Syracosphaera

Cenozoic Taxa

Syracosphaera tanzanensis Bown, 2005

Edited by Lyndsey on Fri, 11/03/2011 - 17:36

Syracosphaera tanzanensis Bown, 2005

Description: Medium sized muroliths with narrow bicyclic rim (bright inner cycle, dark outer cycle) and wide central area.

Remarks: Typical Syracosphaera structure seen in SEM, and large enough to be conspicuous in LM. May be similar to Syracosphaera lamina of de Kaenel & Villa, 1996, which is, however, a homonym of the extant Syracosphaera lamina Lecal-Schlauder, 1951.

Geological Time Data

Geological Time Periods:

NP23

NP16

Biblio Reference:

Varol, O. 1998. Palaeogene. Calcareous nannofossil biostratigraphy. :200-224.

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55 reads
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Neogene: Syracosphaera; Syracosphaera lamina
Paleogene: Syracosphaera lamina; Syracosphaera tanzanensis

Syracosphaera pulchra HOL pirus type

Edited by Lyndsey on Thu, 10/03/2011 - 14:00

Syracosphaera pulchra Lohmann 1902 HOL pirus type

Description: Coccolith structure - dome-shaped, formed of layer of crystallites in hexagonal array with the crystallographic c-axis perpendicular to the surface. In LM the rim is bright and central part dark.

Coccospheres weakly dimorphic, piriform.

Coccolith form - tube about 10 crystallites high, tiered wall fabric; basal flange;
distal cover recessed into tube, domal with ring of 8-10 pores around
contact with tube; internal ridges surround pores in at least some
specimens. Circum-flagellar coccoliths more elevated and with pyramidal central boss.

Remarks:

Original description:

Size: Liths 2-3 µm long.

Life-cycle association: The association of these holococcoliths with Syracosphaera pulchra has been demonstrated by observation of numerous combination coccospheres, Cros et al. (2000), Geisen et al. (2002). Saugestad & Heimdal (2002). oblonga-type holococcoliths also occur in assocaition with S. pulchra and this is interpreted as a result of pseudo-cryptic specieation (Geisen et al. 2002).

Synonyms:

Calyptrosphaera pirus Kamptner 1937
Daktylethra pirus (Kamptner 1937) Norris 1985

Geological Time Data

Notes on occurrence information:

Can be common in well-preserved Quaternary sediments (Crudeli et al. 2006).

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1096 reads
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Neogene: Syracosphaera; Syracosphaera pulchra; Syracosphaera pulchra HOL pirus type; Holococcoliths

Syracosphaera pulchra HOL oblonga type

Edited by Lyndsey on Thu, 10/03/2011 - 13:58

Syracosphaera pulchra Lohmann 1902 HOL oblonga type

Description: Coccolith structure - dome-shaped, formed of layer of crystallites in hexagonal array with the crystalographic c-axis perpendicular to the surface. In LM the rim is bright and cenral part dark.

Coccospheres weakly dimorphic, piriform.

Coccolith form - the coccoliths have simple dome-shaped, with wall showing heaxoganla mesh fabric. Circum-flagellar coccoliths more elevated and with pyramidal central boss.

Remarks:

Original description:

Size: Liths 2-3 µm long.

Life-cycle association: The association of these holococcoliths with Syracosphaera pulchra has been demonstrated by observation of numerous combination coccospheres, Cros et al. (2000), Geisen et al. (2002). Pirus-type holococcoliths also occur in assocaition with S. pulchra and this has been interpreted as result of pseudo-cryptic speciation (Geisen et al. 2002).

Fossil record: Can be common in well-preserved Quaternary sediments (Crudeli et al. 2006).

Synonym: Calyptrosphaera oblonga Lohmann 1902

1253 reads
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Neogene: Syracosphaera; Syracosphaera pulchra; Syracosphaera pulchra HOL oblonga type; Holococcoliths

Coronosphaera

Edited by Lyndsey on Tue, 01/03/2011 - 14:50

Coronosphaera Gaarder in Gaarder & Heimdal 1977

Description: Coccospheres - Monothecate, dimorphic, motile. Body coccoliths flangeless muroliths; rims formed of an outer cycle of strongly imbricate (anticlockwise) elements and an inner cycle of vertical elements. Central area with two radial laths per rim element and central plaque formed of two plates. Circum Flagellar Coccoliths similar but slightly smaller, with low spine.

