Nannotax3 - ntax_cenozoic - Hymenomonadaceae

Citation: Hymenomonadaceae Senn, 1900

Distinguishing features:
Parent taxon (Coccolithales): 2N: Mostly placolith heterococcoliths with V-unit forming the distal shield; R-unit the proximal shield. Non-motile
N: Form holococcoliths formed of single block, or non-calcifying
This taxon: 2N: cells motile, bearing muroliths with open central-area; proximal and distal flanges variably developed. Coccosphere large, monomorphic with many small coccoliths. Neritic. N: non-calcifying.

Coccoliths are goblet-shaped muroliths with open central-area (tremaliths). At the base of the coccoliths there is usually a well-developed proximal flange. At the top of the coccoliths there may be a narrow distal flange or the wall may flare. The coccoliths appear to be entirely formed of a single cycle of <20 crystal-units. In Ochrosphaera, crystal-units have steeply inclined oblique orientations (JRY unpubl obs.).
They differ from Pleurochrysidaceae by the absence of a second cycle of units.
See also Manton & Peterfi (1969), Braarud (1954).

Diploid phase produces heterococcoliths, motile, haploid phase non-calcifying - see Fresnel (1994), Fresnel & Probert (2005),

Affinity of this family is not obvious from coccolith morphology, but molecular genetics, the life-cycle and cytological characters strongly indicate affinity with the Pleurochrysidaceae.

Geological Range:
Last occurrence (top): Extant. Data source: Total of range of species in this database
First occurrence (base): at base of Aquitanian Stage (0% up, 23Ma, in Aquitanian stage). Data source: Total of range of species in this database

References:

Braarud, T. (1954). Coccolith morphology and taxonomic position of Hymenomonas roseola Stein and Syracosphaera carterae Braarud & Fagerland. Nytt Magasin for Botanikk. 3: 1-4. gs

Fresnel, J. & Probert, I. (2005). The ultrastructure and life cycle of the coastal coccolithophorid Ochrosphaera neapolitana (Prymnesiophyceae). European Journal of Phycology. 40(1): 105-122. gs V O

Fresnel, J. (1994). A heteromorphic life cycle in two coastal coccolithophorids, Hymenomonas lacuna and Hymenomonas coronata (Prymnesiophyceae). Canadian Journal of Botany. 72: 1455-1462. gs

Manton, I. & Peterfi, L. S. (1969). Observations on the fine structure of coccoliths, scales and protoplast of freshwater coccolithophorid Hymenomonas roseola Stein, with supplementary observations on the protoplast of Cricosphaera carterae. Proceedings of the Royal Society of London. 172: 1-15. gs

Senn, G. (1900). Chrysomonadineae. In, Engler, A. & Prantl, K. (eds) Die natürlichen Pflanzenfamilien. Engelmann, Leipzig 151-167. gs V O

Daughter taxa (time control age-window is: 0-800Ma)		Granddaughter taxa
	Hymenomonas Coccoliths with serated distal margin	Hymenomonas coronata Hymenomonas globosa Hymenomonas lacuna Hymenomonas roseola Hymenomonas krejcigrafii Hymenomonas sp.
	Jomonlithus Murolith coccoliths with simple rim, partially calcified specimens show beaded ultrastructure.	Jomonlithus littoralis Jomonlithus sp.
	Ochrosphaera Coccoliths with well-developed basal flange and sometimes with distal flange	Ochrosphaera neapolitana Ochrosphaera sp.

Hymenomonadaceae

References:

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