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Nematosphaeropsis
From Williams et al., 2017:
[Nematosphaeropsis, Deflandre and Cookson, 1955, p. 268; Emendations: Williams and Downie, 1966c, p. 222; Wrenn, 1988, p. 137
Tax. sr. syn. of trabeculidinium Duxbury, 1980, according to Stover and Williams, 1987, and Jan du Chene, 1988. Sarjeant, 1989, retained Trabeculidinium as a separate genus.
Type species: Nematosphaeropsis balcombiana, Deflandre & Cookson 1955, p. 258 (pl. 8, fig. 5)] ; Nematosphaeropsis labyrinthea, (Ostenfeld, 1903), Reid, 1974
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Original description: [Deflandre and Cookson, 1955]:
Diagnosis:
Shell globular, divided into fields by ridges, an equatorial series developed as in the genus Hystrichosphaera. Branches of processes joined to one another by trabeculae or filaments as in the genus Cannosphaeropsis.
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Emended descriptions:
Williams and Downie, 1966:
Diagnosis:
Globular to ellipsoidal chorate cysts. Periphragm forms gonal or sutural processes united proximally by sutural ridges or membranes. Adjacent processes distally united by trabeculae.
Archaeopyle precingular.
Affinities:
The tabulation of Nematosphaeropsis is identical to that of Hystrichosphaera ramosa.
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Wrenn, 1988:
Diagnosis:
Chorate to proximochorate cysts with a spherical to slightly elongate, smooth or ornamented central body bearing gonal, or gonal and intergonal, processes that are connected distally by pairs of penitabular trabeculae. One or two wall layers may be present. Gonal processes are distally trifurcate and intergonal processes are bifurcate. Each process furcation generally gives rise to two penitabular trabeculae: six from each trifurcate process and four from each bifurcate process. Pairs of penitabular trabeculae may be partially joined to each other by short, transverse strands or by direct fusing of the trabeculae in the span between the process terminations that they are joining. Trabecular structure varies from solid subcylindrical rods to ribbon-like membranes of various widths. One type of penitabular trabeculae is characteristic of each species. Gonyaulacoid paratabulation (3-4`, 5-6", 6c, 5-6"`, lp, 1"") may be reflected to a greater or lesser degree by the penitabular trabecular network or on the central body by parasutural ridges or membranes that connect adjacent process bases. The precingular archeopyle (Type P) is formed by the loss of the 3" paraplate. The operculum is free.
Discussion/Affinities:
Stover and Evitt (1978) analyzed the characteristics of Cannosphaeropsis and Nematosphaeropsis. In their discussion of Cannosphaeropsis (Stover and Evitt, 1978, p. 143) they noted that this genus differed from Nematosphaeropsis in having single, instead of "at least two," parasutural trabeculae connecting neighboring processes. The trabeculae of Cannosphaeropsis often contact processes below their terminations, thus the furcations stand above the trabecular shell. Some processes are not developed proximally and only the remnant, isolated furcate terminations occur in gonal position on or above the trabecular shell (Evitt, 1985). In addition, Cannosphaeropsis rarely exhibits parasutural ridges or septa connecting the bases of adjacent processes on the central body; such features are more commonly encountered on species of Nematosphaeropsis. However, in their discussion of Nematosphaeropsis, Stover and Evitt (1978, p. 176) stated that this species had either single or pairs trabeculae. Single trabeculae have been reported to occur, though rarely, on specimens with the characteristic paired of trabeculae (e.g., N. ? philippotii by De Coninck, 1969). These occurrences of single trabeculae are here considered to most likely result from specimen damage or aberrant dinocyst development. Nematosphaeropsis differs most clearly from Cannosphaeropsis in that it may exhibit paratabulation on the central body, it has pairs of penitabular trabeculae (Plate 7, fig. 1), and it lacks isolated process termination on or projecting above the trabecular shell. Cannosphaeropsis is characterized by single parasutural trabeculae, isolated process terminations and a lack of paratabulation on the central body. Species of Unipontidinium gen. nov. have single parasutural trabeculae (Plate 7, fig. 2) and may or may not bear parasutural features on the central body.
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Modified description:
Stover and Evitt, 1978, p. 176:
Synopsis:
Cysts proximochorate, body subspherical with gonal (and intergonal) processes; trifurcate or further bifurcate tips of adjacent processes joined by network of single or paired trabeculae; paratabulation gonyaulacacean, indicated by either trabeculae or low parasutural features between bases of processes, or by both; archaeopyle precingular, Type P.
Description:
Shape: Body subspherical, commonly complexly folded.
Wall relationships: Typically autophragm only; occasional specimens may show indications of endophragm and periphragm at bases of processes.
Wall features: Faint parasutural lines or low ridges may occur between bases of processes. Processes gonal (and intergonal), like those on most species of Achomosphaera and Spiniferites. Tips trifurcate and may further bifurcate; tips of adjacent processes connected by network of single or paired ribbon-like or rod-like trabeculae. Trabeculae, processes, and body commonly smooth, rarely pitted or faintly ornamented.