Remarks: Coronosphaera is usually placed in the family Syracosphaeraceae, but has also been considered a genus incertae sedis within the order Syracosphaerales. It is distinguished from Syracosphaera by

the strong imbrication of the rim elements
the occurrence of two laths per rim
Absence of flanges
Absence of exothecal coccoliths

References: Gaarder & Heimdal (1977) - morphology; Geisen et al. (2002) - holococcolith associations; Houdan et al. (2004) - culture observations.

Type species: C. mediterranea.

LM: Isolated body coccoliths typically show a narrow rim with high birefringence and strongly curved isogyres. The central area is weakly birefringent and shows tangential orientation (so blue and yellow sectors show the opposite to normal disposition) and two central elements.

Original description:

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760 reads
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Neogene: Syracosphaerales; Coronosphaera; Syracosphaera; Syracosphaeraceae; Incertae sedis
Paleogene: Coronosphaera

Syracosphaera lamina de Kaenel & Villa, 1996

Submitted by Jeremy Young on Fri, 06/02/2009 - 12:13

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64 reads
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Neogene: Syracosphaera; Syracosphaera lamina
Paleogene: Syracosphaera lamina

Syracosphaera lamina

Edited by Lyndsey on Fri, 11/03/2011 - 17:38

Syracosphaera lamina Lecal-Schlauder 1951

Extant coccolithophores: rarish, deep-photic species.; coccosphere dimorphic with murolith body coccoliths (BCs) and flat disk-like exothecal coccoliths (XCs)

Description: BCs - long elliptical (3-4 µm); wall flaring with corrugated top. Central area flat bottomed, laths show sharp edges in proximal view. Axial structure is an elevated longitudinal ridge, on proximal side this is formed from a couple of elongate laths. CFCs - without spines / not differentiated.

XCs - (sub-)circular (ca. 3.5 µm), flat, broad rim, narrow radial cycle, quadrate central plate formed of two elements; delicate and rarely seen.

Remarks:

Original description:

Comment and discussion:

Geological Time Data

Notes on occurrence information:

Sporadic fossil records, mainly in Pliocene and Pleistocene. The BCs are relatively large and the axial ridge is birefringent in xpl making this an easy to species to recognise in LM.

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487 reads
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Neogene: Syracosphaera; Syracosphaera lamina
Paleogene: Syracosphaera lamina

Reticulofenestra bisecta

Edited by Jeremy Young on Wed, 09/03/2011 - 17:04

Reticulofenestra bisecta (Hay, Mohler and Wade, 1966) Roth, 1970 [Syracosphaera]

Description: Coccoliths medium to large size (ca 8-12µm), with central-area closed by plates on distal surface of coccolith.

Remarks:

Original description:

Synonyms: Dictyococcites bisectus (Hay, Mohler and Wade, 1966) Bukry and Percival, 1971 - alternative combination; R. scissura Hay, Mohler and Wade, 1966 - see Gartner (1971) for discussion.

Variants: R. stavensis (Levin and Joerger, 1967) Varol, 1989, Dictyococcites scrippsae Bukry and Percival, 1971. N.B. Two different taxonomic subdivisions are in use (1) Specimens <10μm = D. scrippsae, >10μm = D. bisectus; (2) Specimens <10μm = R. bisecta, >10μm R. stavensis.

Geological Time Data

Geological Time Periods:

NN1

Eocene

Biblio Reference:

Young, JR. 1998. Neogene. Calcareous nannofossil biostratigraphy. :225-265.

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1051 reads
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Neogene: Reticulofenestra; Reticulofenestra bisecta; Syracosphaera
Paleogene: Reticulofenestra bisecta

Algirosphaera robusta

Edited by Lyndsey on Tue, 01/03/2011 - 16:58

Algirosphaera robusta (Lohmann 1902) Norris 1984 [Syracosphaera]

Coccosphere: Motile, dimorphic. Prominent flagellar opening surrounded by 3 CFCs with higher and wider protrusion.

Coccoliths: Base and protrusion elongate elliptical; protrusion has double-lipped form, especially in LM. Cycle of irregular laths covers proximal face of central area.

Original description:

Holococcolith phase: Combination coccospheres with Sphaerocalyptra quadridentata have been illustrated by Kamptner (1941) and Triantaphyllou & Dimiza (2003).

