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Andalusiella gabonensis
From Fensome et al., 2019:
Andalusiella gabonensis, (Stover and Evitt, 1978, p.115) Wrenn and Hart, 1988, p.362.
Holotype: Malloy, 1972, pl.1, fig.17, as Svalbardella australina.
Originally Palaeocystodinium, subsequently (and now) Andalusiella. This species is based on material described by Malloy (1972, p.63, pl.1, fig.17 not pl.1, fig.20).
Age: Maastrichtian.
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Emended description: [Wrenn and Hart, 1988, p. 362]:
Diagnosis:
Fusiform, dorso-ventrally flattened, cavate dinocysts bearing one long tapering horn at each end of the central body. The apical horn may be distally acuminate, rounded, or blunt. The antapical horn bears a short, posteriorly projecting accessory horn or spike along its length or almost distally (but not proximally). The accessory horn occurs on the dinocysts right side of the antapical horn. The structurally simple, spindle-shaped endocyst may or may not extend into the pericoels of the horns formed by the pericyst. The endophragm and the periphragm may be closely appressed in the central body area but are separated in the region of the horns.
Wall relationship varies from cornucavate to circumcavate. The thin endophragm and periphragm may be smooth to slightly granular. The endophragm may be clear or dark brown in color, whereas the periphragm is clear.
The steno-deltaform intercalary archeopyle is of the 1(2a) Type and the operculum is free.
Paratabulation is absent or poorly developed.
Faint suggestions of the location of the parasulcus and paracingulum may be present. The cysts are large and may be more than 250 µm long.
Comments:
Malloy (1972) emended Palaeocystodinium australinum (referred to as Svalbardella australina Cookson 1965 by Malloy, 1972) by: ( I ) redefining the range of cyst dimensions to include much shorter and broader dinocysts than the type material; (2) including cysts with a proximal location for the accessory spur on the antapical horn, rather than being located well along the horn, as originally described by Cookson (1965); (3) including specimens with a much smaller length-to-width ratio for the species than is indicated by the specimens in photographs of the P. australinum type material; (4) including a fundamentally different and significantly more complex structure for the apical horns; (S) citing the presence of a transverse fold as an indication of the location of the paracingulum; and (6) including specimens with a well-developed flagellar scar in the parasulcus.
We reject the emendation of Palaeocystodinium australinum (Cookson) Lentin and Williams 1976 by Malloy (1972) for the following reasons:
1. The size range of the type material from Australia (length, 293 to 302 µm, width,40 to 61 µm) is significantly different from the Gabon material of Malloy (1972; length, 110 to 175 µm, width, 49 to 74 µm). The Gabon material is much shorter and does not approach the lower end of the dinocyst length range cited for the type material of P. australinum by Cookson (1965). The width of the Gabon material extends from the middle to far beyond the upper range of the dinocyst width of the type material.
2. The relative proportion of the length to width is markedly different, whether based on measurements or simple visual comparison of the Australian and Gabon materials. The proportions exhibited by the Gabon material are more similar to the proportions of the genus Andalusiella than to those of P. australinum.
3. The location of the accessory spur is significantly different on the Gabon material and is, in fact, more reminiscent of species of Andalusiella than of P. australinum (Cookson) Lentin and Williams 1976.
4. The fundamentally different and more complex apical and antapical horns on the Gabon material are unlike any reported elsewhere for P. australinum. Malloy (1972) noted "The structure of the apical and antapical portions of the inner cyst appears complex (text-fg.2), with an inner projection ohen filling the horn and tightly enclosed by the periphragm. This interior portion of the horn is attached basally at an area of thickening which forms a "boss" on the inner capsule." (See Fig. 46.1, 4 for comparative structural sketches of the horns on Morphotypes B and C of Malloy (1972) and those of P. australinum of Cookson (1965). Such horn structures have been reported by Riegel and Sarjeant (1982) in Andalusiella mauthei Riegel. (See Fig. 46.5-10.) The contrasting structure of the horns is enough to separate the Gabon specimens of P. australinum sensu Malloy (Morphotype C) from the Australian type material of P. australinum of Cookson (1965).
5. The transverse fold commonly observed marking the paracingulum on the Gabon material (Morphotype C of Malloy, 1972) has not been noted on specimens of P. australinum elsewhere.
