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Scriniodinium bucinatum

Scriniodinium bucinatum Brenner, 1988

Holotype: Brenner, 1988, pl.12, fig.1
Age: Early Kimmeridgian
Translation Brenner 1988: LPP
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Brenner 1988, p. 72-73, Pl.12, fig.1-2: Scriniodinium bucinatum n. sp.
Holotype: Brenner 1988, PL.12, fig.1, prep. N7 III
Stratum typicum: Upper Jurassic, lowe Malm gamma, platynota Zone (lower Kimmeridgian)
Locus typicus: Hoernlebruch near Neuffen, Germany
Occurrence: rare in Malm beta, rare to abundant in Malm gamma.

Diagnosis: Cavate dinoflagellate cyst with gonyaulacoid paraatabulation, precingular archaeopyle and ovoidal appearance. The apical horn is formed by the periphragm only. The periphragm surface has indentations which merge into tubular connections to the endophragm (siphons). Apart from the siphons, short ledges or pillars may be present, which in single cases also may build a partial reticulum.
Dimensions of the holotype: length 115 µm, width 90 µm, endocyst length 84 µm, width 64 µm.

Description: Cavate dinoflagellate cyst with precingular archaeopyle. Total cyst dimensions: length 100-120 µm, width 80-100 µm, endocyst length 60-80 µm, width 50-70 µm. The cyst has a polygonal outline and a clearly developed horn (length 10-20 µm). Endocyst ovoidal. The generally dorsoventral positioning of the cysts in the preparation points to a similar flattening.

The periphragm surface has indentations which merge into tubular connections or siphons ("funnelform structures" of Evitt 1985: 214, 218) to the endophragm. They mainly occur on the hypocyst. These siphons form a link between endocyst and the medium surrounding the cyst. They are possibly comparable to openings in the periphragm in other cavate cysts, or have a similar task (cf. Norris 1975, Evitt 1985, Gocht 1987).

Between endo- and periphragm additional massive pillars and ledges may be present which, if clustering, may form a partial reticulum.

Comparison: Scriniodinium bucinatum n. sp. differs from the other Scirniodinium species in the presence of tubular connections (siphons) between peri- and endophragm.
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