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Nematosphaeropsis lemniscata
Nematosphaeropsis lemniscata Bujak, 1984; emend. Wrenn, 1988
Tax. sr. synonym of Nematosphaeropsis oblonga Mudie, 1987, according to Wrenn, 1988.
Holotype: Bujak, 1984, pl. 3, fig. 7; Wrenn, 1988, pl. 1, fig. 16-17
Paratype(s): Bujak, 1984
Stratum typicum: Late Oligocene-Early Pleistocene
Locus typicus: DSDP Site 189, Bering Sea
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Nematosphaeropsis lemniscata Bujak, 1984, emend. Wrenn, 1988. Wrenn (1988, 144) noted that this species is characterised by thin, hollow, cylindrical gonal and intergonal processes with terminations that are connected distally by pairs of penitabular trabeculae of relatively consistent width and height. Each hollow process furcation splits at its distal end and gives rise to two narrow, flat, ribbon-like penitabular trabeculae. Paraplate boundaries may be partially delineated by very low, discontinuous parasutural ridges on the smooth to microgranular central body, though they are usually poorly developed. Paratabulation is more completely, and commonly, expressed on the concentric trabecular shell surrounding the central body. Paratabulation (3-4', 6", 6c, 6"’, ?p, 1"”) is expressed by the distribution of the penitabular trabeculae connecting the distal ends of the processes. Precingular archeopyle (Type P) formed by the loss of the 3" paraplate. Size: Jon’s specimens central body diameter 23 x 28 to 37 x 41 µm (Gulf of Mexico specimens): central body diameter 22-28 u,, overall diameter 39-55 µm, process length 12-17 µm.
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Original description: Bujak, 1984, p. 189-190
Diagnosis: Central body spherical to ovoidal, bearing gonal processes with ribbon- like trifurcations and secondarily bifurcate tips. Bifurcate tips of adjacent processes connected by pairs of ribbon-like trabeculae, or occasionally by single trabecular strands, in a pattern replicating tabulation pattern. Bifurcate processes sutural processes may also be present. Archeopyle precingular, formed by loss of plate 3''.
Dimensions: Central body diameter 23 x 28 Ám to 37 x 41 Ám; max. process length 21 to 32 Ám; 30 specimens measured.
Description: The central body is thin-walled and has a smooth to chagrinate surface. It is often folded so that is was not possible to determine if sutural crests are present on the examined material. If they do occur, they are extremely low and poorly developed. The processes arising from the central body are relatively long, their length approaching the central body diameter. They are smooth and thin-walled and appear to be hollow. They do not possess the ribbed extensions of sutural crests often present on Spiniferites. The processes have ribbon-like trifurcations that are terminally bifid. These bifurcations are extended into ribbon- like trabeculae that connect adjacent processes in a pattern reflecting tabulation. Due to folding and compression of most specimens examined, it was not possible to determine the tabulation pattern. The trabeculae connecting adjacent processes are mostly paired as in Nematosphaeropsis labyrinthea, but some processes were observed that are connected by a single trabecula. An archeopyle is formed by the loss of a single plate which is inferred to be the third precingular because of the similarity of this species to N. labyrinthea.
Discussion: N. lemniscata is similar to N. labyrinthea, but differs in having ribbon-like rather than slender trabeculae. Reid (1974) discussed the geographic distribution of N. labyrinthea and concluded that it is a warm-water species because of its record from the Caribbean, Red Sea and the North Atlantic Drift. The distribution of N. lemniscata indicates that is a cold water species, having been recorded from the Bering Sea and the extreme northern North Pacific (this paper), the Beaufort Sea (Bujak and Davies 1981), the Grand Banks of Newfoundland (Williams and Brideaux 1975), and the sea of Japan (Shimakura et al. 1971).
