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Lejeunecysta striata
Lejeunecysta striata Clowes et al., 2016, p.78–79, figs.10a–l.
Holotype: Clowes et al., figs.10a–c.
Age: Oligocene–Miocene.
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Original description (Clowes et al. 2016):
Lejeunecysta striata n. sp. Fig. 10a–l
1999 Lejeunecysta sp. 1; Cape Roberts Science Team, table 5.8, fig. 5.8a
2000 Lejeunecysta sp. 1; Hannah et al., fig. 2, 4h
2001 Lejeunecysta sp. 1; Hannah, Wilson & Wrenn, fig. 1
2004 Lejeunecysta sp. 1; Prebble, pl. 8, fig. 4
2004 Lejeunecysta sp. 6; Prebble, pl. 8, fig. 6–8
2004 Lejeunecysta sp. 7; Prebble, pl. 8, fig. 9
2006 Lejeunecysta sp. 6; Prebble et al., fig. 5o
Description: Shape: Pentagonal with hypocyst generally somewhat larger than epicyst. The sides are straight to slightly convex. The apex and lateral margins are slightly rounded or weakly pointed and the antapical margins are weakly pointed. Specimens are commonly distorted, however, lending considerable variability to the outline (Fig. 10f–l). Phragma: Autophragm fairly thin, brown, adorned with numerous granules and low solid ridges forming longitudinal striae. Horns: Absent or only weakly developed. Short, thickened protuberances usually present at apex and antapical extremities. Archeopyle: Intercalary, 2a, iso- to slightly stenodeltaform. Operculum often remains in position, at other times completely detached. Tabulation: Indicated only by the archeopyle, cingulum, and sometimes a visible sulcus. Cingulum: Fairly prominent and marked by one or two transverse granulate ridges in the middle part of the autocyst. Sulcus: Marked on the ventral surface by a break in the posterior margin of the paracingulum and bordered laterally by one or two granulate septa in the anterior part of the hypocyst.
Dimensions: Length 70.6 (90) 125 μm (16 measurements), width 72.5 (86) 100 μm (20 measurements)
Comparison: This species is distinguished from other described species chiefly by the longitudinal striations on the autophragm surface. Undeformed specimens have a characteristic pentagonal shape with a straight, blunt antapex. In overall shape, Lejeunecysta striata is very similar to Lejeunecysta kammae Willumsen 2011, but Lejeunecysta striata is considerably larger and Lejeunecysta kammae lacks the longitudinal ornament which is characteristic of Lejeunecysta striata.
Reported Stratigraphic Occurrence at Cape Roberts: 225.13 mbsf in CRP-3 to 79.44 mbsf in CRP-2A; 891.90 m to 124.86 m in the composite section; Lejeunecysta katatonos Zone to Lejeunecysta striata Zone; Oligocene to Miocene. The bases of the Lejeunecysta striata Zone (below), and also ‘Zone E’ of Hannah et al. (2001a), are defined by the first appearance of Lejeunecysta striata. The top of ‘Zone E’ appears to be defined by its last appearance, although this is not entirely clear.
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Holotype: Clowes et al., figs.10a–c.
Age: Oligocene–Miocene.
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Original description (Clowes et al. 2016):
Lejeunecysta striata n. sp. Fig. 10a–l
1999 Lejeunecysta sp. 1; Cape Roberts Science Team, table 5.8, fig. 5.8a
2000 Lejeunecysta sp. 1; Hannah et al., fig. 2, 4h
2001 Lejeunecysta sp. 1; Hannah, Wilson & Wrenn, fig. 1
2004 Lejeunecysta sp. 1; Prebble, pl. 8, fig. 4
2004 Lejeunecysta sp. 6; Prebble, pl. 8, fig. 6–8
2004 Lejeunecysta sp. 7; Prebble, pl. 8, fig. 9
2006 Lejeunecysta sp. 6; Prebble et al., fig. 5o
Description: Shape: Pentagonal with hypocyst generally somewhat larger than epicyst. The sides are straight to slightly convex. The apex and lateral margins are slightly rounded or weakly pointed and the antapical margins are weakly pointed. Specimens are commonly distorted, however, lending considerable variability to the outline (Fig. 10f–l). Phragma: Autophragm fairly thin, brown, adorned with numerous granules and low solid ridges forming longitudinal striae. Horns: Absent or only weakly developed. Short, thickened protuberances usually present at apex and antapical extremities. Archeopyle: Intercalary, 2a, iso- to slightly stenodeltaform. Operculum often remains in position, at other times completely detached. Tabulation: Indicated only by the archeopyle, cingulum, and sometimes a visible sulcus. Cingulum: Fairly prominent and marked by one or two transverse granulate ridges in the middle part of the autocyst. Sulcus: Marked on the ventral surface by a break in the posterior margin of the paracingulum and bordered laterally by one or two granulate septa in the anterior part of the hypocyst.
Dimensions: Length 70.6 (90) 125 μm (16 measurements), width 72.5 (86) 100 μm (20 measurements)
Comparison: This species is distinguished from other described species chiefly by the longitudinal striations on the autophragm surface. Undeformed specimens have a characteristic pentagonal shape with a straight, blunt antapex. In overall shape, Lejeunecysta striata is very similar to Lejeunecysta kammae Willumsen 2011, but Lejeunecysta striata is considerably larger and Lejeunecysta kammae lacks the longitudinal ornament which is characteristic of Lejeunecysta striata.
Reported Stratigraphic Occurrence at Cape Roberts: 225.13 mbsf in CRP-3 to 79.44 mbsf in CRP-2A; 891.90 m to 124.86 m in the composite section; Lejeunecysta katatonos Zone to Lejeunecysta striata Zone; Oligocene to Miocene. The bases of the Lejeunecysta striata Zone (below), and also ‘Zone E’ of Hannah et al. (2001a), are defined by the first appearance of Lejeunecysta striata. The top of ‘Zone E’ appears to be defined by its last appearance, although this is not entirely clear.
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