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Stoveracysta kakanuiensis
Stoveracysta kakanuiensis Clowes, 1985
Holotype: Clowes 1985, pl.1, fig.1-3
Locus typicus: Oamaru, New Zealand
Stratum typicum: Early Oligocene
Original diagnosis: Clowes, 1985, p. 32
Proximate gonyaulacoid cysts, not dorso-ventrally compressed, prolate, lacking horns, consisting of a single wall layer. The ornament comprises low, incomplete, essentially sutural, septa which typically fail to develop on the upper margin of the cingulum, and minor intratabular granules. The archeopyle is apical, type tA; the operculum is free and ornamented with septa similar to those of the cyst body. These septa terminate a short distance from the absolute apex, thus leaving a small granular area at the pole. The full tabulation as defined by the ornament is gonyaulacacean, sexiform, formula: ?pr, 4", 6", X to 6c, 6""", 1p, 1"""", ?4s.
Original description: Clowes, 1985, p. 32
Cysts single layered (unless the septa are interpreted as an extra "layer"), subspherical to quite prolate, not dorso-ventrally compressed, sometimes showing one or two small antapical prominences (Plate 2, fig. 7) but lacking true horns. The archeopyle is apical, six-sided in polar view, not much constricted, type tA; the operculum is free. Ornament comprises low septa (up to 5 µm high), which combine some of both penitabular and sutural features, and intratabular granules. The septa usually comprise a thin, raised membrane spanning the sutures, but these are often dissociated into two "penitabular" elements (Plate 2, fig. 2, 7, 9). This trans-sutural membrane might be interpreted as a reduced periphragm or ectophragm. Where the cingulum is subdivided, the dissociation of septa into penitabular elements can sometimes be seen between adjacent cingular plates by means of scanning electron microscopy (Plate 2, fig. 1, 8). Furthermore, when the operculum ruptures, dissociation becomes complete about the principal archeopyle suture (Plate 1, fig. 8, 10; Plate 2, fig. 1-4, 6, 10, 11). When viewed by transmitted light, the septa take on the appearance of fully penitabular features (Plate 1, fig. 1-12) and careful attention is required to determine that they are not. The septa on the operculum terminate a short distance from the absolute apex. The small area lacking septa thus left at the pole may represent a preapical plate or plates. The intratabular areas of the cyst, as revealed by scanning electron microscopy, are quite coarsely granular; this lends a speckled appearance to the cyst when viewed by transmitted light. The surfaces of the septa are smooth (Plate 2, fig. 5). The tabulation is gonyaulacacean; formula ?pr, 4", 6", 6c, 6""", 1p, 1"""", ?4s. The preapical area, if present, is small. The apical series plates are of similar but not quite equal size (1" < 4" < 2" & 3") and plate 1" is roughly equant rather than elongate (as in some other gonyaulacacean genera such as Meiourogonyaulax) (Plate 1, fig. 11; Plate 2, fig. 6).
Plate 6" is broadly triangular and quite small. The cingulum has a poorly delimited upper margin but is often weakly subdivided (Plate 1, fig. 9; Plate 2, fig. 1, 7, 8). Among the plates of the postcingular series, 1""" is very small and intimately associated with the sulcus (Plate 1, fig. 2-5; Plate 2, fig. 11; Text-Fig. 4b), corresponding in position and size to that of "Alisocysta" ornata (see Stover, 1975, text- fig. 5). Plate Ip is rather large. The antapical plate is six-sided and is in contact with plates 1p, 3""" through 6"", and ps. The sulcus is well-defined but rather weakly subdivided. Dimensions (including ornament). Holotype: overall length 70 µm, length from archeopyle margin to antapex 49 µm, overall breadth 62 µm, diameter of archeopyle 46 µm, width of cingulum ca. 5 µm. Range of specimens (including types): overall length including operculum 62 (m = 67.7, s = 3.6) 74 µm (14 observations), length from archeopyle margin to antapex 49 - 57 µm (4 observations). Overall breadth 52 (m = 58.3, s = 3.6) 65 µm (22 observations), diameter of archeopyle 36 (m = 40.9, s= 3.3) 47 µm (17 observations), width of cingulum ca. 5-6 µm.
Affinities:
Clowes, 1985, p. 33: Stoveracysta kakanuiensis differs from S. ornata in that the septa show many of the characteristics of typical "sutural" ornament and in the failure of the septa to develop between the cingulum and precingular plate series. Furthermore, the cingulum is only weakly subdivided unlike that of the latter species. Plate 1" is roughly equant rather than elongate as in many other gonyaulacacean taxa.
