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Phthanoperidinium vozzhennikovae
Phthanoperidinium vozzhennikovae Stotland in Andreeva-Grigorovich et al., 2011, p.38–39, pl.55, figs.1–9; pl.56, figs.1–3.
Holotype: Andreeva-Grigorovich et al., 2011, pl.55, figs.1–9.
Age: Rupelian.
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Original description: [Andreeva-Grigorovich et al., 2011] (translated from Russian):
Phthanoperidinium vozzhennikovae Stotland sp. nov. Plate LV, 1-9; Plate LVI, 1-3
Name: In honor of Tamara Fedorovna Vozhennikova, the founder of the study of fossil dinoflagellates in the USSR.
Diagnosis. Round-shaped, acavate peridiniacean cyst, dorsoventrally com-pressed, paratabulation expressed by very low ridges, often indistinctly. Small apical horn is triangular. in shape, antapical horns very much reduced and are often invisible. Peri- and endophragm are very thin and closely appressed. Sur-face of paraplates is plain, unfigured.
Description. An acavacean cyst with often indistinct peridinioid paratabulation expressed by very low and wide ridges at the base. The outline in the dorsoventral projection is rounded, in the lateral one it is elongated-elliptical. The "compression" coefficient is 0.4-0.5. The epicysta is equal in length to the hypocyst. The apical triangular horn is small (up to 4 μm). Both antapical horns are strongly reduced (Pl. LVI, 16, 26, 22): the left one sometimes rises by 2-3 μm (Pl. LV, 8, LVI, la-12), the right one is practically not expressed. The peri and endophragm are thin, tightly pressed against each other. The surface of the periphragm is smooth. Both phragms take part in the formation of the structure of the horns and parasutural ridges without the formation of the pericoel. The ridges are low (up to 3 microns).
Paratabulation and outline of individual plates are normal for representatives of the genus. Paracingulum wide (up to 8 µm; pl. LV, 3), narrowing toward parasulcus, helicoid, twisted to the left by the value of its width. Parasulcus narrow at the ends of cingulum, significantly widening toward antapex. Archaeopile intercalary, combined, type 31, operculum free.
Holotype. Pl. LV, 1–9. Prep. 79022-82-03 (coordinates relative to the lower left corner of the coverslip: 18.4 × 12). Paratypes: Pl. LVI, Prep. 79022-82-08: first figs. 1a–12 (47.4 × 17.5); second figs. 2a–22 (19.5 × 11); third fig. 3a–3g (27.7 × 19.3).
Location. Outcrop near the village of Novi Petrovtsy, Mezhyhirya suite, amber-bearing layers (Kiev region, right bank of the Dnieper River).
Dimensions (µm). Holotype: pericyst length 46; pericyst width - 44; horn height: apical 3, left antapical 2; width of the paracingulum up to 7. Other specimens (27 specimens): pericyst length 45-50, pericyst width 43-46; horn height: apical 2.5-3, left antapical no more than 2; paracingulum width - up to 8.
Comparison. Based on the smoothness of the surface of the paratabulation plates, the species can be compared with Ph. delicatum Michoux, 1985, but our specimens differ from the latter in a whole range of other morphological features.
Distribution. Ukraine, Zhitomir region, Yemilchansky district, Barashivska amber-bearing zone, Viktorovskaya area; Kiev region, outcrop near the village of Novi Petrovtsy, Mezhyhirya suite (amber-bearing layers). Lower Oligocene (Rupelian).
Holotype: Andreeva-Grigorovich et al., 2011, pl.55, figs.1–9.
Age: Rupelian.
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Original description: [Andreeva-Grigorovich et al., 2011] (translated from Russian):
Phthanoperidinium vozzhennikovae Stotland sp. nov. Plate LV, 1-9; Plate LVI, 1-3
Name: In honor of Tamara Fedorovna Vozhennikova, the founder of the study of fossil dinoflagellates in the USSR.
Diagnosis. Round-shaped, acavate peridiniacean cyst, dorsoventrally com-pressed, paratabulation expressed by very low ridges, often indistinctly. Small apical horn is triangular. in shape, antapical horns very much reduced and are often invisible. Peri- and endophragm are very thin and closely appressed. Sur-face of paraplates is plain, unfigured.
Description. An acavacean cyst with often indistinct peridinioid paratabulation expressed by very low and wide ridges at the base. The outline in the dorsoventral projection is rounded, in the lateral one it is elongated-elliptical. The "compression" coefficient is 0.4-0.5. The epicysta is equal in length to the hypocyst. The apical triangular horn is small (up to 4 μm). Both antapical horns are strongly reduced (Pl. LVI, 16, 26, 22): the left one sometimes rises by 2-3 μm (Pl. LV, 8, LVI, la-12), the right one is practically not expressed. The peri and endophragm are thin, tightly pressed against each other. The surface of the periphragm is smooth. Both phragms take part in the formation of the structure of the horns and parasutural ridges without the formation of the pericoel. The ridges are low (up to 3 microns).
Paratabulation and outline of individual plates are normal for representatives of the genus. Paracingulum wide (up to 8 µm; pl. LV, 3), narrowing toward parasulcus, helicoid, twisted to the left by the value of its width. Parasulcus narrow at the ends of cingulum, significantly widening toward antapex. Archaeopile intercalary, combined, type 31, operculum free.
Holotype. Pl. LV, 1–9. Prep. 79022-82-03 (coordinates relative to the lower left corner of the coverslip: 18.4 × 12). Paratypes: Pl. LVI, Prep. 79022-82-08: first figs. 1a–12 (47.4 × 17.5); second figs. 2a–22 (19.5 × 11); third fig. 3a–3g (27.7 × 19.3).
Location. Outcrop near the village of Novi Petrovtsy, Mezhyhirya suite, amber-bearing layers (Kiev region, right bank of the Dnieper River).
Dimensions (µm). Holotype: pericyst length 46; pericyst width - 44; horn height: apical 3, left antapical 2; width of the paracingulum up to 7. Other specimens (27 specimens): pericyst length 45-50, pericyst width 43-46; horn height: apical 2.5-3, left antapical no more than 2; paracingulum width - up to 8.
Comparison. Based on the smoothness of the surface of the paratabulation plates, the species can be compared with Ph. delicatum Michoux, 1985, but our specimens differ from the latter in a whole range of other morphological features.
Distribution. Ukraine, Zhitomir region, Yemilchansky district, Barashivska amber-bearing zone, Viktorovskaya area; Kiev region, outcrop near the village of Novi Petrovtsy, Mezhyhirya suite (amber-bearing layers). Lower Oligocene (Rupelian).