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Ctenidodinium schizoblatum
Cteniodinium? schizoblatum (Norris, 1965) Lentin and Williams, 1973
Originally Leptodinium, subsequently Dichadogonyaulax, thirdly Ctenidodinium, fourthly (and now) Ctenidodinium?.
Sarjeant, 1975, retained this species in Dichadogonyaulax Sarjeant, 1966.
Stover and Evitt, 1978, agreed with Lentin and Williams, 1973, but Woollam, 1983, emended Dichadogonyaulax and retained Dichadogonyaulax schizoblata in that genus.
Benson, 1985, questionably retained this species in Ctenidodinium.
Courtinat, 1989, retained the species in Dichadogonyaulax.
Lentin and Williams, 1989, agreed with Benson, 1985.
Holotype: Norris, 1965, figs.5, 15-17
Locus typicus: Durlston Bay, Southern England
Stratum typicum: Portlandian
Original diagnosis: Norris, 1965, p.798: Leptodinium schizoblatum
Midbody globular, usually oblate. Both epitheca and hypotheca rounded. Epitheca with a small solid projection at the apex. Division into fields distinct: 5", 6"", 5 or 6g, 5""", 1p, 1"""", 1av. 5iv, 1pv. Fields bordered by distinct. occasionally slightly sinuous, solid muri about 1 Ám, wide and 1.5 Ám high, up to 2 Ám high bordering girdle. Girdle distinctly spiralled, ends separated antero-posteriorly one to one and a half girdle widths and laterally by about one-fifth of the equatorial diameter. Shell surface irregularly punctate: muri folded perpendicularly to the shell surface, serrated and split. Shell of organic material. 0.25 Ám or less in thickness. Epithecal archeopyle developed.
Original description: Norris, 1965, p. 798-799: Leptodinium schizoblatum
Field 1" is long and narrow and a direct continuation of the ventral area. 3" is very small. The remaining apical fields are more or less square or oblong. A small, solid, truncated horn, 3 or 4 Á high and 3 or 4 Á wide is developed at the junction of 1", 2", and 5". Precingular fields large, approximately equal in size, equidimensional or elongated transversely. Postcingular fields roughly equidimensional or elongated transversely: 1""" smaller than 2-5""". Antapical field square or rhomboidal, Iarge, about half the maximum midbody diameter in width.
Girdle floor level with shell surface, flat, bordered by muri which are slightly higher than the remaining field borders. Ventral area not noticeably, or only very slightly, depressed. Anterior ventral field (lav) extends forward from the posterior border or middle of the anterior end of the girdle. lntermediate ventral fields (1-5iv) distinct or not, consisting of a transverse row of three smaller fields underlain by two larger fields. Posterior ventral field (1pv) large but rather variable. Posterior intcrcalary field (1p) adjacent to posterior ventral field and situated between 1""" and 2""".
Archeopyle margin clean-cut, running immediately anterior to, or up to 2 Ám from, the anterior girdle border, or even variably on the same specimen.
Operculum integral, probably attached. consisting of 11 fields (1"-5" and 1"-6"). On approaching the anterior edge of the girdle, the precingular field borders usually deteriorate in height and thickness (from 1 Ám, wide to 0.25 Ám, or less, or even disappear completely) and also become deeply, and widely serrated, degenerating to isolated granules. The operculum frequently hinges on the ventral area, but may be completely detached. In the latter case, rupture is usually completed by skirting round the anterior end of the ventral area beneath 1"; alternatively it may pass across the ventral area in an irregular line.
Dimensions: Maximum diameter of midbody at girdle 53-71 Ám, (holotype 69 Ám) Apex to antapex 47-58 Ám, (holotype 58 Ám).
Originally Leptodinium, subsequently Dichadogonyaulax, thirdly Ctenidodinium, fourthly (and now) Ctenidodinium?.
Sarjeant, 1975, retained this species in Dichadogonyaulax Sarjeant, 1966.
Stover and Evitt, 1978, agreed with Lentin and Williams, 1973, but Woollam, 1983, emended Dichadogonyaulax and retained Dichadogonyaulax schizoblata in that genus.
Benson, 1985, questionably retained this species in Ctenidodinium.
Courtinat, 1989, retained the species in Dichadogonyaulax.
Lentin and Williams, 1989, agreed with Benson, 1985.
Holotype: Norris, 1965, figs.5, 15-17
Locus typicus: Durlston Bay, Southern England
Stratum typicum: Portlandian
Original diagnosis: Norris, 1965, p.798: Leptodinium schizoblatum
Midbody globular, usually oblate. Both epitheca and hypotheca rounded. Epitheca with a small solid projection at the apex. Division into fields distinct: 5", 6"", 5 or 6g, 5""", 1p, 1"""", 1av. 5iv, 1pv. Fields bordered by distinct. occasionally slightly sinuous, solid muri about 1 Ám, wide and 1.5 Ám high, up to 2 Ám high bordering girdle. Girdle distinctly spiralled, ends separated antero-posteriorly one to one and a half girdle widths and laterally by about one-fifth of the equatorial diameter. Shell surface irregularly punctate: muri folded perpendicularly to the shell surface, serrated and split. Shell of organic material. 0.25 Ám or less in thickness. Epithecal archeopyle developed.
Original description: Norris, 1965, p. 798-799: Leptodinium schizoblatum
Field 1" is long and narrow and a direct continuation of the ventral area. 3" is very small. The remaining apical fields are more or less square or oblong. A small, solid, truncated horn, 3 or 4 Á high and 3 or 4 Á wide is developed at the junction of 1", 2", and 5". Precingular fields large, approximately equal in size, equidimensional or elongated transversely. Postcingular fields roughly equidimensional or elongated transversely: 1""" smaller than 2-5""". Antapical field square or rhomboidal, Iarge, about half the maximum midbody diameter in width.
Girdle floor level with shell surface, flat, bordered by muri which are slightly higher than the remaining field borders. Ventral area not noticeably, or only very slightly, depressed. Anterior ventral field (lav) extends forward from the posterior border or middle of the anterior end of the girdle. lntermediate ventral fields (1-5iv) distinct or not, consisting of a transverse row of three smaller fields underlain by two larger fields. Posterior ventral field (1pv) large but rather variable. Posterior intcrcalary field (1p) adjacent to posterior ventral field and situated between 1""" and 2""".
Archeopyle margin clean-cut, running immediately anterior to, or up to 2 Ám from, the anterior girdle border, or even variably on the same specimen.
Operculum integral, probably attached. consisting of 11 fields (1"-5" and 1"-6"). On approaching the anterior edge of the girdle, the precingular field borders usually deteriorate in height and thickness (from 1 Ám, wide to 0.25 Ám, or less, or even disappear completely) and also become deeply, and widely serrated, degenerating to isolated granules. The operculum frequently hinges on the ventral area, but may be completely detached. In the latter case, rupture is usually completed by skirting round the anterior end of the ventral area beneath 1"; alternatively it may pass across the ventral area in an irregular line.
Dimensions: Maximum diameter of midbody at girdle 53-71 Ám, (holotype 69 Ám) Apex to antapex 47-58 Ám, (holotype 58 Ám).