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Enneadocysta
From Williams et al., 2017:
[Enneadocysta, Stover and Williams, 1995, p. 108–109, 115-118; Emendation: Fensome et al., 2007, p. 394.
Name was not validly published in Bujak (1994, p.119), since it was merely used in anticipation of future acceptance of the name (I.C.N. Article 36.1b).
Type species: as Baltisphaeridium pectiniforme, Gerlach, 1961 (pl.28, fig.14)]
Stratigraphic range: early Mid Eocene (Lutetian) to Early Oligocene (Rupelian). Records of Late Oligocene occurrences require substantiation.
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Original description: [Stover and Williams, 1995]:
Synopsis:
Cysts skolochorate, central body subspherical to lenticular and bearing 18 to 24 intratabular processes with solid, fibroid stems and variously shaped tips including vasiform, licrate, branched and irregularly rounded; paratabulation formula, based on number of processes: 4`, 5-6``, 0-6c, 6```, 2````, 0-1as, 1ps; hypocystal process configuration partiform; archeopyle apical, operculum tetratabular, simple and free.
Description:
Shape: Cysts skolochorate, central body generally subspherical but may be broadly ellipsoidal or lenticular, with some dorsal-ventral compression.
Wall relationships: Autophragm only.
Wall features: Autophragm smooth or variously ornamented with features of low relief. Number of intratabular processes varies from 18 to 24, but the number on individual species is more or less constant; usually one intratabular process per paraplate although some paraplates may lack processes, particularly in the paracingular area; process stems solid, smooth or fibroid, rarely branched, expanded distally and less expanded proximally; process t ps variable, commonly licrate, less frequently simply or complexly branched and rarely vasiform or irregularly rounded. On processes with licrate tips the arcuations are semicircular to horseshoe-shaped with smooth inner margins and denticulate to spinulate outer margins.
Excystment type: Archeopyle apical; operculum tetratabular, simple, equidimensional or longer transversely than dorso-ventrally and free.
Paratabulation: Indicated by principal and short accessory archeopyle sutures and by positions of the intratabular processes; composite paratabulation formula: 4`, 5-6``, 0-6c, 6```, 2````, 0-1as, 1ps; hypocystal processes arranged in partiform pattern.
Paracingulum: Indicated by up to six intratabular processes or absence of processes.
Parasulcus: Position indicated anteriorly by medial to slightly offset parasulcal notch, additionally by an anterior parasulcal process, when present, and posteriorly by a posterior parasulcal process.
Size: Intermediate to large; overall diameter 63 µm to 128 µm.
Affinities:
Enneadocysta is characterized by having a skolochorate, usually subspherical central body bearing solid intratabular processes generally with licrate or branched tips and by having the hypocystal processes arranged in the partiform pattern (text-fig. 1, no. D). Areosphaeridium, which is also skolochorate with a subspherical central body bearing solid intratabular processes, has vasiforrn, infundibular and clypeate process terminations, rather than licrate or branched tips (pl. 1, figs. 2a, 5, 6c). The hypocystal process arrangement on Areosphaeridium is standard sexiforrn, rather than partiforrn. Cooksonidium possesses not only intratabular processes but also process complexes (pl. 7, fig. 4), both with solid stems. The distal ends of the processes and process complexes may be simply flared, shallowly arcuate or licrate (pl. 7, figs. 4, 5a-b). Cooksonidium also has a standard sexiform hypocyst.
Comparison of described Enneadocysta species:
Species of Enneadocysta share the following attributes:
1) the cyst is skolochorate with intratabular processes;
2) the central body is comprised of autophragm and is smooth or ornamented with features of low relief;
3) the archeopyle is apical with tetratabular, simple and free opercula;
4) the process stems are solid and generally fibroid although narrow processes, such as those in the paracingular area, are commonly non-fibroid;
5) the hypocystal processes have a partiform paratabulation arrangement.
Differences among species include the number of intratabular processes, which reflects the presence or absence of processes on certain paraplates, and the sizes and shapes of the processes, particularly their terminal structures. These and other differentiating characteristics are summarized on Table 2.
