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Pierceites deccanensis
Pierceites deccanensis sp. nov., Prasad et al., 2018
Holotype: specimen BSIP slide no 15574, Coordinates X82, Fig. 5Q, Prasad et al., 2018
Type locality and stratigraphic horizon: Ashtona village, Yeotmal, central India, clay horizon of the Infratappean in the bore core: Cretaceous
Original description: Prasad et al., 2018:
Proximate cysts with rounded-pentagonal peridinioid outline.
Cyst wall: thin ~0.5 mm thick. Pericoel lacking, apical horn broadly based and tapers smoothly to a rounded apex. Antapical horns very small and appear rudimentary and are of equal length, cingulum and sulcus weakly developed and is not evident.
Cyst surface: evenly, scabrate to psilate.
Tabulation: Except for the archeopyle, evidence of cyst tabulation lacks in all the specimens. Tabulation is expressed by the sutural lines of dehiscence defining plate boundaries of the apical, intercalary, and percingular series and by the separation of individual plates, especially in the precingular series.
Hypocystal tabulation: is not evident.
Partial tabulation formula is peridiniacean: 4', 3a, 7''. Apical series distinguished by a first apical plate (1') which extend to the apex; sutural boundary of second apical (2') and fourth apical (4') plates in direct contact with the ventral side of the apical horn. Intercalary series typically peridiniacean; mid-dorsal second intercalary plate (2a) attenuated but with the 2a/3' boundary not much shorter than the 2 a/4'' boundary. Precingular plates may dehisce individually along the cingular margin and from the remainder of epicyst.
Archeopyle: intercalary, 3I. It is expressed by sutural lines of dehiscence defining plate boundaries, and not by positive structures such as ridges, septa, or processes, or by patterns of ornamentation.
Operculum: compound, with each opercular piece corresponding to a plate of the intercalary series; opercular pieces generally separate, but may remain in place.
Dimensions:
Cyst length ranges from 70 to 85 µm long and 49-62 µm broad. Apical horn ranges from 10 to 12 µm in length while antapical horns are weakly developed.
Affinities/Comparison:
Pierceites is distinguished from other dinoflagellate peridinioid cyst genera by 3I archeopyle and by its lack of pericoels underlying any area of the periphragm. Both Trithyrodinium Drugg and Ginginodinium Cookson and Eisenack possess a 3I archeopyle, but are proximocavate. Pareodinia Wiggins also lacks pericoels but does not possess antapical horns and are more or less rounded in shape. Pierceites deccanensis sp. nov. differs from Pierceites schizocystis Habib and Drugg and Pierceites pentagonum Habib and Drugg in possessing both antapical horns of equal length.
Holotype: specimen BSIP slide no 15574, Coordinates X82, Fig. 5Q, Prasad et al., 2018
Type locality and stratigraphic horizon: Ashtona village, Yeotmal, central India, clay horizon of the Infratappean in the bore core: Cretaceous
Original description: Prasad et al., 2018:
Proximate cysts with rounded-pentagonal peridinioid outline.
Cyst wall: thin ~0.5 mm thick. Pericoel lacking, apical horn broadly based and tapers smoothly to a rounded apex. Antapical horns very small and appear rudimentary and are of equal length, cingulum and sulcus weakly developed and is not evident.
Cyst surface: evenly, scabrate to psilate.
Tabulation: Except for the archeopyle, evidence of cyst tabulation lacks in all the specimens. Tabulation is expressed by the sutural lines of dehiscence defining plate boundaries of the apical, intercalary, and percingular series and by the separation of individual plates, especially in the precingular series.
Hypocystal tabulation: is not evident.
Partial tabulation formula is peridiniacean: 4', 3a, 7''. Apical series distinguished by a first apical plate (1') which extend to the apex; sutural boundary of second apical (2') and fourth apical (4') plates in direct contact with the ventral side of the apical horn. Intercalary series typically peridiniacean; mid-dorsal second intercalary plate (2a) attenuated but with the 2a/3' boundary not much shorter than the 2 a/4'' boundary. Precingular plates may dehisce individually along the cingular margin and from the remainder of epicyst.
Archeopyle: intercalary, 3I. It is expressed by sutural lines of dehiscence defining plate boundaries, and not by positive structures such as ridges, septa, or processes, or by patterns of ornamentation.
Operculum: compound, with each opercular piece corresponding to a plate of the intercalary series; opercular pieces generally separate, but may remain in place.
Dimensions:
Cyst length ranges from 70 to 85 µm long and 49-62 µm broad. Apical horn ranges from 10 to 12 µm in length while antapical horns are weakly developed.
Affinities/Comparison:
Pierceites is distinguished from other dinoflagellate peridinioid cyst genera by 3I archeopyle and by its lack of pericoels underlying any area of the periphragm. Both Trithyrodinium Drugg and Ginginodinium Cookson and Eisenack possess a 3I archeopyle, but are proximocavate. Pareodinia Wiggins also lacks pericoels but does not possess antapical horns and are more or less rounded in shape. Pierceites deccanensis sp. nov. differs from Pierceites schizocystis Habib and Drugg and Pierceites pentagonum Habib and Drugg in possessing both antapical horns of equal length.