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Gonyaulacysta aldorfensis
Gonyaulacysta aldorfiensis Gocht, 1970
Now Aldorfia. Originally Gonyaulacysta, subsequently (and now) Aldorfia.
Holotype: Gocht, 1970, pl.31, figs.10a-c; Jan du Chene et al., 1986, pl.6, figs.1-3
Locus typicus: Aldorf 12 bore, near Diepholz, northwest Germany
Stratum typicum: Early Bathonian
Translation Gocht, 1970: Fensome et al., 1993
Original diagnosis: Gocht, 1970, p.136
Body slightly elongated, with pointed epitract and rounded hypotract. Cingulum indented, and displaced by about l1/2 times its width. Posteriorly from the line of the cingulum, the sulcus is deeply indented. Sutures generally suppressed; when present, Gonyaulax-like. Archeopyle precingular, corresponds to 3".
Periphragm and endophragm distinctly separate. Pericoel bridged by curved, partially net-like, interconnected lists or by simple fibres, which stand up radially from the membranous surfaces and are especially high at the poles. The "flagellar mark" is distinct.
Original description: Gocht, 1970, p.136-137
The species, which is very variable in outline and ornamentation, can be readily recognized by the design and strong brown colouration of the wall. The epitract, which is rounded bell-shaped, emphasizes the apex and the commonly distinct cingular zone, whereas the hypotract is in the form of an elongate cone and is rounded-off or truncated only in the area of the antapical field.
Plate boundaries are mostly either missing or barely discernible. However, the middorsal precingular plate is well developed, even when the archeopyle - which develops from it - is still closed. The crests, which surround the cingulum, can likewise be clearly seen. Of the remaining sutures, only the crests in the dorsal postcingular series are occasionally visible. Only in exceptional cases do we find specimens of the type shown in [Gocht, 1970] Plate 30, Figure 2, which shows almost the entire ventral tabulation. In the drawing shown in [Gocht, 1970] Text-Figure 5 we have attempted to interpret the tabulation. The different degrees of clarity of the plate boundaries are not to be looked upon as states of preservation, but are an expression of the normal range of variation.
On the ventral surface, running between the plates at both poles, is an elongate sulcal area, which interrupts the cingulum. The true, deeply indented sulcus belongs to the hypotract and begins at the "flagellar mark" (located between the ends of the cingulum) and - in the form of a narrow furrow - extends posteriorly, up to a point about half-way along the hypotract, at which point it flattens out again ([Gocht, 1970] Plate 31, Figure 10c; Plate 32, Figure 3b). When viewed under the light microscope, this true sulcus appears more translucent than the surrounding membrane.
Scanning electron microscope studies clearly revealed the structure of the cyst wall of the specimens illustrated in [Gocht, 1970] Plate 30, Figures 1-3. For the present purpose, the specimen shown in [Gocht, 1970] Figures 3a-d proved to be especially suitable. Its dorsal side is facing up and its archeopyle operculum is in place. The gap between the operculum and the [rest of the] cyst-wall appears to be wider extemally than internally. This widening must be a secondary phenomenon, since the fommation of the gap must have occurred from the inside, possibly through partial dissolution. Also the remarkable denticulation of the opercular margin (in contrast to the tear on the left half of the operculum) could be explained by such dissolution. However, it is more probable that the denticulate boundary of the operculum is connected with the hollow areas which lie below the operculum: the periphragm, which is very thin at this point, contracts, whereas the margin of the excystment aperture ... is reinforced by a ridge and remains smooth. Fairly smooth excystment aperture margins were also found in the other studied specimens, which possess no opercula.
Endophragm and periphragm are held together by single or clustered fibrous strands. The latter stand by themselves or are arranged in the form of ridges and open reticulations. Between these supporting elements, hollow areas remain which, taken as a whole, represent the pericoel. Because the supporting elements become broader toward the top and bottom, the hollow areas take on a rounded shape; the larger of these cavities are covered over solely by thin periphragm, which dips slightly into the cavities. This explains the undulating surface of the cyst: the periphragm is tightly stretched over a system of supporting elements and supporting ridges and, in areas between the latter, sinks into the individual pericoel cavities ([Gocht, 1970] Plate 30, Figures 3b, 3c; Text-Figure 9c). When studied under the light microscope and viewed from above, the supporting elements show up as dark points, as curved lines or as portions of reticulation ([Gocht, 1970] Plate 31, Figures 10a, 10c; Plate 32, Figures 2, 3). At the margins, however, especially at the poles (where they are very high), these supporting elements are recognizable as supports between the membranes ([Gocht, 1970] Plate 31, Figures 10b, 11; Plate 32, Figure 1). [Gocht, 1970] Text-Figure 9b provides an idealized three-dimensional view of the supporting elements which have joined together to form a network, whereas [Gocht, 1970] Text-Figure 9a shows a schematic reconstruction of the wall structure of the entire external covering.
