Back
Palaeoperidinium minusculatum
Palaeoperidinium minusculatum sp. nov., Vieira and Mahdi, 2021
Holotype: Plate 5, figure 1, Vieira and Mahdi, 2021
Type locality: Møre Basin (Norway)
Stratigraphic extent: Early Paleocene, Danian
Original description: Vieira and Mahdi, 2021:
Diagnosis:
Proximate, very small subspherical to pentagonal dinoflagellate cysts possessing a thin and pale outer wall; specimens occasionally show a degree of degradation that
resembles a kalyptra, surrounding a moderately thick endophragm. Cingulum always present and the tabulation is not clear. The antapical end is usually rounded and bears a well-developed, short, pointed left horn and one barely developed right horn.
Description:
Proximate, cavate, rounded to pentagonal dinoflagellate cysts of very small size, length and breadth of cyst are almost equal; occasionally the length exceeds the width. Wall: Cysts have two layers: a thin periphragm, with scattered fine granulation/punctation, and the relatively thick (up to 1 µm) endophragm.
Central body dorso-ventrally compressed; apical and antapical regions are equal in length.
Cingulum: often present, edged by low ridges or folds.
Archaeopyle: Type 313 P, the operculum often remains attached.
Three horns are usually observed, consisting of one short and blunt apical horn, one short, pointed, well-developed left antapical and one barely developed or scarcely visible, right antapical horn. This short, pointed antapical horn often tends to be offset slightly towards the right.
Dimensions:
Central body length 53 (46) 42 µm, width 49 (42) 37 µm, apical horn length 7 (5) 3 µm, width 10 (5) 2 µm.
15 specimens measured
Affinities/Comparison:
The very small size of this new species together with its one well-developed short and pointed antapical horn allows a clear separation from previously described species within the genus (in particular P. pyrophorum and P. cretaceum).
Holotype: Plate 5, figure 1, Vieira and Mahdi, 2021
Type locality: Møre Basin (Norway)
Stratigraphic extent: Early Paleocene, Danian
Original description: Vieira and Mahdi, 2021:
Diagnosis:
Proximate, very small subspherical to pentagonal dinoflagellate cysts possessing a thin and pale outer wall; specimens occasionally show a degree of degradation that
resembles a kalyptra, surrounding a moderately thick endophragm. Cingulum always present and the tabulation is not clear. The antapical end is usually rounded and bears a well-developed, short, pointed left horn and one barely developed right horn.
Description:
Proximate, cavate, rounded to pentagonal dinoflagellate cysts of very small size, length and breadth of cyst are almost equal; occasionally the length exceeds the width. Wall: Cysts have two layers: a thin periphragm, with scattered fine granulation/punctation, and the relatively thick (up to 1 µm) endophragm.
Central body dorso-ventrally compressed; apical and antapical regions are equal in length.
Cingulum: often present, edged by low ridges or folds.
Archaeopyle: Type 313 P, the operculum often remains attached.
Three horns are usually observed, consisting of one short and blunt apical horn, one short, pointed, well-developed left antapical and one barely developed or scarcely visible, right antapical horn. This short, pointed antapical horn often tends to be offset slightly towards the right.
Dimensions:
Central body length 53 (46) 42 µm, width 49 (42) 37 µm, apical horn length 7 (5) 3 µm, width 10 (5) 2 µm.
15 specimens measured
Affinities/Comparison:
The very small size of this new species together with its one well-developed short and pointed antapical horn allows a clear separation from previously described species within the genus (in particular P. pyrophorum and P. cretaceum).