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Aprobolocysta plicata
Plate 3, Figsures 5, 9, 10, 11, 13, 14
Holotype: Plate 3, Figures 10, 11 Type Locality: Speeton Bed C7G, early Hauterivian, inversum ammonite Zone. Holotype, slide C7G(1), E.F. R44.2.
Derivation of Name: From the Latin plicatus, folded - in reference to the characteristic periphragm folds of this species.
Diagnosis: Cyst proximochorate, ovoidal to ellipsoidal and without horns. Both wall layers are smooth and the periphragm is folded, forming well-defined distally entire crests of even height over much of the cyst surface, but reduced towards the apex. Folding appears to reflect a typically pareodiniacean tabulation. A broad cingulum, offset ventrally by about one cingular width, is marked by a row of relatively small fields. Archeopyle apical, with a deep sulcal notch typical of the genus.
Dimensions: Holotype (operculum detached): Length - 53μm. Width - 43μm
Complete specimens: 66 (62) 58 μm × 46 (44) 43 μm
Specimens Measured: 3
Operculum lost: 56 (54) 53 μm × 43 (43) 43 μm
Specimens Measured: 2
Remarks: This species is similar to Aprobolocysta neista in having high periphragm folds but, whereas A. neista has irregular, spiky crests, A. plicata has distally entire crests of even height over much of the cyst.
Aprobolocysta plicata is a rare form, restricted in this study to the early Hauterivian, being observed between Speeton Beds C10 and C7F (regale to inversum ammonite Zones). Only six specimens were recorded, but despite this rarity it is felt to be sufficiently distinctive for inclusion here.
Holotype: Plate 3, Figures 10, 11 Type Locality: Speeton Bed C7G, early Hauterivian, inversum ammonite Zone. Holotype, slide C7G(1), E.F. R44.2.
Derivation of Name: From the Latin plicatus, folded - in reference to the characteristic periphragm folds of this species.
Diagnosis: Cyst proximochorate, ovoidal to ellipsoidal and without horns. Both wall layers are smooth and the periphragm is folded, forming well-defined distally entire crests of even height over much of the cyst surface, but reduced towards the apex. Folding appears to reflect a typically pareodiniacean tabulation. A broad cingulum, offset ventrally by about one cingular width, is marked by a row of relatively small fields. Archeopyle apical, with a deep sulcal notch typical of the genus.
Dimensions: Holotype (operculum detached): Length - 53μm. Width - 43μm
Complete specimens: 66 (62) 58 μm × 46 (44) 43 μm
Specimens Measured: 3
Operculum lost: 56 (54) 53 μm × 43 (43) 43 μm
Specimens Measured: 2
Remarks: This species is similar to Aprobolocysta neista in having high periphragm folds but, whereas A. neista has irregular, spiky crests, A. plicata has distally entire crests of even height over much of the cyst.
Aprobolocysta plicata is a rare form, restricted in this study to the early Hauterivian, being observed between Speeton Beds C10 and C7F (regale to inversum ammonite Zones). Only six specimens were recorded, but despite this rarity it is felt to be sufficiently distinctive for inclusion here.