... Briefly, species of Enneadocysta are characterized by having solid, intratabular processes with fibroid or smooth stems of which the majority have licrate tips, and by having the hypocystal processes arranged in the partiform configuration. An anterior sulcal process and paracingular processes are present on some species. Enneadocysta arcuata Var. A of Eaton ( 1971 ) is interpreted as the "root" stock and appears in the early part of the early Mid Eocene (Lutetian). On this form the last precingular paraplate (6``) does not bear a process nor are paracingular processes present. Enneadocysta arcuata Var. B of Eaton (1971) appears slightly later, but still in the early Mid Eocene. This form has a process on the last precingular paraplate, otherwise it is essentially identical to Enneadocysta arcuata Var. A. Both varieties have relatively long, narrow processes in contrast to the short and generally wider processes on Enneadocysta robusta which, because it does not have a process on paraplate 6``, is regarded as an offshoot of Enneadocysta arcuata Var. A. Enneadocysta robusta is devoid of paracingular processes. Enneadocysta multicornuta is considered a younger derivative of Enneadocysta arcuata Var. A from which it differs by having paracingular processes. This species appears in the late Mid Eocene (Bartonian). Presumably Enneadocysta fenestrata developed from Enneadocysta multicornuta, also in the Bartonian and from which it differs primarily in the nature of the processes distally.
Stratigraphic ranges support the hypothesis that Enneadocysta arcuata Var. B gave rise to Enneadocysta deconinckii in the early Mid Eocene. The latter species, like Enneadocysta arcuata Var. B, has a process on paraplate 6`` and an anterior parasulcal process. Thus, Enneadocysta deconinckii always has seven processes subjacent to the archeopyle margin. Processes on this species are typically stout; those on the dorsal surface usually have relatively wide stems and robust licrate tips. The last species in the lineage is the late Mid Eocene (Bartonian) appearing Enneadocysta pectiniforrnis This species has the same basic morphology, process number and process distribution as Enneadocysta deconinckii from which it differs by having narrower processes with less substantial licrate terminations and a thinner autophragm.
The postulated Enneadocysta lineage consists of Northern Hemisphere species only. Thus far, only two species of Enneadocysta (Enneadocysta harrisii and Enneadocysta partridgei) are recognized unconditionally from Southern Hemisphere dinoflagellate assemblages. With the discovery of additional Southern Hemisphere species, a comparable Paleogene lineage for that area may be ascertained.
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Emended description:
Fensome et al., 2007:
Diagnosis:
Chorate areoligeracean cysts with a subspheroidal to lenticular central body. Processes mostly one per plate, generally mesotabular, but can be obtabular; there are two antapical processes located on or, usually, toward the lateral margin of the antapical plate, rather than a single mesotabular antapical process; occasional plates elsewhere may be represented by two, or rarely more, processes. Process endings generally well developed, commonly licrate and/or entire clypeate to ragged clypeate and usually asymmetrical.
Remarks:
The emended diagnosis of Enneadocysta is based on a re-interpretation of its tabulation and the observation that, although most of its processes are mesotabular to obtabular, those toward the antapex are not. The two circum-antapical processes, thought by Stover and Williams (1995) to be mesotabular and indicative of a partiform tabulation, actually occur toward the margin of the single antapical plate.
Stover and Williams provided the following process formula: 4', 5-6'', 0-6c, 6''', 2'''', 0-1as, 1ps. Based on the reinterpretation of the circum-antapical processes and other new observations, our revised process formula is as follows: 4', 3-6'', 0-6c, 6''', 0-1 as, 0-1 ps, 0p, 2''''. This restatement illustrates how misleading such formulae can be, because 2'''' in our formulation represents two penitabular processes on a single antapical plate rather than reflecting, more conventionally, two plate-centered processes on separate plates. Regardless, in light of the re-interpretation of Enneadocysta as an areoligeracean rather than a cladopyxiinean, its reflected tabulation would be standard gonyaulacalean (Fensome et al. 1996a). We consider that all species assigned to Enneadocysta by Stover and Williams (1995) can be similarly interpreted.
