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Thalassiphora rota
Thalassiphora rota Schiøler, 2005, p.31–32, pl.5, figs.1–4; text-figs.7a–b.
Holotype: Schiøler, 2005, pl.5, fig.1; text-fig.7a.
Age: latest Aquitanian–earliest Burdigalian.
Original description (Schioler, 2005):
Thalassiphora rota sp. nov. (Pl. 5, figs 1–4; Fig. 7)
1986b Thalassiphora? sp. A Powell: 121, pl. 5, fig. 4.
1986c Thalassiphora? sp. A Powell: 139, pl. 1, fig. 4.
1989 ?Invertocysta sp. 1 Manum et al.: 642, pl. 3, fig. 9.
1995 Dalella siciliense Zevenboom & Santarelli (in Zevenboom): 169, pl. III, figs 1–6.
Type species. Thalassiphora pelagica (Eisenack, 1954) Eisenack & Gocht, 1960 emend. Benedek & Gocht, 1981.
Derivation of name. Latin: rota, -ae, wheel. With reference to the general shape of the species.
Diagnosis. Chorate gonyaulacoid cyst surrounded by a subcircular, ring-shaped membranous and perforated ectophragm connected to the cyst body by nine processes. Archaeopyle precingular (type P3´´).
Holotype. MGUH 26748, SM 452 (Pl. 5, fig. 1; Fig. 7a).
Paratypes. (1) MGUH 26749 (Pl. 5, fig. 2; Fig. 7b); (2) MGUH 26750, SM 509 (Pl. 5, fig. 4).
Horizon. Lark Formation, 5270–5300# (1615.4–1606.3 m). Lowermost Burdigalian.
Description. Large gonyaulacoid autocyst, composed of a subcircular to oval central body and a ring-shaped membranous ectophragm. The central body is thin-walled and smooth, lacking indication of paratabulation apart from the angular precingular archaeopyle. The ectophragm is separated from the central body by nine, usually straight to slightly curved processes which are oval in cross-section at their proximal point of attachment, but elsewhere are flat with a thickened central ridge. The processes appear almost evenly distributed on the dorsal surface of the central body close to its ambitus, giving the cyst a wheel-like appearance. It is not possible to determine the exact location of the processes, as the paratabulation of the species cannot be determined, except for the archaeopyle. The processes are probably attached on precingular, cingular and postcingular paraplates, as well as apically and antapically. For ease of recognition, the nine processes have been numbered 1–9 in a counterclockwise manner on the cyst positioned with its dorsal side up, with 1 being the process located directly above the archaeopyle (Fig. 7). When numbered in this way, processes 5 and 6 can be found in antapical position, 4 and 7 occupying postcingular positions, 8 and 3 cingular positions and 2 and 9 in precingular positions (Fig. 7). Distally, the processes are connected by a thin-walled ectophragm that curls over to the ventral side of the cyst. Ventrally, the ectophragm has a very large sub-circular opening that extends almost to the perimeter. The ectophragm usually has two large perforations in apical and antapical position, located above processes 1, 2 and 9 and 4–7 (Pl. 5, figs 1–3; Fig. 7). These two perforations are located on the dorsal side of the cyst and create a ribbon-like connection between the adjacent processes (between processes 1, 9 and 4, 5 in Fig. 7a; between 1, 2, 9 and 5, 6, 7 in Fig. 7b). Additional perforations may occur between the two large perforations (Fig. 7b). The archaeopyle is precingular, type P3´´, from its shape and position. The paracingulum is indicated on some specimens by low ridges on the periphragm (Fig. 7a above process 8; Pl. 5, fig. 1). Apart from the archaeopyle and rare indications of paracingulum, the paratabulation is not indicated on the cyst.
Dimensions (15 specimens were measured (µm)
Holotype: Length cyst body, 48 ; Width cyst body 45 ; Overall diameter (mean) 112
Range: Length cyst body, 39 (44) 50 ; Width cyst body 30 (37) 47 ; Overall diameter (mean) 80 (100) 121
Stratigraphical range. Uppermost Aquitanian to lowermost Burdigalian in Alma-1X.
