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Bitectatodinium readwallii
Bitectatodinium raedwaldii, Head, 1997, p.175, fig.7, nos.7-20; fig.15, nos.15-17; fig.16, nos.1-3.
Holotype: Head, 1997, fig.7, nos.7-11.
Type stratum and locality: Sudbourne member of the coralline crag forrmation at Rockhall Woord, Suffikj
Occurence: Upper Pliocene (upper Gauss magnetochron) of ODP Site 644, Norwegian Sea (as "cf. Bitectatodinium sp." of Head in Head and Wrenn, 1992), upper Pliocene of south-western England (as "Genus and Species indeterminate" of Head, 1993), and mid Pliocene of the present study.
Age: mid Pliocene.
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Original description: [Head, 1997, p.175]:
Diagnosis:
Cyst proximate, spherical or subspherical with very thin (less than 0.3 µm) solid pedium bearing closely spaced pili that constitute luxuria. Pili have circular cross-section, smooth surface, even thickness (ca. 0.1-0.2 µm) for much of length but widen at base, and blunt rounded distal terminations. Pili aris straight and perpendicular or subperpendicular to pedium. Then, if short, pili fuse terminally with adjacent pili to form clusters. Longer pili bend distally and drape for short distance over surface of luxuria, fusing distally with adjacent pili and creating faint pattern of diffuse irregular ridges.
Archeopyle intercalary Type 2P; operculum compound, free.
Dimensions:
Holotype: width (including luxuria), 48 µm; wall thickness, ca. 1.3 µm
Range: diameter 31 (37.9) 48 µm, standard deviation, 3.8; wall thickness, ca. 0.8-1.8 µm. Thirty-two mostly uncompressed specimens were measured.
Discussion:
Distal fusion of pili is a definite character for this species. The Coralline Crag specimens have pili of variable length, but length is fairly constant on individuals. Specimens with relatively long pili (as in the holotype; Figure 7.7-7.11) appear distinctly hirsute, and ridges of fused pili are easily resolved under the light microscope. Specimens with shorter pili can appear almost granulate (Figure 7.15-7.17), the "granules" being clusters of short, distally fused pili (Figures 15.17, 16.1). The archeopyle is formed by loss of plates 3" and 4"whose anterior margins are dithigmate-geniculate and monothigmate-rectinilinear, respectively.
Affinities/Comparison:
Bitectotadinium tepikiense Wilson, 1973 has a luxuria consisting of a complex arrangement of mostly perpendicular or subpendicular lamellae that may arise from variably developed basal thickenings (Head, 1994a, 1996). Habibacysta tectata Head et al., 1989d has a Type 1P Archeopyle with rounded angles and thin discontinuous tegillum supported by columellae. "Headinium miocenicum" (ms name in Zevenboom 1995; synonymous with Filisphaera filifera auct. non. Bujak in Rusbült and Strauss, 1992, and "cf. Habibacysta sp." Of zevenboom in Head, 1994b) has a Type 2P archeopyle, but differs in bearing thin, possibly continuous tegillum that connects rods distally. Bitectatodinium cg. tepikense of McMinn (1992b), recorded from an undifferentiated Pliocene to Holocene interval in Australia, appears similar to B.? raedwalli put may not have the distal fusion of pili that characterizes B. raedwalli new species.
Holotype: Head, 1997, fig.7, nos.7-11.
Type stratum and locality: Sudbourne member of the coralline crag forrmation at Rockhall Woord, Suffikj
Occurence: Upper Pliocene (upper Gauss magnetochron) of ODP Site 644, Norwegian Sea (as "cf. Bitectatodinium sp." of Head in Head and Wrenn, 1992), upper Pliocene of south-western England (as "Genus and Species indeterminate" of Head, 1993), and mid Pliocene of the present study.
Age: mid Pliocene.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Head, 1997, p.175]:
Diagnosis:
Cyst proximate, spherical or subspherical with very thin (less than 0.3 µm) solid pedium bearing closely spaced pili that constitute luxuria. Pili have circular cross-section, smooth surface, even thickness (ca. 0.1-0.2 µm) for much of length but widen at base, and blunt rounded distal terminations. Pili aris straight and perpendicular or subperpendicular to pedium. Then, if short, pili fuse terminally with adjacent pili to form clusters. Longer pili bend distally and drape for short distance over surface of luxuria, fusing distally with adjacent pili and creating faint pattern of diffuse irregular ridges.
Archeopyle intercalary Type 2P; operculum compound, free.
Dimensions:
Holotype: width (including luxuria), 48 µm; wall thickness, ca. 1.3 µm
Range: diameter 31 (37.9) 48 µm, standard deviation, 3.8; wall thickness, ca. 0.8-1.8 µm. Thirty-two mostly uncompressed specimens were measured.
Discussion:
Distal fusion of pili is a definite character for this species. The Coralline Crag specimens have pili of variable length, but length is fairly constant on individuals. Specimens with relatively long pili (as in the holotype; Figure 7.7-7.11) appear distinctly hirsute, and ridges of fused pili are easily resolved under the light microscope. Specimens with shorter pili can appear almost granulate (Figure 7.15-7.17), the "granules" being clusters of short, distally fused pili (Figures 15.17, 16.1). The archeopyle is formed by loss of plates 3" and 4"whose anterior margins are dithigmate-geniculate and monothigmate-rectinilinear, respectively.
Affinities/Comparison:
Bitectotadinium tepikiense Wilson, 1973 has a luxuria consisting of a complex arrangement of mostly perpendicular or subpendicular lamellae that may arise from variably developed basal thickenings (Head, 1994a, 1996). Habibacysta tectata Head et al., 1989d has a Type 1P Archeopyle with rounded angles and thin discontinuous tegillum supported by columellae. "Headinium miocenicum" (ms name in Zevenboom 1995; synonymous with Filisphaera filifera auct. non. Bujak in Rusbült and Strauss, 1992, and "cf. Habibacysta sp." Of zevenboom in Head, 1994b) has a Type 2P archeopyle, but differs in bearing thin, possibly continuous tegillum that connects rods distally. Bitectatodinium cg. tepikense of McMinn (1992b), recorded from an undifferentiated Pliocene to Holocene interval in Australia, appears similar to B.? raedwalli put may not have the distal fusion of pili that characterizes B. raedwalli new species.