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Cribroperidinium wilsonii ssp. trabeculosum
From Fensome et al., 2019:
Cribroperidinium wilsonii subsp. trabeculosum Slimani and Louwye, 2013, p.13,15; pl.2, figs.1–9,11,13. Holotype: Slimani and Louwye, 2013, pl.2, figs.1–3. Originally (and now) Cribroperidinium wilsonii (Yun Hyesu) subsp. trabeculosum, subsequently Cribroperidinium graemei subsp. trabeculosum. Slimani and Louwye (2013) did not specify whether they were including this subspecies in Cribroperidinium wilsonii (Yun Hyesu, 1981) Poulsen or Cribroperidinium wilsonii (Slimani, 1994) Schiøler. Williams and Fensome (2016, p.140) assumed that the intended assignment was to the latter, which is illegitimate, and so transferred the subspecies to the substitute name Cribroperidinium graemei. However, H. Slimani (personal communication to GLW) affirms that the taxon was intended to be a subspecies of Cribroperidinium wilsonii (Yun Hyesu, 1981) Poulsen. Age: late Campanian.
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Original description: [Slimani and Louwye, 2013]:
Cribroperidinium wilsonii subsp. trabeculosum subsp. nov. (Plate II, 1–9, 11, 13)
1974 Acanthaulax “saetosa”; Wilson, unpublished Ph.D. Thesis, pp. 231–232, pl. 28, figs. 6–8.
1995 Acanthaulax wilsonii; Slimani, unpublished Ph.D. Thesis, p. 78, pl. 29, fig. 11.
2000 Acanthaulax wilsonii; Slimani, pl. 7, fig. 11.
2011 Cribroperidinium wilsonii Forma B; Slimani et al., p. 156, figs. 5d–f.
Holotype: Sample Turnhout 933 m, slide 17, EF coordinates K48/2.
Specimen dimensions: total length 60 μm, total width 60 μm, central body length 50 μm, central body width 50 μm (Plate II, 1–3).
Paratype: Sample Meer 1089 m, slide 2, EF coordinates P29. Specimen dimensions: total length 70 μm, total width 60 μm, central body length 50 μm, central body width 50 μm (Plate II, 7–9).
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 Belgian Geological Survey.
Stratigraphic horizon: Upper Campanian, Turnhout borehole, 933 m depth.
Etymology: From Latin traba (piece of wood or stem), with reference to the processes connected distally by trabeculae.
Diagnosis: A new subspecies of Cribroperidinium wilsonii with slender processes that are connected distally by thin trabeculae in a uniform fashion. The tabulation is indicated by a precingular archaeopyle type P, aligned penitabular and intratabular processes, and intratabular clusters of processes.
Description: The proximate dinocyst is of intermediate size and has a spheroidal, ovoidal to rhomboidal central body. The cyst wall consists
of a closely appressed endophragm and a periphragm. The endophragm is smooth and has a maximum thickness of 1 μm. The periphragm is
thin (0.5 μm) and is microperforate (maximum diameter of perforation 1.5 μm) to microreticulate. The cyst wall bears numerous, solid, slender
processes (3–7 μm length), that are slightly expanded distally and distributed in penitabular rows, intratabular rows and intratabular clusters, reflecting a tabulation. The length of the processes is almost constant on a specimen, but varies slightly within the subspecies. The processes aligned in penitabular and intratabular rows are closely spaced and connected proximally by thin membraneous ridges. Furthermore, their distal extremities are uniformly joined by thin trabeculae. The solitary processes forming intratabular clusters are proximally free, but connected distally by trabeculae. Other intratabular solitary processes may occasionally be present, but they are often irregularly distributed, widely spaced and not connected. A distinct, blunt, solid, simple or branched apical process (3–10 μm length) arises on a small (3–4 μm length) apical protrusion of the central body. The reflected gonyaulacoid tabulation is 4′, 6″, 6‴, 1p, 1″″. The strongly laevorotatory cingulum is relatively narrow (maximum 6 μm width), and is bordered by two parallel, sutural rows of processes. No intratabular processes occur within the cingulum. The sulcus is separated from the adjacent areas by rows of processes and can occasionally bear intratabular solitary processes. The antapical plate is hexagonal, and the boundary with the sulcus is concave. The arrangement of the hypocystal plates appears sexiform. A posterior sulcal plate (ps) may be present and is partially separated from the sulcus by a short row of processes. The archaeopyle is precingular (type P) and is formed by the release of precingular plate 3″. The operculum is free.
