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Spinidinium delicatum
Spinidinium delicatum Slimani and Louwye, 2013, p.19, pl.4, figs.11–18.
Holotype: Slimani and Louwye, 2013, pl.4, figs.11–14.
Age: latest Maastrichtian.
Original description (Slimani, and Louwye, 2013)
Holotype: Sample Turnhout 748 m, slide 1, EF coordinates O31/2. Specimen dimensions: length 45 μm, width 32 μm (Plate IV, 11–14).
Paratype: Sample Turnhout 748 m, slide 1, EF coordinates P31. Specimen dimensions: length 40 μm, width 30 μm (Plate IV, 17–18).
Repository: Botanical collection of the National Herbarium (RAB), Scientific Institute, Mohammed V-Agdal University, Rabat, Morocco.
Type locality: Turnhout, Antwerp province, northern Belgium, well no. 17E225 (S120) of the Geological Survey of Belgium.
Stratigraphic horizon: Uppermost part of the Upper Maastrichtian, Turnhout borehole, 748 m depth.
Etymology: With reference to the sutural crests with very delicately ornamented distal edges.
Diagnosis: A small, cornucavate species of Spinidinium with a sub-pentagonal, longer than broad outline and very fine sutural crests. The distal edges of the crests are very finely serrate to finely denticulate. The tabulation is indicated by the sutural crests and the archaeopyle. The intratabular areas are devoid of ornamentation.
Description: The small, proximate, peridinioid, cornucavate dinocyst is dorsoventrally compressed and has a pentagonal to subpentagonal endocyst and pericyst. The width of the cyst is about 3/4 of the total cyst length. The pericyst bears a stiff, conical apical horn with an oblate or indented tip, and two pointed antapical horns of unequal length. The right antapical horn is reduced to absent. The left antapical horn is always present and longer, broad-based and tapering distally to a pointed tip. The thin endophragm has a maximum thickness of 0.5 μm. The periphragm is smooth, thinner than the endophragm, hyaline and closely adpressed to the endocyst, excepted for the horns where they are narrowly separated. The periphragm bears thin and continuous sutural crests (up to 2 μm height) which indicate a tabulation (4′, 3a, 7″, xc, 5‴, 2″″). The distal edges of the sutural crests – which are only faintly visible under high magnification – are very finely serrate to finely denticulate. The relatively wide (max. 5 μm width) cingulum is slightly laevorotatory and unsegmented. The sulcus is also unsegmented and extends on the epicyst and hypocyst. A flagellar scar can be observed. The sulcus is narrow between the cingular extremities and broadens progressively towards the apex and antapex, and contacts respectively apical plate (4′) and antapical plates 1″″ and 2″″. No crests have been observed between the unsegmented cingulum and the sulcus. The rarely visible archaeopyle is intercalary and isodeltaform type I (2a). The operculum is free.
Discussion: Quattrocchio and Sarjeant (2003) erected the genus Volkheimeridium in order to separate species with sutural crests from species of Spinidinium Cookson and Eisenack, 1962, which are devoid of sutural crests. Sluijs et al. (2009, p. 37) however considered Volkheimeridium to be a taxonomic junior synonym of Spinidinium because of the relatively minor differences between both genera, especially when it is not possible to assess whether the crests are sutural or proximosutural. Spinidinium delicatum sp. nov. is thus included here in Spinidinium since it bears very fine sutural crests with finely serrate to finely denticulate distal margins. Spinidinium delicatum sp. nov. is conspecific with a species recognized as Palaeoperidinium subconicoides (Lejeune-Carpentier, 1942) Lentin and Williams, 1973 by Slimani (1995), and with Spinidinium sp. A. of Slimani et al. (2011). It differs from all the other Spinidinium species by its smaller size, the absence of intratabular ornamentation and its thin and continuous sutural crests with finely serrate to finely denticulate distal edges, only observed under high magnification. Spinidinium clavus Harland, 1973 and Spinidinium uncinatum May, 1980 also do not show intratabular ornamentation but they possess a larger pericoel, much larger and discontinuous sutural crests, and irregular large spines and processes. Palaeoperidinium? subconioides (Lejeune-Carpentier, 1941) Lentin and Williams, 1973 resembles the new species, but differs in having a segmented cingulum, crests separating the cingulum and sulcus, unornamented sutural crests and intratabular striations.
Dimensions of measured specimens: Length 30(38)45 μm, width 27(31)35 μm. 12 specimens measured.
Stratigraphic range: Upper Maastrichtian of Turnhout, northern Belgium ( Slimani, 1995); Upper Maastrichtian–Lower Danian of Meer, northern Belgium (Slimani et al., 2011).