Emended description: Wrenn, 1988, p. 143-144
Diagnosis: A species of Nematosphaeropsis characterized by thin, hollow cylindrical gonal and intergonal processes with terminations that are connected distally by pairs of penitabular trabeculae of relatively consistent width and height. Each hollow process furcation splits at its distal end and gives rise to two narrow, flat, ribbon-like penitabular trabeculae. Paraplate boundaries may be partially delineated by very low, discontinuous parasutural ridges on the smooth to microgranular central body, though they are usually poorly developed. Paratabulation is more completely, and commonly, expressed on the concentric trabecular shell surrounding the central body. Paratabulation (3-4', 6'', 6c, 6''', ?p, 1'''') is expressed by the distribution of the penitabular trabeculae connecting the distal ends of the processes. Precingular archeopyle (Type P) formed by the loss of the 3'' paraplate.
Description (annotated): The number of intergonal processes varies. A total of six trabeculae arise from gonal processes and four from intergonal processes. The trabeculae are generally oriented on edge, relative to the subspherical central body, (i.e., oriented like a knife blade about to cut into an orange). Rarely, two processes arise from a single base. Paratabulation may be clearly delineated on well preserved specimens by the distribution of the penitabular trabeculae. However, paratabulation is usually obscured by folding of the thin central body and collapse of the flexible trabeculae and processes onto the central body.
Dimensions: Central body diameter 22(25)28 Ám; overall diameter 39(52)55 Ám; process length 12-17 Ám. 10 specimens measured.
Affinities:
Wrenn, 1988
N. lemniscata differs from all species of Nematosphaeropsis recognized in this paper by having relatively long, thin, hollow cylindrical processes and flat, uniformly narrow trabeculae.
REMARKS:
1) Wrenn, 1988, considers Nematosphaeropsis labyrinthea (Ostenfeld, 1903) sensu Reid, 1974 [not Pterococcus labyrinthus (Ostenfeld (1903) Lohmann 1904] conspecific with Nematosphaeropsis lemniscata. Reid's transfer of N. balcombiana to N. labyrinthea (Ostenfeld, 1903) Reid, 1974, is not accepted by Wrenn, 1988. The original description and drawing of Pterosperma labyrinthea Ostenfeld 1903 suggests that it does not concern a dinoflagellate cyst at all, according to Wrenn, 1988 (see Wrenn, 1988, p. 129-137 for an extensive discussion).
2) Due to the above, the proposed use of N. lemniscata as a cold water indicator (versus N. labyrinthea as a warm water indicator), Bujak 1984, is untenable.
Tax. sr. synonym of Nematosphaeropsis oblonga Mudie, 1987, according to Wrenn, 1988.
Holotype: Bujak, 1984, pl. 3, fig. 7; Wrenn, 1988, pl. 1, fig. 16-17
Paratype(s): Bujak, 1984
Stratum typicum: Late Oligocene-Early Pleistocene
Locus typicus: DSDP Site 189, Bering Sea
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Nematosphaeropsis lemniscata Bujak, 1984, emend. Wrenn, 1988. Wrenn (1988, 144) noted that this species is characterised by thin, hollow, cylindrical gonal and intergonal processes with terminations that are connected distally by pairs of penitabular trabeculae of relatively consistent width and height. Each hollow process furcation splits at its distal end and gives rise to two narrow, flat, ribbon-like penitabular trabeculae. Paraplate boundaries may be partially delineated by very low, discontinuous parasutural ridges on the smooth to microgranular central body, though they are usually poorly developed. Paratabulation is more completely, and commonly, expressed on the concentric trabecular shell surrounding the central body. Paratabulation (3-4', 6", 6c, 6"’, ?p, 1"”) is expressed by the distribution of the penitabular trabeculae connecting the distal ends of the processes. Precingular archeopyle (Type P) formed by the loss of the 3" paraplate. Size: Jon’s specimens central body diameter 23 x 28 to 37 x 41 µm (Gulf of Mexico specimens): central body diameter 22-28 u,, overall diameter 39-55 µm, process length 12-17 µm.
--------------------------------------------------
Original description: Bujak, 1984, p. 189-190
Diagnosis: Central body spherical to ovoidal, bearing gonal processes with ribbon- like trifurcations and secondarily bifurcate tips. Bifurcate tips of adjacent processes connected by pairs of ribbon-like trabeculae, or occasionally by single trabecular strands, in a pattern replicating tabulation pattern. Bifurcate processes sutural processes may also be present. Archeopyle precingular, formed by loss of plate 3''.