6. The intercalary 2a archeopyle outlined on the apical horn structural diagram by Malloy (text-fig. 2; 1972) is an omegaform hexa archeopyle, rather than a steno-deltaform archeopyle that is characteristic of Palaeocystodinium and Svalbardella The archeopyle in Malloy's figure is also unlike any of those shown on specimens in Plate I (Malloy, 1972). We consider this to be a drafting error and not an indication that Malloy (1972) believed Svalbardella and Palaeocystodinium have an omegaform archeopyle. The "inverted" archeopyle on Malloy's diagram -if turned right-side-up is more similar to the archeopyle of Andalusiella than to that of Palaeocystodinium.
7. Finally, the specimens referred to as S. australina and shown in Plate 1, Figures 17 and 20 of Malloy (1972) appear to bear a comma shaped flagellar scar in the parasulcal area. Such structures have not been reported elsewhere for P. australinum. They are evident on the Morphotype B specimens of Malloy (Plate 1, Figs. 8-16, 21; 1972), and on specimens of Andalusiella (see Riegel, 1974, and Riegel and Sarjeant, 1982, for example).
Stover and Evitt (1978) established Palaeocystodinium gabonense to accommodate dinocysts similar to those illustrated in Plate 1, Figures 17 and 20 of Malloy (1972). (A sketch of the former specimen, the Holotype of P. gabonense, is shown in Plate 46, Figure 2, of this paper.) However, they did not alter the emendation of P. australinum proposed by Malloy (1972). We believe that P. gabonense is more closely related to Andalusiella than to Palaeocystodinium because of its overall aspect, the relative proportion of cyst length to width, the presence of a distinct flagellar scar in the parasulcal area, and the presence of dark wall thickenings at the poles of the broadly elongate endocyst. These morphologic features are not characteristic of Palaeocystodinium, but they are of Andalusiella Therefore, we herein transfer P. gabonense Stover and Evitt, 1978, to the genus Andalusiella The specimen illustrated by Malloy (1972) in Plate I, Figure 20, is an example of Andalusiella polymorpha (Malloy, 1972) Lentin and Williams 1977 and is very similar to specimens of that species illustrated in Plate 1, Figures 8 and 16, by Malloy (1972).
The Seymour Island specimens of Palaeocystodinium australinum resemble those from the Pebble Point Formation (Cookson, 1965), but are generally shorter and darker. The darker coloration may be a preser- vational artifact because other taxa in the same samples are similarly colored. Many Seymour Island specimens of P. australinum are broken anteriorly of the paracingular area. Such specimens can only be differentiated from broken specimens of P. golzowense by the presence of the accessory spur on the antapical horn of the former. The operculum of the 2a archeopyle is often in place, even though open parasutures may completely surround it.
Dimensions:
Observed range (10 specimens): pericyst length, 170 to 226 µm (mean 196 µm); pericyst width, 29 to 48 µm (mean 38 µm); endocyst length, 77 to 122 µm (mean,99 µm); endocyst width 29 to 48 µm (mean 38 µm).
Selected Previous Occurrences:
Palaeocystodinium australinum was described from the Paleocene Pebble Point Formation of southwest Victoria, Australia (Cookson, 1965). Subsequent planktonic foraminiferal studies indicated a middle Paleocene age for the Pebble Point Formation (McGowan, 1965, 1968). In addition to Australian occurrences (Cookson, 1965; Deflandre and Cookson, 1955), P. australinum has been reported from the middle-late Paleocene of DSDP 283 (Haskell and Wilson, 1975) and the middle Paleocene of DSDP 214, in the Indian Ocean (Harris, 1974). P. aff. australinum has been recovered from the Upper Cretaceous on Campbell Island, south of New Zealand (Wilson, 1967b) and from DSDP 275 cores on the Campbell Plateau (Wilson, 1975). The reported occurrences indicate that P. australinum was widely distributed in the high southern latitudes during the Maastichtian and Paleocene. Stover and Williams (1977) reported that the stratigraphic range of P. australinum is limited to the upper Paleocene, whereas Williams and Kidson (1975) and Williams (1977) considered the stratigraphic range to be lower Maastrichtian to Paleocene. Williams and Bujak (1985) indicated a total range of late Campanian to late Paleocene; this range is used herein.
