Nannotax3 - ntax_cenozoic - narrow rimmed placoliths

Citation: narrow rimmed placoliths - informal Young et al., 2003

Taxonomic discussion: This grouping is discussed in detail in Young & Andruleit (2006).

Distinguishing features:
Parent taxon (Coccolith families inc sed): 2N: Various heterococcolith groups not obviously related to the well-defined orders
N: mostly unknown
This taxon: Diverse group of coccoliths with narow placolith rims and variable central structures, usually showing four-fold symmetry.

Farinacci & Howe catalog pages: narrow rimmed placoliths [no catalog entry yet]

Rims in these genera appear to reformed of a single cycle of non-imbricate elements with radial sutures. Central area structures are highly variable but disjunct and usually with four-fold symmetry

Coccoliths very small 0.5-2.5 mm) except in Tetralithoides (4-7.5 µm)

Calyptrosphaera sphaeroidea has both holococcolith and heterococcolith phases and has been cultured (Noël et al. 2004), the other taxa are so far only known from the heterococcolith phase and have not been cultured.

Calyptrosphaera sphaeroidea falls within the Coccolithales clade in molecular genetic analyses (Fujiwara et al., 2001; Saez et al., 2004, Young et al. 2014 Cryptogamie)

Geological Range:
Notes: Only Tetralithoides has a documented fossil record, extending back to the Early Miocene (Theodoridis, 1984; Young, 1998).
Last occurrence (top): Extant. Data source: Total of ranges of the species in this database
First occurrence (base): within NP9 zone (55.86-57.21Ma, base in Thanetian stage). Data source: Total of ranges of species in this database

References:

Fujiwara, S., Tsuzuki, M., Kawachi, M., Minaka, N. & Inouye, I. (2001). Molecular phylogeny of the haptophyta based on the rbcL gene and sequence variation in the spacer region of the RUBISCO operon. Journal of Phycology. 37: 121-129. gs

Noël, M. -H., Kawachi, M. & Inouye, I. (2004). Induced dimorphic life cycle of a coccolithophorid, Calyptrosphaera sphaeroidea. Journal of Phycology. 40(1): 112-129. gs

Sáez, A. G., Probert, I., Young, J. R., Edvardsen, B., Wenche, E. & Medlin, L. K. (2004). A review of the phylogeny of the Haptophyta. In, Thierstein, H. R. & Young, J. R. (eds) Coccolithophores - from molecular processes to global impact. Springer, Berlin 251-270. gs

Theodoridis, S. (1984). Calcareous nannofossil biostratigraphy of the Miocene and revision of the helicoliths and discoasters. Utrecht Micropaleontological Bulletin. 32: 1-271. gs O

Young, J. R. & Andruleit, H. (2006). Navilithus altivelum: a remarkable new genus and species of deep photic coccolithophores. Journal of Micropalaeontology. 25(2): 141-152. gs

Young, J. R. (1998). Neogene. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 225-265. 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. gs

Young, J. R., Liu, H., Probert, I., Aris-Brosou, S. & de Vargas, C. (2014). Morphospecies versus phylospecies concepts for evaluating phytoplankton diversity: The Case of the Coccolithophores. Cryptogamie Algologie. 35(4): 353-377. gs

Daughter taxa (time control age-window is: 0-800Ma)		Granddaughter taxa
	Calyptrosphaera sphaeroidea HET Coccoliths elliptical narrow-rimmed placoliths with plate formed from numerous small elements in central area
	Navilithus Coccoliths narrow-rimmed placoliths with robust central spine; CFCs with tall, sail-like, spines	Navilithus altivelum Navilithus sp.
	Placorhombus Coccoliths rhombic narrow-rimmed placoliths with four plates in central area	Placorhombus ziveriae Placorhombus sp. cf. ziveriae Placorhombus sp.
	Tetralithoides Coccoliths elliptical narrow-rimmed placoliths with four plates in central area	Tetralithoides quadrilaminata Tetralithoides symeonidesii Tetralithoides sp.
	Turrilithus Coccoliths elliptical narrow-rimmed placoliths with quadrate tower-like central structure	Turrilithus latericioides Turrilithus sp.

narrow rimmed placoliths

References:

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