Because the fibrous strands are closely spaced and the cavities are commonly very small ([Gocht, 1970] Plate 30, Figures 3b, 3c), the boundaries between the three structural elements (namely the endophragm, the radial supporting elements and the periphragm) are not very distinct, a phenomenon which is further promoted by the tendency of the cavities to be rounded. The cyst covering is represented by a fairly uniform, radially fibrous wall of a foamy consistency, while the pericoel is divided into numerous cavities or labyrinth-like ducts. It is somewhat of a paradox that the light microscope, which suppresses the fine structural elements and shows the body in transmitted light, is the one which allows for the more rapid recognition of the basic structural plan. It should be pointed out here that, on the whole, G. aldorfensis is a model example of the different results obtained with experimental techniques using both the scanning electron microscope and the light microscope.
As with the individual lumina of the reticulum, the plate boundaries, where present, are similarly formed by ridges which, in turn, are made up of interconnected radial supporting elements. Since these are usually strongly developed, field boundaries of the first order are formed, between which the entire paraplate area sinks downwards. The paraplate surface itself is again subdivided into areas with lower indentations by means of the remaining supporting ridges. The archeopyle margin, a plate boundary, is bordered by a supporting ridge of the first order. In the vicinity [of the archeopyle margin], the fibrous strands must be especially sturdy and the cavities must be especially small; thus, the [structure at the] break in the shell, formed as the operculum separated, is not necessarily representative for the entire shell in its construction. Actually, the specimens shown in [Gocht, 1970] Plate 30, Figures 3b and 3c illustrate clearly that the pericoel cavities on the other side of the bordering ridge have a larger diameter than those located immediately at the margin of the excystment aperture. It should be re-emphasized that not all of the supporting ridges should be thought of as solid elements, but rather as consolidations of connective strands.
It is not yet clear why the membranes become thinner in the area around the sulcal depression. Sharp "fracture-margins" around the depression possibly indicate that one of the two membranous layers, probably the periphragm, is absent. It is a common phenomenon that the membrane is thinner above the sulcus.
The entire periphragm is perforated by small round pores (diameter 0.1-0.2 Ám).
Holotype: length 79 Ám, width 65 Ám. Range of 90 specimens: length 61-113 Ám, width 53-97 Ám.
Now Aldorfia. Originally Gonyaulacysta, subsequently (and now) Aldorfia.
Holotype: Gocht, 1970, pl.31, figs.10a-c; Jan du Chene et al., 1986, pl.6, figs.1-3
Locus typicus: Aldorf 12 bore, near Diepholz, northwest Germany
Stratum typicum: Early Bathonian
Translation Gocht, 1970: Fensome et al., 1993
Original diagnosis: Gocht, 1970, p.136
Body slightly elongated, with pointed epitract and rounded hypotract. Cingulum indented, and displaced by about l1/2 times its width. Posteriorly from the line of the cingulum, the sulcus is deeply indented. Sutures generally suppressed; when present, Gonyaulax-like. Archeopyle precingular, corresponds to 3".
Periphragm and endophragm distinctly separate. Pericoel bridged by curved, partially net-like, interconnected lists or by simple fibres, which stand up radially from the membranous surfaces and are especially high at the poles. The "flagellar mark" is distinct.
Original description: Gocht, 1970, p.136-137
The species, which is very variable in outline and ornamentation, can be readily recognized by the design and strong brown colouration of the wall. The epitract, which is rounded bell-shaped, emphasizes the apex and the commonly distinct cingular zone, whereas the hypotract is in the form of an elongate cone and is rounded-off or truncated only in the area of the antapical field.
Plate boundaries are mostly either missing or barely discernible. However, the middorsal precingular plate is well developed, even when the archeopyle - which develops from it - is still closed. The crests, which surround the cingulum, can likewise be clearly seen. Of the remaining sutures, only the crests in the dorsal postcingular series are occasionally visible. Only in exceptional cases do we find specimens of the type shown in [Gocht, 1970] Plate 30, Figure 2, which shows almost the entire ventral tabulation. In the drawing shown in [Gocht, 1970] Text-Figure 5 we have attempted to interpret the tabulation. The different degrees of clarity of the plate boundaries are not to be looked upon as states of preservation, but are an expression of the normal range of variation.
On the ventral surface, running between the plates at both poles, is an elongate sulcal area, which interrupts the cingulum. The true, deeply indented sulcus belongs to the hypotract and begins at the "flagellar mark" (located between the ends of the cingulum) and - in the form of a narrow furrow - extends posteriorly, up to a point about half-way along the hypotract, at which point it flattens out again ([Gocht, 1970] Plate 31, Figure 10c; Plate 32, Figure 3b). When viewed under the light microscope, this true sulcus appears more translucent than the surrounding membrane.
