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Nannoceratopsis magnicornis
Nannoceratopsis magnicornis Bucefalo Palliani and Riding, 1997b, p.116, pl.1, figs.9–15; text-fig.9 (part).
The epithet spelling is revised to accord grammatically with a meaning "big horned"; the neuter would be magnicorne (J. Jansonius and J. Riding, pers. comm.).
Holotype: Bucefalo Palliani and Riding, 1997b, pl.1, fig.9.
Age: late Pliensbachian.
Original description: Bucefalo Palliani & Riding, 1997: Nannoceratopsis magnicornus sp. nov. (Pl. 1, fig. 9-15)
Derivation of name: The specific name is derived from the long antapical horn.
Holotype: Specimen MPK 10758, Sample 013, England Finder coordinate E 56/1-3.
Repository: Collections of the Basin Analysis and Stratigraphy Group, British Geological Survey, Nottingham, United Kingdom.
Type localities: Lower Loubressac section, Ouercy, southwest France.
Stratigraphical horizon: Late Pliensbachian, Spinatum Zone, sample 013.
Diagnosis: A species of Nannoceratopsis having a single, prominent. oblong, distally rounded antapical horn, and microperforate autophragm which thins toward the central lateral areas.
Description: A species of Nannoceratopsis which is longitudinally elongate and has an ellipsoidal to subtriangular lateral outline. The large hypocyst is characterised by a well-developed, single, bulbous, oblong, distally rounded (occasionally distally subangular [Pl. 1, fig. 10, 12]) antapical horn. The length of the horn is variable and ranges from 7 μm to 15 μm. The autophragm is microperforate and thick in the sagittal area and the immediately surrounding regions. In the mid lateral area, the autophragm becomes extremely thin. Frequently, this mid lateral thin autophragm is absent due to its inherent fragility. The cyst therefore appears to have two large subcircular holes in the autophragm on each lateral surface (Pl. 1, fig. 9-15). These prominent subcircular apertures are here interpreted as the results of mechanical damage. The sagittal band is not thickened and the paracingulum is consistently well developed.
Dimensions (Min.(Mean)Max.):
Overall length of cyst: 51 (60) 69 µm
Overall width of cyst: 24 (34) 40 µm
32 specimens measured.
Comparison: No other species of this genus exhibits the large, subcircular, mid lateral thinned autophragm, which is largely absent due to mechanical damage, characteristic of Nannoceratopsis magnicornus sp. nov. Nannoceratopsis magnicornus sp. nov. differs from N. ridingii and N. triceras, in having one, not three, hypocystal horns. It also differs from Nannoceratopsis evae which lacks horns and N. deflandrei subsp. deflandrei, N. gracilis, N. pel/ucida, N. plegas, N. radiata, N. spiculata and N. triangulata, which have two horns. Furthermore, Nannoceratopsis gracilis has smooth reticulate autophragm according to Piel & Evitt (1980) and ILYINA et al. (1994). The prominent oblong antapical horn with a rounded, bulbous extremity distinguishes Nannoceratopsis magnicornus sp. nov. from all the other species of Nannoceratopsis with shorter, distally-pointed antapical horns (e.g. N. deflandrei subsp. senex). The sagittal band of Nannoceratopsis magnicornus sp. nov. is not thickened as in N. ambonis and N. dictyambonis.
The epithet spelling is revised to accord grammatically with a meaning "big horned"; the neuter would be magnicorne (J. Jansonius and J. Riding, pers. comm.).
Holotype: Bucefalo Palliani and Riding, 1997b, pl.1, fig.9.
Age: late Pliensbachian.
Original description: Bucefalo Palliani & Riding, 1997: Nannoceratopsis magnicornus sp. nov. (Pl. 1, fig. 9-15)
Derivation of name: The specific name is derived from the long antapical horn.
Holotype: Specimen MPK 10758, Sample 013, England Finder coordinate E 56/1-3.
Repository: Collections of the Basin Analysis and Stratigraphy Group, British Geological Survey, Nottingham, United Kingdom.
Type localities: Lower Loubressac section, Ouercy, southwest France.
Stratigraphical horizon: Late Pliensbachian, Spinatum Zone, sample 013.
Diagnosis: A species of Nannoceratopsis having a single, prominent. oblong, distally rounded antapical horn, and microperforate autophragm which thins toward the central lateral areas.
Description: A species of Nannoceratopsis which is longitudinally elongate and has an ellipsoidal to subtriangular lateral outline. The large hypocyst is characterised by a well-developed, single, bulbous, oblong, distally rounded (occasionally distally subangular [Pl. 1, fig. 10, 12]) antapical horn. The length of the horn is variable and ranges from 7 μm to 15 μm. The autophragm is microperforate and thick in the sagittal area and the immediately surrounding regions. In the mid lateral area, the autophragm becomes extremely thin. Frequently, this mid lateral thin autophragm is absent due to its inherent fragility. The cyst therefore appears to have two large subcircular holes in the autophragm on each lateral surface (Pl. 1, fig. 9-15). These prominent subcircular apertures are here interpreted as the results of mechanical damage. The sagittal band is not thickened and the paracingulum is consistently well developed.
Dimensions (Min.(Mean)Max.):
Overall length of cyst: 51 (60) 69 µm
Overall width of cyst: 24 (34) 40 µm
32 specimens measured.
Comparison: No other species of this genus exhibits the large, subcircular, mid lateral thinned autophragm, which is largely absent due to mechanical damage, characteristic of Nannoceratopsis magnicornus sp. nov. Nannoceratopsis magnicornus sp. nov. differs from N. ridingii and N. triceras, in having one, not three, hypocystal horns. It also differs from Nannoceratopsis evae which lacks horns and N. deflandrei subsp. deflandrei, N. gracilis, N. pel/ucida, N. plegas, N. radiata, N. spiculata and N. triangulata, which have two horns. Furthermore, Nannoceratopsis gracilis has smooth reticulate autophragm according to Piel & Evitt (1980) and ILYINA et al. (1994). The prominent oblong antapical horn with a rounded, bulbous extremity distinguishes Nannoceratopsis magnicornus sp. nov. from all the other species of Nannoceratopsis with shorter, distally-pointed antapical horns (e.g. N. deflandrei subsp. senex). The sagittal band of Nannoceratopsis magnicornus sp. nov. is not thickened as in N. ambonis and N. dictyambonis.