Abstract

An unusual new coccolithophore species is described from the deep photic zone. The species is dimorphic with small body coccoliths bearing short spines and larger spine-coccoliths with exceptionally long, hollow, quadrate spines. The species is rare but has been observed in the Pacific, Indian and Atlantic Oceans reinforcing other evidence that the deep photic zone nannoflora is more diverse and heterogeneous than previously assumed.

The species also shows remarkable morphological similarity to some species of the non-calcifying haptophyte Chysochromulina of a type which has frequently been cited as evidence for possible multiple origins of calcification in haptophytes. However, the coccolith structure strongly indicates that the species is a member of the Papposphaeraceae. Available phylogenetic data from molecular genetics and biomineralization modes make it extremely unlikely that the Papposphaeraceae are closely related to the spine-bearing Chrysochromulina species and so the striking morphological similarity is almost certainly a case of homoeomorphy, and possibly functional convergence.

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