Scanning electron microscope studies clearly revealed the structure of the cyst wall of the specimens illustrated in [Gocht, 1970] Plate 30, Figures 1-3. For the present purpose, the specimen shown in [Gocht, 1970] Figures 3a-d proved to be especially suitable. Its dorsal side is facing up and its archeopyle operculum is in place. The gap between the operculum and the [rest of the] cyst-wall appears to be wider extemally than internally. This widening must be a secondary phenomenon, since the fommation of the gap must have occurred from the inside, possibly through partial dissolution. Also the remarkable denticulation of the opercular margin (in contrast to the tear on the left half of the operculum) could be explained by such dissolution. However, it is more probable that the denticulate boundary of the operculum is connected with the hollow areas which lie below the operculum: the periphragm, which is very thin at this point, contracts, whereas the margin of the excystment aperture ... is reinforced by a ridge and remains smooth. Fairly smooth excystment aperture margins were also found in the other studied specimens, which possess no opercula.
Endophragm and periphragm are held together by single or clustered fibrous strands. The latter stand by themselves or are arranged in the form of ridges and open reticulations. Between these supporting elements, hollow areas remain which, taken as a whole, represent the pericoel. Because the supporting elements become broader toward the top and bottom, the hollow areas take on a rounded shape; the larger of these cavities are covered over solely by thin periphragm, which dips slightly into the cavities. This explains the undulating surface of the cyst: the periphragm is tightly stretched over a system of supporting elements and supporting ridges and, in areas between the latter, sinks into the individual pericoel cavities ([Gocht, 1970] Plate 30, Figures 3b, 3c; Text-Figure 9c). When studied under the light microscope and viewed from above, the supporting elements show up as dark points, as curved lines or as portions of reticulation ([Gocht, 1970] Plate 31, Figures 10a, 10c; Plate 32, Figures 2, 3). At the margins, however, especially at the poles (where they are very high), these supporting elements are recognizable as supports between the membranes ([Gocht, 1970] Plate 31, Figures 10b, 11; Plate 32, Figure 1). [Gocht, 1970] Text-Figure 9b provides an idealized three-dimensional view of the supporting elements which have joined together to form a network, whereas [Gocht, 1970] Text-Figure 9a shows a schematic reconstruction of the wall structure of the entire external covering.
Because the fibrous strands are closely spaced and the cavities are commonly very small ([Gocht, 1970] Plate 30, Figures 3b, 3c), the boundaries between the three structural elements (namely the endophragm, the radial supporting elements and the periphragm) are not very distinct, a phenomenon which is further promoted by the tendency of the cavities to be rounded. The cyst covering is represented by a fairly uniform, radially fibrous wall of a foamy consistency, while the pericoel is divided into numerous cavities or labyrinth-like ducts. It is somewhat of a paradox that the light microscope, which suppresses the fine structural elements and shows the body in transmitted light, is the one which allows for the more rapid recognition of the basic structural plan. It should be pointed out here that, on the whole, G. aldorfensis is a model example of the different results obtained with experimental techniques using both the scanning electron microscope and the light microscope.
As with the individual lumina of the reticulum, the plate boundaries, where present, are similarly formed by ridges which, in turn, are made up of interconnected radial supporting elements. Since these are usually strongly developed, field boundaries of the first order are formed, between which the entire paraplate area sinks downwards. The paraplate surface itself is again subdivided into areas with lower indentations by means of the remaining supporting ridges. The archeopyle margin, a plate boundary, is bordered by a supporting ridge of the first order. In the vicinity [of the archeopyle margin], the fibrous strands must be especially sturdy and the cavities must be especially small; thus, the [structure at the] break in the shell, formed as the operculum separated, is not necessarily representative for the entire shell in its construction. Actually, the specimens shown in [Gocht, 1970] Plate 30, Figures 3b and 3c illustrate clearly that the pericoel cavities on the other side of the bordering ridge have a larger diameter than those located immediately at the margin of the excystment aperture. It should be re-emphasized that not all of the supporting ridges should be thought of as solid elements, but rather as consolidations of connective strands.
It is not yet clear why the membranes become thinner in the area around the sulcal depression. Sharp "fracture-margins" around the depression possibly indicate that one of the two membranous layers, probably the periphragm, is absent. It is a common phenomenon that the membrane is thinner above the sulcus.
The entire periphragm is perforated by small round pores (diameter 0.1-0.2 Ám).
Holotype: length 79 Ám, width 65 Ám. Range of 90 specimens: length 61-113 Ám, width 53-97 Ám.