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Lejeunecysta katatonos
Lejeunecysta katatonos Clowes et al. 2016, p.75–77, figs.8a–l.
Holotype: Clowes et al., figs.8a–c.
Age: Oligocene.
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Original description (Clowes et al., 2016):
Lejeunecysta katatonos n. sp. Fig. 8a-l
2000a Lejeunecysta sp. 9; Cape Roberts Science Team, p. 155, table 5.4, fig.5.7i
2001 Lejeunecysta sp. 9; Hannah, Wilson & Wrenn, fig. 1
2001 Lejeunecysta sp. 9; Hannah, Wrenn & Wilson, table 1
Description: Shape: Pentagonal to subrounded; relatively shortened and extremely broad, so that polar orientations are as common as dorso-ventral; epicyst and hypocyst approximately equal in height. Shallow posterior concavity between antapical horns. The sides of the epicyst are straight to slightly convex, whereas those of the hypocyst are straight-to slightly concave. Phragma: Autophragm thin (b1.0 to 1.5 μm thick) smooth and devoid of sculpturing. Horns: Extremely short, broad-based horns arise almost imperceptibly from the margin of the cyst. Both the apical and antapical horns are capped by a papilla. Archeopyle: Intercalary, 2a, iso- to eurydeltaform and typically quite rounded. The operculum is sometimes detached, but usually present and only slightly dislodged from the archeopyle margins. Tabulation: Indicated only by the archeopyle, cingulum, and sometimes a visible sulcus. Cingulum: Strongly marked by parallel smooth folds. Slight excavation is sometimes visible (e.g., Fig. 8f). Sulcus: Visible in polar view (Fig. 8g–h). Marked on the ventral surface by a break in the cingular fold and a slight concavity between the antapical horns on the posterior margin. Occasional specimens show a flagellar scar in the sulcus.
Dimensions: Length 58 (73) 96 μm, width 74 (96) 118 μm (range of 19 specimens); archeopyle length 20–30 μm, width 28–42 μm (range of 7 specimens).
Comparison: Both the large size and broad aspect of Lejeunecysta katatonos distinguish it from other Lejeunecysta species in the Cape Roberts cores. It most closely resembles Lejeunecysta globosa Biffi and Grignani, 1983 differing only (?) in being wider than tall, whereas the length and width of Lejeunecysta globosa are approximately equal. It also resembles Lejeunecysta lata Biffi and Grignani, 1983 in overall shape but differs in lacking denticulate folds bordering the cingulum. Lejeunecysta katatonos is similar in shape to Lejeunecysta spatiosa (Morgenroth, 1966) Wilson and Clowes 1980 and Lejeunecysta diversiforma (Bradford 1977) Artzner and Dörhöfer, 1978, but is much larger than both, and its smooth to chagrinate autophragm lacks the ornamentation characteristic of these species. As noted above, the polar-axis foreshortening of the species causes it to present frequently in polar view. Isolated specimens may be difficult to distinguish from Selenopemphix. Here again, the large size is a useful distinguishing feature. Moreover, we have not observed conspicuous offset of the archeopyle relative to the mid-dorsal line which is common in Selenopemphix.
Reported Stratigraphic Occurrence at Cape Roberts: 225.13 mbsf in CRP-3 to 20.69 mbsf in CRP-3; 891.90 m to 687.46 m in the composite section; Lejeunecysta katatonos Zone to Cymatiosphaera robertsii Zone; Oligocene. The base of the Lejeunecysta katatonos Zone (below) is defined by the first appearance of Lejeunecysta katatonos. The base of ‘Zone C’ of Hannah et al. (2001a) is defined by the first appearances of Lejeunecysta sp. 7 (=Lejeunecysta attenuata) and Lejeunecysta sp. 9 (=Lejeunecysta katatonos) which are depicted (on their fig. 1) as appearing together at the base of CRP-2A. The published data used herein, however, indicates that the two taxa first appear in CRP-3, some 200 m apart.
