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Xiphophoridium
From Williams et al., 2017:
[Xiphophoridium, Sarjeant, 1966b, p. 146–147.
Tax. sr. syn.: Oodnadattia, according to Below (1981a, p.64) — however, Lentin and Williams (1981, p.294) retained Xiphophoridium.
Type species: Hystrichodinium alatum, Cookson and Eisenack, 1962b (pl.2, fig.1)]
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Original description: [Sarjeant, 1966]
Diagnosis:
Proximo- chorate dinoflagellate cysts, spheroidal to ovoidal or polygonal with tabulation ?4`, 1a, 6``, 0-1p, 6```, 1````. Cingulum strongly or weakly spiral., laevorotatory. Apical and antapical horns lacking. Sutures marked by high crests bearing long, dagger-like spines, broadly spaced; crests bordering cingulum especially high and prominent. Surface smooth, granular, punctate or tuberculate. Archaeopyle formed by loss of apical plates; not all individuals have an archaeopyle.
Affinities:
It is distinguish- able from Heliodinium, Hystrichodinium and Ctenidodinium by the mode of archaeopyle formation, from Heliodinium and Hystrichodinium also by the fact that the sutural spines arise from crests; and from Ctenidodinium also by the fact that the cingulum is bordered on both sides by high crests.
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Modified description:
Stover and Evitt 1978, p. 88-89:
Synopsis:
Cysts proximochorate, subspherical to subpolyhedral; gonyaulacacean; paratabulation indicated by high sutural septa with
widely to closely spaced crestal spines; archeopyle apical, Type tA.
Description:
Shape: Subspherical to subpolyhedral; outline subpolygonal in dorsal view, circular or nearly so in apical-antapical view.
Wall relationships: Autophragm only.
Wall features: Parasutural septa high and surmounted with accuminate, widely to closely spaced spines. Areas between parasutural septa smooth and with discrete, isolated tuberculae.
Paratabulation: Indicated by parasutural septa; gonyaulacacean, formula: 4`?, 1a, 6``, Xc, 6```, 0-1p, 1````.
Archeopyle: Apical, Type tA; operculum free.
Paracingulum: Indicated by transverse, parallel, parasutural septa, which are slightly higher than other parasutural septa and apparently have a larger number of crestal spines.
Parasulcus: Mode of expression uncertain.
Size: Intermediate to large.
Affinities:
The presence of an apical archeopyle serves to distinguish Xiphophoridium from Hystrichodinium and from Dinopterygium, which have precingular and combination archeopyles, respectively.
[Xiphophoridium, Sarjeant, 1966b, p. 146–147.
Tax. sr. syn.: Oodnadattia, according to Below (1981a, p.64) — however, Lentin and Williams (1981, p.294) retained Xiphophoridium.
Type species: Hystrichodinium alatum, Cookson and Eisenack, 1962b (pl.2, fig.1)]
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Original description: [Sarjeant, 1966]
Diagnosis:
Proximo- chorate dinoflagellate cysts, spheroidal to ovoidal or polygonal with tabulation ?4`, 1a, 6``, 0-1p, 6```, 1````. Cingulum strongly or weakly spiral., laevorotatory. Apical and antapical horns lacking. Sutures marked by high crests bearing long, dagger-like spines, broadly spaced; crests bordering cingulum especially high and prominent. Surface smooth, granular, punctate or tuberculate. Archaeopyle formed by loss of apical plates; not all individuals have an archaeopyle.
Affinities:
It is distinguish- able from Heliodinium, Hystrichodinium and Ctenidodinium by the mode of archaeopyle formation, from Heliodinium and Hystrichodinium also by the fact that the sutural spines arise from crests; and from Ctenidodinium also by the fact that the cingulum is bordered on both sides by high crests.
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Modified description:
Stover and Evitt 1978, p. 88-89:
Synopsis:
Cysts proximochorate, subspherical to subpolyhedral; gonyaulacacean; paratabulation indicated by high sutural septa with
widely to closely spaced crestal spines; archeopyle apical, Type tA.
Description:
Shape: Subspherical to subpolyhedral; outline subpolygonal in dorsal view, circular or nearly so in apical-antapical view.
Wall relationships: Autophragm only.
Wall features: Parasutural septa high and surmounted with accuminate, widely to closely spaced spines. Areas between parasutural septa smooth and with discrete, isolated tuberculae.
Paratabulation: Indicated by parasutural septa; gonyaulacacean, formula: 4`?, 1a, 6``, Xc, 6```, 0-1p, 1````.
Archeopyle: Apical, Type tA; operculum free.
Paracingulum: Indicated by transverse, parallel, parasutural septa, which are slightly higher than other parasutural septa and apparently have a larger number of crestal spines.
Parasulcus: Mode of expression uncertain.
Size: Intermediate to large.
Affinities:
The presence of an apical archeopyle serves to distinguish Xiphophoridium from Hystrichodinium and from Dinopterygium, which have precingular and combination archeopyles, respectively.