Andalusiella gabonensis, (Stover and Evitt, 1978, p.115) Wrenn and Hart, 1988, p.362.
Holotype: Malloy, 1972, pl.1, fig.17, as Svalbardella australina.
Originally Palaeocystodinium, subsequently (and now) Andalusiella. This species is based on material described by Malloy (1972, p.63, pl.1, fig.17 not pl.1, fig.20).
Age: Maastrichtian.
---------------------------------------------------------------------------------------------------
Emended description: [Wrenn and Hart, 1988, p. 362]:
Diagnosis:
Fusiform, dorso-ventrally flattened, cavate dinocysts bearing one long tapering horn at each end of the central body. The apical horn may be distally acuminate, rounded, or blunt. The antapical horn bears a short, posteriorly projecting accessory horn or spike along its length or almost distally (but not proximally). The accessory horn occurs on the dinocysts right side of the antapical horn. The structurally simple, spindle-shaped endocyst may or may not extend into the pericoels of the horns formed by the pericyst. The endophragm and the periphragm may be closely appressed in the central body area but are separated in the region of the horns.
Wall relationship varies from cornucavate to circumcavate. The thin endophragm and periphragm may be smooth to slightly granular. The endophragm may be clear or dark brown in color, whereas the periphragm is clear.
The steno-deltaform intercalary archeopyle is of the 1(2a) Type and the operculum is free.
Paratabulation is absent or poorly developed.
Faint suggestions of the location of the parasulcus and paracingulum may be present. The cysts are large and may be more than 250 µm long.
Comments:
Malloy (1972) emended Palaeocystodinium australinum (referred to as Svalbardella australina Cookson 1965 by Malloy, 1972) by: ( I ) redefining the range of cyst dimensions to include much shorter and broader dinocysts than the type material; (2) including cysts with a proximal location for the accessory spur on the antapical horn, rather than being located well along the horn, as originally described by Cookson (1965); (3) including specimens with a much smaller length-to-width ratio for the species than is indicated by the specimens in photographs of the P. australinum type material; (4) including a fundamentally different and significantly more complex structure for the apical horns; (S) citing the presence of a transverse fold as an indication of the location of the paracingulum; and (6) including specimens with a well-developed flagellar scar in the parasulcus.
We reject the emendation of Palaeocystodinium australinum (Cookson) Lentin and Williams 1976 by Malloy (1972) for the following reasons:
1. The size range of the type material from Australia (length, 293 to 302 µm, width,40 to 61 µm) is significantly different from the Gabon material of Malloy (1972; length, 110 to 175 µm, width, 49 to 74 µm). The Gabon material is much shorter and does not approach the lower end of the dinocyst length range cited for the type material of P. australinum by Cookson (1965). The width of the Gabon material extends from the middle to far beyond the upper range of the dinocyst width of the type material.
2. The relative proportion of the length to width is markedly different, whether based on measurements or simple visual comparison of the Australian and Gabon materials. The proportions exhibited by the Gabon material are more similar to the proportions of the genus Andalusiella than to those of P. australinum.
3. The location of the accessory spur is significantly different on the Gabon material and is, in fact, more reminiscent of species of Andalusiella than of P. australinum (Cookson) Lentin and Williams 1976.
4. The fundamentally different and more complex apical and antapical horns on the Gabon material are unlike any reported elsewhere for P. australinum. Malloy (1972) noted "The structure of the apical and antapical portions of the inner cyst appears complex (text-fg.2), with an inner projection ohen filling the horn and tightly enclosed by the periphragm. This interior portion of the horn is attached basally at an area of thickening which forms a "boss" on the inner capsule." (See Fig. 46.1, 4 for comparative structural sketches of the horns on Morphotypes B and C of Malloy (1972) and those of P. australinum of Cookson (1965). Such horn structures have been reported by Riegel and Sarjeant (1982) in Andalusiella mauthei Riegel. (See Fig. 46.5-10.) The contrasting structure of the horns is enough to separate the Gabon specimens of P. australinum sensu Malloy (Morphotype C) from the Australian type material of P. australinum of Cookson (1965).
5. The transverse fold commonly observed marking the paracingulum on the Gabon material (Morphotype C of Malloy, 1972) has not been noted on specimens of P. australinum elsewhere.
