Back
Hapsocysta dictyota
Hapsocysta dictyota Davey, 1979
Holotype: Davey, 1979, pl.3, figs.5-6
Age: Albian
Original description (Davey, 1979b)
Derivation of name: Greek, diktyon, net - with reference to the appearance of the outer membrane.
Diagnosis: A species of Hapsocysta possessing a thin, subspherical endocyst partly surrounded by an extensive net-like periphragm membrane. Parasutural ribs strengthen the latter structure and the thin periphragm of the intratabular regions is perforated by subpolygonal to circular holes of various sizes. The periphragm appears to join the endocyst around its lateral margins hence leaving most of the dorsal surface unenclosed. An archeopyle is typically present.
Holotype: MPK 1675, DSDP Leg 48, Hole 400A, Sample 63-2, 80-83 cm, Albian, northern Bay of Biscay.
Dimensions: Holotype Range
Overall diameter 58 x 64 μm 44 (60) 69 μm
Endocyst diameter 32 x 38 μm 26 (36) 52 μm
Description: Both the endocyst and the periphragm are extremely thin walled and easily distorted thus making the position of the archeopyle and the tabulation difficult to discern. However the large pre- and postcingular and elongate cingular paraplates are sometimes apparent. The intratabular perforations in the majority of specimens resemble those of the holotype in that they are typically quite large. However, rarer examples are present where the periphragm is perforated by only a few circular holes (Plate 3, Figures 10, 13, 14). The parasutural ribs appear to consist of single hollow strands and are more strongly developed on the specimen having smaller perforations where gonal prominences are present around the antapical paraplate.
Remarks: H. dictyota sp. nov. is easily distinguished from H. peridictya by the presence of an intratabular periphragm membrane. The tabulation appears to be similar in both species, but in H. dictyota is defined by
single strands and in H. peridictya by double strands. The only other species with a rather similar periphragm reticulation is Thalassiphora reticulata Morgenroth, 1966, from the Oligocene of Germany. The periphragm
of this species differs, however, by its lack of tabulation, its antapical prolongation and that it almost completely surrounds the endocyst.
Holotype: Davey, 1979, pl.3, figs.5-6
Age: Albian
Original description (Davey, 1979b)
Derivation of name: Greek, diktyon, net - with reference to the appearance of the outer membrane.
Diagnosis: A species of Hapsocysta possessing a thin, subspherical endocyst partly surrounded by an extensive net-like periphragm membrane. Parasutural ribs strengthen the latter structure and the thin periphragm of the intratabular regions is perforated by subpolygonal to circular holes of various sizes. The periphragm appears to join the endocyst around its lateral margins hence leaving most of the dorsal surface unenclosed. An archeopyle is typically present.
Holotype: MPK 1675, DSDP Leg 48, Hole 400A, Sample 63-2, 80-83 cm, Albian, northern Bay of Biscay.
Dimensions: Holotype Range
Overall diameter 58 x 64 μm 44 (60) 69 μm
Endocyst diameter 32 x 38 μm 26 (36) 52 μm
Description: Both the endocyst and the periphragm are extremely thin walled and easily distorted thus making the position of the archeopyle and the tabulation difficult to discern. However the large pre- and postcingular and elongate cingular paraplates are sometimes apparent. The intratabular perforations in the majority of specimens resemble those of the holotype in that they are typically quite large. However, rarer examples are present where the periphragm is perforated by only a few circular holes (Plate 3, Figures 10, 13, 14). The parasutural ribs appear to consist of single hollow strands and are more strongly developed on the specimen having smaller perforations where gonal prominences are present around the antapical paraplate.
Remarks: H. dictyota sp. nov. is easily distinguished from H. peridictya by the presence of an intratabular periphragm membrane. The tabulation appears to be similar in both species, but in H. dictyota is defined by
single strands and in H. peridictya by double strands. The only other species with a rather similar periphragm reticulation is Thalassiphora reticulata Morgenroth, 1966, from the Oligocene of Germany. The periphragm
of this species differs, however, by its lack of tabulation, its antapical prolongation and that it almost completely surrounds the endocyst.