Daughter taxa (time control age-window is: 0-800Ma)
A. capulata group - distal flange with sub-vertical extension
Alisphaera capulata Flange extension sub-vertical, L-shaped. Central area elements short, leaving wide central opening instead of narrow fissure (but organic scale often present in central area).
Alisphaera ordinata Flange extension a rounded sub-vertical wing extending the full length of the central area. Teeth well-developed.
Alisphaera quadrilatera Flange extension sub-vertical, angular with sub-parallel sides and pointed end. Similar to A. capulata but with distinct central fissure and flange extension simpler.
A. extenta group - distal flange with wing-like extension
Alisphaera extenta Broad side of flange extended into pointed wing. In oblique and side views it can be seen that the wing flares upwards and ends in sub-vertical wall. Teeth absent.
Alisphaera gaudii Similar to A. extenta but more ornate and varimorphic, wing extended into a sharply pointed spur in some specimens. Teeth well developed. Combination coccospheres with “Polycrater” coccoliths observed (Cros & Fortuño 2002).
A. unicornis group - distal flange with spike-like protrusion formed from a single element, or smooth
Alisphaera unicornis Most coccoliths with well-developed horn-like spine on broad margin of flange. Inner margin of distal flange smooth, without teeth.
Alisphaera bidentata Like A.unicornis but with teeth along bckedge and at ends of the cenral area.
Alisphaera pinnigera Dimorphic, most coccoliths with no protrusion, a few with a sharp spike-like protrusion. Coccoliths also smaller and smoother than those of A. unicornis with narrower central area and well-developed teeth (but often hidden on the coccosphere by the overlapping flange of the adjacent coccolith).
Alisphaera sp. Specimens which cannot be assigned to established species
Polycrater Manton & Oates 1980 - alternate life-cycle stage, producing nannoliths. The type species P. galapagensis is now known to be the alternate life-cycle stage of Alisphaera unicornis, based oncomibnation coccosphere vidence of Supraha et al. (2018)
Taxonomic discussion: The species-level taxonomy of the genus was reviewed by Jordan & Chamberlain (1993) and by Kleijne et al. (2002). N.B. As well as describing new species Kleijne et al (2002) significantly revised the taxonomic concepts of A. unicornis and A. spatula. Essentially A. unicornis sensu Jordan & Chamberlain (1993) corresponds to A. gaudii whilst A. spatula sensu Jordan & Chamberlain (1993) corresponds to A. unicornis sensu Kleijne et al. (2002). The confusion stems from the fact that Okada & McIntyre (1977) illustrated two rather different specimens as A. unicornis, See Kleijne et al. (2002) for detailed synonymies.
Distinguishing features: Parent taxon (Alisphaeraceae): Heterococcoliths asymetric, arranged in meridional rows on coccosphere; V-unit forms flange, R-unit basal. Also nannolith phase "Polycrater" with quadrate aragonitic liths. This taxon: Coccoliths placolith-like, with asymmetrical distal flange
Morphology: Coccosphere monothecate, ellipsoidal with apical opening. Coccoliths arranged on coccosphere with long axis aligned equatorially and broader flange directed toward apical opening. Coccoliths placolith-like, with asymmetrical distal flange, one side broader with a variable extension, other side narrow and in many species with 8-10 teeth projecting into central area. Plate in central area formed by extension of tube elements inward, usually with irregular central fissure. No discrete circumflagellar coccoliths. Heterococcolith structure - see Alisphaeraceae Size:
Ecology & Biogeography Biology & life-cyclesCombination cells of Polycrater sp. and Alisphaera gaudii have been observed (Cros et al. 2000, Cros & Fortuño 2002), and of P. galapagensis with A. unicornis (Supraha et al. 2018). Phylogenetic relations
The morphological data given here can be used on the advanced search page. See also these notes
Geological Range: Notes: Only occasional specimens observed and these are probably best referred to as Alisphaera sp. Last occurrence (top): Extant. Data source: Total of range of species in this database First occurrence (base): at base of Gelasian Stage (0% up, 2.6Ma, in Piacenzian stage). Data source: Total of range of species in this database
Plot of occurrence data:
Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Neptune data: This is a higher taxon page so Neptune data is not plotted. See also: customisable plot Parent: Alisphaeraceae
References:
Cros, L. & Fortuño, J. -M. (2002). Atlas of northwestern Mediterranean coccolithophores. Scientia Marina. 66: 1-186. gsVO
Cros, L., Kleijne, A. & Young, J. R. (2000a). Coccolithophorid diversity in the genus Polycrater and possible relationships with other genera. Journal of Nannoplankton Research. 22(2): 92-92. gsVO
Heimdal, B. R. (1973). Two new taxa of Recent coccolithophorids. “Meteor” Forschungsergebnisse. 70-75. gs
Manton, I. & Oates, K. (1980). Polycrater galapagensis gen. et sp. nov., a putative coccolithophorid from the Galapagos Islands with an unusual aragonitic periplast. British Phycological Journal. 15: 95-103. gsVO
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. S1: 1-132. gsVO
Alisphaera compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 6-2-2023
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