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Holotype: Clowes et al., figs.8a–c.
Age: Oligocene.
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Original description (Clowes et al., 2016):
Lejeunecysta katatonos n. sp. Fig. 8a-l
2000a Lejeunecysta sp. 9; Cape Roberts Science Team, p. 155, table 5.4, fig.5.7i
2001 Lejeunecysta sp. 9; Hannah, Wilson & Wrenn, fig. 1
2001 Lejeunecysta sp. 9; Hannah, Wrenn & Wilson, table 1
Description: Shape: Pentagonal to subrounded; relatively shortened and extremely broad, so that polar orientations are as common as dorso-ventral; epicyst and hypocyst approximately equal in height. Shallow posterior concavity between antapical horns. The sides of the epicyst are straight to slightly convex, whereas those of the hypocyst are straight-to slightly concave. Phragma: Autophragm thin (b1.0 to 1.5 μm thick) smooth and devoid of sculpturing. Horns: Extremely short, broad-based horns arise almost imperceptibly from the margin of the cyst. Both the apical and antapical horns are capped by a papilla. Archeopyle: Intercalary, 2a, iso- to eurydeltaform and typically quite rounded. The operculum is sometimes detached, but usually present and only slightly dislodged from the archeopyle margins. Tabulation: Indicated only by the archeopyle, cingulum, and sometimes a visible sulcus. Cingulum: Strongly marked by parallel smooth folds. Slight excavation is sometimes visible (e.g., Fig. 8f). Sulcus: Visible in polar view (Fig. 8g–h). Marked on the ventral surface by a break in the cingular fold and a slight concavity between the antapical horns on the posterior margin. Occasional specimens show a flagellar scar in the sulcus.
Dimensions: Length 58 (73) 96 μm, width 74 (96) 118 μm (range of 19 specimens); archeopyle length 20–30 μm, width 28–42 μm (range of 7 specimens).
Comparison: Both the large size and broad aspect of Lejeunecysta katatonos distinguish it from other Lejeunecysta species in the Cape Roberts cores. It most closely resembles Lejeunecysta globosa Biffi and Grignani, 1983 differing only (?) in being wider than tall, whereas the length and width of Lejeunecysta globosa are approximately equal. It also resembles Lejeunecysta lata Biffi and Grignani, 1983 in overall shape but differs in lacking denticulate folds bordering the cingulum. Lejeunecysta katatonos is similar in shape to Lejeunecysta spatiosa (Morgenroth, 1966) Wilson and Clowes 1980 and Lejeunecysta diversiforma (Bradford 1977) Artzner and Dörhöfer, 1978, but is much larger than both, and its smooth to chagrinate autophragm lacks the ornamentation characteristic of these species. As noted above, the polar-axis foreshortening of the species causes it to present frequently in polar view. Isolated specimens may be difficult to distinguish from Selenopemphix. Here again, the large size is a useful distinguishing feature. Moreover, we have not observed conspicuous offset of the archeopyle relative to the mid-dorsal line which is common in Selenopemphix.
Reported Stratigraphic Occurrence at Cape Roberts: 225.13 mbsf in CRP-3 to 20.69 mbsf in CRP-3; 891.90 m to 687.46 m in the composite section; Lejeunecysta katatonos Zone to Cymatiosphaera robertsii Zone; Oligocene. The base of the Lejeunecysta katatonos Zone (below) is defined by the first appearance of Lejeunecysta katatonos. The base of ‘Zone C’ of Hannah et al. (2001a) is defined by the first appearances of Lejeunecysta sp. 7 (=Lejeunecysta attenuata) and Lejeunecysta sp. 9 (=Lejeunecysta katatonos) which are depicted (on their fig. 1) as appearing together at the base of CRP-2A. The published data used herein, however, indicates that the two taxa first appear in CRP-3, some 200 m apart.
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