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Halodinium scopaeum
Halodinium scopaeum Head, 1993
ACRITARCH
Holotype: Head, 1993, fig.27.14
Locus typicus: St. Erth Beds, Cornwall, SW England
Stratum typicum: Pliocene
Original diagnosis: Head, 1993, p.47
Biphragmal, pale yellow-brown, organic-walled microfossils, smooth or with faintly scabrate ornament. Central body has strong polar compression and circular or subcircular outline in polar view. Pylome located centrally and circular or subcircular, with an entire and usually unthickened margin. Periphragm, which is much thinner than the endophragm, visible as small wrinkles over surface of endocyst, to which it is appressed except at ambitus where it extends into a diaphanous flange that surrounds central body. This ambital flange of approximately constant width; its outer margin usually ragged but may be partially entire on some specimens.
Original description: Head, 1993, p.47
Central body discoidal as a primary feature, this being indicated by polar-compressed orientation of all specimens encountered. Pylome margin usually unthickened (as for holotype) but weak thickening just discernible on some specimens. Operculum not observed. Specimens had resisted uptake of safranin-o stain: central body pale brown, ambital flange almost colorless with pale brown tint. Endophragm thin (about 0.25 Ám thick, perhaps thickening slightly at ambitus) and periphragm much thinner. On central body, periphragm frequently seen only as narrow wrinkles, often subradial and extending onto flange, and sometimes occurring around pylome margin (e.g., Figure 28.3). Wrinkles may also be sub-latitudinal. Accumulation bodies (analogous to omphalos in dinoflagellates) found in two specimens (not holotype), occurring as clusters of 0.5-2.0 Ám subspheres (Figure 28.1, 28.4).
Dimensions.--Holotype: central body maximum diameter, 23 Ám; average width of ambital flange, 4.5 Ám; pylome maximum diameter, 7 Ám. Range: central body maximum diameter, 21(22.6)24 Á; average width of ambital flange, 3.0(4.7)5.5 Ám; pylome maximum diameter, 5.5(6.4)8.0 Ám. Twelve specimens were measured.
Affinities:
Head, 1993, p.47: Halodinium scopaeum differs from H. minor by its smaller size (central body diameter: H. scopaeum, 21-24 Ám; H. minor, 46-63 Ám) and perhaps by its relatively wider ambital flange. Halodinium scopaeum is smaller than all previously reported specimens of Halodinium (see Comments and previous records under Halodinium).
ACRITARCH
Holotype: Head, 1993, fig.27.14
Locus typicus: St. Erth Beds, Cornwall, SW England
Stratum typicum: Pliocene
Original diagnosis: Head, 1993, p.47
Biphragmal, pale yellow-brown, organic-walled microfossils, smooth or with faintly scabrate ornament. Central body has strong polar compression and circular or subcircular outline in polar view. Pylome located centrally and circular or subcircular, with an entire and usually unthickened margin. Periphragm, which is much thinner than the endophragm, visible as small wrinkles over surface of endocyst, to which it is appressed except at ambitus where it extends into a diaphanous flange that surrounds central body. This ambital flange of approximately constant width; its outer margin usually ragged but may be partially entire on some specimens.
Original description: Head, 1993, p.47
Central body discoidal as a primary feature, this being indicated by polar-compressed orientation of all specimens encountered. Pylome margin usually unthickened (as for holotype) but weak thickening just discernible on some specimens. Operculum not observed. Specimens had resisted uptake of safranin-o stain: central body pale brown, ambital flange almost colorless with pale brown tint. Endophragm thin (about 0.25 Ám thick, perhaps thickening slightly at ambitus) and periphragm much thinner. On central body, periphragm frequently seen only as narrow wrinkles, often subradial and extending onto flange, and sometimes occurring around pylome margin (e.g., Figure 28.3). Wrinkles may also be sub-latitudinal. Accumulation bodies (analogous to omphalos in dinoflagellates) found in two specimens (not holotype), occurring as clusters of 0.5-2.0 Ám subspheres (Figure 28.1, 28.4).
Dimensions.--Holotype: central body maximum diameter, 23 Ám; average width of ambital flange, 4.5 Ám; pylome maximum diameter, 7 Ám. Range: central body maximum diameter, 21(22.6)24 Á; average width of ambital flange, 3.0(4.7)5.5 Ám; pylome maximum diameter, 5.5(6.4)8.0 Ám. Twelve specimens were measured.
Affinities:
Head, 1993, p.47: Halodinium scopaeum differs from H. minor by its smaller size (central body diameter: H. scopaeum, 21-24 Ám; H. minor, 46-63 Ám) and perhaps by its relatively wider ambital flange. Halodinium scopaeum is smaller than all previously reported specimens of Halodinium (see Comments and previous records under Halodinium).