Paratabulation: Indicated by parasutural lines or low ridges between bases of processes, or by the course of the trabeculae, or by both; gonyaulacacean, formula: 3-4`, 5-6``, 6c, 5-6```, 1p, 1````. Paratabulation often obscured and impossible to decipher because of complex folding or breaking of trabeculae.
Archaeopyle: Precingular, Type P (3`` only); archaeopyle very rarely discernible; operculum free.
Paracingulum: Indicated by series of elongate lumina in network or trabeculae; only rarely discernible.
Parasulcus: Indicated by parasutural features, but rarely recognizable.
Size: Small to intermediate.
Affinities:
Nematosphaeropsis differs from Achomosphaera and Spiniferites in having the tips of adjacent processes connected by trabeculae. In Achomosphaera and Spiniferites the tips of processes are not interconnected. On many species of Spiniferites the paratabulation is expressed clearly by the parasutural ridges or septa, whereas in Nematosphaeropsis, the paratabulation is obscure and difficult to determine completely, but may be evident here and there by the arrangement of the parasutural trabeculae.
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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.
Nematosphaeropsis Deflandre and Cookson, 1955, emend. Williams and Downie, 1966c, emend. Wrenn, 1988. Nematosphaeropsis was emended by Wrenn (1988, p.137) as follows: Chorate to proximochorate cysts with a spherical to slightly elongate, smooth or ornamented central body bearing gonal, or gonal and intergonal, processes that are connected distally by pairs of penitabular trabeculae. One or two wall layers may be present. Gonal processes are distally trifurcate and intergonal processes are bifurcate. Each process furcation generally gives rise to two penitabular trabeculae: six from each trifurcate process and four from each bifurcate process. Pairs of penitabular trabeculae may be partially joined to each other by short, transverse strands or by direct fusing of the trabeculae in the span between the process terminations that they are joining. Trabecular structure varies from solid subcylindrical rods to ribbon-like membranes of various widths. One type of penitabular trabeculae is characteristic of each species. Gonyaulacoid paratabulation (3-4`, 5-6", 6c, 5-6"', 1p, 1"'') may be reflected to a greater or lesser degree by the penitabular trabecular network or on the central body by parasutural ridges or membranes that connect adjacent process bases. The precingular archeopyle (type P) is formed by the loss of the 3" paraplate. The operculum is free.
[Nematosphaeropsis, Deflandre and Cookson, 1955, p. 268; Emendations: Williams and Downie, 1966c, p. 222; Wrenn, 1988, p. 137
Tax. sr. syn. of trabeculidinium Duxbury, 1980, according to Stover and Williams, 1987, and Jan du Chene, 1988. Sarjeant, 1989, retained Trabeculidinium as a separate genus.
Type species: Nematosphaeropsis balcombiana, Deflandre & Cookson 1955, p. 258 (pl. 8, fig. 5)] ; Nematosphaeropsis labyrinthea, (Ostenfeld, 1903), Reid, 1974
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Original description: [Deflandre and Cookson, 1955]:
Diagnosis:
Shell globular, divided into fields by ridges, an equatorial series developed as in the genus Hystrichosphaera. Branches of processes joined to one another by trabeculae or filaments as in the genus Cannosphaeropsis.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended descriptions:
Williams and Downie, 1966:
Diagnosis:
Globular to ellipsoidal chorate cysts. Periphragm forms gonal or sutural processes united proximally by sutural ridges or membranes. Adjacent processes distally united by trabeculae.
Archaeopyle precingular.
Affinities:
The tabulation of Nematosphaeropsis is identical to that of Hystrichosphaera ramosa.
--------------------------------------
Wrenn, 1988:
Diagnosis:
Chorate to proximochorate cysts with a spherical to slightly elongate, smooth or ornamented central body bearing gonal, or gonal and intergonal, processes that are connected distally by pairs of penitabular trabeculae. One or two wall layers may be present. Gonal processes are distally trifurcate and intergonal processes are bifurcate. Each process furcation generally gives rise to two penitabular trabeculae: six from each trifurcate process and four from each bifurcate process. Pairs of penitabular trabeculae may be partially joined to each other by short, transverse strands or by direct fusing of the trabeculae in the span between the process terminations that they are joining. Trabecular structure varies from solid subcylindrical rods to ribbon-like membranes of various widths. One type of penitabular trabeculae is characteristic of each species. Gonyaulacoid paratabulation (3-4`, 5-6", 6c, 5-6"`, lp, 1"") may be reflected to a greater or lesser degree by the penitabular trabecular network or on the central body by parasutural ridges or membranes that connect adjacent process bases. The precingular archeopyle (Type P) is formed by the loss of the 3" paraplate. The operculum is free.
