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Bitectatodinium serratum
Bitectatodinium serratum, (Head et al., 1989), Lentin and Williams, 1993
Originally Gongylodinium, subsequently (and now) Bitectatodinium?.
The new combination Bitectatodinium? serratum is necessitated by the treatment of Gongylodinium Fenton et al., 1980, as a taxonomic junior synonym of Dissiliodinium Drugg, 1978, in Lentin and Williams, 1993; however, the morphology of this species seems to accord more with Bitectatodinium than Dissiliodinium. Lentin and Williams, 1993, questionably included this species in Bitectatodinium because of its simpler, nontectate wall structure.
Holotype: Head et al., 1989, pl.3, fig.14-16
Locus typicus: ODP leg 105, site 646, Labrador Sea
Stratum typicum: Late Miocene
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Original description as Gongylodinium serratum: [Head et al., 1989, p. 457]:
Diagnosis:
Cyst proximate, autophragmal, and spherical. Surface nearly smooth or faintly granulate to faintly granulorugulose.
Archeopyle precingular Type 2P, operculum free, probably compound. Principal archeopyle suture, angular and with finely serrated margins. There is no other expression of paratabulation.
Description:
Uncompressed cysts are spherical but may be folded into a broadly elliptical outline. The principal archeopyle suture is angular and has distinctively serrated archeopyle margins. The adapical margin of the archeopyle may be irregular, particularly in thinner walled (i.e., 0.5 µm or less) specimens. Accessory sutures were not identified with certainty. The operculum is free and compound (indicated by separated opercular pieces, observed within two cysts). Observed opercular pieces have serrated margins. We were unable to determine specific precingular paraplates involved in archeopyle formation because of the somewhat irregular adapical archeopyle margin.
Dimensions:
Holotype: maximum diameter, 40 µm.
Range in maximum diameter, 34(42.5)49 µm (based on relatively uncompressed cysts). Wall thickness, up to 1.2 µm. Thirteen specimens were measured.
Affinities:
The serrated archeopyle margin of this species distinguished it from all other species of Gongylodinium.
Originally Gongylodinium, subsequently (and now) Bitectatodinium?.
The new combination Bitectatodinium? serratum is necessitated by the treatment of Gongylodinium Fenton et al., 1980, as a taxonomic junior synonym of Dissiliodinium Drugg, 1978, in Lentin and Williams, 1993; however, the morphology of this species seems to accord more with Bitectatodinium than Dissiliodinium. Lentin and Williams, 1993, questionably included this species in Bitectatodinium because of its simpler, nontectate wall structure.
Holotype: Head et al., 1989, pl.3, fig.14-16
Locus typicus: ODP leg 105, site 646, Labrador Sea
Stratum typicum: Late Miocene
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Original description as Gongylodinium serratum: [Head et al., 1989, p. 457]:
Diagnosis:
Cyst proximate, autophragmal, and spherical. Surface nearly smooth or faintly granulate to faintly granulorugulose.
Archeopyle precingular Type 2P, operculum free, probably compound. Principal archeopyle suture, angular and with finely serrated margins. There is no other expression of paratabulation.
Description:
Uncompressed cysts are spherical but may be folded into a broadly elliptical outline. The principal archeopyle suture is angular and has distinctively serrated archeopyle margins. The adapical margin of the archeopyle may be irregular, particularly in thinner walled (i.e., 0.5 µm or less) specimens. Accessory sutures were not identified with certainty. The operculum is free and compound (indicated by separated opercular pieces, observed within two cysts). Observed opercular pieces have serrated margins. We were unable to determine specific precingular paraplates involved in archeopyle formation because of the somewhat irregular adapical archeopyle margin.
Dimensions:
Holotype: maximum diameter, 40 µm.
Range in maximum diameter, 34(42.5)49 µm (based on relatively uncompressed cysts). Wall thickness, up to 1.2 µm. Thirteen specimens were measured.
Affinities:
The serrated archeopyle margin of this species distinguished it from all other species of Gongylodinium.