Nannotax Enabling nannofossil research

Description: Holococcoliths are formed of numerous, minute rhombohedral calcite crystallites. They are produced during the haploid phase of the life-cycle of a wide range of coccolithophores that bear heterococcoliths in their diploid life-cycle phase.

Coccosphere of Syacrosphaera pulchra holococcoliths	Coccosphere of Helicosphaera carteri holococcoliths	Combination coccosphere of Calcidiscus quadriperforatus	Fossil holococcoliths - Syracolithus schilleri

Remarks: Although diverse holococcolith assemblages have been described from Cretaceous and Palaeogene assemblages, they are virtually absent from Neogene nannofloras. This is rather surprising, given that modern nannofloras include >60 holococcolithophores (see, e.g., Kleijne, 1991; Jordan & Kleijne, 1994; Young et al. 2003), but most species produce very small holococcoliths (often <2μm) with low preservation potential.

Only the relatively few holococcoliths with a reasonable Neogene fossil record are included here. Where the heterococcolith phase is known the taxonomy has been adjusted, as recommended by Thomsen et al. (1991), Cros et al. (2000) and Young et al. (2003).

Range: Mesozoic to Recent

Synonym: Family CALYPTROSPHAERACEAE Boudreaux & Hay, 1969. It used to be conventional to place all holococcoliths in the Famly Calyptrosphaeraceae, however this is manifestly artificial, since it is now known that holococcoliths are formed during the haploid life-cycle stage of species belonging to numerous different families. Moreover, the type species of the Family Calyptrosphaeraceae, Calyptrosphaera oblonga , is now known to be a life-cycle phase of Syracosphaera pulchra, hence the name Calyptrosphaeraceae is a junior synonym of Syracosphaeraceae.

It is convenient to group the holococcoliths together for identification purposes, but  giving this artificial grouping a formal taxonomic name (e.g. Calyptrosphaeraceae) is not defensible.