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Selenopemphix bothrion
Selenopemphix bothrion Harland and Pudsey, 2002, p.273,275, pl.2, figs.1–4; pl.3, figs.7–8; pl.4, figs.1–2.
Holotype: Harland and Pudsey, 2002, pl.2, figs.1–2. N.I.A.
Age: late Miocene.
Original description (Harland & Pudsey, 2002)
Derivation of name: Greek, bothrion, neuter, diminutive, meaning small trench, pit and trough in respect of the negative ornament that occurs on the epicystal and hypocystal borders to the paracingulum.
Diagnosis: A brown, intermediate-sized cyst with reniform outline in both polar and dorso-ventral compression. Cyst wall unstratified under light microscopy and with a smooth to striate surface. Paracingulum planar and conspicuous. There are a series of slit-like negative features along both the epi- and hypocystal margins to the paracingulum. This negative ornament can appear as simple elongate channels or can be more complex and developed into basin-like depressions. Archaeopyle may be almost symmetrical to dorsoventral midline to slightly offset to the left, monoplacoid and iso-deltaform. Operculum free.
Description: This intermediate-sized dinoflagellate cyst is usually seen in polar compression such that it has a reniform ambitus. The cyst wall is brown, made up of a single unstratified layer that appears smooth in bright field optical microscopy; some specimens are somewhat striate. The cyst, when seen in dorso-ventral compression, is peridinioid exhibiting a broad conical epicyst, with an apex that is occasionally thickened, and a hypocyst that is broad and conical with a flat antapex ( Plate III, 7–8). The planar paracingulum runs around the circumference of the cyst in polar compression and is characterised by a series of slit-like negative ornament on both the epi- and hypocystal margins (Plate IV, 2). These markings are conspicuous and may appear as a series of interconnecting basin-like depressions radially aligned. Apart from the paracingulum, and a broad shallow parasulcus, there is no additional evidence of a paratabulation except for the archaeopyle. The archaeopyle appears to be almost symmetrical to the dorsoventral midline to slightly asymmetrical, offset to the left; it is large, presumably intercalary, 2a, iso-deltaform in shape with secondary archaeopyle sutures developed from the antapical corners down through the precingular paraplates to the paracingulum. The operculum is monoplacoid and free.
Nomenclatural types: The holotype is designated Specimen No. R.8001.5, Plate II, 1–2, slide RH 308A, ODP 1095B-24X-3, 101–103, England Finder Q30/0 and is lodged in the collections of the British Antarctic Survey, Cambridge. Age: Late Miocene at 7.15 Ma.
The isotype is designated Specimen No. R.8001.14, Plate III, 7–8, slide RH 308A, ODP 1095B-24X-3, 101–103, England Finder H39/4 and is lodged in the collections of the British Antarctic Survey, Cambridge. Age: Late Miocene at 7.15 Ma.
Dimensions: Holotype, minimum dimension between the ventral and dorsal surfaces of the cyst in apical/antapical compression, 72 μm. Maximum dimension between the lateral sides of the cyst, 87 μm.
Range: minimum dimension (usually between the ventral and dorsal surfaces in polar compression), 49(61.9)72 μm. Maximum dimension (usually between the lateral sides of the cyst in polar compression), 60(75.7)89 μm. Fourteen specimens measured.
Remarks: This easily identifiable species had previously been noted by Duffield and Stein (1986) in their study of the Miocene of the Gulf of Mexico and was given the informal designation of Selenopemphix sp. E. These authors show a stratigraphic range for this species of Early to Late Miocene, planktonic foraminiferal zone (after Blow, 1969) of N6 to N17. Our record of this species is consistent with the data of Duffield and Stein (1986). We record this species throughout the Late Miocene as Selenopemphix sp. E of Duffield and Stein (1986) in our study of ODP Leg 178 (Pudsey and Harland, 2001).
