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Membranigonyaulax granulatum
Membranigonyaulax granulata Slimani, 1994, p.20-21, pl.2, figs.1-9.
Holotype: Slimani, 1994, pl.2, figs.1-2.
Age: Early Campanian-Early Maastrichtian.
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Original description (Slimani, 1994) (translated from French):
Membranigonyaulax granulatum sp.nov. (Pl.2, Fig.1-9)
Name derivation: Latin: granulum, small grain; refers to the granulated endocyst.
Holotype: Turnhout -933 m, preparation 6, E.F. coordinate W41/2
Type locality: Turnhout -933 m.
Type horizon: Campanian
Diagnosis: Small subspheroidal cyst. The endocyst is slightly to densely granulated. The smooth to dotted, thin, and fragile ectophragm is supported by more or less continuous parasutural ridges or, very rarely, by very fine parasutural processes, joined proximally or not. The intratabular support structures are more or less dense and may form a reticulum. The paratabulation is gonyaulacoid, conforming to the following formula: 4', 6'', 5-6c, 4-5''', 1p, pv, 1''''. The configuration of the hypocystal paraplates is quinqueform. The archaeopyle is apical type (4A), broad with a hexagonal edge and a deep sulcal notch; the operculum is a single piece, free or attached.
Dimensions:
Holotype: maximum diameter: 38 µm
Variations: maximum diameter: 30–48 µm
Number of specimens measured: 20
Material: >70 specimens.
Description: The thin endophragm is in close contact with the 2 µm thick periphragm. The thin, fragile ectophragm is weakly to strongly separated from the endocyst. The epicystal and hypocystal intratabular areas are ornamented by secondary ridges, vermicules, processes, and granules, which are often connected to form a more or less perfect reticulum, while the paracingulate paraplates lack them. The separation distance between the endocyst and the ectophragm is often very small (0.25 to 2 µm), but in very rare forms, it is greater and reaches up to 6 µm; the paratabulation in these latter forms is often vague. The segmented paracingulum, up to 8 µm wide, is slightly laevorotatory. The parasulcus is unsegmented and delimited laterally and antapically by parasuturous ridges or ornaments and apically by the base of the sulcal notch. The archaeopyle can reach up to 30 µm in width. Note: Specimens with widely spaced endocysts and ectophragms probably belong to another species to be separated from M. granulata sp.nov., but the rarity of this type of cyst and the presence of intermediate forms prevent us from creating a new species for the time being to classify these specimens.
Comparison: This species can be confused with Histiocysta palla Davey (1969a), but it differs by a quinqueform gonyaulacoid paratabulation, a broad archaeopyle with a hexagonal edge and a deep sulcal notch, and a paracingulum that is consistently devoid of intratabular structures. H. palla has a small archaeopyle, a paracingulum with intratabular ridges, and its paratabulation is partiform gonyaulacoid.
Stratigraphic distribution: Beutenaken: samples 1 to 21, Halembaye: samples 1 to 21. 1 to 31, Lower Campanian. – Maastrischtien inf. (Zone with G. quadrata – Zone with B. lanceolata). Turnhout: -956 to -900 m, upper Campanian. lower part. from the lower Maastrachtian.
Holotype: Slimani, 1994, pl.2, figs.1-2.
Age: Early Campanian-Early Maastrichtian.
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Original description (Slimani, 1994) (translated from French):
Membranigonyaulax granulatum sp.nov. (Pl.2, Fig.1-9)
Name derivation: Latin: granulum, small grain; refers to the granulated endocyst.
Holotype: Turnhout -933 m, preparation 6, E.F. coordinate W41/2
Type locality: Turnhout -933 m.
Type horizon: Campanian
Diagnosis: Small subspheroidal cyst. The endocyst is slightly to densely granulated. The smooth to dotted, thin, and fragile ectophragm is supported by more or less continuous parasutural ridges or, very rarely, by very fine parasutural processes, joined proximally or not. The intratabular support structures are more or less dense and may form a reticulum. The paratabulation is gonyaulacoid, conforming to the following formula: 4', 6'', 5-6c, 4-5''', 1p, pv, 1''''. The configuration of the hypocystal paraplates is quinqueform. The archaeopyle is apical type (4A), broad with a hexagonal edge and a deep sulcal notch; the operculum is a single piece, free or attached.
Dimensions:
Holotype: maximum diameter: 38 µm
Variations: maximum diameter: 30–48 µm
Number of specimens measured: 20
Material: >70 specimens.
Description: The thin endophragm is in close contact with the 2 µm thick periphragm. The thin, fragile ectophragm is weakly to strongly separated from the endocyst. The epicystal and hypocystal intratabular areas are ornamented by secondary ridges, vermicules, processes, and granules, which are often connected to form a more or less perfect reticulum, while the paracingulate paraplates lack them. The separation distance between the endocyst and the ectophragm is often very small (0.25 to 2 µm), but in very rare forms, it is greater and reaches up to 6 µm; the paratabulation in these latter forms is often vague. The segmented paracingulum, up to 8 µm wide, is slightly laevorotatory. The parasulcus is unsegmented and delimited laterally and antapically by parasuturous ridges or ornaments and apically by the base of the sulcal notch. The archaeopyle can reach up to 30 µm in width. Note: Specimens with widely spaced endocysts and ectophragms probably belong to another species to be separated from M. granulata sp.nov., but the rarity of this type of cyst and the presence of intermediate forms prevent us from creating a new species for the time being to classify these specimens.
Comparison: This species can be confused with Histiocysta palla Davey (1969a), but it differs by a quinqueform gonyaulacoid paratabulation, a broad archaeopyle with a hexagonal edge and a deep sulcal notch, and a paracingulum that is consistently devoid of intratabular structures. H. palla has a small archaeopyle, a paracingulum with intratabular ridges, and its paratabulation is partiform gonyaulacoid.
Stratigraphic distribution: Beutenaken: samples 1 to 21, Halembaye: samples 1 to 21. 1 to 31, Lower Campanian. – Maastrischtien inf. (Zone with G. quadrata – Zone with B. lanceolata). Turnhout: -956 to -900 m, upper Campanian. lower part. from the lower Maastrachtian.