6. The intercalary 2a archeopyle outlined on the apical horn structural diagram by Malloy (text-fig. 2; 1972) is an omegaform hexa archeopyle, rather than a steno-deltaform archeopyle that is characteristic of Palaeocystodinium and Svalbardella The archeopyle in Malloy's figure is also unlike any of those shown on specimens in Plate I (Malloy, 1972). We consider this to be a drafting error and not an indication that Malloy (1972) believed Svalbardella and Palaeocystodinium have an omegaform archeopyle. The "inverted" archeopyle on Malloy's diagram -if turned right-side-up is more similar to the archeopyle of Andalusiella than to that of Palaeocystodinium.
7. Finally, the specimens referred to as S. australina and shown in Plate 1, Figures 17 and 20 of Malloy (1972) appear to bear a comma shaped flagellar scar in the parasulcal area. Such structures have not been reported elsewhere for P. australinum. They are evident on the Morphotype B specimens of Malloy (Plate 1, Figs. 8-16, 21; 1972), and on specimens of Andalusiella (see Riegel, 1974, and Riegel and Sarjeant, 1982, for example).
Stover and Evitt (1978) established Palaeocystodinium gabonense to accommodate dinocysts similar to those illustrated in Plate 1, Figures 17 and 20 of Malloy (1972). (A sketch of the former specimen, the Holotype of P. gabonense, is shown in Plate 46, Figure 2, of this paper.) However, they did not alter the emendation of P. australinum proposed by Malloy (1972). We believe that P. gabonense is more closely related to Andalusiella than to Palaeocystodinium because of its overall aspect, the relative proportion of cyst length to width, the presence of a distinct flagellar scar in the parasulcal area, and the presence of dark wall thickenings at the poles of the broadly elongate endocyst. These morphologic features are not characteristic of Palaeocystodinium, but they are of Andalusiella Therefore, we herein transfer P. gabonense Stover and Evitt, 1978, to the genus Andalusiella The specimen illustrated by Malloy (1972) in Plate I, Figure 20, is an example of Andalusiella polymorpha (Malloy, 1972) Lentin and Williams 1977 and is very similar to specimens of that species illustrated in Plate 1, Figures 8 and 16, by Malloy (1972).
The Seymour Island specimens of Palaeocystodinium australinum resemble those from the Pebble Point Formation (Cookson, 1965), but are generally shorter and darker. The darker coloration may be a preser- vational artifact because other taxa in the same samples are similarly colored. Many Seymour Island specimens of P. australinum are broken anteriorly of the paracingular area. Such specimens can only be differentiated from broken specimens of P. golzowense by the presence of the accessory spur on the antapical horn of the former. The operculum of the 2a archeopyle is often in place, even though open parasutures may completely surround it.
Dimensions:
Observed range (10 specimens): pericyst length, 170 to 226 µm (mean 196 µm); pericyst width, 29 to 48 µm (mean 38 µm); endocyst length, 77 to 122 µm (mean,99 µm); endocyst width 29 to 48 µm (mean 38 µm).
Selected Previous Occurrences:
Palaeocystodinium australinum was described from the Paleocene Pebble Point Formation of southwest Victoria, Australia (Cookson, 1965). Subsequent planktonic foraminiferal studies indicated a middle Paleocene age for the Pebble Point Formation (McGowan, 1965, 1968). In addition to Australian occurrences (Cookson, 1965; Deflandre and Cookson, 1955), P. australinum has been reported from the middle-late Paleocene of DSDP 283 (Haskell and Wilson, 1975) and the middle Paleocene of DSDP 214, in the Indian Ocean (Harris, 1974). P. aff. australinum has been recovered from the Upper Cretaceous on Campbell Island, south of New Zealand (Wilson, 1967b) and from DSDP 275 cores on the Campbell Plateau (Wilson, 1975). The reported occurrences indicate that P. australinum was widely distributed in the high southern latitudes during the Maastichtian and Paleocene. Stover and Williams (1977) reported that the stratigraphic range of P. australinum is limited to the upper Paleocene, whereas Williams and Kidson (1975) and Williams (1977) considered the stratigraphic range to be lower Maastrichtian to Paleocene. Williams and Bujak (1985) indicated a total range of late Campanian to late Paleocene; this range is used herein.