Affinities:
Both Enneadocysta and Areosphaeridium can have licrate or clypeate processes. Enneadocysta differs from Areosphaeridium in having two circum-antapical or penitabular processes, rather than a single antapical process (text-figure 5). Moreover, Areosphaeridium tends to have a subspherical central body and a symmetrical overall shape, whereas Enneadocysta tends to have a lenticular central body and an asymmetrical shape. Like Enneadocysta and other typical areoligeraceans, Glaphyrocysta tends to have an asymmetrical, lenticular central body and a sulcal notch offset to the left. However, in Glaphyrocysta the processes are generally more irregularly arranged, rarely is there only one per plate, and process endings are not distinctly licrate or clypeate. Areoligera has process complexes basally joined by well-developed arcuate to annulate ridges in all major plate series, not just at the antapex. Ramidinium has primarily sutural processes that are sometimes joined basally by low, sutural ridges near the cingular area, but not at the antapex. Smaller, more spheroidal forms of Enneadocysta, such as Enneadocysta multicornuta, can be distinguished from similar forms of Cleistosphaeridium and Licracysta by the presence of apparently mesotabular processes. Cleistosphaeridium and Licracysta have nontabular to contabular processes, and Cleistosphaeridium consistently lacks dorso-ventral bald areas. Nevertheless, species such as Cleistosphaeridium polypetellum can be difficult to differentiate from specimens of Enneadocysta multicornuta that lack dorsoventral bald areas: an assessment has to be made as to whether a specimen bears more than one process per plate. Also, the process endings in Cleistosphaeridium polypetellum tend to be more irregular than in Enneadocysta multicornuta
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Enneadocysta Stover and Williams, 1995. Synopsis from Stover and Williams (1995, p.108), Cysts skolochorate, central body subspherical to lenticular and bearing 18-24 intratabular processes with solid, fibroid stems and variously shaped tips including vasiform, licrate, branched and irregularly rouonded; paratabulation formula, based on number of processes: 4`, 5-6", 0-6c, 6"', 2" , 0-1as, 1ps; hypocystal process configuration partiform: archeopyle apical, operculum tetratabular, simple and free.
[Enneadocysta, Stover and Williams, 1995, p. 108–109, 115-118; Emendation: Fensome et al., 2007, p. 394.
Name was not validly published in Bujak (1994, p.119), since it was merely used in anticipation of future acceptance of the name (I.C.N. Article 36.1b).
Type species: as Baltisphaeridium pectiniforme, Gerlach, 1961 (pl.28, fig.14)]
Stratigraphic range: early Mid Eocene (Lutetian) to Early Oligocene (Rupelian). Records of Late Oligocene occurrences require substantiation.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Stover and Williams, 1995]:
Synopsis:
Cysts skolochorate, central body subspherical to lenticular and bearing 18 to 24 intratabular processes with solid, fibroid stems and variously shaped tips including vasiform, licrate, branched and irregularly rounded; paratabulation formula, based on number of processes: 4`, 5-6``, 0-6c, 6```, 2````, 0-1as, 1ps; hypocystal process configuration partiform; archeopyle apical, operculum tetratabular, simple and free.
Description:
Shape: Cysts skolochorate, central body generally subspherical but may be broadly ellipsoidal or lenticular, with some dorsal-ventral compression.
Wall relationships: Autophragm only.
Wall features: Autophragm smooth or variously ornamented with features of low relief. Number of intratabular processes varies from 18 to 24, but the number on individual species is more or less constant; usually one intratabular process per paraplate although some paraplates may lack processes, particularly in the paracingular area; process stems solid, smooth or fibroid, rarely branched, expanded distally and less expanded proximally; process t ps variable, commonly licrate, less frequently simply or complexly branched and rarely vasiform or irregularly rounded. On processes with licrate tips the arcuations are semicircular to horseshoe-shaped with smooth inner margins and denticulate to spinulate outer margins.
Excystment type: Archeopyle apical; operculum tetratabular, simple, equidimensional or longer transversely than dorso-ventrally and free.