Discussion/Affinities:
Stover and Evitt (1978) analyzed the characteristics of Cannosphaeropsis and Nematosphaeropsis. In their discussion of Cannosphaeropsis (Stover and Evitt, 1978, p. 143) they noted that this genus differed from Nematosphaeropsis in having single, instead of "at least two," parasutural trabeculae connecting neighboring processes. The trabeculae of Cannosphaeropsis often contact processes below their terminations, thus the furcations stand above the trabecular shell. Some processes are not developed proximally and only the remnant, isolated furcate terminations occur in gonal position on or above the trabecular shell (Evitt, 1985). In addition, Cannosphaeropsis rarely exhibits parasutural ridges or septa connecting the bases of adjacent processes on the central body; such features are more commonly encountered on species of Nematosphaeropsis. However, in their discussion of Nematosphaeropsis, Stover and Evitt (1978, p. 176) stated that this species had either single or pairs trabeculae. Single trabeculae have been reported to occur, though rarely, on specimens with the characteristic paired of trabeculae (e.g., N. ? philippotii by De Coninck, 1969). These occurrences of single trabeculae are here considered to most likely result from specimen damage or aberrant dinocyst development. Nematosphaeropsis differs most clearly from Cannosphaeropsis in that it may exhibit paratabulation on the central body, it has pairs of penitabular trabeculae (Plate 7, fig. 1), and it lacks isolated process termination on or projecting above the trabecular shell. Cannosphaeropsis is characterized by single parasutural trabeculae, isolated process terminations and a lack of paratabulation on the central body. Species of Unipontidinium gen. nov. have single parasutural trabeculae (Plate 7, fig. 2) and may or may not bear parasutural features on the central body.
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Modified description:
Stover and Evitt, 1978, p. 176:
Synopsis:
Cysts proximochorate, body subspherical with gonal (and intergonal) processes; trifurcate or further bifurcate tips of adjacent processes joined by network of single or paired trabeculae; paratabulation gonyaulacacean, indicated by either trabeculae or low parasutural features between bases of processes, or by both; archaeopyle precingular, Type P.
Description:
Shape: Body subspherical, commonly complexly folded.
Wall relationships: Typically autophragm only; occasional specimens may show indications of endophragm and periphragm at bases of processes.
Wall features: Faint parasutural lines or low ridges may occur between bases of processes. Processes gonal (and intergonal), like those on most species of Achomosphaera and Spiniferites. Tips trifurcate and may further bifurcate; tips of adjacent processes connected by network of single or paired ribbon-like or rod-like trabeculae. Trabeculae, processes, and body commonly smooth, rarely pitted or faintly ornamented.
Paratabulation: Indicated by parasutural lines or low ridges between bases of processes, or by the course of the trabeculae, or by both; gonyaulacacean, formula: 3-4`, 5-6``, 6c, 5-6```, 1p, 1````. Paratabulation often obscured and impossible to decipher because of complex folding or breaking of trabeculae.
Archaeopyle: Precingular, Type P (3`` only); archaeopyle very rarely discernible; operculum free.
Paracingulum: Indicated by series of elongate lumina in network or trabeculae; only rarely discernible.
Parasulcus: Indicated by parasutural features, but rarely recognizable.
Size: Small to intermediate.
Affinities:
Nematosphaeropsis differs from Achomosphaera and Spiniferites in having the tips of adjacent processes connected by trabeculae. In Achomosphaera and Spiniferites the tips of processes are not interconnected. On many species of Spiniferites the paratabulation is expressed clearly by the parasutural ridges or septa, whereas in Nematosphaeropsis, the paratabulation is obscure and difficult to determine completely, but may be evident here and there by the arrangement of the parasutural trabeculae.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Nematosphaeropsis Deflandre and Cookson, 1955, emend. Williams and Downie, 1966c, emend. Wrenn, 1988. Nematosphaeropsis was emended by Wrenn (1988, p.137) as follows: Chorate to proximochorate cysts with a spherical to slightly elongate, smooth or ornamented central body bearing gonal, or gonal and intergonal, processes that are connected distally by pairs of penitabular trabeculae. One or two wall layers may be present. Gonal processes are distally trifurcate and intergonal processes are bifurcate. Each process furcation generally gives rise to two penitabular trabeculae: six from each trifurcate process and four from each bifurcate process. Pairs of penitabular trabeculae may be partially joined to each other by short, transverse strands or by direct fusing of the trabeculae in the span between the process terminations that they are joining. Trabecular structure varies from solid subcylindrical rods to ribbon-like membranes of various widths. One type of penitabular trabeculae is characteristic of each species. Gonyaulacoid paratabulation (3-4`, 5-6", 6c, 5-6"', 1p, 1"'') may be reflected to a greater or lesser degree by the penitabular trabecular network or on the central body by parasutural ridges or membranes that connect adjacent process bases. The precingular archeopyle (type P) is formed by the loss of the 3" paraplate. The operculum is free.