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Chatangiella porata
Chatangiella porata, Aurisano, 1984
Holotype: Aurisano 1984: Figure 3A
Locus typicus: Transcontinental Well No. 5, NewJersey, 230.73 meters depth
Stratum typium: late Campanian.
Occurrence: New Jersey and Delaware from the upper part of the Ventilabrella glabrala and Globotrruncana elevata zones and the middle part of the Bolivinoides decoratus Zone which indicates a late Campanian age. Specimens fitting the circumscription of C. porata have been regularly observed in the late Campanian of the Western Interior (E. Kidson, pers. comm.).
Age: Late Campanian
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Original description: Aurisano 1984, p. 1-2
Diagnosis:
A species of Chatangiella whose pericyst surface appears to be uniformly porate in optical section but is actually foveolate.
Description:
A circumcavate dinoflagellate cyst which is pentagonal to ellipsoidal in outline. The pericyst terminates in one apical and two antapical horns, the left of which is fully developed and pointed, while the right is weakly developed, when present. The apical horn terminates in a sharp invagination. Epicystal expression of shoulders varies from weak to strong. The pericyst is dorsally convex, ventrally planar. The pericyst surface appears porate in optical section but is demonstrated to be foveolate through scanning electron microscopy. The individual foveolae are less than 1 µm in diameter and uniformly and densely distributed. In addition, pericyst is characterized, more or less, by intratabular fields of large granules and/or rods (granules larger than foveolae but smaller than 1 µm in diameter), separated by pandasutural bare zones - especially in the pre- and postcingular series of paraplates. The density of distribution of positive ornament is variable but foveolate condition is a more or less consistent feature of this species. Endocyst is spherical in outline; surface is finely granulate to smooth.
Paracingulum is denoted by finely serrated parasutural ridges and is tripartite on the dorsal surface.
Paratabulation is incompletely expressed but peridinoid on the basis of archeopyle type, the interrupted paracingulum, and pandasutural bare zones in the pre- and post-cingular series. Occasionally, weakly developed granules in apical region are arranged intratabularly and delimit the apical plate series.
Archeopyle formula is 1/1 (2a 2a); the outline is an omega form hexa. The peri-operculum and endo-operculum are posteriorly attached.
Dimensions:
(on 10 specimens) Maximum length 55-80 µm; maximum width 35-50 µm.
Affinities/Remarks:
Chatangiella porata is distinguished from other species of Chatangiella by its distinctively foveolate periphragm. That its foveolate condition is a specific taxonomic character and not due to a preservational factor is determined by the uniform character of the individual foveolae, the dense distribution of the foveolae and the consistent appearance of the foveolae on several specimens. That is, specimens are equally foveolate from sample to sample and section to section.
Holotype: Aurisano 1984: Figure 3A
Locus typicus: Transcontinental Well No. 5, NewJersey, 230.73 meters depth
Stratum typium: late Campanian.
Occurrence: New Jersey and Delaware from the upper part of the Ventilabrella glabrala and Globotrruncana elevata zones and the middle part of the Bolivinoides decoratus Zone which indicates a late Campanian age. Specimens fitting the circumscription of C. porata have been regularly observed in the late Campanian of the Western Interior (E. Kidson, pers. comm.).
Age: Late Campanian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: Aurisano 1984, p. 1-2
Diagnosis:
A species of Chatangiella whose pericyst surface appears to be uniformly porate in optical section but is actually foveolate.
Description:
A circumcavate dinoflagellate cyst which is pentagonal to ellipsoidal in outline. The pericyst terminates in one apical and two antapical horns, the left of which is fully developed and pointed, while the right is weakly developed, when present. The apical horn terminates in a sharp invagination. Epicystal expression of shoulders varies from weak to strong. The pericyst is dorsally convex, ventrally planar. The pericyst surface appears porate in optical section but is demonstrated to be foveolate through scanning electron microscopy. The individual foveolae are less than 1 µm in diameter and uniformly and densely distributed. In addition, pericyst is characterized, more or less, by intratabular fields of large granules and/or rods (granules larger than foveolae but smaller than 1 µm in diameter), separated by pandasutural bare zones - especially in the pre- and postcingular series of paraplates. The density of distribution of positive ornament is variable but foveolate condition is a more or less consistent feature of this species. Endocyst is spherical in outline; surface is finely granulate to smooth.
Paracingulum is denoted by finely serrated parasutural ridges and is tripartite on the dorsal surface.
Paratabulation is incompletely expressed but peridinoid on the basis of archeopyle type, the interrupted paracingulum, and pandasutural bare zones in the pre- and post-cingular series. Occasionally, weakly developed granules in apical region are arranged intratabularly and delimit the apical plate series.
Archeopyle formula is 1/1 (2a 2a); the outline is an omega form hexa. The peri-operculum and endo-operculum are posteriorly attached.
Dimensions:
(on 10 specimens) Maximum length 55-80 µm; maximum width 35-50 µm.
Affinities/Remarks:
Chatangiella porata is distinguished from other species of Chatangiella by its distinctively foveolate periphragm. That its foveolate condition is a specific taxonomic character and not due to a preservational factor is determined by the uniform character of the individual foveolae, the dense distribution of the foveolae and the consistent appearance of the foveolae on several specimens. That is, specimens are equally foveolate from sample to sample and section to section.