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Dracodinium brevicornutum
Dracodinium brevicornutum (Heilmann-Clausen in Heilmann-Clausen and Costa, 1989, p.472, pl.6, figs.1,6) Williams et al., 2015, p.304.
Originally Wetzeliella articulata subsp. brevicornuta, subsequently (and now) Dracodinium? brevicornutum. Questionable assignment: Williams et al. (2015, p.304).
Holotype: Heilmann-Clausen and Costa, 1989, pl.6, fig.1.
Age: late Ypresian.
Original description: Heilmann-Clausen in Heilmann-Clausen and Costa 1989, p. 742
This is a large and flat subspecies of W. articulata with a very low antapical horn. The lateral horns are long. The hypocyst is much longer than the epicyst The endophragm and periphragm are clearly, and often widely, separated at the ambitus.
Dimensions of holotype: Pericystlength: 139 µm, Pericystwidth: 152 µm, Endocyst length: 92 µm, Endocyst width: 84 µm.
Remarks: W. articulata ssp. brevicornuta is an extreme form in a morphological lineage, which can be traced from typical W. articulata, occurring in the Ypresian.
Intermediate forms from the Lutetian are figured in De Coninck, 1977, pl. 2, figs. 17, 18. As remarked by De Coninck, 1977, these forms differ from typical W. articulata by a relatively short epicyst and a long hypocyst. In the present study only forms with extreme reduction of the apical horn have been classified with the new subspecies.
Originally Wetzeliella articulata subsp. brevicornuta, subsequently (and now) Dracodinium? brevicornutum. Questionable assignment: Williams et al. (2015, p.304).
Holotype: Heilmann-Clausen and Costa, 1989, pl.6, fig.1.
Age: late Ypresian.
Original description: Heilmann-Clausen in Heilmann-Clausen and Costa 1989, p. 742
This is a large and flat subspecies of W. articulata with a very low antapical horn. The lateral horns are long. The hypocyst is much longer than the epicyst The endophragm and periphragm are clearly, and often widely, separated at the ambitus.
Dimensions of holotype: Pericystlength: 139 µm, Pericystwidth: 152 µm, Endocyst length: 92 µm, Endocyst width: 84 µm.
Remarks: W. articulata ssp. brevicornuta is an extreme form in a morphological lineage, which can be traced from typical W. articulata, occurring in the Ypresian.
Intermediate forms from the Lutetian are figured in De Coninck, 1977, pl. 2, figs. 17, 18. As remarked by De Coninck, 1977, these forms differ from typical W. articulata by a relatively short epicyst and a long hypocyst. In the present study only forms with extreme reduction of the apical horn have been classified with the new subspecies.