Remarks. Manum et al. (1989, pl. 3, fig. 9) figured a specimen of a dinoflagellate cyst similar to Thalassiphora rota from ODP Site 643 in the Norwegian Sea as ?Invertocysta sp. 1. This taxon has nine processes connecting the cyst body with the ectophragm. The two taxa are considered conspecific. The taxon recorded by Manum and collaborators is restricted to the Early Miocene Evitosphaerula paratabulata Zone of Manum et al. (1989) and thus occurs in the same interval as T. rota. Zevenboom & Santarelli in Zevenboom (1995) figured two specimens of the manuscript species ‘Dalella siciliense’ from strata of Serravallian–Tortonian (Mid–Late Miocene) age in Sicily, South Italy. The taxon is similar to T. rota and the two taxa are probably conspecific. However, the stratigraphical occurrence interval for the Sicilian specimens is clearly above that of the specimens reported from the North Sea and the Greenland Sea. Powell (1986b, pl. 5, fig. 4; 1986c, pl. 1, fig. 4) figured specimens similar to T. rota as Thalassiphora? sp. A from the Aquitanian and Tortonian stages of the Piedmont Basin, north Italy. The specimens are considered conspecific with T. rota. Head et al. (1989a, pl. 4, figs 1, 2, 4; pl. 6, figs 1–3, 6, 7) figured specimens similar to the new species (as Gen. et sp. indet. 1) from the Upper Miocene of ODP Leg 105, Labrador Sea. However, these differ in having fewer connecting processes than the new species and in being much smaller; only two-thirds of the size of T. rota. Specimens of Thalassiphora cf. delicata, an undescribed taxon from the Paleocene of the North Sea illustrated by Powell (1992, pl. 4.4, fig. 5), are similar to T. rota in being wheel-shaped and in having perforations in the periphragm. The new taxon differs from T. cf. delicata in having larger perforations and thinner processes.
Holotype: Schiøler, 2005, pl.5, fig.1; text-fig.7a.
Age: latest Aquitanian–earliest Burdigalian.
Original description (Schioler, 2005):
Thalassiphora rota sp. nov. (Pl. 5, figs 1–4; Fig. 7)
1986b Thalassiphora? sp. A Powell: 121, pl. 5, fig. 4.
1986c Thalassiphora? sp. A Powell: 139, pl. 1, fig. 4.
1989 ?Invertocysta sp. 1 Manum et al.: 642, pl. 3, fig. 9.
1995 Dalella siciliense Zevenboom & Santarelli (in Zevenboom): 169, pl. III, figs 1–6.
Type species. Thalassiphora pelagica (Eisenack, 1954) Eisenack & Gocht, 1960 emend. Benedek & Gocht, 1981.
Derivation of name. Latin: rota, -ae, wheel. With reference to the general shape of the species.
Diagnosis. Chorate gonyaulacoid cyst surrounded by a subcircular, ring-shaped membranous and perforated ectophragm connected to the cyst body by nine processes. Archaeopyle precingular (type P3´´).
Holotype. MGUH 26748, SM 452 (Pl. 5, fig. 1; Fig. 7a).
Paratypes. (1) MGUH 26749 (Pl. 5, fig. 2; Fig. 7b); (2) MGUH 26750, SM 509 (Pl. 5, fig. 4).
Horizon. Lark Formation, 5270–5300# (1615.4–1606.3 m). Lowermost Burdigalian.
