Nannotax3 - ntax_cenozoic

Nannotax3 - ntax_cenozoic - Helicosphaera Nannotax3 - ntax_cenozoic - Helicosphaera

Helicosphaera

Classification: ntax_cenozoic -> Zygodiscales -> Helicosphaeraceae -> Helicosphaera
Sister taxa: Helicosphaera

Daughter taxa (time control age-window is: 0-800Ma)		Granddaughter taxa
	H. carteri group Living and Neogene medium to large species (typically 7-11 microns) with flanges that end in distinct wings.	Helicosphaera pavimentum Helicosphaera hyalina Helicosphaera carteri Helicosphaera wallichii Helicosphaera princei Helicosphaera inversa Helicosphaera sellii Helicosphaera ethologa Helicosphaera huangii Helicosphaera mediterranea Helicosphaera minima Helicosphaera intermedia Helicosphaera rhomba Helicosphaera euphratis Helicosphaera leesiae Helicosphaera truempyi
	H. walbersdorfensis group Miocene small to medium sized Helicosphaera species with wing ending flush with flange rather than terminating abruptly. Openings usually strongly oblique. Blanket confiend to central area, in xpl flange dark around whole coccolith.	Helicosphaera stalis Helicosphaera vedderi Helicosphaera walbersdorfensis Helicosphaera waltrans Helicosphaera watkinsii
	H. ampliaperta group Early Miocene group of Helicosphaera species without a sinlge central opening, blanket confined to central area, variably developed wing.	Helicosphaera ampliaperta Helicosphaera scissura Helicosphaera magnifica Helicosphaera alata
	H. recta group Late Oligocene to Mid Miocene species; flange terminates abruptly rather than expanding into a wing; blanket largely confined to central area, so flange is dark is dark in cross-polars; bar conjunct with rim, horizontal or inversely oriented.	Helicosphaera orientalis Helicosphaera pacifica Helicosphaera obliqua Helicosphaera perch-nielseniae Helicosphaera lenticulata Helicosphaera elongata Helicosphaera theodoridisii Helicosphaera recta Helicosphaera bipuncta Helicosphaera truncata Helicosphaera inversasera Helicosphaera gertae
	H. lophota group Paleogene species; flange does not expand into a wing; bar conjunct or disjunct with rim, normally oriented.	Helicosphaera clarissima Helicosphaera compacta Helicosphaera disrupta Helicosphaera reticulata Helicosphaera robinsoniae Helicosphaera bramlettei Helicosphaera lophota Helicosphaera papillata Helicosphaera prolixa Helicosphaera seminulum Helicosphaera wilcoxonii
	Helicosphaera sp. Specimens which cannot be assigned to established species

Taxonomy:

Citation: Helicosphaera Kamptner, 1954

taxonomic rank: Genus

Type species: Coccosphaera carteri Wallich 1865

Synonyms:

Helicopontosphaera Hay & Mohler 1967 - this was an alternative name based on an interpretation that the type species of Helicosphaera, Coccosphaera carteri Wallch 1875 was not actually Helicosphaera. However, Jafar & Martini (1975) showed this interpretation was incorrect and so that Helicosphaera was the valid name.
Helicosphaerella Aubry, Liu, de Vargas, and Probert, in Aubry & Bord 2009 (= H. recta group)
Helicosphaeroides Aubry, Liu, de Vargas, and Probert, in Aubry & Bord 2009 (= H. lophota group)