Paratabulation: Indicated by principal and short accessory archeopyle sutures and by positions of the intratabular processes; composite paratabulation formula: 4`, 5-6``, 0-6c, 6```, 2````, 0-1as, 1ps; hypocystal processes arranged in partiform pattern.
Paracingulum: Indicated by up to six intratabular processes or absence of processes.
Parasulcus: Position indicated anteriorly by medial to slightly offset parasulcal notch, additionally by an anterior parasulcal process, when present, and posteriorly by a posterior parasulcal process.
Size: Intermediate to large; overall diameter 63 µm to 128 µm.
Affinities:
Enneadocysta is characterized by having a skolochorate, usually subspherical central body bearing solid intratabular processes generally with licrate or branched tips and by having the hypocystal processes arranged in the partiform pattern (text-fig. 1, no. D). Areosphaeridium, which is also skolochorate with a subspherical central body bearing solid intratabular processes, has vasiforrn, infundibular and clypeate process terminations, rather than licrate or branched tips (pl. 1, figs. 2a, 5, 6c). The hypocystal process arrangement on Areosphaeridium is standard sexiforrn, rather than partiforrn. Cooksonidium possesses not only intratabular processes but also process complexes (pl. 7, fig. 4), both with solid stems. The distal ends of the processes and process complexes may be simply flared, shallowly arcuate or licrate (pl. 7, figs. 4, 5a-b). Cooksonidium also has a standard sexiform hypocyst.
Comparison of described Enneadocysta species:
Species of Enneadocysta share the following attributes:
1) the cyst is skolochorate with intratabular processes;
2) the central body is comprised of autophragm and is smooth or ornamented with features of low relief;
3) the archeopyle is apical with tetratabular, simple and free opercula;
4) the process stems are solid and generally fibroid although narrow processes, such as those in the paracingular area, are commonly non-fibroid;
5) the hypocystal processes have a partiform paratabulation arrangement.
Differences among species include the number of intratabular processes, which reflects the presence or absence of processes on certain paraplates, and the sizes and shapes of the processes, particularly their terminal structures. These and other differentiating characteristics are summarized on Table 2.
... Briefly, species of Enneadocysta are characterized by having solid, intratabular processes with fibroid or smooth stems of which the majority have licrate tips, and by having the hypocystal processes arranged in the partiform configuration. An anterior sulcal process and paracingular processes are present on some species. Enneadocysta arcuata Var. A of Eaton ( 1971 ) is interpreted as the "root" stock and appears in the early part of the early Mid Eocene (Lutetian). On this form the last precingular paraplate (6``) does not bear a process nor are paracingular processes present. Enneadocysta arcuata Var. B of Eaton (1971) appears slightly later, but still in the early Mid Eocene. This form has a process on the last precingular paraplate, otherwise it is essentially identical to Enneadocysta arcuata Var. A. Both varieties have relatively long, narrow processes in contrast to the short and generally wider processes on Enneadocysta robusta which, because it does not have a process on paraplate 6``, is regarded as an offshoot of Enneadocysta arcuata Var. A. Enneadocysta robusta is devoid of paracingular processes. Enneadocysta multicornuta is considered a younger derivative of Enneadocysta arcuata Var. A from which it differs by having paracingular processes. This species appears in the late Mid Eocene (Bartonian). Presumably Enneadocysta fenestrata developed from Enneadocysta multicornuta, also in the Bartonian and from which it differs primarily in the nature of the processes distally.
Stratigraphic ranges support the hypothesis that Enneadocysta arcuata Var. B gave rise to Enneadocysta deconinckii in the early Mid Eocene. The latter species, like Enneadocysta arcuata Var. B, has a process on paraplate 6`` and an anterior parasulcal process. Thus, Enneadocysta deconinckii always has seven processes subjacent to the archeopyle margin. Processes on this species are typically stout; those on the dorsal surface usually have relatively wide stems and robust licrate tips. The last species in the lineage is the late Mid Eocene (Bartonian) appearing Enneadocysta pectiniforrnis This species has the same basic morphology, process number and process distribution as Enneadocysta deconinckii from which it differs by having narrower processes with less substantial licrate terminations and a thinner autophragm.