Synonyms:

Algirosphaera oryza Schlauder 1945;
Algirosphaera quadricornu (Schiller 1914) Norris 1984 [Syracosphaera];
Algirosphaera aurea (Bernard & Lecal 1960) [Anthosphaera];
Anthosphaera bicornu Schlauder 1945;

There are also others, see Kleijne (1992). Subdivisions on nature of circum-flagellar coccoliths, coccosphere shape, and shape of body coccoliths have been suggested but do not seem meaningful (Kleijne 1992, Probert et al., 2007).

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484 reads
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Neogene: Algirosphaera; Algirosphaera robusta; Syracosphaera
Paleogene: Algirosphaera

Syracosphaera pulchra

Edited by Lyndsey on Tue, 01/03/2011 - 14:53

Syracosphaera pulchra Lohmann 1902

Extant coccolithophore: A common species, with weak preference for oligotrophic areas (Ziveri et al. 2004); coccosphere large, trimorphic with body coccoliths (BCs), spine-bearing circum-flagellar coccoliths (CFCs), and exothecal coccoliths (XCs).
Coccospheres 15-25 µm

Coccolith types:

	Body coccoliths (BCs) - large (4.5-8 µm); mid-wall flange prominent; inner wall-cycle well developed; central area with three concentric cycles of thin radial laths, occasionally incipient spine in centre
	Circum flagellar coccoliths (CFCs) - similar to BCs but with robust bifurcate-tipped spine
	Exothecal coccoliths (XCs) - dome-shaped, rim sub-horizontal, flange-like. Radial cycle formsvertical part of wall, numerous elements with wide slits. Central part formed of several cycles of laths; with a central conical depression.

Life-cycle: There is a well-estabished alternate holococcolith-bearing phase. Holococcoliths previously refered to as = Calyptrosphaera oblonga and Calyptrosphaera pirus, see Cros et al. (2000), Geisen et al. (2002), Saugestad & Heimdal (2002). Since the oblonga-type and pirus-type holococcoliths are well differentiated we suspect that S. pulchra consists of two species which are only differentiable in the holococcolithophore life-cycle stage (Geisen et al. 2002, 2004).

Remarks:

Original description:

Fossil record: BCs commonly recorded from Pliocene and Pleistocene sediments, reasonably reliable default identification for large (>5µm) Syracosphaera coccoliths.

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1014 reads
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Neogene: Syracosphaera; Syracosphaera pulchra; Holococcoliths

Syracosphaera

Edited by Lyndsey on Tue, 01/03/2011 - 14:51

Syracosphaera Lohmann 1902

Description: Coccospheres usually dithecate, Exothecal coccoliths (XCs) highly variable. Endothecal coccoliths are muroliths with 1, 2 or 3 flanges, (the forms with 2 flanges are often placolith-like), these are often differentiated into body coccoliths (BCs), circum-flagellar coccoliths (CFCs) and antapical coccoliths (AACs).


S. pulchra	S. anthos	S. lamina	S. molischii	S. ossa	S. borealis

Fossil record: About 60 modern species of Syracosphaera are known (Young et al. 2003) and their coccolith morphology is well established (see examples above). Most Pleistocene specimens of Syracosphaera can be asigned to modern taxa, e.g. S. pulchra and S. lamina. However, in older sediments the occasional Syracosphaera specimens often appear to belong to different species. A few examples are shown below.

LM: Isolated body coccoliths typically show a narrow rim with moderate birefringence and strongly curved isogyres. The central area is weakly birefringent and shows tangential orientation (so blue and yellow sectors show the opposite to normal disposition). Outline is usually ratherirregularly elliptical.

Type species: S. pulchra.

Exothecal coccolith structure: As argued by Inouye & Pienaar
(1988), Cros (2000) and Young et al. (2004), exothecal coccoliths appear to be modified versions of the endothecal coccoliths, and are composed of the same set of components - rim, radial lath cycle and axial structure. However, the morphology of the coccoliths is highly variable and often radically different to that of the body coccoliths.

Synonyms: Caneosphaera Gaarder in Gaarder & Heimdal 1977; Deutschlandia Lohmann 1912; Gaarderia Kleijne 1993. NB Caneosphaera and Deutschlandia are usually considered synonyms of Syracosphaera following Jordan & Young (1990). Gaarderia was recombined in Syracosphaera by Young et al. (2003) on the grounds that it showed too few unique features to be regarded as a separate genus.

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1591 reads
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Neogene: Syracosphaera

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