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Nexosispinum adinum
Plate 30, Figures 4, 6, 8, 10, 11, 13
Holotype: Plate 30, Figure 11.
Type Locality: Speeton Bed C7C, early Hauterivian, inversum ammonite Zone. Holotype: Slide Lr.C7C(2), E.F. N45.3.
Derivation of Name: From the Greek adinos, thick, dense, crowded - in reference to the tightly-packed surface ornament of this species.
Diagnosis: Asmall, spheroidal dinoflagellate cyst covered with slender intratabular spines which are short and solid; these join laterally to form a complex, dense network. The archeopyle is precingular, type 2P, formed by the loss of plates 3" and 4", which can be separately retained within the cyst cavity.
Dimensions: Holotype: Length - 48 μm. Width - 51 μm.
Overall: 53 (48) 46 μm × 51 (46) 43 μm.
Specimens Measured: 6.
Remarks: This species was recorded only in the early Hauterivian of Speeton, between Beds C9D and C7C (regale to inversum ammonite Zones). It is similar to Nexosispinum minimum in size and in having short spines but differs in the high complexity and density of its ornament. In his description of Nexosispinum vetusculum, Davey (1974, p. 45) stated that processes assumed, “various complex configurations”. However, the process complexity and density of ornament in N. adinum significantly exceeds that of N. vetusculum. In addition, N. adinum is smaller than N. vetusculum, and its spines are more delicate.
Holotype: Plate 30, Figure 11.
Type Locality: Speeton Bed C7C, early Hauterivian, inversum ammonite Zone. Holotype: Slide Lr.C7C(2), E.F. N45.3.
Derivation of Name: From the Greek adinos, thick, dense, crowded - in reference to the tightly-packed surface ornament of this species.
Diagnosis: Asmall, spheroidal dinoflagellate cyst covered with slender intratabular spines which are short and solid; these join laterally to form a complex, dense network. The archeopyle is precingular, type 2P, formed by the loss of plates 3" and 4", which can be separately retained within the cyst cavity.
Dimensions: Holotype: Length - 48 μm. Width - 51 μm.
Overall: 53 (48) 46 μm × 51 (46) 43 μm.
Specimens Measured: 6.
Remarks: This species was recorded only in the early Hauterivian of Speeton, between Beds C9D and C7C (regale to inversum ammonite Zones). It is similar to Nexosispinum minimum in size and in having short spines but differs in the high complexity and density of its ornament. In his description of Nexosispinum vetusculum, Davey (1974, p. 45) stated that processes assumed, “various complex configurations”. However, the process complexity and density of ornament in N. adinum significantly exceeds that of N. vetusculum. In addition, N. adinum is smaller than N. vetusculum, and its spines are more delicate.