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Exiguisphaera lita
Plate 29, Figures 2, 6, 10, 12, 16
Holotype: Plate 29, Figures 12, 16
Paratype: Plate 29, Figure 10
Type Locality: Speeton Clay Formation, early Hauterivian.
Holotype: Slide C9B(1), E.F. K51.2, regale ammonite Zone.
Paratype: Slide D2B(1), E.F. D30.1 amblygonium ammonite Zone.
Derivation of Name: From the Greek litos, plain, simple - in reference to the rudimentary surface ornament and sutural features of this species.
Diagnosis: A small, spheroidal dinoflagellate cyst with a sexiform gonyaulacacean tabulation pattern typical of the genus, displaying a range of surface ornament and sutural lineations, but all very low. Surface ornament may be absent or range from a small number of surface granules to a dense cover of small, evenly spaced grana or coni. Tabulation typical of the genus is marked by continuous very fine ridges or rows of small, isolated grana or coni. The archeopyle is precingular, type 2P, formed by the loss of plates 3'' and 4'', which are often separately retained within the cyst cavity.
Dimensions: Holotype: 41 × 48 μm.
Paratype: 48 × 48 μm
Overall: 48 (44) 43 μm × 51 (47) 43 μm
Specimens measured: 10
Remarks: This is essentially a “catch-all” species encompassing specimens which are relatively small and simple, with none of the higher, more elaborate sutural crests or surface ornament described for other species here. It is typical of the early Hauterivian, being recorded between Speeton Beds D2D and C7E (amblygonium to inversum ammonite Zones).
Holotype: Plate 29, Figures 12, 16
Paratype: Plate 29, Figure 10
Type Locality: Speeton Clay Formation, early Hauterivian.
Holotype: Slide C9B(1), E.F. K51.2, regale ammonite Zone.
Paratype: Slide D2B(1), E.F. D30.1 amblygonium ammonite Zone.
Derivation of Name: From the Greek litos, plain, simple - in reference to the rudimentary surface ornament and sutural features of this species.
Diagnosis: A small, spheroidal dinoflagellate cyst with a sexiform gonyaulacacean tabulation pattern typical of the genus, displaying a range of surface ornament and sutural lineations, but all very low. Surface ornament may be absent or range from a small number of surface granules to a dense cover of small, evenly spaced grana or coni. Tabulation typical of the genus is marked by continuous very fine ridges or rows of small, isolated grana or coni. The archeopyle is precingular, type 2P, formed by the loss of plates 3'' and 4'', which are often separately retained within the cyst cavity.
Dimensions: Holotype: 41 × 48 μm.
Paratype: 48 × 48 μm
Overall: 48 (44) 43 μm × 51 (47) 43 μm
Specimens measured: 10
Remarks: This is essentially a “catch-all” species encompassing specimens which are relatively small and simple, with none of the higher, more elaborate sutural crests or surface ornament described for other species here. It is typical of the early Hauterivian, being recorded between Speeton Beds D2D and C7E (amblygonium to inversum ammonite Zones).