Life-cycle associations and nomenclatural treatment
Combination coccospheres demonstrate that morphologically distinct holococcolith [HOL] and heterococcolith [HET] forms may represent different phases of the same biological life cycle. However, the ICN contains no specific provision requiring such independently named morphotypes to be united under a single taxon, nor does it establish priority of the HOL or HET phase when such an association is demonstrated.
This creates a nomenclatural difficulty in cases such as
Syracosphaera dalmatica Kamptner, 1927 [HOL] and Helicosphaera pavimentum Okada & McIntyre, 1977 [HET]
Helicosphaera wallichii (Lohmann, 1902) [HET] and Corisphaera ponticulifera Kamptner, 1941 [HOL] & Syracosphaera catilliferus Kamptner, 1937 [HOL],
Helicosphaera carteri (Wallich, 1877) Kamptner, 1954 [HET], and Syracosphaera catilliferus Kamptner, 1937 [HOL].
Application of the normal principle of priority under ICN Art. 11 does not necessarily provide a satisfactory solution because priority of the specific epithet may reside in one morphotype, whereas priority of the generic name may reside in another. Strict application could therefore produce combinations that were never originally associated with either morphotype and may obscure their distinctive morphology and taxonomic history.
A further complication is that the demonstrated life-cycle associations do not necessarily represent simple one-to-one relationships between HOL and HET morphotypes. For example, Syracosphaera catillifera [HOL] has been reported in association with both Helicosphaera carteri and H. wallichii [HET]. Such observations indicate that the biological relationships among these morphotypes may be more complex than is implied by combining each HOL–HET association into a single formally named taxon. Moreover, the taxonomic interpretation of these associations is not yet consistent among specialists. As additional combination coccospheres and life-cycle associations are discovered, formally combining the associated morphotypes could therefore create progressively more complicated and potentially unstable nomenclature.
Until the ICN provides specific guidance for the nomenclature of linked coccolithophore life-cycle phases, we prefer to retain independently established HOL and HET morphotypes as separate taxa, while explicitly indicating their known or probable life-cycle associations where appropriate. This approach preserves morphological and nomenclatural clarity while allowing biological relationships to be recorded and revised as additional evidence becomes available.
Thus, nomenclatural independence does not imply biological independence: morphotypes may represent phases of the same life cycle while retaining their independently established taxonomic names.