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Neosphaerodictyon filosum
Neosphaerodictyon filosum Slimani, 2003, p.274–275, pl.1, figs.8–12. Holotype: Slimani, 2003, pl.1, figs.8–9. Taxonomic junior synonym: Sphaerodictyon filosum (name not validly published) according to Slimani (2003, p.274). Age: Campanian–early Maastrichtian
Original description (Slimani, 2003)
Holotype: Slide Turhout 933 m, preparation 5, EF Y35/3-Z35/1 (Plate I, 8,9).
Paratype: Slide Beutenaken sample 16, preparation 2, EF J28 (Plate I, 10).
Repository: micropaleontological collections of the Laboratory of Paleontology, Department of Geology, University of Ghent, Belgium.
Type locality: Turnhout (northern Belgium), borehole 17 E225 (S120) of the Geological Survey of Belgium.
Type stratum: Upper Campanian, White chalk, Zeven Wegen Member, Turnhout 933 m (below ground surface).
Etymology: Latin, filosus, full of threads, with reference to the structure of the periphragm and processes.
Diagnosis: A species of Neosphaerodictyon with a smooth endophragm, a reticulate periphragm, and
fillamentous processes which are broad, fat and closed at their distal ends. Gonyaulacoid paratabulation
expressed by 1 intratabular process per plate. Apical archeopyle (type tA) with sub-hexagonal outline and free operculum. Description: Chorate cyst with spherical to subspherical central body. Wall is relatively thick (up to 2 µm) and consists of a smooth endophragm and a highly reticulate periphragm (2-12 µm lumina size), completely covering the external surface of the central body. Intratabular processes (1
process per plate) consisting of ¢laments arise from the periphragmal reticulum. The filaments
are joined by a very fine delicate flaring membrane that also covers the tip of the process. Processes
have variable width but constant length on a specimen. The paratabulation pattern is gonyaulacoid:
4P, 6Q, 6c, ?s, 5^6R, 1p, 1S. The cingular and sulcal processes are narrower than the apical, precingular and postcingular processes. The archeopyle outline is sub-hexagonal with a parasulcal notch suggesting the presence of six precingular and 4 apical paraplates.
Dimensions: Holotype: diameter of central body, 40 µm, length of processes, up to 14 µm; Paratype: diameter of central body, 36 µm, length of processes, up to 12 µm. Range of 10 measured specimens: diameter of central body, 30(37)44 µm, length of processes, 10(13)16 µm.
Discussion: Neosphaerodictyon filosum Slimani, sp. nov. is characterized by having a reticulate eriphragm
bearing ¢lamentous processes of equal length on a specimen, combined with an apical (tA) archeopyle. The new species is very closely comparable to specimens of the taxon ‘Sphaerodictyon filosum’ described informally by Wilson’s (1974). Stratigraphical occurrences: Campanian-Lower Maastrichtian of Beutenaken and Hallembaye (Maastricht area) and Turnhout (northern Belgium) (Slimani, 1995, 2000, 2001) and herein; Upper Campanian-Lower Maastrichtian of Denmark and the Maastricht area (Wilson, 1974);Upper Campanian of Knokke (western Belgium) (Louwye, 1991, 1992).
Original description (Slimani, 2003)
Holotype: Slide Turhout 933 m, preparation 5, EF Y35/3-Z35/1 (Plate I, 8,9).
Paratype: Slide Beutenaken sample 16, preparation 2, EF J28 (Plate I, 10).
Repository: micropaleontological collections of the Laboratory of Paleontology, Department of Geology, University of Ghent, Belgium.
Type locality: Turnhout (northern Belgium), borehole 17 E225 (S120) of the Geological Survey of Belgium.
Type stratum: Upper Campanian, White chalk, Zeven Wegen Member, Turnhout 933 m (below ground surface).
Etymology: Latin, filosus, full of threads, with reference to the structure of the periphragm and processes.
Diagnosis: A species of Neosphaerodictyon with a smooth endophragm, a reticulate periphragm, and
fillamentous processes which are broad, fat and closed at their distal ends. Gonyaulacoid paratabulation
expressed by 1 intratabular process per plate. Apical archeopyle (type tA) with sub-hexagonal outline and free operculum. Description: Chorate cyst with spherical to subspherical central body. Wall is relatively thick (up to 2 µm) and consists of a smooth endophragm and a highly reticulate periphragm (2-12 µm lumina size), completely covering the external surface of the central body. Intratabular processes (1
process per plate) consisting of ¢laments arise from the periphragmal reticulum. The filaments
are joined by a very fine delicate flaring membrane that also covers the tip of the process. Processes
have variable width but constant length on a specimen. The paratabulation pattern is gonyaulacoid:
4P, 6Q, 6c, ?s, 5^6R, 1p, 1S. The cingular and sulcal processes are narrower than the apical, precingular and postcingular processes. The archeopyle outline is sub-hexagonal with a parasulcal notch suggesting the presence of six precingular and 4 apical paraplates.
Dimensions: Holotype: diameter of central body, 40 µm, length of processes, up to 14 µm; Paratype: diameter of central body, 36 µm, length of processes, up to 12 µm. Range of 10 measured specimens: diameter of central body, 30(37)44 µm, length of processes, 10(13)16 µm.
Discussion: Neosphaerodictyon filosum Slimani, sp. nov. is characterized by having a reticulate eriphragm
bearing ¢lamentous processes of equal length on a specimen, combined with an apical (tA) archeopyle. The new species is very closely comparable to specimens of the taxon ‘Sphaerodictyon filosum’ described informally by Wilson’s (1974). Stratigraphical occurrences: Campanian-Lower Maastrichtian of Beutenaken and Hallembaye (Maastricht area) and Turnhout (northern Belgium) (Slimani, 1995, 2000, 2001) and herein; Upper Campanian-Lower Maastrichtian of Denmark and the Maastricht area (Wilson, 1974);Upper Campanian of Knokke (western Belgium) (Louwye, 1991, 1992).