The postulated Enneadocysta lineage consists of Northern Hemisphere species only. Thus far, only two species of Enneadocysta (Enneadocysta harrisii and Enneadocysta partridgei) are recognized unconditionally from Southern Hemisphere dinoflagellate assemblages. With the discovery of additional Southern Hemisphere species, a comparable Paleogene lineage for that area may be ascertained.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Fensome et al., 2007:
Diagnosis:
Chorate areoligeracean cysts with a subspheroidal to lenticular central body. Processes mostly one per plate, generally mesotabular, but can be obtabular; there are two antapical processes located on or, usually, toward the lateral margin of the antapical plate, rather than a single mesotabular antapical process; occasional plates elsewhere may be represented by two, or rarely more, processes. Process endings generally well developed, commonly licrate and/or entire clypeate to ragged clypeate and usually asymmetrical.
Remarks:
The emended diagnosis of Enneadocysta is based on a re-interpretation of its tabulation and the observation that, although most of its processes are mesotabular to obtabular, those toward the antapex are not. The two circum-antapical processes, thought by Stover and Williams (1995) to be mesotabular and indicative of a partiform tabulation, actually occur toward the margin of the single antapical plate.
Stover and Williams provided the following process formula: 4', 5-6'', 0-6c, 6''', 2'''', 0-1as, 1ps. Based on the reinterpretation of the circum-antapical processes and other new observations, our revised process formula is as follows: 4', 3-6'', 0-6c, 6''', 0-1 as, 0-1 ps, 0p, 2''''. This restatement illustrates how misleading such formulae can be, because 2'''' in our formulation represents two penitabular processes on a single antapical plate rather than reflecting, more conventionally, two plate-centered processes on separate plates. Regardless, in light of the re-interpretation of Enneadocysta as an areoligeracean rather than a cladopyxiinean, its reflected tabulation would be standard gonyaulacalean (Fensome et al. 1996a). We consider that all species assigned to Enneadocysta by Stover and Williams (1995) can be similarly interpreted.
Affinities:
Both Enneadocysta and Areosphaeridium can have licrate or clypeate processes. Enneadocysta differs from Areosphaeridium in having two circum-antapical or penitabular processes, rather than a single antapical process (text-figure 5). Moreover, Areosphaeridium tends to have a subspherical central body and a symmetrical overall shape, whereas Enneadocysta tends to have a lenticular central body and an asymmetrical shape. Like Enneadocysta and other typical areoligeraceans, Glaphyrocysta tends to have an asymmetrical, lenticular central body and a sulcal notch offset to the left. However, in Glaphyrocysta the processes are generally more irregularly arranged, rarely is there only one per plate, and process endings are not distinctly licrate or clypeate. Areoligera has process complexes basally joined by well-developed arcuate to annulate ridges in all major plate series, not just at the antapex. Ramidinium has primarily sutural processes that are sometimes joined basally by low, sutural ridges near the cingular area, but not at the antapex. Smaller, more spheroidal forms of Enneadocysta, such as Enneadocysta multicornuta, can be distinguished from similar forms of Cleistosphaeridium and Licracysta by the presence of apparently mesotabular processes. Cleistosphaeridium and Licracysta have nontabular to contabular processes, and Cleistosphaeridium consistently lacks dorso-ventral bald areas. Nevertheless, species such as Cleistosphaeridium polypetellum can be difficult to differentiate from specimens of Enneadocysta multicornuta that lack dorsoventral bald areas: an assessment has to be made as to whether a specimen bears more than one process per plate. Also, the process endings in Cleistosphaeridium polypetellum tend to be more irregular than in Enneadocysta multicornuta
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Enneadocysta Stover and Williams, 1995. Synopsis from Stover and Williams (1995, p.108), Cysts skolochorate, central body subspherical to lenticular and bearing 18-24 intratabular processes with solid, fibroid stems and variously shaped tips including vasiform, licrate, branched and irregularly rouonded; paratabulation formula, based on number of processes: 4`, 5-6", 0-6c, 6"', 2" , 0-1as, 1ps; hypocystal process configuration partiform: archeopyle apical, operculum tetratabular, simple and free.