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Adnatosphaeridium regulatum
Adnatosphaeridium regulatum, Willumsen, 2012, p. 55,57–58, pl.1, figs.1–6.
Holotype: Willumsen, 2012, pl.1, figs.1–2.
Type locality: Mid-Waipara River section, North Canterbury, New Zealand.
Type stratum: Uppermost Maastrichtian strata, uppermost part of the Conway Formation.
Age: latest Maastrichtian–earliest Paleocene.
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Original description: [Willumsen, 2012]:
Diagnosis:
Areoligeracean proximochorate to chorate, acavate cysts, with solid intratabular processes. The numerous processes rising from each paraplate are branched distally and interconnected forming ring trabeculae that indicate the paratabulation of the cyst.
Apical archeopyle, type tA with zigzag margin.
Surface of autocyst is finely punctuated.
Description:
A circular intermediate-sized proximochorate to chorate, acavate cyst, with solid intratabular processes which form distal ring trabeculae indicating each paraplate of the cyst. The cyst surface is finely punctatae and c. 2 µm thick.
The numerous (40–50) thin (1–2 µm thick), solid and fairly long (20–25 µm) intratabular processes are connected distally by trabeculae. The base of the intratabular processes in each ring form an annular complex on each plate. Processes branch out distally into smooth trifurcate branches that are interconnected with trabeculae forming a ring (Plate 1, figure 5).
Archeopyle is apical, type tA with zigzag margin; operculum is often detached.
Paratabulation is reflected by the intratabular complexes, ring trabeculae, and the apical archeopyle.
Dimensions:
Specimens measured 10; length 48(51)58 µm; width 42(45)55 µm; length of processes 15(19)25 µm.
Affinities/Discussion:
Wilson (1987, plate 2, figures 1, 2) illustrated a similar specimen and placed it in the genus Systematophora, but the penitabular processes arising from the cyst are interconnected distally forming a ring trabeculae reflecting paratabulation of the cyst. Willumsen (2003) placed a specimen similar to Wilson’s (1987) Systematophora in the genus Adnatosphaeridium (plate 1, figures 1–3), but later transferred it to Alisocysta sp. cf. A. circumtabulata (figure 7E, Willumsen 2011). Adnatosphaeridium regulatum sp. nov. differs from the type species A. vittatum (Williams and Downie 1966) by having thin, solid and relatively elongated processes that are distally connected forming a ring trabeculae. Additionally, A. vittatum has hollow and open branched processes on the central body and branches of processes can be interconnected with processes from other plates. A. regulatum sp. nov. differs from A. multispinosum (Williams and Downie 1966) by lacking short unconnected spines on the trabecula. Fensome et al. (2009) consider A. vittatum and A. multispinosum to be synonymous. Adnatosphaeridium regulatum sp. nov. differs from A. membraniphorum (Jan du Chêne and Adediran 1985) by not having perforated membranes at the tip of each process corresponding to a paraplate. A parasulcal platform diagnostic of the species A. buccinum (Hultberg 1985) was not observed in any of the studied specimens of A. regulatum sp. nov. A. regulatum sp. nov. differs from A. filiferum (Cookson and Eisenack 1958) by having processes of equal length and width that are not flattened distally. Processes of A. williamsii (Islam 1983) branch out to trabeculae that are interconnected, but differ by bearing a few free spines and by not forming ring trabeculae.
Holotype: Willumsen, 2012, pl.1, figs.1–2.
Type locality: Mid-Waipara River section, North Canterbury, New Zealand.
Type stratum: Uppermost Maastrichtian strata, uppermost part of the Conway Formation.
Age: latest Maastrichtian–earliest Paleocene.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Willumsen, 2012]:
Diagnosis:
Areoligeracean proximochorate to chorate, acavate cysts, with solid intratabular processes. The numerous processes rising from each paraplate are branched distally and interconnected forming ring trabeculae that indicate the paratabulation of the cyst.
Apical archeopyle, type tA with zigzag margin.
Surface of autocyst is finely punctuated.
Description:
A circular intermediate-sized proximochorate to chorate, acavate cyst, with solid intratabular processes which form distal ring trabeculae indicating each paraplate of the cyst. The cyst surface is finely punctatae and c. 2 µm thick.
The numerous (40–50) thin (1–2 µm thick), solid and fairly long (20–25 µm) intratabular processes are connected distally by trabeculae. The base of the intratabular processes in each ring form an annular complex on each plate. Processes branch out distally into smooth trifurcate branches that are interconnected with trabeculae forming a ring (Plate 1, figure 5).
Archeopyle is apical, type tA with zigzag margin; operculum is often detached.
Paratabulation is reflected by the intratabular complexes, ring trabeculae, and the apical archeopyle.
Dimensions:
Specimens measured 10; length 48(51)58 µm; width 42(45)55 µm; length of processes 15(19)25 µm.
Affinities/Discussion:
Wilson (1987, plate 2, figures 1, 2) illustrated a similar specimen and placed it in the genus Systematophora, but the penitabular processes arising from the cyst are interconnected distally forming a ring trabeculae reflecting paratabulation of the cyst. Willumsen (2003) placed a specimen similar to Wilson’s (1987) Systematophora in the genus Adnatosphaeridium (plate 1, figures 1–3), but later transferred it to Alisocysta sp. cf. A. circumtabulata (figure 7E, Willumsen 2011). Adnatosphaeridium regulatum sp. nov. differs from the type species A. vittatum (Williams and Downie 1966) by having thin, solid and relatively elongated processes that are distally connected forming a ring trabeculae. Additionally, A. vittatum has hollow and open branched processes on the central body and branches of processes can be interconnected with processes from other plates. A. regulatum sp. nov. differs from A. multispinosum (Williams and Downie 1966) by lacking short unconnected spines on the trabecula. Fensome et al. (2009) consider A. vittatum and A. multispinosum to be synonymous. Adnatosphaeridium regulatum sp. nov. differs from A. membraniphorum (Jan du Chêne and Adediran 1985) by not having perforated membranes at the tip of each process corresponding to a paraplate. A parasulcal platform diagnostic of the species A. buccinum (Hultberg 1985) was not observed in any of the studied specimens of A. regulatum sp. nov. A. regulatum sp. nov. differs from A. filiferum (Cookson and Eisenack 1958) by having processes of equal length and width that are not flattened distally. Processes of A. williamsii (Islam 1983) branch out to trabeculae that are interconnected, but differ by bearing a few free spines and by not forming ring trabeculae.