Discussion: Cribroperidinium wilsonii subsp. trabeculosum subsp. nov. is distinguished from C. wilsonii (Yun Hyesu, 1981) Poulsen, 1996 subsp.
wilsonii (autonym; Plate II, 10, 12, and 14) by its thinner and much slender processes. The processes forming the penitabular and intratabular
rows and intratabular clusters are closely spaced and uniformly connected distally by thin trabeculae. These processes are equal in length
on a single specimen and their distal ends do not exceed distally the trabeculae. Furthermore, C. wilsonii subsp. wilsonii possesses rigid and stronger processes that are more widely spaced. The penitabular and intratabular processes are distally acuminate or capitate, while the processes forming the intratabular clusters are capitate or forked. The processes are never connected distally by trabeculae. The processes forming rows can be connected proximally to medially, but their tips are always free and their length is not constant as on C. wilsonii subsp. trabeculosum. Perforations of the processes can be observed. Cribroperidinium wilsonii subsp. trabeculosum subsp. nov. is identical to the specimens figured as Acanthaulax wilsonii by Slimani (1995, pl. 29, fig. 11; 2000, pl. 7, fig. 11) and A. wilsonii Forma B by Slimani et al. (2011, figs. 5d–f). Acanthaulax “saetosa” was described informally by Wilson (1974) as having slender and closely spaced processes that may be connected distally by thin trabeculae, and appears to be conspecific with the new species.
Dimensions of measured specimens: Total length 60(76)90 μm, total width 60(73)82 μm, central body length 57(65)80 μm, central body width 50(62)70 μm. 18 specimens measured.
Remarks: The highest occurrence of the new subspecies lies in the Upper Campanian (Wilson, 1974; Kirsch, 1991; Louwye, 1993; Slimani, 1995, 2000, 2001) while the autonym occurs in the Lower Maastrichtian of the Turnhout borehole and the lower part of the Upper Maastrichtian of the Meer borehole.
Stratigraphic range: Lower Campanian–Upper Campanian of Beutenaken and Hallembaye, Maastricht region (Slimani, 1995, pl. 29, fig. 11;
Slimani, 2000, pl. 7, fig. 11); Campanian–Lower Maastrichtian of Turnhout, northern Belgium (personal observation, H. Slimani); Lower
Campanian–lower part of Upper Maastrichtian of Meer, northern Belgium (Slimani et al., 2011). Upper Campanian of Hallembaye, Maastricht region (as Achantaulax saetosa with processes distally connected by trabeculae, Wilson, 1974).
Cribroperidinium wilsonii subsp. trabeculosum Slimani and Louwye, 2013, p.13,15; pl.2, figs.1–9,11,13. Holotype: Slimani and Louwye, 2013, pl.2, figs.1–3. Originally (and now) Cribroperidinium wilsonii (Yun Hyesu) subsp. trabeculosum, subsequently Cribroperidinium graemei subsp. trabeculosum. Slimani and Louwye (2013) did not specify whether they were including this subspecies in Cribroperidinium wilsonii (Yun Hyesu, 1981) Poulsen or Cribroperidinium wilsonii (Slimani, 1994) Schiøler. Williams and Fensome (2016, p.140) assumed that the intended assignment was to the latter, which is illegitimate, and so transferred the subspecies to the substitute name Cribroperidinium graemei. However, H. Slimani (personal communication to GLW) affirms that the taxon was intended to be a subspecies of Cribroperidinium wilsonii (Yun Hyesu, 1981) Poulsen. Age: late Campanian.
---------------------------------------------------------------------------------------------------
Original description: [Slimani and Louwye, 2013]:
Cribroperidinium wilsonii subsp. trabeculosum subsp. nov. (Plate II, 1–9, 11, 13)
1974 Acanthaulax “saetosa”; Wilson, unpublished Ph.D. Thesis, pp. 231–232, pl. 28, figs. 6–8.
1995 Acanthaulax wilsonii; Slimani, unpublished Ph.D. Thesis, p. 78, pl. 29, fig. 11.
2000 Acanthaulax wilsonii; Slimani, pl. 7, fig. 11.
2011 Cribroperidinium wilsonii Forma B; Slimani et al., p. 156, figs. 5d–f.
Holotype: Sample Turnhout 933 m, slide 17, EF coordinates K48/2.
Specimen dimensions: total length 60 μm, total width 60 μm, central body length 50 μm, central body width 50 μm (Plate II, 1–3).
Paratype: Sample Meer 1089 m, slide 2, EF coordinates P29. Specimen dimensions: total length 70 μm, total width 60 μm, central body length 50 μm, central body width 50 μm (Plate II, 7–9).
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 Belgian Geological Survey.
Stratigraphic horizon: Upper Campanian, Turnhout borehole, 933 m depth.