Holotype: Slimani and Louwye, 2013, pl.4, figs.11–14.
Age: latest Maastrichtian.
Original description (Slimani, and Louwye, 2013)
Holotype: Sample Turnhout 748 m, slide 1, EF coordinates O31/2. Specimen dimensions: length 45 μm, width 32 μm (Plate IV, 11–14).
Paratype: Sample Turnhout 748 m, slide 1, EF coordinates P31. Specimen dimensions: length 40 μm, width 30 μm (Plate IV, 17–18).
Repository: Botanical collection of the National Herbarium (RAB), Scientific Institute, Mohammed V-Agdal University, Rabat, Morocco.
Type locality: Turnhout, Antwerp province, northern Belgium, well no. 17E225 (S120) of the Geological Survey of Belgium.
Stratigraphic horizon: Uppermost part of the Upper Maastrichtian, Turnhout borehole, 748 m depth.
Etymology: With reference to the sutural crests with very delicately ornamented distal edges.
Diagnosis: A small, cornucavate species of Spinidinium with a sub-pentagonal, longer than broad outline and very fine sutural crests. The distal edges of the crests are very finely serrate to finely denticulate. The tabulation is indicated by the sutural crests and the archaeopyle. The intratabular areas are devoid of ornamentation.
Description: The small, proximate, peridinioid, cornucavate dinocyst is dorsoventrally compressed and has a pentagonal to subpentagonal endocyst and pericyst. The width of the cyst is about 3/4 of the total cyst length. The pericyst bears a stiff, conical apical horn with an oblate or indented tip, and two pointed antapical horns of unequal length. The right antapical horn is reduced to absent. The left antapical horn is always present and longer, broad-based and tapering distally to a pointed tip. The thin endophragm has a maximum thickness of 0.5 μm. The periphragm is smooth, thinner than the endophragm, hyaline and closely adpressed to the endocyst, excepted for the horns where they are narrowly separated. The periphragm bears thin and continuous sutural crests (up to 2 μm height) which indicate a tabulation (4′, 3a, 7″, xc, 5‴, 2″″). The distal edges of the sutural crests – which are only faintly visible under high magnification – are very finely serrate to finely denticulate. The relatively wide (max. 5 μm width) cingulum is slightly laevorotatory and unsegmented. The sulcus is also unsegmented and extends on the epicyst and hypocyst. A flagellar scar can be observed. The sulcus is narrow between the cingular extremities and broadens progressively towards the apex and antapex, and contacts respectively apical plate (4′) and antapical plates 1″″ and 2″″. No crests have been observed between the unsegmented cingulum and the sulcus. The rarely visible archaeopyle is intercalary and isodeltaform type I (2a). The operculum is free.
Discussion: Quattrocchio and Sarjeant (2003) erected the genus Volkheimeridium in order to separate species with sutural crests from species of Spinidinium Cookson and Eisenack, 1962, which are devoid of sutural crests. Sluijs et al. (2009, p. 37) however considered Volkheimeridium to be a taxonomic junior synonym of Spinidinium because of the relatively minor differences between both genera, especially when it is not possible to assess whether the crests are sutural or proximosutural. Spinidinium delicatum sp. nov. is thus included here in Spinidinium since it bears very fine sutural crests with finely serrate to finely denticulate distal margins. Spinidinium delicatum sp. nov. is conspecific with a species recognized as Palaeoperidinium subconicoides (Lejeune-Carpentier, 1942) Lentin and Williams, 1973 by Slimani (1995), and with Spinidinium sp. A. of Slimani et al. (2011). It differs from all the other Spinidinium species by its smaller size, the absence of intratabular ornamentation and its thin and continuous sutural crests with finely serrate to finely denticulate distal edges, only observed under high magnification. Spinidinium clavus Harland, 1973 and Spinidinium uncinatum May, 1980 also do not show intratabular ornamentation but they possess a larger pericoel, much larger and discontinuous sutural crests, and irregular large spines and processes. Palaeoperidinium? subconioides (Lejeune-Carpentier, 1941) Lentin and Williams, 1973 resembles the new species, but differs in having a segmented cingulum, crests separating the cingulum and sulcus, unornamented sutural crests and intratabular striations.
Dimensions of measured specimens: Length 30(38)45 μm, width 27(31)35 μm. 12 specimens measured.
Stratigraphic range: Upper Maastrichtian of Turnhout, northern Belgium ( Slimani, 1995); Upper Maastrichtian–Lower Danian of Meer, northern Belgium (Slimani et al., 2011).