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Yolkinigymnium elongatum
Yolkinigymnium elongatum (May, 1977) Lentin and Vozzhennikova, 1990
Originally Dinogymnium, subsequently (and now) Yolkinigymnium.
Holotype: May, 1977, pl.2, figs.11-12; Lentin and Vozzhennikova, 1990, Appendix, A, fig.42.
Age: Late Campanian-Early Maastrichtian
Type locality: Atlantic Highlands, New Jersey.
Type stratum: Mount Laurel Sands
Original description: May, 1977 (Dinogymnium elongatum):
Description: Delicate elongate test, ca. 10 times longer than wide; appears single layered. Epitract is less than 1/3 total length, is narrow, digitate, and tapers to a point. Hypotract is immediately broader than epitract across the cingulum; however, is markedly narrow also, expanding slightly posterior of the cingulum, then tapering to an acuminate antapex.
Cingulum well defined, is slightly elevated on hypotract side, and is levorotatory; offset ca. ½ cingulum width. Sulcus is short, extending a short distance onto both epitract and hypotract. Surface smooth to finely scabrate.
No archeopyle observed.
Dimensions: Observed range (2 specimens measured): length 186-300 µm, width 11-28 µm near cingulum. Cyst wall ca. 0.5 µm thick.
Affinity: Dinogymnium elongatum shares certain morphological features with some modern gymnodinium species. Feature resembling the modern G. filum Lebour 1917 are: the smooth noncostate wall; high, well-defined cingulum; sulcus extending into both epitract and hypotract (hypocone and epicone, resp. for G. filum); and tapering apex and antapex. Gymnodinium massarti (Conrad) Schiller 1926 resembles D. elongatum, having a high cingulum, smooth walls, tapering hypocone (epicone is rounded), and sulcus extending onto both hypocone and epicone.
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Lentin and Vozzhennikova, 1990:
Originally Dinogymnium, subsequently (and now) Yolkinigymnium.
Holotype: May, 1977, pl.2, figs.11-12; Lentin and Vozzhennikova, 1990, Appendix, A, fig.42.
Age: Late Campanian-Early Maastrichtian
Type locality: Atlantic Highlands, New Jersey.
Type stratum: Mount Laurel Sands
Original description: May, 1977 (Dinogymnium elongatum):
Description: Delicate elongate test, ca. 10 times longer than wide; appears single layered. Epitract is less than 1/3 total length, is narrow, digitate, and tapers to a point. Hypotract is immediately broader than epitract across the cingulum; however, is markedly narrow also, expanding slightly posterior of the cingulum, then tapering to an acuminate antapex.
Cingulum well defined, is slightly elevated on hypotract side, and is levorotatory; offset ca. ½ cingulum width. Sulcus is short, extending a short distance onto both epitract and hypotract. Surface smooth to finely scabrate.
No archeopyle observed.
Dimensions: Observed range (2 specimens measured): length 186-300 µm, width 11-28 µm near cingulum. Cyst wall ca. 0.5 µm thick.
Affinity: Dinogymnium elongatum shares certain morphological features with some modern gymnodinium species. Feature resembling the modern G. filum Lebour 1917 are: the smooth noncostate wall; high, well-defined cingulum; sulcus extending into both epitract and hypotract (hypocone and epicone, resp. for G. filum); and tapering apex and antapex. Gymnodinium massarti (Conrad) Schiller 1926 resembles D. elongatum, having a high cingulum, smooth walls, tapering hypocone (epicone is rounded), and sulcus extending onto both hypocone and epicone.
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Lentin and Vozzhennikova, 1990: