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Ampulladinium
From Williams et al., 2017:
[Ampulladinium, Riding, Helby and Parker in Riding and Helby, 2001g, p.181, 183
Type species: Ampulladinium variabile, Riding and Helby, 2001g (figs.2I–L)]
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Original description: [Riding and Helby, 2001g]:
Diagnosis:
Small to intermediate sized, rounded triangular dinoflagellate cysts, that are acavate to holocavate, proximate to proximochorate, and exhibit some dorsoventral flattening. The widest part of the cyst is at the antapex, and the antapical lateral areas are extended into prominent lobes or protuberances. The apex is much narrower. Ornamentation is nontabular and of low relief; the autophragm may be differentiated. Archaeopyle apical, operculum simple, normally free. The principal archaeopyle suture has a prominent midventral parasulcal notch and is consistent with a gonyaulacean paratabulation pattern. Accessory archaeopyle sutures may be developed. Except for the archaeopyle, paratabulation is not evident.
Remarks:
Ampulladinium has a distinctive rounded triangular outline. The autophragm forms two antapical lateral lobes, while the apex is subspherical. The genus is typically holocavate with a narrow ectocoel, however, in the type, A. variabile, the ectophragm appears susceptible to physical-chemical degradation.
Affinities:
This new genus is similar in size and shape to Woodinia Riding & Helby (this volume). However Woodinia is not holocavate and has intratabular areas of ornamentation differentiated on the major paraplate series, which indicate gonyaulacean paratabulation. Furthermore, the paracingulum of Woodinia is high on the cyst due to the unusually long postcingular paraplates. Ampulladinium also resembles Dissimulidinium May et al., 1987 in having paired antapical lobes, but the latter is laterally compressed, consistently proximochorate and may have parasutural ornamentation. The Late Cretaceaous Dorocysta Davey 1970 has longer processes and lacks the trilobate shape of Ampulladinium. Phallocysta Dörhöfer & Davies 1980 is, like Ampulladinium, flask-shaped, trilobate and widest at the antapex, but has an anterior intercalary archaeopyle and is epicavate (Riding, 1984;1994). Members of the Early-Mid Jurassic 'Parvocysta suite' of Riding (1984) also bear a superficial resemblance to Ampulladinium,but these taxa have an anterior intercalary archaeopyle. Stenopyxinium Deflandre 1968 is similar in shape to Ampulladinium, but is destinguished by its spinose antapical protustions and possible combination (apical/precingular) or epicystal archaeopyle. Tetrachacysta Blackhouse 1988 is a quadrilobate genus with a pair of lateral protuberances on both the epicyst and hypocyst (Blackhouse, 1988, fig 32).
[Ampulladinium, Riding, Helby and Parker in Riding and Helby, 2001g, p.181, 183
Type species: Ampulladinium variabile, Riding and Helby, 2001g (figs.2I–L)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Riding and Helby, 2001g]:
Diagnosis:
Small to intermediate sized, rounded triangular dinoflagellate cysts, that are acavate to holocavate, proximate to proximochorate, and exhibit some dorsoventral flattening. The widest part of the cyst is at the antapex, and the antapical lateral areas are extended into prominent lobes or protuberances. The apex is much narrower. Ornamentation is nontabular and of low relief; the autophragm may be differentiated. Archaeopyle apical, operculum simple, normally free. The principal archaeopyle suture has a prominent midventral parasulcal notch and is consistent with a gonyaulacean paratabulation pattern. Accessory archaeopyle sutures may be developed. Except for the archaeopyle, paratabulation is not evident.
Remarks:
Ampulladinium has a distinctive rounded triangular outline. The autophragm forms two antapical lateral lobes, while the apex is subspherical. The genus is typically holocavate with a narrow ectocoel, however, in the type, A. variabile, the ectophragm appears susceptible to physical-chemical degradation.
Affinities:
This new genus is similar in size and shape to Woodinia Riding & Helby (this volume). However Woodinia is not holocavate and has intratabular areas of ornamentation differentiated on the major paraplate series, which indicate gonyaulacean paratabulation. Furthermore, the paracingulum of Woodinia is high on the cyst due to the unusually long postcingular paraplates. Ampulladinium also resembles Dissimulidinium May et al., 1987 in having paired antapical lobes, but the latter is laterally compressed, consistently proximochorate and may have parasutural ornamentation. The Late Cretaceaous Dorocysta Davey 1970 has longer processes and lacks the trilobate shape of Ampulladinium. Phallocysta Dörhöfer & Davies 1980 is, like Ampulladinium, flask-shaped, trilobate and widest at the antapex, but has an anterior intercalary archaeopyle and is epicavate (Riding, 1984;1994). Members of the Early-Mid Jurassic 'Parvocysta suite' of Riding (1984) also bear a superficial resemblance to Ampulladinium,but these taxa have an anterior intercalary archaeopyle. Stenopyxinium Deflandre 1968 is similar in shape to Ampulladinium, but is destinguished by its spinose antapical protustions and possible combination (apical/precingular) or epicystal archaeopyle. Tetrachacysta Blackhouse 1988 is a quadrilobate genus with a pair of lateral protuberances on both the epicyst and hypocyst (Blackhouse, 1988, fig 32).