Dimensions: Central body diameter 23 x 28 Ám to 37 x 41 Ám; max. process length 21 to 32 Ám; 30 specimens measured.
Description: The central body is thin-walled and has a smooth to chagrinate surface. It is often folded so that is was not possible to determine if sutural crests are present on the examined material. If they do occur, they are extremely low and poorly developed. The processes arising from the central body are relatively long, their length approaching the central body diameter. They are smooth and thin-walled and appear to be hollow. They do not possess the ribbed extensions of sutural crests often present on Spiniferites. The processes have ribbon-like trifurcations that are terminally bifid. These bifurcations are extended into ribbon- like trabeculae that connect adjacent processes in a pattern reflecting tabulation. Due to folding and compression of most specimens examined, it was not possible to determine the tabulation pattern. The trabeculae connecting adjacent processes are mostly paired as in Nematosphaeropsis labyrinthea, but some processes were observed that are connected by a single trabecula. An archeopyle is formed by the loss of a single plate which is inferred to be the third precingular because of the similarity of this species to N. labyrinthea.
Discussion: N. lemniscata is similar to N. labyrinthea, but differs in having ribbon-like rather than slender trabeculae. Reid (1974) discussed the geographic distribution of N. labyrinthea and concluded that it is a warm-water species because of its record from the Caribbean, Red Sea and the North Atlantic Drift. The distribution of N. lemniscata indicates that is a cold water species, having been recorded from the Bering Sea and the extreme northern North Pacific (this paper), the Beaufort Sea (Bujak and Davies 1981), the Grand Banks of Newfoundland (Williams and Brideaux 1975), and the sea of Japan (Shimakura et al. 1971).
Emended description: Wrenn, 1988, p. 143-144
Diagnosis: A species of Nematosphaeropsis characterized by thin, hollow cylindrical gonal and intergonal processes with terminations that are connected distally by pairs of penitabular trabeculae of relatively consistent width and height. Each hollow process furcation splits at its distal end and gives rise to two narrow, flat, ribbon-like penitabular trabeculae. Paraplate boundaries may be partially delineated by very low, discontinuous parasutural ridges on the smooth to microgranular central body, though they are usually poorly developed. Paratabulation is more completely, and commonly, expressed on the concentric trabecular shell surrounding the central body. Paratabulation (3-4', 6'', 6c, 6''', ?p, 1'''') is expressed by the distribution of the penitabular trabeculae connecting the distal ends of the processes. Precingular archeopyle (Type P) formed by the loss of the 3'' paraplate.
Description (annotated): The number of intergonal processes varies. A total of six trabeculae arise from gonal processes and four from intergonal processes. The trabeculae are generally oriented on edge, relative to the subspherical central body, (i.e., oriented like a knife blade about to cut into an orange). Rarely, two processes arise from a single base. Paratabulation may be clearly delineated on well preserved specimens by the distribution of the penitabular trabeculae. However, paratabulation is usually obscured by folding of the thin central body and collapse of the flexible trabeculae and processes onto the central body.
Dimensions: Central body diameter 22(25)28 Ám; overall diameter 39(52)55 Ám; process length 12-17 Ám. 10 specimens measured.
Affinities:
Wrenn, 1988
N. lemniscata differs from all species of Nematosphaeropsis recognized in this paper by having relatively long, thin, hollow cylindrical processes and flat, uniformly narrow trabeculae.
REMARKS:
1) Wrenn, 1988, considers Nematosphaeropsis labyrinthea (Ostenfeld, 1903) sensu Reid, 1974 [not Pterococcus labyrinthus (Ostenfeld (1903) Lohmann 1904] conspecific with Nematosphaeropsis lemniscata. Reid's transfer of N. balcombiana to N. labyrinthea (Ostenfeld, 1903) Reid, 1974, is not accepted by Wrenn, 1988. The original description and drawing of Pterosperma labyrinthea Ostenfeld 1903 suggests that it does not concern a dinoflagellate cyst at all, according to Wrenn, 1988 (see Wrenn, 1988, p. 129-137 for an extensive discussion).
2) Due to the above, the proposed use of N. lemniscata as a cold water indicator (versus N. labyrinthea as a warm water indicator), Bujak 1984, is untenable.