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Lejeunecysta challengerensis
Lejeunecysta challengerensis Louwye et al., 2008, p.136, pl.2, figs.1–9.
Holotype: Louwye et al., 2008, pl.2, figs.1–9.
Age: early-middle Miocene.
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Original description (Louwye et al., 2008):
Lejeunecysta challengerensis sp. nov. Plate 2, figs. 1–9
Lejeunecysta sp. A, Louwye et al., 2007, text-figs. 4b, 6i–k.
Holotype.Plate 2, figs. 1–9. Slide 02-P1, sample U1318B- 11H-3, 23–25 cm, 93.7 mbsf. England Finder reference N39/1. IRSNB catalogue number b5105. Locality: Porcupine Basin, offshore southwest Ireland. Age: Middle Miocene (Chron C5An.1r, Serravallian).
Etymology.Named after the Challenger Mound (Belgica mound province, Porcupine Basin) drilled during IODP Leg 307.
Diagnosis. A species of Lejeunecysta characterized by a convex epicyst, a reduced or absent apical horn, longitudinal striae on the hypocyst and epicyst. The cingular ridges are ornamented with discrete spines.
Description. Intermediate-sized, peridinioid cyst with a pentagonal outline and dorsoventrally compressed. The wall is single-layered and is light brown in color. The thickness of the autophragm is less than 1 µm, and, as a consequence, the fragile cysts are often folded. The length of the epicyst and the hypocyst are similar. The sides of the epicyst are distinctly convex, while the sides of the hypocyst are straight to slightly concave. The well-developed antapical horns are distally solid, caused by slight thickening of the wall, although this feature is difficult to observe. The apical horn is faintly developed; only a thickening of the apex is normally observed. The smooth wall is sparsely ornamented with isolated granules and linear thickenings or striae on both the epicyst and hypocyst. The ridge-like thickenings run longitudinally from the apex and antapical horns towards the cingulum, but do not reach it. The cingulum is formed by two equatorial, narrow ridges. The ridges appear continuous and are only interrupted by the well-developed sulcus. Both cingular ridges are ornamented with short, simple, discrete spines less than 1 µm long. The archeopyle is formed by the release of an intercalary plate, probably 2a. The operculum is attached.
Dimensions. Holotype: length: 60 µm; width: 72 µm. Range: length: 55(61)66 µm; width: 55(63)74. Number of specimens measured: 9.
Comparison. Lejeunecysta challengerensis sp. nov. is easily distinguished by its broad, convex epicyst, straight to slightly concave hypocyst, and the longitudinal striae or thickenings. Lejeunecysta cinctoria (Bujak in Bujak et al. 1980) Lentin & Williams 1981 differs by the straight epicystal sides, the absence of ridges on the epicyst and hypocyst, and the complex cingular spines. Spines are sometimes present at the apex, ambital periphery, and between the antapical horns. The dimensions of Lejeuncecysta cinctoria are furthermore smaller (width: 41–63 µm; length: 44–62 µm). The epicyst of Lejeunecysta communis Biffi & Grignani 1983 has straight sides, and lacks the pronounced cingulum. Selenopemphix selenoides Benedek 1972 is similar in possessing a cingulum ornamented with spines, but differs from Lejeunecysta challengerensis sp. nov. in having a conical epicyst, an apical horn, and lacking striae. Lejeunecysta hyalina (Gerlach 1961) Artzner & Dörhöfer 1978 is similar in possessing longitudinal striae but lacks the cingular spines, and is larger (width: 93 µm; length: 93 µm).
Occurrence. The only records of Lejeunecysta challengerensis sp. nov. (as Lejeunecysta sp. A) are from the Early and Middle Miocene of the Porcupine Basin (Louwye et al., 2007). Although not continuously present, Lejeunecysta challengerensis sp. nov. is present throughout the late Burdigalian to late Serravallian interval.
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Holotype: Louwye et al., 2008, pl.2, figs.1–9.
Age: early-middle Miocene.
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Original description (Louwye et al., 2008):
Lejeunecysta challengerensis sp. nov. Plate 2, figs. 1–9
Lejeunecysta sp. A, Louwye et al., 2007, text-figs. 4b, 6i–k.
Holotype.Plate 2, figs. 1–9. Slide 02-P1, sample U1318B- 11H-3, 23–25 cm, 93.7 mbsf. England Finder reference N39/1. IRSNB catalogue number b5105. Locality: Porcupine Basin, offshore southwest Ireland. Age: Middle Miocene (Chron C5An.1r, Serravallian).
Etymology.Named after the Challenger Mound (Belgica mound province, Porcupine Basin) drilled during IODP Leg 307.
Diagnosis. A species of Lejeunecysta characterized by a convex epicyst, a reduced or absent apical horn, longitudinal striae on the hypocyst and epicyst. The cingular ridges are ornamented with discrete spines.
Description. Intermediate-sized, peridinioid cyst with a pentagonal outline and dorsoventrally compressed. The wall is single-layered and is light brown in color. The thickness of the autophragm is less than 1 µm, and, as a consequence, the fragile cysts are often folded. The length of the epicyst and the hypocyst are similar. The sides of the epicyst are distinctly convex, while the sides of the hypocyst are straight to slightly concave. The well-developed antapical horns are distally solid, caused by slight thickening of the wall, although this feature is difficult to observe. The apical horn is faintly developed; only a thickening of the apex is normally observed. The smooth wall is sparsely ornamented with isolated granules and linear thickenings or striae on both the epicyst and hypocyst. The ridge-like thickenings run longitudinally from the apex and antapical horns towards the cingulum, but do not reach it. The cingulum is formed by two equatorial, narrow ridges. The ridges appear continuous and are only interrupted by the well-developed sulcus. Both cingular ridges are ornamented with short, simple, discrete spines less than 1 µm long. The archeopyle is formed by the release of an intercalary plate, probably 2a. The operculum is attached.
Dimensions. Holotype: length: 60 µm; width: 72 µm. Range: length: 55(61)66 µm; width: 55(63)74. Number of specimens measured: 9.
Comparison. Lejeunecysta challengerensis sp. nov. is easily distinguished by its broad, convex epicyst, straight to slightly concave hypocyst, and the longitudinal striae or thickenings. Lejeunecysta cinctoria (Bujak in Bujak et al. 1980) Lentin & Williams 1981 differs by the straight epicystal sides, the absence of ridges on the epicyst and hypocyst, and the complex cingular spines. Spines are sometimes present at the apex, ambital periphery, and between the antapical horns. The dimensions of Lejeuncecysta cinctoria are furthermore smaller (width: 41–63 µm; length: 44–62 µm). The epicyst of Lejeunecysta communis Biffi & Grignani 1983 has straight sides, and lacks the pronounced cingulum. Selenopemphix selenoides Benedek 1972 is similar in possessing a cingulum ornamented with spines, but differs from Lejeunecysta challengerensis sp. nov. in having a conical epicyst, an apical horn, and lacking striae. Lejeunecysta hyalina (Gerlach 1961) Artzner & Dörhöfer 1978 is similar in possessing longitudinal striae but lacks the cingular spines, and is larger (width: 93 µm; length: 93 µm).
Occurrence. The only records of Lejeunecysta challengerensis sp. nov. (as Lejeunecysta sp. A) are from the Early and Middle Miocene of the Porcupine Basin (Louwye et al., 2007). Although not continuously present, Lejeunecysta challengerensis sp. nov. is present throughout the late Burdigalian to late Serravallian interval.
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