Alisphaera unicornis

Classification: Coccolithophores -> Coccolith families inc sed -> Alisphaeraceae -> Alisphaera -> A. unicornis group -> Alisphaera unicornis
Sister taxa: A. pinnigera, A. unicornis,


Citation: Alisphaera unicornis Okada & McIntyre, 1977
Rank: Species
Variants: Alisphaera spatula Steinmetz 1991 (not figured) Similar to A. unicornis, and poorly differentiated from it, but spine flatter and broader, coccolith smaller and bearing teeth.
Notes & discussion: Historically this was the most commonly recorded species, but many records are probably of other species.

Distinguishing features: Most coccoliths with well-developed horn-like spine on broad margin of flange. Inner margin of distal flange smooth, without teeth.

Farinacci & Howe catalog pages: Alisphaera unicornis + * , Alisphaera spatula *

Size: liths 2-3 µm

See also: Alisphaera unicornis POL - alternate life-cycle phase;

Search data:
TagsLITHS: placolith, asymmetric, elliptical, RIM: spine(s), CA: axial-slit, plate, vacant,
CSPH: oblate (broad), ovoid, spherical, equant, monomorphic, V-UNITS: distal shield, V-prominent, R-UNITS: prox shield, px-plate, R-prominent, DETAILS: ca_conjunct,
MetricsLith size: 1.5->3.1µm; Coccosphere size: 10->16µm; Liths per sphere: 80->150
Sources: lith size from Kleijne et al. 2002 and slightly extended; csph size from illustrated specs; csph data from Cros & Fortuño 2003; lith numbers from Yang & Wei 2003, range of estimates
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): Extant Data source: present in the plankton (Young et al. 2003)
First occurrence (base): within Quaternary Period (0.00-2.59Ma, base in Gelasian stage). Data source: [JRY rough estimate]

Plot of occurrence data:

  • (NB There is no histogram as there are no occurrence records for the taxon in the Neptune database) Parent: A. unicornis group


    Andruleit, H., Rogalla, U. & Staeger, S. (2005). Living coccolithophores recorded during the onset of upwelling conditions off Oman in the western Arabian Sea. Journal of Nannoplankton Research. 27(1): 1-14. gs :: view :: open

    Cros, L. & Fortuño, J. -M. (2002). Atlas of northwestern Mediterranean coccolithophores. Scientia Marina. 66: 1-186. gs :: ::

    Konno, S. & Jordan, R. W. (2006). Lagoon coccolithophorids from the Republic of Palau, NW Equatorial Pacific. Journal of Nannoplankton Research. 28(2): 95-110. gs :: view :: open

    Okada, H. & McIntyre, A. (1977). Modern coccolithophores of the Pacific and North Atlantic Oceans. Micropaleontology. 23(1): 1-55. gs :: ::

    Steinmetz, J. C. (1991). Calcareous nannoplankton biocoenosis: sediment trap studies in the Equatorial Atlantic, Central Pacific, and Panama Basin. Woods Hole Oceanographic Institution, U.S.A.. 1: 1-85. gs :: ::

    Supraha, L., Ljubesic, Z. & Henderiks, J. (2018). Combination coccospheres from the Eastern Adriatic coast: New, verified and possible life-cycle associations. Marine Micropaleontology. 141: 23-30. gs :: ::

    Young, J. R., Geisen, M., Cros, L., Kleijne, A., Probert, I. & Ostergaard, J. B. (2003). A guide to extant coccolithophore taxonomy. Journal of Nannoplankton Research, Special Issue. 1: 1-132. gs :: view :: open


    Alisphaera unicornis compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 2-6-2020

    Taxon Search:
    Advanced Search

    Short stable page link: Go to to create a permanent copy of this page - citation notes

    Comments (0)

    No comments yet on this page. Please do add comments if you spot any problems, or have information to share

    Add Comment

    * Required information
    Captcha Image
    Powered by Commentics