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Cerodinium nielsii
Cerodinium nielsii, Willumsen, 2011, p.218–219, figs.7D,J.
Holotype: Willumsen, 2011, fig.7J.
Type unit and locality: Mead Hill Formation, Mead Stream section, Clarence Valley, Marlborough, New Zealand.
Age and distribution: ranges within the uppermost RP2 to lower RP3 radiolarian zones, corresponding to an early Paleocene age of ca 64.3–63.8 Ma (Fig. 6); rare to common in following New Zealand sections: Branch Stream, Fairfield Quarry, Grey River, Mead Stream and mid-Waipara River (Willumsen 2003; see Fig. 1 for the location of mentioned sections).
Age: early Paleocene.
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Original description: [Willumsen, 2011]:
Diagnosis:
Pericyst ovoid, convex-sided Cerodinium with three relatively short, conical horns. Endocyst spherical to ellipsoidal and only slightly smaller than the pericyst. Cyst wall smooth. Cingulum and sulcus indicated by folds. Intercalary archeopyle of steno-deltaform type, expressed by the loss of intercalary plate 2a. Operculum is detached.
Description:
Peridinioid, proximate, cornucavate to bicavate, dorsoventrally compressed cyst with thin hyaline endophragm and periphragm.
Endocyst is spherical to ellipsoidal and smaller than the pericyst. Cyst wall layers are hyaline, 1–2 μm thick.
The apical and two antapical horns are short, each with a rounded conical tip.
Parasulcus is not indicated and the paratabulation is marked by longitudinal folds at the cingulum.
The archeopyle is located on the mid-dorsal line and is intercalary, steno-deltaform, type I(2a).
Dimensions:
The total length is 129(102)86 μm [5 specimens measured] and total width 76(64) 59 μm [5 specimens measured]. Endocyst 68(64)57 μm [5 specimens measured].
Affinities/Remarks:
Cerodinium nielsii sp. nov. differs from C. albertii, C. subquadrum Corradini, 1973, C. balticum Vozzhennikova, 1967, C. sibiricum Vozzhennikova, 1963 and C. striatum Drugg, 1967 in having a thin, smooth, hyaline periphragm and a hyaline endocyst. Cerodinium warrenii Schumacker-Lambry, 1978 has serrated edges in the apical and precingular areas; Cerodinium navarrianum Srivastava, 1995 has a circular endocyst, and C. pannuceum Stanley, 1965 and C. conspicuum Marheinecke, 1992 have a paracingulum. Cerodinium nielsii differs from C. cordiferum May, 1980 by having a circular endocyst, a smooth periphragm and no indication of the sulcus. Cerodinium nielsii differs from C. mediterraneum Slimani, 2007 by having three short conical horns with rounded tips and a smooth periphragm.
Holotype: Willumsen, 2011, fig.7J.
Type unit and locality: Mead Hill Formation, Mead Stream section, Clarence Valley, Marlborough, New Zealand.
Age and distribution: ranges within the uppermost RP2 to lower RP3 radiolarian zones, corresponding to an early Paleocene age of ca 64.3–63.8 Ma (Fig. 6); rare to common in following New Zealand sections: Branch Stream, Fairfield Quarry, Grey River, Mead Stream and mid-Waipara River (Willumsen 2003; see Fig. 1 for the location of mentioned sections).
Age: early Paleocene.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Willumsen, 2011]:
Diagnosis:
Pericyst ovoid, convex-sided Cerodinium with three relatively short, conical horns. Endocyst spherical to ellipsoidal and only slightly smaller than the pericyst. Cyst wall smooth. Cingulum and sulcus indicated by folds. Intercalary archeopyle of steno-deltaform type, expressed by the loss of intercalary plate 2a. Operculum is detached.
Description:
Peridinioid, proximate, cornucavate to bicavate, dorsoventrally compressed cyst with thin hyaline endophragm and periphragm.
Endocyst is spherical to ellipsoidal and smaller than the pericyst. Cyst wall layers are hyaline, 1–2 μm thick.
The apical and two antapical horns are short, each with a rounded conical tip.
Parasulcus is not indicated and the paratabulation is marked by longitudinal folds at the cingulum.
The archeopyle is located on the mid-dorsal line and is intercalary, steno-deltaform, type I(2a).
Dimensions:
The total length is 129(102)86 μm [5 specimens measured] and total width 76(64) 59 μm [5 specimens measured]. Endocyst 68(64)57 μm [5 specimens measured].
Affinities/Remarks:
Cerodinium nielsii sp. nov. differs from C. albertii, C. subquadrum Corradini, 1973, C. balticum Vozzhennikova, 1967, C. sibiricum Vozzhennikova, 1963 and C. striatum Drugg, 1967 in having a thin, smooth, hyaline periphragm and a hyaline endocyst. Cerodinium warrenii Schumacker-Lambry, 1978 has serrated edges in the apical and precingular areas; Cerodinium navarrianum Srivastava, 1995 has a circular endocyst, and C. pannuceum Stanley, 1965 and C. conspicuum Marheinecke, 1992 have a paracingulum. Cerodinium nielsii differs from C. cordiferum May, 1980 by having a circular endocyst, a smooth periphragm and no indication of the sulcus. Cerodinium nielsii differs from C. mediterraneum Slimani, 2007 by having three short conical horns with rounded tips and a smooth periphragm.