Occurrence: This species was recorded in samples RH308, RH310, RH399, RH311 and RH402, Late Miocene dated between 7.15 and 9.88 Ma.
Holotype: Harland and Pudsey, 2002, pl.2, figs.1–2. N.I.A.
Age: late Miocene.
Original description (Harland & Pudsey, 2002)
Derivation of name: Greek, bothrion, neuter, diminutive, meaning small trench, pit and trough in respect of the negative ornament that occurs on the epicystal and hypocystal borders to the paracingulum.
Diagnosis: A brown, intermediate-sized cyst with reniform outline in both polar and dorso-ventral compression. Cyst wall unstratified under light microscopy and with a smooth to striate surface. Paracingulum planar and conspicuous. There are a series of slit-like negative features along both the epi- and hypocystal margins to the paracingulum. This negative ornament can appear as simple elongate channels or can be more complex and developed into basin-like depressions. Archaeopyle may be almost symmetrical to dorsoventral midline to slightly offset to the left, monoplacoid and iso-deltaform. Operculum free.
Description: This intermediate-sized dinoflagellate cyst is usually seen in polar compression such that it has a reniform ambitus. The cyst wall is brown, made up of a single unstratified layer that appears smooth in bright field optical microscopy; some specimens are somewhat striate. The cyst, when seen in dorso-ventral compression, is peridinioid exhibiting a broad conical epicyst, with an apex that is occasionally thickened, and a hypocyst that is broad and conical with a flat antapex ( Plate III, 7–8). The planar paracingulum runs around the circumference of the cyst in polar compression and is characterised by a series of slit-like negative ornament on both the epi- and hypocystal margins (Plate IV, 2). These markings are conspicuous and may appear as a series of interconnecting basin-like depressions radially aligned. Apart from the paracingulum, and a broad shallow parasulcus, there is no additional evidence of a paratabulation except for the archaeopyle. The archaeopyle appears to be almost symmetrical to the dorsoventral midline to slightly asymmetrical, offset to the left; it is large, presumably intercalary, 2a, iso-deltaform in shape with secondary archaeopyle sutures developed from the antapical corners down through the precingular paraplates to the paracingulum. The operculum is monoplacoid and free.
Nomenclatural types: The holotype is designated Specimen No. R.8001.5, Plate II, 1–2, slide RH 308A, ODP 1095B-24X-3, 101–103, England Finder Q30/0 and is lodged in the collections of the British Antarctic Survey, Cambridge. Age: Late Miocene at 7.15 Ma.
The isotype is designated Specimen No. R.8001.14, Plate III, 7–8, slide RH 308A, ODP 1095B-24X-3, 101–103, England Finder H39/4 and is lodged in the collections of the British Antarctic Survey, Cambridge. Age: Late Miocene at 7.15 Ma.
Dimensions: Holotype, minimum dimension between the ventral and dorsal surfaces of the cyst in apical/antapical compression, 72 μm. Maximum dimension between the lateral sides of the cyst, 87 μm.
Range: minimum dimension (usually between the ventral and dorsal surfaces in polar compression), 49(61.9)72 μm. Maximum dimension (usually between the lateral sides of the cyst in polar compression), 60(75.7)89 μm. Fourteen specimens measured.
Remarks: This easily identifiable species had previously been noted by Duffield and Stein (1986) in their study of the Miocene of the Gulf of Mexico and was given the informal designation of Selenopemphix sp. E. These authors show a stratigraphic range for this species of Early to Late Miocene, planktonic foraminiferal zone (after Blow, 1969) of N6 to N17. Our record of this species is consistent with the data of Duffield and Stein (1986). We record this species throughout the Late Miocene as Selenopemphix sp. E of Duffield and Stein (1986) in our study of ODP Leg 178 (Pudsey and Harland, 2001).
Occurrence: This species was recorded in samples RH308, RH310, RH399, RH311 and RH402, Late Miocene dated between 7.15 and 9.88 Ma.