Etymology: From Latin traba (piece of wood or stem), with reference to the processes connected distally by trabeculae.
Diagnosis: A new subspecies of Cribroperidinium wilsonii with slender processes that are connected distally by thin trabeculae in a uniform fashion. The tabulation is indicated by a precingular archaeopyle type P, aligned penitabular and intratabular processes, and intratabular clusters of processes.
Description: The proximate dinocyst is of intermediate size and has a spheroidal, ovoidal to rhomboidal central body. The cyst wall consists
of a closely appressed endophragm and a periphragm. The endophragm is smooth and has a maximum thickness of 1 μm. The periphragm is
thin (0.5 μm) and is microperforate (maximum diameter of perforation 1.5 μm) to microreticulate. The cyst wall bears numerous, solid, slender
processes (3–7 μm length), that are slightly expanded distally and distributed in penitabular rows, intratabular rows and intratabular clusters, reflecting a tabulation. The length of the processes is almost constant on a specimen, but varies slightly within the subspecies. The processes aligned in penitabular and intratabular rows are closely spaced and connected proximally by thin membraneous ridges. Furthermore, their distal extremities are uniformly joined by thin trabeculae. The solitary processes forming intratabular clusters are proximally free, but connected distally by trabeculae. Other intratabular solitary processes may occasionally be present, but they are often irregularly distributed, widely spaced and not connected. A distinct, blunt, solid, simple or branched apical process (3–10 μm length) arises on a small (3–4 μm length) apical protrusion of the central body. The reflected gonyaulacoid tabulation is 4′, 6″, 6‴, 1p, 1″″. The strongly laevorotatory cingulum is relatively narrow (maximum 6 μm width), and is bordered by two parallel, sutural rows of processes. No intratabular processes occur within the cingulum. The sulcus is separated from the adjacent areas by rows of processes and can occasionally bear intratabular solitary processes. The antapical plate is hexagonal, and the boundary with the sulcus is concave. The arrangement of the hypocystal plates appears sexiform. A posterior sulcal plate (ps) may be present and is partially separated from the sulcus by a short row of processes. The archaeopyle is precingular (type P) and is formed by the release of precingular plate 3″. The operculum is free.
Discussion: Cribroperidinium wilsonii subsp. trabeculosum subsp. nov. is distinguished from C. wilsonii (Yun Hyesu, 1981) Poulsen, 1996 subsp.
wilsonii (autonym; Plate II, 10, 12, and 14) by its thinner and much slender processes. The processes forming the penitabular and intratabular
rows and intratabular clusters are closely spaced and uniformly connected distally by thin trabeculae. These processes are equal in length
on a single specimen and their distal ends do not exceed distally the trabeculae. Furthermore, C. wilsonii subsp. wilsonii possesses rigid and stronger processes that are more widely spaced. The penitabular and intratabular processes are distally acuminate or capitate, while the processes forming the intratabular clusters are capitate or forked. The processes are never connected distally by trabeculae. The processes forming rows can be connected proximally to medially, but their tips are always free and their length is not constant as on C. wilsonii subsp. trabeculosum. Perforations of the processes can be observed. Cribroperidinium wilsonii subsp. trabeculosum subsp. nov. is identical to the specimens figured as Acanthaulax wilsonii by Slimani (1995, pl. 29, fig. 11; 2000, pl. 7, fig. 11) and A. wilsonii Forma B by Slimani et al. (2011, figs. 5d–f). Acanthaulax “saetosa” was described informally by Wilson (1974) as having slender and closely spaced processes that may be connected distally by thin trabeculae, and appears to be conspecific with the new species.
Dimensions of measured specimens: Total length 60(76)90 μm, total width 60(73)82 μm, central body length 57(65)80 μm, central body width 50(62)70 μm. 18 specimens measured.
Remarks: The highest occurrence of the new subspecies lies in the Upper Campanian (Wilson, 1974; Kirsch, 1991; Louwye, 1993; Slimani, 1995, 2000, 2001) while the autonym occurs in the Lower Maastrichtian of the Turnhout borehole and the lower part of the Upper Maastrichtian of the Meer borehole.
Stratigraphic range: Lower Campanian–Upper Campanian of Beutenaken and Hallembaye, Maastricht region (Slimani, 1995, pl. 29, fig. 11;
Slimani, 2000, pl. 7, fig. 11); Campanian–Lower Maastrichtian of Turnhout, northern Belgium (personal observation, H. Slimani); Lower
Campanian–lower part of Upper Maastrichtian of Meer, northern Belgium (Slimani et al., 2011). Upper Campanian of Hallembaye, Maastricht region (as Achantaulax saetosa with processes distally connected by trabeculae, Wilson, 1974).