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Corrudinium devernaliae
Corrudinium devernaliae Head and Norris, 2003, p.8, fig.7, nos.1-20.
Holotype: Head and Norris, 2003, fig.7, nos.14-17.
Age: Early Pliocene.
"Corrudinium devernaliae new species Figure 7
Corrudinium harlandii auct. non Matsuoka, 1983. Mudie, 1987, pl. 3, fig. 9a, 9b.
Corrudinium sp. I. de Vernal and Mudie, 1989, p. 413, pl. 3, figs. 14–16.
Corrudinium sp. I of de Vernal and Mudie, 1989. Kolev, 1993, p. 41, pl. 1, figs. 10, 11.
Diagnosis
Small, ovoid, proximate cysts having smooth surface and ridges that form coarse irregular reticulum, reflecting tabulation only obscurely. Ridges of even height arise from wide bases and narrow distally towards crests that are entire. Small vesicles occur at bases of some or most ridges, and may also occur upwards through ridges at ridge junctions. Archeopyle precingular 1P, formed by loss of plate 3″, has unornamented margins, well defined angles. Operculum free.
Description
Ovoid proximate cysts lacking apical protuberance. Wall is an autophragm and has smooth surface. Color varies from light yellow-brown to colorless. Between ridges, wall appears unstructured and has thickness less than ca. 0.5 μm. Ridges form complete or incomplete irregular reticulum over entire surface of cyst. Reticulation for each cyst contains lumina in a range of sizes, smallest mostly about 2–4 μm and largest about 7–14 μm. Ridges have smooth surface, arise from wide (ca. 1.0 μm) bases, narrow distally towards crests that are entire and of generally even height. Clusters of small (mostly less than 0.5 μm) vesicles occur at bases of some or most ridges, and may also occur upwards through ridges at ridge junctions. Occasionally these vesicles occur elsewhere on ridges along with occasional minute perforations of ridge. Tabulation generally obscure, but ridges occasionally reflect tabulation around cingulum and in ventral area. Archeopyle surrounded by unornamented margin about 1–3 μm wide; angles of archeopyle well defined.
Etymology
Named for Anne de Vernal who first recognized the stratigraphic significance of this species (de Vernal and Mudie, 1989).
Type
Holotype, sample DSDP 603C-28-6, 35–37 cm; slide 1 (ROM 55080); England Finder reference Q15/2. Lower Pliocene. Figure 7.14–7.17.
Measurements
Holotype: length of central body 28 μm, breadth of central body 26 μm; ridge height 1.5 μm. Range: length of central body 27(30.7)35 μm, standard deviation 2.3 μm; equatorial diameter of central body 23(26.7)30 μm, standard deviation 2.1 μm; ridge height 1.5(2.2)3.5 μm. Twenty-one specimens measured.
Occurrence
Lower Pliocene (nannofossil zones NN12 though NN15) of ODP Site 646, Labrador Sea, being common in nannofossil zones NN13 though NN15 (as Corrudinium sp. I in de Vernal and Mudie, 1989; Knüttel et al., 1989). Sporadic higher occurrences that extend into the Upper Pliocene of the Labrador Sea (de Vernal and Mudie, 1989, figs. 3 and 6) possibly represent reworking. A specimen has also been recorded from the Lower Pliocene (nannofossil zone NN15) of DSDP Site 611 in the northern North Atlantic (as Corrudinium harlandii in Mudie, 1987). Corrudinium devernaliae has a narrow and well-defined range within the Lower Pliocene of DSDP Hole 603C.
Comparison
Cerebrocysta perforocresta (MS name) Zevenboom and Santarelli in Zevenboom, 1995, from the Upper Miocene of Italy (which Zevenboom and Santarelli synonymised with Cerebrocysta sp. A of Powell, 1986; and Cerebrocysta sp. A of Powell, 1986 in Engel, 1992), is similar in overall morphology but much larger (length, 60–85 μm; Zevenboom, 1995). Cerebrocysta perforocresta (op. cit.) does not occur in DSDP Hole 603C. Corrudinium harlandii Matsuoka, 1983, described from the Pliocene or Lower Pleistocene of Japan, differs from Corrudinium devernaliae n. sp. in being thinner walled (and hence greater propensity for folding), and in having more delicate septa, more complete expression of tabulation, and a coarsely striate surface."
