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Ginginodinium
From Williams et al., 2017:
[Ginginodinium, Cookson and Eisenack 1960a, p. 7; Emendation: Lentin and Williams, 1976, p. 95-96
Type species: Ginginodinium spinosulum, Cookson and Eisenack, 1960a (pl.2, fig.9)]
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Original description: [Cookson and Eisenack, 1960]:
Description:
Shell somewhat flat, with convex ventral and dorsal surfaces, a pentagonal outline, and an apical and two antapical horns and without tabulation and capsule. Girdle broad, helicoid; longitudinal furrow broad and deep, restricted to the hypotheca.
Affinities:
Ginginodinium is distinct from Peridinium Ehrenberg in the absence of tabulation, and from Deflandrea Eisenack in the absence of a capsule.
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Emended description:
Lentin and Williams, 1976:
Description:
Shape: Pericyst: Ambitus ovoidal, to rhomboidal to pentagonal to elongate pentagonal. Apex rounded or produced into short apical horn. Antapex produced into two symmetrically located unequal antapical horns, the right antapical horn may be reduced or vestigial. Compression moderate to extreme dorso-ventral.
Endocyst: Reflects the outline of the pericyst to which it is appressed other than in vicinity of the horns.
Pericoels: A single small apical pericoel and one or two small antapical pericoels.
Phragma: Periphragm: Thin, with laevigate to granulate pandasutural bands and penitabular and intratabular ornamentation, which may be granules, echinae, tubercles or processes. Processes may be acuminate, oblate, or bifid distally.
Endophragm: Thin, laevigate.
Paratabulation: Pericyst: The pandasutural bands and penetabular ornamentation delineate a peridinoid paratabulation of 4`, 3a, 7``, ?0c, 5```, 2````. Paraplates 2` and 4` are slender and difficult to determine.
Pericingulum: Prominent and delineated by anterior and posterior parasutural ridges which may be denticulate or bear processes. Sometimes partite. Pericingulum helicoidal.
Perisulcus: Usually strongly delineated on both the epipericyst and hypopericyst. Considerably larger on the hypopericyst and posteriorly extending to the antapex.
Endocyst: Presumably identical to that of the pericyst.
Archaeopyle: Combination archaeopyle with the formula 3I+3Pa(3``-5``). Compound operculum with paraplates 1a, 2a and 3a being removed separately. 2a may be removed with 1a and 3a sometimes remaining attached to the 3`` and 5`` paraplates respectively. Alternatively 1a and 3a are detached while 2a remains attached along parasuture H4. Accessory archaeopyle sutures between the precingular the precingular paraplates 2``-3``, 3``-4``, 4``-5`` and 5``-6``. The precingulars always remain attached along the posterior margin. When the three anterior interclaries are lost and the accessory archaeopyle sutures between the precingulars are not developed, the archaeopyle appears to be 3I. Since the endophragm and periphragm are appressed in the vicinity of the archaeopyle, there is no separation of the endoperculum and perioperculum so that efficiently there is one archaeopyle and one operculum.
Archaeopyle formula: 3I(1a-3a)+3Pa(3``-5``).
Dimensions: Pericyst length 62-84 µm, breadth 54-69 µm
Affinities:
Gingiodinium is characterized by having a peridinoid outline, an apical horn, one or two antapical horns, a combination 3I+3Pa(3``-5``) archaeopyle and periphragm ornamentation. Laciniadinium McIntyre, 1975, has a "3I3Pa(3``-5``)" archaeopyle with an operculum that remains attached posteriorly. The operculum is always simple, however, in Laciniadinium. Palaeoperidinium also has a combined archaeopyle involving the loss of three anterior intercalaries and three precingulars, but also including paraplate 3`. Palaeoperidinium always has a simple operculum with no separation into individual paraplates.
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Modified description:
Stover and Evitt, 1978, p. 105-106:
Synopsis:
Cysts proximate, cornucavate, compressed; peridinioid to subcircular in outline. Paratabulation peridiniacean, hexa style, indicated by the distribution of ornamentation and, less commonly, by pandasuturate features as well; archeopyle intercalary, Type 3I; archeopyle index >0.5.
Description:
Shape: Compressed, peridinioid to subcircular, usually with one short apical and two short antapical horns.
Wall relationships: Cysts cornucavate; endophragm and periphragm separated only slightly at the bases of the horns.
Wall features: Pandasuturate bands smooth or granular, widest in the precingular and postcingular areas, diminishing in width toward the apical and antapical ends. Intratabular areas finely to coarsely granular; some granules may be arranged in penitabular rows.
Paratabulation: Indicated by pandasuturate bands in conjunction with the intratabular and/or penitabular features; peridiniacean, hexa style; formula: 4`, 3a, 7", Xc, 5```, 2````. Paraplates 1` and 3` usually discernible, 2` and 4` rarely clearly differentiated.
Archeopyle: Intercalary, Type 3I; archeopyle wide, extending nearly to the lateral margins; archeopyle index >0.5; operculum normally free and consists of three disassociated opercular pieces (paraplates 1a to 3a). Accessory archeopyle sutures may occur between dorsal precingular paraplates.
Paracingulum: Clearly indicated by parallel transverse equatorial ridges bordering a concave depression.
Parasulcus: Generally clearly indicated as a depressed midventral area extending from the antapical end of paraplate 1` to the antapical concavity.
Size: Intermediate.
Affinities:
Ginginodinium differs from Spinidinium and Phthanoperidinium in having a Type 3I rather than a Type I archeopyle. The antapical horns on Ginginodinium are generally short and about the same length. In Spinidinium, one asymmetrically placed antapical horn is prominent and the other reduced or absent; and in Phthanoperidinium, antapical horns are lacking, although a short medial projection may be present.