Description. Large gonyaulacoid autocyst, composed of a subcircular to oval central body and a ring-shaped membranous ectophragm. The central body is thin-walled and smooth, lacking indication of paratabulation apart from the angular precingular archaeopyle. The ectophragm is separated from the central body by nine, usually straight to slightly curved processes which are oval in cross-section at their proximal point of attachment, but elsewhere are flat with a thickened central ridge. The processes appear almost evenly distributed on the dorsal surface of the central body close to its ambitus, giving the cyst a wheel-like appearance. It is not possible to determine the exact location of the processes, as the paratabulation of the species cannot be determined, except for the archaeopyle. The processes are probably attached on precingular, cingular and postcingular paraplates, as well as apically and antapically. For ease of recognition, the nine processes have been numbered 1–9 in a counterclockwise manner on the cyst positioned with its dorsal side up, with 1 being the process located directly above the archaeopyle (Fig. 7). When numbered in this way, processes 5 and 6 can be found in antapical position, 4 and 7 occupying postcingular positions, 8 and 3 cingular positions and 2 and 9 in precingular positions (Fig. 7). Distally, the processes are connected by a thin-walled ectophragm that curls over to the ventral side of the cyst. Ventrally, the ectophragm has a very large sub-circular opening that extends almost to the perimeter. The ectophragm usually has two large perforations in apical and antapical position, located above processes 1, 2 and 9 and 4–7 (Pl. 5, figs 1–3; Fig. 7). These two perforations are located on the dorsal side of the cyst and create a ribbon-like connection between the adjacent processes (between processes 1, 9 and 4, 5 in Fig. 7a; between 1, 2, 9 and 5, 6, 7 in Fig. 7b). Additional perforations may occur between the two large perforations (Fig. 7b). The archaeopyle is precingular, type P3´´, from its shape and position. The paracingulum is indicated on some specimens by low ridges on the periphragm (Fig. 7a above process 8; Pl. 5, fig. 1). Apart from the archaeopyle and rare indications of paracingulum, the paratabulation is not indicated on the cyst.
Dimensions (15 specimens were measured (µm)
Holotype: Length cyst body, 48 ; Width cyst body 45 ; Overall diameter (mean) 112
Range: Length cyst body, 39 (44) 50 ; Width cyst body 30 (37) 47 ; Overall diameter (mean) 80 (100) 121
Stratigraphical range. Uppermost Aquitanian to lowermost Burdigalian in Alma-1X.
Remarks. Manum et al. (1989, pl. 3, fig. 9) figured a specimen of a dinoflagellate cyst similar to Thalassiphora rota from ODP Site 643 in the Norwegian Sea as ?Invertocysta sp. 1. This taxon has nine processes connecting the cyst body with the ectophragm. The two taxa are considered conspecific. The taxon recorded by Manum and collaborators is restricted to the Early Miocene Evitosphaerula paratabulata Zone of Manum et al. (1989) and thus occurs in the same interval as T. rota. Zevenboom & Santarelli in Zevenboom (1995) figured two specimens of the manuscript species ‘Dalella siciliense’ from strata of Serravallian–Tortonian (Mid–Late Miocene) age in Sicily, South Italy. The taxon is similar to T. rota and the two taxa are probably conspecific. However, the stratigraphical occurrence interval for the Sicilian specimens is clearly above that of the specimens reported from the North Sea and the Greenland Sea. Powell (1986b, pl. 5, fig. 4; 1986c, pl. 1, fig. 4) figured specimens similar to T. rota as Thalassiphora? sp. A from the Aquitanian and Tortonian stages of the Piedmont Basin, north Italy. The specimens are considered conspecific with T. rota. Head et al. (1989a, pl. 4, figs 1, 2, 4; pl. 6, figs 1–3, 6, 7) figured specimens similar to the new species (as Gen. et sp. indet. 1) from the Upper Miocene of ODP Leg 105, Labrador Sea. However, these differ in having fewer connecting processes than the new species and in being much smaller; only two-thirds of the size of T. rota. Specimens of Thalassiphora cf. delicata, an undescribed taxon from the Paleocene of the North Sea illustrated by Powell (1992, pl. 4.4, fig. 5), are similar to T. rota in being wheel-shaped and in having perforations in the periphragm. The new taxon differs from T. cf. delicata in having larger perforations and thinner processes.