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Ovoidinium glebulentum
Plate 13, Figs. 8, 12, 16
Holotype: Plate 13, Figures 12, 16
Type Locality: Vergol outcrop, early Valanginian, Bed V10M, pertransiens ammonite Zone, salinarium Sub-zone. Holotype: Slide V10M/3, E.F. P41.2.
Derivation of Name: From the Latin glebulentus, lumpy- in reference to the mesotabular thickenings.
Diagnosis: A sub-spherical cyst with a thick, multi-layered endophragm and a delicate periphragm. The latter is usually broken and represented by fragments. Solid, domed, circular mesotabular thickenings occur over the surface of the endophragm, one per plate. A combination archeopyle is always developed and the operculum usually remains attached. No sutural or cingular features.
Dimensions: Holotype Length - 56 μm. Width - 63 μm.
Overall - 56 (49) 43 μm × 63 (50) 41 μm.
Specimens measured - 7.
Remarks: Ovoidinium? glebulentum is most similar to Ovoidinium diversum Davey 1979a, particularly in its thick endophragm which has "a spongy appearance" (Davey, op cit. p. 558). Ovoidinium diversum does not have the mesotabular thickenings characteristic of O.? glebulentum, however.
Ovoidinium? glebulentum is only questionably assigned to the genus Ovoidinium Davey 1970 because it has not been possible here to determine the exact composition of the operculum. Davey (1979a, p. 558) stated that the archeopyle of O. diversum, "could be mistaken for a simple apical archeopyle", although the most distinctive characteristic is, "the straight paraplate boundary parallel to the paracingulum on the dorsal surface". Davey (op. cit.) interpreted this as the boundary between intercalary plate 2a and plate 4". The true archeopyle type was described by Davey as compound 4A3I and this was clearly demonstrated in some of his illustrations (Davey op. cit., pl. 6, figs. 6-8, 11 and 16).
The observed range of Ovoidinium? glebulentum was between Vergol Beds B111M and V76M, late Berriasian, alpillensis Zone, alpillensis Sub-zone to early Valanginian, neocomiensis Zone, campylotoxus Sub-zone. This is significantly older than most other records of Ovoidinium spp., which are mainly of a mid-Cretaceous age. However, Leereveld (1997a) recorded "Ovoidinium diversum" throughout the Valanginian (i.e., post-otopeta Subzone) interval at Rio Argos; the specimen he illustrated (op. cit., fig. 8k) does not show the mesotabular thickenings characteristic of O.? glebulentum.
Holotype: Plate 13, Figures 12, 16
Type Locality: Vergol outcrop, early Valanginian, Bed V10M, pertransiens ammonite Zone, salinarium Sub-zone. Holotype: Slide V10M/3, E.F. P41.2.
Derivation of Name: From the Latin glebulentus, lumpy- in reference to the mesotabular thickenings.
Diagnosis: A sub-spherical cyst with a thick, multi-layered endophragm and a delicate periphragm. The latter is usually broken and represented by fragments. Solid, domed, circular mesotabular thickenings occur over the surface of the endophragm, one per plate. A combination archeopyle is always developed and the operculum usually remains attached. No sutural or cingular features.
Dimensions: Holotype Length - 56 μm. Width - 63 μm.
Overall - 56 (49) 43 μm × 63 (50) 41 μm.
Specimens measured - 7.
Remarks: Ovoidinium? glebulentum is most similar to Ovoidinium diversum Davey 1979a, particularly in its thick endophragm which has "a spongy appearance" (Davey, op cit. p. 558). Ovoidinium diversum does not have the mesotabular thickenings characteristic of O.? glebulentum, however.
Ovoidinium? glebulentum is only questionably assigned to the genus Ovoidinium Davey 1970 because it has not been possible here to determine the exact composition of the operculum. Davey (1979a, p. 558) stated that the archeopyle of O. diversum, "could be mistaken for a simple apical archeopyle", although the most distinctive characteristic is, "the straight paraplate boundary parallel to the paracingulum on the dorsal surface". Davey (op. cit.) interpreted this as the boundary between intercalary plate 2a and plate 4". The true archeopyle type was described by Davey as compound 4A3I and this was clearly demonstrated in some of his illustrations (Davey op. cit., pl. 6, figs. 6-8, 11 and 16).
The observed range of Ovoidinium? glebulentum was between Vergol Beds B111M and V76M, late Berriasian, alpillensis Zone, alpillensis Sub-zone to early Valanginian, neocomiensis Zone, campylotoxus Sub-zone. This is significantly older than most other records of Ovoidinium spp., which are mainly of a mid-Cretaceous age. However, Leereveld (1997a) recorded "Ovoidinium diversum" throughout the Valanginian (i.e., post-otopeta Subzone) interval at Rio Argos; the specimen he illustrated (op. cit., fig. 8k) does not show the mesotabular thickenings characteristic of O.? glebulentum.