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Spiniferella grigorovichiae
Derivation of name. Named after the palynologist Dr Aida S. Andreyeva-Grigorovich.
Holotype. Plate 1, figure 2, slide R-43/57A, coordinates 100.5�21, lateral view, Ravninnaya R43 borehole, sample R43-57, collection number IGG-1/23-02. Specimen dimensions: total length 128mm, total width 54mm; central body length 49mm, central body width 43mm, length of processes 11mm; length of apical horn 79mm, height of septa 3.5mm.
Paratype. Plate 1, figures 6, 7, slide R43/57B, coordinates 95�13. Specimen in dorsal view, figure 6 – middle focus, figure 7 – high focus, Ravninnaya R43 borehole, sample R43- 57, collection number IGG-2/23-03. Specimen dimensions: total length 132mm, total width 52mm, central body length 54mm, central body width 38mm, length of processes 14mm, length of apical horn 62mm, height of septa 2.0mm.
Type locality. The village of Ravninny in the vicinity of Volgograd, Volgograd region, Russia.
Type stratum. The Keresta Formation, Volga–Caspian subregion.
Diagnosis. Gonyaulacacean proximochorate cyst with an ellipsoidal body bearing a long apical horn, spiniferate gonal and sutural processes and sutural septa. Last precingular plate subquadrangular to pentangular. The wall is thick, two- layered. Cysts are acavate. Archaeopyle precingular, type P (3ʺ); operculum free. Cingulum is laevorotatory.
Description. Species of Spiniferella, characterised by an ellipsoidal body with a thick bilaminar wall. Endophragm and periphragm are probably of equal thicknesses. Periphragm is finely- granular. Processes are gonal and sutural, distally dissected, trifurcate and bifurcate, respectively. The processes are proximally dilated and turn into septa that delimit the plates. Septum is thin, transparent, finely-granular, with the edges ornamented with denticles (Plate 1, figure 3). The apical horn is long, slender, hollow, generally curved, dilated in proximal part that bears spines (Plate 1, figures 1–3). The apical horn is longer than the central body generally by no less than 1.3–1.5. Archaeopyle is large, precingular, type P (3ʺ); operculum free. Tabulation distinct 40, 600, 6c, 5–6000, 1p, 10000(Figure 2). Last precingular plate (600of rotund-pentagonal shape) (Plate 1, figures 4, 5). Cingulum is narrow, formed by hexangular or rectangular plates (Plate 1, figures 3, 7). The sulcus widens downwards, and is limited by low septa (Plate 1, figure 10).
Dimensions. Cyst total length 108 (120) 137mm, cyst total width 50 (56) 65, central body length 43 (50) 55mm, central body width 36 (41) 43mm, apical horn length 58 (66) 80mm, process length 10 (13) 14mm, wall width 1.5mm, height of septa 1.5 (3.1) 3.6mm. Number of specimens measured: 18. Variability. Apical horn shapes vary, as do the heights of the spines at the base of the apical horn (Plate 1, figures 1, 6). Apical horn is occasionally broken off (Plate 1, figure 12).
Comparison. The species Spiniferella grigorovichiae sp. nov. differs from Spiniferella cornuta in terms of the central body/ apical horn length ratio, and the shape of apical horn. In the type species Spiniferella cornuta (Plate 1, figure 13) the apical horn lengths (31–46mm) do not exceed the central body lengths (50–56mm) (Stover and Hardenbol 1994), while the apical horn length in Spiniferella grigorovichiae sp. nov. is generally 1.3–1.5 times larger than its body length. Note that the two species occur in the same samples of the Keresta Formation. Statistical measurements of these forms show that the areas of distribution of the main parameters (total length/total width) of the two species do not overlap (Figure 3). This distribution of features suggests a stable divergence.
Occurrence. The south of the Russian Platform, the Keresta Formation in the Ravninnaya R43 borehole, Volgograd–Volga region. Crimean Peninsula, the Kuma Formation in the Bakhchisarai section. Middle Eocene, Lutetian stage.