Holotype: Head and Norris, 2003, fig.7, nos.14-17.
Age: Early Pliocene.
"Corrudinium devernaliae new species Figure 7
Corrudinium harlandii auct. non Matsuoka, 1983. Mudie, 1987, pl. 3, fig. 9a, 9b.
Corrudinium sp. I. de Vernal and Mudie, 1989, p. 413, pl. 3, figs. 14–16.
Corrudinium sp. I of de Vernal and Mudie, 1989. Kolev, 1993, p. 41, pl. 1, figs. 10, 11.
Diagnosis
Small, ovoid, proximate cysts having smooth surface and ridges that form coarse irregular reticulum, reflecting tabulation only obscurely. Ridges of even height arise from wide bases and narrow distally towards crests that are entire. Small vesicles occur at bases of some or most ridges, and may also occur upwards through ridges at ridge junctions. Archeopyle precingular 1P, formed by loss of plate 3″, has unornamented margins, well defined angles. Operculum free.
Description
Ovoid proximate cysts lacking apical protuberance. Wall is an autophragm and has smooth surface. Color varies from light yellow-brown to colorless. Between ridges, wall appears unstructured and has thickness less than ca. 0.5 μm. Ridges form complete or incomplete irregular reticulum over entire surface of cyst. Reticulation for each cyst contains lumina in a range of sizes, smallest mostly about 2–4 μm and largest about 7–14 μm. Ridges have smooth surface, arise from wide (ca. 1.0 μm) bases, narrow distally towards crests that are entire and of generally even height. Clusters of small (mostly less than 0.5 μm) vesicles occur at bases of some or most ridges, and may also occur upwards through ridges at ridge junctions. Occasionally these vesicles occur elsewhere on ridges along with occasional minute perforations of ridge. Tabulation generally obscure, but ridges occasionally reflect tabulation around cingulum and in ventral area. Archeopyle surrounded by unornamented margin about 1–3 μm wide; angles of archeopyle well defined.
Etymology
Named for Anne de Vernal who first recognized the stratigraphic significance of this species (de Vernal and Mudie, 1989).
Type
Holotype, sample DSDP 603C-28-6, 35–37 cm; slide 1 (ROM 55080); England Finder reference Q15/2. Lower Pliocene. Figure 7.14–7.17.
Measurements
Holotype: length of central body 28 μm, breadth of central body 26 μm; ridge height 1.5 μm. Range: length of central body 27(30.7)35 μm, standard deviation 2.3 μm; equatorial diameter of central body 23(26.7)30 μm, standard deviation 2.1 μm; ridge height 1.5(2.2)3.5 μm. Twenty-one specimens measured.
Occurrence
Lower Pliocene (nannofossil zones NN12 though NN15) of ODP Site 646, Labrador Sea, being common in nannofossil zones NN13 though NN15 (as Corrudinium sp. I in de Vernal and Mudie, 1989; Knüttel et al., 1989). Sporadic higher occurrences that extend into the Upper Pliocene of the Labrador Sea (de Vernal and Mudie, 1989, figs. 3 and 6) possibly represent reworking. A specimen has also been recorded from the Lower Pliocene (nannofossil zone NN15) of DSDP Site 611 in the northern North Atlantic (as Corrudinium harlandii in Mudie, 1987). Corrudinium devernaliae has a narrow and well-defined range within the Lower Pliocene of DSDP Hole 603C.
Comparison
Cerebrocysta perforocresta (MS name) Zevenboom and Santarelli in Zevenboom, 1995, from the Upper Miocene of Italy (which Zevenboom and Santarelli synonymised with Cerebrocysta sp. A of Powell, 1986; and Cerebrocysta sp. A of Powell, 1986 in Engel, 1992), is similar in overall morphology but much larger (length, 60–85 μm; Zevenboom, 1995). Cerebrocysta perforocresta (op. cit.) does not occur in DSDP Hole 603C. Corrudinium harlandii Matsuoka, 1983, described from the Pliocene or Lower Pleistocene of Japan, differs from Corrudinium devernaliae n. sp. in being thinner walled (and hence greater propensity for folding), and in having more delicate septa, more complete expression of tabulation, and a coarsely striate surface."