[Ginginodinium, Cookson and Eisenack 1960a, p. 7; Emendation: Lentin and Williams, 1976, p. 95-96
Type species: Ginginodinium spinosulum, Cookson and Eisenack, 1960a (pl.2, fig.9)]
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Original description: [Cookson and Eisenack, 1960]:
Description:
Shell somewhat flat, with convex ventral and dorsal surfaces, a pentagonal outline, and an apical and two antapical horns and without tabulation and capsule. Girdle broad, helicoid; longitudinal furrow broad and deep, restricted to the hypotheca.
Affinities:
Ginginodinium is distinct from Peridinium Ehrenberg in the absence of tabulation, and from Deflandrea Eisenack in the absence of a capsule.
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Emended description:
Lentin and Williams, 1976:
Description:
Shape: Pericyst: Ambitus ovoidal, to rhomboidal to pentagonal to elongate pentagonal. Apex rounded or produced into short apical horn. Antapex produced into two symmetrically located unequal antapical horns, the right antapical horn may be reduced or vestigial. Compression moderate to extreme dorso-ventral.
Endocyst: Reflects the outline of the pericyst to which it is appressed other than in vicinity of the horns.
Pericoels: A single small apical pericoel and one or two small antapical pericoels.
Phragma: Periphragm: Thin, with laevigate to granulate pandasutural bands and penitabular and intratabular ornamentation, which may be granules, echinae, tubercles or processes. Processes may be acuminate, oblate, or bifid distally.
Endophragm: Thin, laevigate.
Paratabulation: Pericyst: The pandasutural bands and penetabular ornamentation delineate a peridinoid paratabulation of 4`, 3a, 7``, ?0c, 5```, 2````. Paraplates 2` and 4` are slender and difficult to determine.
Pericingulum: Prominent and delineated by anterior and posterior parasutural ridges which may be denticulate or bear processes. Sometimes partite. Pericingulum helicoidal.
Perisulcus: Usually strongly delineated on both the epipericyst and hypopericyst. Considerably larger on the hypopericyst and posteriorly extending to the antapex.
Endocyst: Presumably identical to that of the pericyst.
Archaeopyle: Combination archaeopyle with the formula 3I+3Pa(3``-5``). Compound operculum with paraplates 1a, 2a and 3a being removed separately. 2a may be removed with 1a and 3a sometimes remaining attached to the 3`` and 5`` paraplates respectively. Alternatively 1a and 3a are detached while 2a remains attached along parasuture H4. Accessory archaeopyle sutures between the precingular the precingular paraplates 2``-3``, 3``-4``, 4``-5`` and 5``-6``. The precingulars always remain attached along the posterior margin. When the three anterior interclaries are lost and the accessory archaeopyle sutures between the precingulars are not developed, the archaeopyle appears to be 3I. Since the endophragm and periphragm are appressed in the vicinity of the archaeopyle, there is no separation of the endoperculum and perioperculum so that efficiently there is one archaeopyle and one operculum.
Archaeopyle formula: 3I(1a-3a)+3Pa(3``-5``).
Dimensions: Pericyst length 62-84 µm, breadth 54-69 µm
Affinities:
Gingiodinium is characterized by having a peridinoid outline, an apical horn, one or two antapical horns, a combination 3I+3Pa(3``-5``) archaeopyle and periphragm ornamentation. Laciniadinium McIntyre, 1975, has a "3I3Pa(3``-5``)" archaeopyle with an operculum that remains attached posteriorly. The operculum is always simple, however, in Laciniadinium. Palaeoperidinium also has a combined archaeopyle involving the loss of three anterior intercalaries and three precingulars, but also including paraplate 3`. Palaeoperidinium always has a simple operculum with no separation into individual paraplates.
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Modified description:
Stover and Evitt, 1978, p. 105-106:
Synopsis:
Cysts proximate, cornucavate, compressed; peridinioid to subcircular in outline. Paratabulation peridiniacean, hexa style, indicated by the distribution of ornamentation and, less commonly, by pandasuturate features as well; archeopyle intercalary, Type 3I; archeopyle index >0.5.
Description:
Shape: Compressed, peridinioid to subcircular, usually with one short apical and two short antapical horns.
Wall relationships: Cysts cornucavate; endophragm and periphragm separated only slightly at the bases of the horns.
Wall features: Pandasuturate bands smooth or granular, widest in the precingular and postcingular areas, diminishing in width toward the apical and antapical ends. Intratabular areas finely to coarsely granular; some granules may be arranged in penitabular rows.
Paratabulation: Indicated by pandasuturate bands in conjunction with the intratabular and/or penitabular features; peridiniacean, hexa style; formula: 4`, 3a, 7", Xc, 5```, 2````. Paraplates 1` and 3` usually discernible, 2` and 4` rarely clearly differentiated.
Archeopyle: Intercalary, Type 3I; archeopyle wide, extending nearly to the lateral margins; archeopyle index >0.5; operculum normally free and consists of three disassociated opercular pieces (paraplates 1a to 3a). Accessory archeopyle sutures may occur between dorsal precingular paraplates.
Paracingulum: Clearly indicated by parallel transverse equatorial ridges bordering a concave depression.
Parasulcus: Generally clearly indicated as a depressed midventral area extending from the antapical end of paraplate 1` to the antapical concavity.
Size: Intermediate.
Affinities:
Ginginodinium differs from Spinidinium and Phthanoperidinium in having a Type 3I rather than a Type I archeopyle. The antapical horns on Ginginodinium are generally short and about the same length. In Spinidinium, one asymmetrically placed antapical horn is prominent and the other reduced or absent; and in Phthanoperidinium, antapical horns are lacking, although a short medial projection may be present.