Holotype. Plate 1, figure 2, slide R-43/57A, coordinates 100.5�21, lateral view, Ravninnaya R43 borehole, sample R43-57, collection number IGG-1/23-02. Specimen dimensions: total length 128mm, total width 54mm; central body length 49mm, central body width 43mm, length of processes 11mm; length of apical horn 79mm, height of septa 3.5mm.
Paratype. Plate 1, figures 6, 7, slide R43/57B, coordinates 95�13. Specimen in dorsal view, figure 6 – middle focus, figure 7 – high focus, Ravninnaya R43 borehole, sample R43- 57, collection number IGG-2/23-03. Specimen dimensions: total length 132mm, total width 52mm, central body length 54mm, central body width 38mm, length of processes 14mm, length of apical horn 62mm, height of septa 2.0mm.
Type locality. The village of Ravninny in the vicinity of Volgograd, Volgograd region, Russia.
Type stratum. The Keresta Formation, Volga–Caspian subregion.
Diagnosis. Gonyaulacacean proximochorate cyst with an ellipsoidal body bearing a long apical horn, spiniferate gonal and sutural processes and sutural septa. Last precingular plate subquadrangular to pentangular. The wall is thick, two- layered. Cysts are acavate. Archaeopyle precingular, type P (3ʺ); operculum free. Cingulum is laevorotatory.
Description. Species of Spiniferella, characterised by an ellipsoidal body with a thick bilaminar wall. Endophragm and periphragm are probably of equal thicknesses. Periphragm is finely- granular. Processes are gonal and sutural, distally dissected, trifurcate and bifurcate, respectively. The processes are proximally dilated and turn into septa that delimit the plates. Septum is thin, transparent, finely-granular, with the edges ornamented with denticles (Plate 1, figure 3). The apical horn is long, slender, hollow, generally curved, dilated in proximal part that bears spines (Plate 1, figures 1–3). The apical horn is longer than the central body generally by no less than 1.3–1.5. Archaeopyle is large, precingular, type P (3ʺ); operculum free. Tabulation distinct 40, 600, 6c, 5–6000, 1p, 10000(Figure 2). Last precingular plate (600of rotund-pentagonal shape) (Plate 1, figures 4, 5). Cingulum is narrow, formed by hexangular or rectangular plates (Plate 1, figures 3, 7). The sulcus widens downwards, and is limited by low septa (Plate 1, figure 10).
Dimensions. Cyst total length 108 (120) 137mm, cyst total width 50 (56) 65, central body length 43 (50) 55mm, central body width 36 (41) 43mm, apical horn length 58 (66) 80mm, process length 10 (13) 14mm, wall width 1.5mm, height of septa 1.5 (3.1) 3.6mm. Number of specimens measured: 18. Variability. Apical horn shapes vary, as do the heights of the spines at the base of the apical horn (Plate 1, figures 1, 6). Apical horn is occasionally broken off (Plate 1, figure 12).
Comparison. The species Spiniferella grigorovichiae sp. nov. differs from Spiniferella cornuta in terms of the central body/ apical horn length ratio, and the shape of apical horn. In the type species Spiniferella cornuta (Plate 1, figure 13) the apical horn lengths (31–46mm) do not exceed the central body lengths (50–56mm) (Stover and Hardenbol 1994), while the apical horn length in Spiniferella grigorovichiae sp. nov. is generally 1.3–1.5 times larger than its body length. Note that the two species occur in the same samples of the Keresta Formation. Statistical measurements of these forms show that the areas of distribution of the main parameters (total length/total width) of the two species do not overlap (Figure 3). This distribution of features suggests a stable divergence.
Occurrence. The south of the Russian Platform, the Keresta Formation in the Ravninnaya R43 borehole, Volgograd–Volga region. Crimean Peninsula, the Kuma Formation in the Bakhchisarai section. Middle Eocene, Lutetian stage.