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Spinidinium bellum
Spinidinium bellum Lucas-Clark, 2006, p.202,204, pl.4, figs.5–9.
Holotype: Lucas-Clark, 2006, pl.4, figs.5–7.
Age: Paleocene.
Original description (Lucas-Clark, 2006)
Holotype. Plate 4, fig. 5–7. South Carolina, Savannah River Site, core P21 132 m, sample 8643.1143, slide c, CGS Zeiss Sh., coordinates 95.0 × 10.0, England Finder reference K32. Carnegie Museum of Natural History CM 19148.
Derivation of name: From the Latin bellus, meaning pretty.
Diagnosis: Small to medium peridinioid cysts, circumcavate, with small to medium apical horn and small, unequally developed antapical horns. Covered in a unique spinose to reticulate ornamentation involving small knobs with widened and sometimes interconnected tips. Distinguished by its ornamentation.
Description:
Small to medium, proximate peridiniacean, cornucavate to circumcavate cysts with a short apical horn and one or two short antapical horns. Antapical horns are unequal in length; right antapical horn reduced or absent. Endophragm smooth to finely granular, about equal in thickness to periphragm, may be appressed to the periphragm in the cingular region. Endocyst circular to ovoidal. Pericyst outline round edperidinioid; later almargin scon vex; antapical marg in concave. Periphragm surface ornamented with coarse, irregularly shaped granules and small processes with knobs and cauliflorate tips. Some knobs appear to be connected as if beginning to form an ectophragm. Ornament intratabular with bare or less ornamented spaces along most sutures. Tabulation indicated by archeopyle, cingulum, and intratabular ornamentation. Tabulation formula 4′, 3a, 7″, ?c, 5′″,?s,2″″. Archeopyletype I (2a), hexagonal, eurydeltaform; operculum free. Accessory archeopyle sutures lie on either side of plate 4′. Exact relationship of endoarcheopyle and periarcheopyle not clear. Cingulum indicated by ornamented ridges and by local indentation in the periphragm; offset at the sulcal region. Sulcus indicated by break in cingulum and depression in the ventral hypocyst. Accumulation bodies sometimes present.
Dimensions:
Length, 75–85 μm; width, 55–65 μm (5 specimens measured).
Remarks: Tabulation is not as clearly expressed in this species in some other forms, but some sutural smooth areas are discernible in all specimens. Tabulation is often not clear in this genus, e.g. in Spinidinium densispinatum. The unusual ornamentation of the periphragm makes generic assignment difficult, as no such ornamentation is included in the description of the genus, however, the intratabular arrangement and general aspect are similar to other species of Spinidinium.
Comparison: The unusual ornamentation of this species distinguishes it from others.
Previously Reported Occurrence: Paleogene, Germany.
Occurrence in Present Study: Lower Paleocene, lower Ellenton Formation, Savanna River Site, South Carolina.
Holotype: Lucas-Clark, 2006, pl.4, figs.5–7.
Age: Paleocene.
Original description (Lucas-Clark, 2006)
Holotype. Plate 4, fig. 5–7. South Carolina, Savannah River Site, core P21 132 m, sample 8643.1143, slide c, CGS Zeiss Sh., coordinates 95.0 × 10.0, England Finder reference K32. Carnegie Museum of Natural History CM 19148.
Derivation of name: From the Latin bellus, meaning pretty.
Diagnosis: Small to medium peridinioid cysts, circumcavate, with small to medium apical horn and small, unequally developed antapical horns. Covered in a unique spinose to reticulate ornamentation involving small knobs with widened and sometimes interconnected tips. Distinguished by its ornamentation.
Description:
Small to medium, proximate peridiniacean, cornucavate to circumcavate cysts with a short apical horn and one or two short antapical horns. Antapical horns are unequal in length; right antapical horn reduced or absent. Endophragm smooth to finely granular, about equal in thickness to periphragm, may be appressed to the periphragm in the cingular region. Endocyst circular to ovoidal. Pericyst outline round edperidinioid; later almargin scon vex; antapical marg in concave. Periphragm surface ornamented with coarse, irregularly shaped granules and small processes with knobs and cauliflorate tips. Some knobs appear to be connected as if beginning to form an ectophragm. Ornament intratabular with bare or less ornamented spaces along most sutures. Tabulation indicated by archeopyle, cingulum, and intratabular ornamentation. Tabulation formula 4′, 3a, 7″, ?c, 5′″,?s,2″″. Archeopyletype I (2a), hexagonal, eurydeltaform; operculum free. Accessory archeopyle sutures lie on either side of plate 4′. Exact relationship of endoarcheopyle and periarcheopyle not clear. Cingulum indicated by ornamented ridges and by local indentation in the periphragm; offset at the sulcal region. Sulcus indicated by break in cingulum and depression in the ventral hypocyst. Accumulation bodies sometimes present.
Dimensions:
Length, 75–85 μm; width, 55–65 μm (5 specimens measured).
Remarks: Tabulation is not as clearly expressed in this species in some other forms, but some sutural smooth areas are discernible in all specimens. Tabulation is often not clear in this genus, e.g. in Spinidinium densispinatum. The unusual ornamentation of the periphragm makes generic assignment difficult, as no such ornamentation is included in the description of the genus, however, the intratabular arrangement and general aspect are similar to other species of Spinidinium.
Comparison: The unusual ornamentation of this species distinguishes it from others.
Previously Reported Occurrence: Paleogene, Germany.
Occurrence in Present Study: Lower Paleocene, lower Ellenton Formation, Savanna River Site, South Carolina.