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Colonsaydinium psilatum
Colonsaydinium psilatum, Hunt in Hunt et al., 1985
Holotype: Hunt in Hunt et al., 1985, pl.2, figs.4-5
Type locality: Loch Cholla, Colonsay
Type strat.: Early Holocene silty peat
Distribution: known only from Early Holocene deposits from Loch Cholla, Colonsay.
Age: Late Quaternary
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Original description: [Hunt et al., 1985]:
Diagnosis:
Proximate, cornucavate to circumcavate dinoflagellate cysts. Pericyst and endocyst rounded peridinioid, with a rounded epicyst and two blunt antapical horns.
Periphragm and endophragm both psilate and less than 0.5 μm thick.
Tabulation probably cinctoid, indicated only by combination archaeopyle. Operculum free, interpreted as plates 1-2i 3-5".
Dimensions (in μm):
Minimum, Mean, Maximum
Pericyst length 78, 83, 94
Pericyst breadth 60, 73, 84,
Endocyst length 72, 77, 88
Endocyst breadth 56, 66, 76
Minimum
(14 specimens measured).
Remarks/Affinities:
Colonsaydinium psilatum sp. nov. has an asymmetrical, compound archaeopyle (Pl. 2, figs. 8, 9; Fig. 3). The morphology of this achaeopyle is inconsistent with a bipesoid tabulation of the type possessed, for instance, by Saeptodinium skipseaense sp. nov. (Fig. 2). It is, however, consistent with interpretation as plates 1-2i, 3-5" of a cintoid tabulation and is shown as such in the hypothetical reconstruction (Fig. 3). All published Tertiary and Quaternary freshwater dinoflagellate cysts have bipesoid tabulations, with the exception of the cysts of modern Peridinium cinctum (Muller) Ehrenberg and P. gatunense Nygaard. P. cinctum cysts have hemiepicystal archaeopyles, while P. gatunense cysts have epicystal archaeopyles (Boltovskoy, 1973, 1975).
Holotype: Hunt in Hunt et al., 1985, pl.2, figs.4-5
Type locality: Loch Cholla, Colonsay
Type strat.: Early Holocene silty peat
Distribution: known only from Early Holocene deposits from Loch Cholla, Colonsay.
Age: Late Quaternary
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Hunt et al., 1985]:
Diagnosis:
Proximate, cornucavate to circumcavate dinoflagellate cysts. Pericyst and endocyst rounded peridinioid, with a rounded epicyst and two blunt antapical horns.
Periphragm and endophragm both psilate and less than 0.5 μm thick.
Tabulation probably cinctoid, indicated only by combination archaeopyle. Operculum free, interpreted as plates 1-2i 3-5".
Dimensions (in μm):
Minimum, Mean, Maximum
Pericyst length 78, 83, 94
Pericyst breadth 60, 73, 84,
Endocyst length 72, 77, 88
Endocyst breadth 56, 66, 76
Minimum
(14 specimens measured).
Remarks/Affinities:
Colonsaydinium psilatum sp. nov. has an asymmetrical, compound archaeopyle (Pl. 2, figs. 8, 9; Fig. 3). The morphology of this achaeopyle is inconsistent with a bipesoid tabulation of the type possessed, for instance, by Saeptodinium skipseaense sp. nov. (Fig. 2). It is, however, consistent with interpretation as plates 1-2i, 3-5" of a cintoid tabulation and is shown as such in the hypothetical reconstruction (Fig. 3). All published Tertiary and Quaternary freshwater dinoflagellate cysts have bipesoid tabulations, with the exception of the cysts of modern Peridinium cinctum (Muller) Ehrenberg and P. gatunense Nygaard. P. cinctum cysts have hemiepicystal archaeopyles, while P. gatunense cysts have epicystal archaeopyles (Boltovskoy, 1973, 1975).