, SE Spain. Stockholm Contributions in Geology 32, 93-114.

Bergen, J. A., de Kaenel, E., Blair, S. A., Boesiger, T. M., Browning, E., 2017. Oligocene-Pliocene taxonomy and stratigraphy of the genus Sphenolithus in the circum North Atlantic Basin: Gulf of Mexico and ODP Leg 154. Journal of Nannoplankton Research 37(2-3), 77-112.

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.

Brönnimann, P., Stradner, H., 1960. Die Foraminiferen- und Discoasteriden-zonen von Kuba und ihre interkontinentale Korrelation. Erdoel-Zeitschrift 76(10), 364-369.

Deflandre, G., 1952. Classe des Coccolithophoridés. (Coccolithophoridae. Lohmann, 1902). In: Grassé, P. P. (ed.), Traité de Zoologie. Masson, Paris 439-470.

Deflandre, G., 1953. Hétérogénéité intrinsèque et pluralité des éleménts dans les coccolithes actuels et fossiles. Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences, Paris 237, 1785-1787.

Deflandre, G., Fert, C., 1954. Observations sur les coccolithophoridés actuels et fossiles en microscopie ordinaire et électronique. Annales de Paléontologie 40, 115-176.