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Wilsonidium compactum
Wilsonidium compactum Michoux, 1988
Originally Wilsonidium, subsequently (and now) Castellodinium.
Holotype: Michoux, 1988, pl.9, figs.1-3, text-figs.13A-B
Locus typicus: "Couches de Nousse" Nousse area, France
Stratum typicum: Middle Eocene
Original diagnosis: Michoux, 1988, p. 38
Circumcavate peridinioid cyst, pentagonal to subcircular in outline, with moderate
dorso-ventral compression. Paratabulation outlined by short, blunt, parasutural processes, sometimes supported by a proximal membrane. Archeopyle rounded-rectangular. Opercula free, often adherent.
Original description: Michoux, 1988, p. 39-39
Cyst shape is highly variable, due to differential horn development, ranging from pentagonal to rhomboidal to subcircular. The endophragm is subcircular to rhomboidal. The cyst is typically circumcavate, although in some cases the periphragm and endophragm may come in contact over a limited portion of the perimeter. The periphragm is smooth, and the endophragm slightly granular. Relatively short (up to 6 µm in length), blunt processes are aligned along the parasutures, isolated or arising from a proximal membrane. The complete sulcal paratabulation is expressed. Anterior sulcal (as) paraplate is quadrangular, overlying two adjacent, elongated, oblique paraplates separated by a row of free standing processes. The posterior sulcal (ps) paraplate occupies the entire posterior part of the ventral hypocyst. The archeopyle is rectangular with rounded corners. The periarcheopyle is slightly higher than the endoarcheopyle. Although the archeopyle suture is developed around the entire perimeter of paraplate 2a, the opercula generally remain adherent. Paratabulation formula: 4", 3a, 7", Xc, 5""", 2"""", 4s.
Dimensions. Pericyst. Length: 90 (99) 108 µm. Width: 90 (94) 99 µm. Holotype: 99 x 90 µm. Archeopyle. Length: 21 (22.8) 23 µm. Width: 18 (21.6) 22 µm. Holotype: 22 x 22 µm.
Affinities:
Michoux, 1988, p. 39: Wilsonidium compactum is comparable to Wilsonidium echinosuturatum (Wilson) Lentin & Williams in possessing parasutural membranes supporting the processes. W. echinosuturatum, however, is much larger (up to 160 µm in length, according to Wilson, 1967, p. 479), with larger horns, and bears more prominent parasutural crests and longer processes (up to 16 µm in length) that are oblate or capitate rather than blunt.
Originally Wilsonidium, subsequently (and now) Castellodinium.
Holotype: Michoux, 1988, pl.9, figs.1-3, text-figs.13A-B
Locus typicus: "Couches de Nousse" Nousse area, France
Stratum typicum: Middle Eocene
Original diagnosis: Michoux, 1988, p. 38
Circumcavate peridinioid cyst, pentagonal to subcircular in outline, with moderate
dorso-ventral compression. Paratabulation outlined by short, blunt, parasutural processes, sometimes supported by a proximal membrane. Archeopyle rounded-rectangular. Opercula free, often adherent.
Original description: Michoux, 1988, p. 39-39
Cyst shape is highly variable, due to differential horn development, ranging from pentagonal to rhomboidal to subcircular. The endophragm is subcircular to rhomboidal. The cyst is typically circumcavate, although in some cases the periphragm and endophragm may come in contact over a limited portion of the perimeter. The periphragm is smooth, and the endophragm slightly granular. Relatively short (up to 6 µm in length), blunt processes are aligned along the parasutures, isolated or arising from a proximal membrane. The complete sulcal paratabulation is expressed. Anterior sulcal (as) paraplate is quadrangular, overlying two adjacent, elongated, oblique paraplates separated by a row of free standing processes. The posterior sulcal (ps) paraplate occupies the entire posterior part of the ventral hypocyst. The archeopyle is rectangular with rounded corners. The periarcheopyle is slightly higher than the endoarcheopyle. Although the archeopyle suture is developed around the entire perimeter of paraplate 2a, the opercula generally remain adherent. Paratabulation formula: 4", 3a, 7", Xc, 5""", 2"""", 4s.
Dimensions. Pericyst. Length: 90 (99) 108 µm. Width: 90 (94) 99 µm. Holotype: 99 x 90 µm. Archeopyle. Length: 21 (22.8) 23 µm. Width: 18 (21.6) 22 µm. Holotype: 22 x 22 µm.
Affinities:
Michoux, 1988, p. 39: Wilsonidium compactum is comparable to Wilsonidium echinosuturatum (Wilson) Lentin & Williams in possessing parasutural membranes supporting the processes. W. echinosuturatum, however, is much larger (up to 160 µm in length, according to Wilson, 1967, p. 479), with larger horns, and bears more prominent parasutural crests and longer processes (up to 16 µm in length) that are oblate or capitate rather than blunt.