Lithraphidites


Classification: Mesozoic -> Nannoliths inc sedis -> Microrhabdulaceae -> Lithraphidites
Sister taxa: Lithraphidites, Microrhabdulus, Pseudomicula,

Distinguishing features: Bladed, rod-shaped nannoliths that typically taper towards both ends and with a cruciform cross-section and variably developed lateral projections; the rod is formed from long crystal units which appear to run the length of the lith.


Daughter taxa: (blue => in age window 0-300Ma) Granddaughter taxa

Lithraphidites with four narrow, triangular processes projecting outwards from the rod



Lithraphidites with blades that taper gradually from their broadest point near one end. The overall shape is like a closed umbrella. 



Rod-shaped nannolith with parallel sides and a relatively wide axial canal. The outer surfaces are irregular. 



Simple, long, slender Lithraphidites that tapers towards both ends. Well preserved specimens may have a minute basal coccolith, hese hve sometimes been identified as R. aqutanicus but the spineare identical to thoe of L. carniolensis without the basal coccolith.



Robust ?Lithraphidites species- consists of two slightly twisted interlocking blades with two attached wings. Two blades are slightly offset from one another and taper to a blunt point at their extremity

Lithraphidites with long, serrated blades.



Lithraphidites species with a finely serrated blade. The blade may be quite broad but is generally broken to a more slender shape

Lithraphidites with short, broad projections that have a single curved indentation and spikes at each end. The projections are one third or less then the total length.

Lithraphidites with broad scalloped blades that terminate abruptly near the ends of the lith.

Lithraphidites with moderately broad blades that taper sharply near each end. Each blade is similar in width to the central rod.



Lithraphidites with broad blades that taper sharply near each end. Each blade is broader than the central rod.

Specimens not identified to species level

Taxonomy:

Citation: Lithraphidites Deflandre, 1963
Rank: Genus
Type species: Lithraphidites carniolensis Deflandre, 1963.
Synonyms:

Rhabdophidites Manivit (1971) emend. Lambert (1987) - the type of Rhabdophidites is R. moeslensis which is Lithraphidities carniolensis with a basal coccolith preserved.

Notes & discussion: Inclusion of Lithraphidites in the Microrhabdulaceae is solely based on gross morhology not ultrastructure. This and the fact that basal cocolithsoften occur suggests it should be reclassified as a heterococclith, probably in the Chiastozygaceae, if the Rhabdophidites species are related.  [my interpretation - JRY 2015]

Farinacci & Howe catalog pages: Lithraphidites *   [no catalog entry yet]

Distinguishing features: Bladed, rod-shaped nannoliths that typically taper towards both ends and with a cruciform cross-section and variably developed lateral projections; the rod is formed from long crystal units which appear to run the length of the lith.


Morphology remarks: When preservation is good these rods may be observed with minute basal murolith coccoliths and so we assume that, in general, they represent disarticulated spines. A very similar morphology is seen in Rhabdophidites where the coccolith is more strongly attached to the spines.The nannolith genus Lithraphidites has previously been included in the family Microrhabdulaceae Deflandre, 1963 (Perch-Nielsen, 1985; Bown and Young, 1997), however Microrhabdulus ultrastructure is significantly different to Lithraphidites and their appears to be no phylogenetic relationship between the two groups. Microrhabdulus liths have round cross sections and are formed from numerous small laths, forming crystallographically-continuous blocks, which appear as a checkerboard pattern of alternating extinct and birefringent blocks in XPL. Lithraphidites liths are formed from larger crystal units, which appear to run the length of the rod.

Janin (1998) pesents interesting observations on Lithraphidites structure, and suggest that hey re typically bilamellar. We do not, howver, find her suggestion of affinities with Actinozoa compelling.

Evolution & Phylogeny: The basal coccoliths resemble those of Staurolithites, as shown by Lambert (1993). Hence the genus probably should be placed in the Chiastozygaceae.

See also: Rhabdophidites - possibly a synonym.;

Geological Range:
Last occurrence (top): within Maastrichtian Stage (66.04-72.05Ma, top in Maastrichtian stage). Data source: Total of range of species in this database
First occurrence (base): within Berriasian Stage (139.39-145.01Ma, base in Berriasian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Bown, P.R. & Young, J.R., (1997). Mesozoic calcareous nannoplankton classification. Journal of Nannoplankton Research, 19(1): 21-36.

Bown, P.R.; Rutledge, D.C.; Crux, J.A. & Gallagher, L.T., (1998). Early Cretaceous. In: Bown, P.R. (Editor), Calcareous nannofossil biostratigraphy. British Micropalaeontological Society Publication Series. Chapman & Hall, pp. 86-131.

Burnett, J.A., (1998). Upper Cretaceous. In: Bown, P.R. (Editor), Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publications Series. Chapman & Hall, London, pp. 132-199.

Deflandre, G., (1963). Sur les Microrhabdulidés, famille nouvelle de nannofossiles calcaires. Comptes Rendus (Hebdomadaires des Séances) de l'Académie des Sciences Paris, 256: 3484-3487.

Janin, M.-C., (1998). Remarques sur l'ultrastructure et les affinities biologiques des Lithraphidites, nannofossiles calcaires du Crétacé. Revue de Micropaleontologie, 41(4): 281-296.

Lambert, B., (1987). Nannofossiles calcaires de l'Albien supérieur et du Vraconnien du Cameroun méridional. Cahiers de Micropaleontologie, 2(2): 33-60.

Lambert, B., (1993). Nannofossiles calcaires de l'Albien supérieur et du Vraconnien du Cameroun méridional (Deuxième Partie). Cahiers de Micropaleontologie, 8(2): 183-225.

Perch-Nielsen, K., (1985). Mesozoic calcareous nannofossils. In: Bolli, H.M., Saunders, J.B. and Perch-Nielsen, K. (Editors), Plankton Stratigraphy. Cambridge University Press, Cambridge, pp. 329-426.


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Lithraphidites compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 19-11-2018

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