Taxonomic discussion: Drawings: the drawings used in the table above are from Theodoridis (1984).
Subdivision: The large number of described species have been variously subdivided into sub-groups by different workers (e.g. Theodoridis 1984, Aubry 1990, Young 1998). The subdivision followed here is based on Young (1998) which followed previous work. The main Paleogene and Neogene groups are respectively the lophota and carteri groups. The recta group is an additional well-separated Oligo-Miocene lineage. Finally the walbersdorfensis and ampliaperta groups include some distinctive Miocene species, although the separation from the carteri group is somewhat subjective.
Alternative taxonomy: Aubry & Bord (2009) proposed an alternative taxonomy for the species conventionally included in Helicosphaera on the basis that there is "morphostructural evidence" that Helicosphaera carteri evolved from Pontosphaera in the Late Oligocene, rather than from other Helicosphaera species such as H. intermedia or H. euphratis. The nature of this morphostructural evidence is not explained, however, the proposal seems extremely unlikely to us since Helicosphaera is a distinctive and unique set of species. In particular the spiral coiling of the shield in Helicosphaera is a unique feature within the coccolithophores and is essentially identical in all species conventionally included in Helicosphaera. Moreover intermediates occur between the species H. euphratis, H. intermedia and H. carteri, indeed in the Early Miocene it is often dificult to separate these species. Hence we regard it as highly unlikely that Helicosphaera is polyphyletic and this further means that the genera Helicosphaerella, and Helicosphaeroides, are unnecessary. They could, of course, still be used - for respectively the H. recta group and the H. lophota group as recognised here. However, the proposed names are confusingly similar so using them does not seem advantageous.

Distinguishing features:
Parent taxon (Helicosphaeraceae): Varimorphic; liths placolith-like but with helical shield structure; arranged in spiral on coccosphere
This taxon: Coccoliths with helical flange; arranged spirally on the coccosphere

Farinacci & Howe catalog pages: Helicosphaera + * , Helicopontosphaera * , Helicosphaerella * , Helicosphaeroides *

Morphology:

Coccoliths with helical flange, formed of V-units. surrounding a proximal plate of regular R-units. The R-units also extend to thedistal surrface but show much les sregular shape and ar termed the "blanket". Theosdoridis 1984 gives a very detailed descrition and Young et al. (2004) a modern analysis uing observations from culture.
Various sub-groups can be recognised based on presence/absence of a disjunct bar, bar orientation, degree to which the blanket (R-units) covrs the flange (V-units), termintion of the flange, etc. (see e.g. Theodoridis 1984, Perch-Nielsen 1985b, Aubry 1990, Young 1998).
There is however also signifiant variation within all species, notably in degree of development of the wing. In modern Helicosphaera carteri this can be seen to be relsted to position on the coccosphere, with the coccoliths around the flagellar opning typiclly having especially wel-devloped wings.

Search data:

LITHS: placolith, asymmetric,
CSPH: elongated, monomorphic, CROSS-POLARS: V-prominent, R-prominent, rim-bicyclic,

Lith size: 4->22µm;

The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): Extant. Data source: Total of ranges of the species in this database
First occurrence (base): within NP12 zone (50.50-53.70Ma, base in Ypresian stage). Data source: Total of ranges of species in this database

Plot of occurrence data:

Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Neptune data: This is a higher taxon page so Neptune data is not plotted. See also: customisable plot Parent: Helicosphaeraceae

References:

Aubry, M. -P. & Bord, D. (2009). Reshuffling the cards in the photic zone at the Eocene/Oligocene boundary. In, Koeberl, C. & Montanari, A. (eds) The Late Eocene Earth—Hothouse, Icehouse, and Impacts. Geological Society of America, Special Papers . 452: 279-301. gs

Aubry, M. -P. (1990). Handbook of Cenozoic calcareous nannoplankton. Book 4: Heliolithae (Helicoliths, Cribriliths, Lopadoliths and others). Micropaleontology Press, American Museum of Natural History, New York. 1-381. gs

Jafar, S. A. & Martini, E. (1975). On the validity of the calcareous nannoplankton genus Helicosphaera. Senckenbergiana Lethaea. 56: 381-397. gs

Kamptner, E. (1954). Untersuchungen über den Feinbau der Coccolithen. Archiv für Protistenkunde. 100: 1-90. gs

Perch-Nielsen, K. (1985). Cenozoic calcareous nannofossils. In, Bolli, H. M., Saunders, J. B. & Perch-Nielsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge (1): 427-555. 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. (1998). Neogene. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 225-265. gs

Young, J. R., Henriksen, K. & Probert, I. (2004b). Structure and morphogenesis of the coccoliths of the CODENET species. In, Thierstein, H. R. & Young, J. R. (eds) Coccolithophores - From molecular processes to global impact. Springer, Berlin 191-216. gs O