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Protoellipsodinium clavulus

Protoellipsodinium clavulum Davey and Verdier, 1974, p.637–638, pl.93, fig.7. Emendation: Duxbury, 1983, p.53.

Taxonomic junior synonym: Operculodinium? (as Protoellipsodinium) spinigerum, according to Duxbury (1983, p.53).

Holotype: Davey and Verdier, 1974, pl.93, fig.7
Locus typicus: Gargas, SE France
Stratum typicum: Late Aptian (Gargasian)

Original description: Davey and Verdier, 1974, p. 637
Diagnosis: The cyst is elongate to ovoidal with a smooth wall. The cingulum usually lacks processes, and the hypotract is larger than epitract. The processes are fairly numerous and less than half the cyst width in length. They are typically hollow with a restricted lumen, and distally are capitate or rarely bear two or three small spines. The archaeopyle is precingular, formed by the loss of a single plate.

Description: The cyst is thin-walled and often distorted, hence making orientation and archaeopyle identification difficult. The shape and structure of the processes are, however, very characteristic. Each process has a relatively broad base (2-3 microns wide), narrows rapidly above this, and for the more distal part of its length tapers only slightly and is more or less parallel sided (width approx. 1 micron). The processes expand at their distal extremities and are basically capitate; this expansion is usually slight (approx. 1 micron in width) but occasionally is wider and gives rise to two or three recurved spines (up to 2,5 microns long). The processes are rigid to slightly flexuous.

Emended diagnosis: Duxbury, 1983, p. 53
An elongate ovoidal to ellipsoidal, smooth-walled cyst bearing fairly numerous slender processes which may be absent around the equator. The processes are less than half the cyst width in length and may be solid or hollow with a restricted lumen. Distally the processes may be capitate, bifurcate, trifurcate or multifurcate. The archaeopyle is single paraplate precingular.

Affinities:
Davey and Verdier, 1974, p. 637-638
The distal extremities of the processes distinguish P. clavulum from the two other species in this genus (at that time: P.spinocristatum and P.spinosum). The form of the processes is very similar to that found in Cleistosphaeridium huguoniotii (Valensi, 1955) var. pertusum Davey 1969 from the Upper Cenomanian of southern England and northern France. That species, however, is spherical to subspherical in shape and has an apical archaeopyle.
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