Holotype: Clowes 1985, pl.1, fig.1-3
Locus typicus: Oamaru, New Zealand
Stratum typicum: Early Oligocene
Original diagnosis: Clowes, 1985, p. 32
Proximate gonyaulacoid cysts, not dorso-ventrally compressed, prolate, lacking horns, consisting of a single wall layer. The ornament comprises low, incomplete, essentially sutural, septa which typically fail to develop on the upper margin of the cingulum, and minor intratabular granules. The archeopyle is apical, type tA; the operculum is free and ornamented with septa similar to those of the cyst body. These septa terminate a short distance from the absolute apex, thus leaving a small granular area at the pole. The full tabulation as defined by the ornament is gonyaulacacean, sexiform, formula: ?pr, 4", 6", X to 6c, 6""", 1p, 1"""", ?4s.
Original description: Clowes, 1985, p. 32
Cysts single layered (unless the septa are interpreted as an extra "layer"), subspherical to quite prolate, not dorso-ventrally compressed, sometimes showing one or two small antapical prominences (Plate 2, fig. 7) but lacking true horns. The archeopyle is apical, six-sided in polar view, not much constricted, type tA; the operculum is free. Ornament comprises low septa (up to 5 µm high), which combine some of both penitabular and sutural features, and intratabular granules. The septa usually comprise a thin, raised membrane spanning the sutures, but these are often dissociated into two "penitabular" elements (Plate 2, fig. 2, 7, 9). This trans-sutural membrane might be interpreted as a reduced periphragm or ectophragm. Where the cingulum is subdivided, the dissociation of septa into penitabular elements can sometimes be seen between adjacent cingular plates by means of scanning electron microscopy (Plate 2, fig. 1, 8). Furthermore, when the operculum ruptures, dissociation becomes complete about the principal archeopyle suture (Plate 1, fig. 8, 10; Plate 2, fig. 1-4, 6, 10, 11). When viewed by transmitted light, the septa take on the appearance of fully penitabular features (Plate 1, fig. 1-12) and careful attention is required to determine that they are not. The septa on the operculum terminate a short distance from the absolute apex. The small area lacking septa thus left at the pole may represent a preapical plate or plates. The intratabular areas of the cyst, as revealed by scanning electron microscopy, are quite coarsely granular; this lends a speckled appearance to the cyst when viewed by transmitted light. The surfaces of the septa are smooth (Plate 2, fig. 5). The tabulation is gonyaulacacean; formula ?pr, 4", 6", 6c, 6""", 1p, 1"""", ?4s. The preapical area, if present, is small. The apical series plates are of similar but not quite equal size (1" < 4" < 2" & 3") and plate 1" is roughly equant rather than elongate (as in some other gonyaulacacean genera such as Meiourogonyaulax) (Plate 1, fig. 11; Plate 2, fig. 6).
Plate 6" is broadly triangular and quite small. The cingulum has a poorly delimited upper margin but is often weakly subdivided (Plate 1, fig. 9; Plate 2, fig. 1, 7, 8). Among the plates of the postcingular series, 1""" is very small and intimately associated with the sulcus (Plate 1, fig. 2-5; Plate 2, fig. 11; Text-Fig. 4b), corresponding in position and size to that of "Alisocysta" ornata (see Stover, 1975, text- fig. 5). Plate Ip is rather large. The antapical plate is six-sided and is in contact with plates 1p, 3""" through 6"", and ps. The sulcus is well-defined but rather weakly subdivided. Dimensions (including ornament). Holotype: overall length 70 µm, length from archeopyle margin to antapex 49 µm, overall breadth 62 µm, diameter of archeopyle 46 µm, width of cingulum ca. 5 µm. Range of specimens (including types): overall length including operculum 62 (m = 67.7, s = 3.6) 74 µm (14 observations), length from archeopyle margin to antapex 49 - 57 µm (4 observations). Overall breadth 52 (m = 58.3, s = 3.6) 65 µm (22 observations), diameter of archeopyle 36 (m = 40.9, s= 3.3) 47 µm (17 observations), width of cingulum ca. 5-6 µm.
Affinities:
Clowes, 1985, p. 33: Stoveracysta kakanuiensis differs from S. ornata in that the septa show many of the characteristics of typical "sutural" ornament and in the failure of the septa to develop between the cingulum and precingular plate series. Furthermore, the cingulum is only weakly subdivided unlike that of the latter species. Plate 1" is roughly equant rather than elongate as in many other gonyaulacacean taxa.