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Heterosphaeridium heteracanthum
Heterosphaeridium? heteracanthum (Deflandre and Cookson, 1955) Eisenack and Kjellström, 1971; Emendation: Radmacher et al., 2014, p.33,36, as Heterosphaeridium heteracanthum.
Originally Hystrichosphaeridium, subsequently Baltisphaeridium (acritarch), thirdly Cleistosphaeridium, fourthly (and now) Heterosphaeridium, fifthly Heterosphaeridium?Questionable assignment: Stover and Evitt (1978, p.52); however, Fauconnier and Begouën in Fauconnier and Masure (2004, p.269) considered that this species should be assigned to Heterosphaeridium without question.
Holotype: Deflandre and Cookson, 1955, pl.2, fig.5; Fauconnier and Masure, 2004, pl.35, figs.7–8
Locus typicus: Victoria, Australia
Stratum typicum: ?Late Cretaceous-Early Eocene
Original description: Deflandre and Cookson, 1955, p. 276: Hystrichosphaeridium heteracanthum
Shell large, approximately circular in outline, with numerous appandages of variable size, shape and form. Appandages solid, usually elongated, frequently filiform, sometimes as beoad as long, the apices either pointed, everted, or irregulary branched. Surface of shell punctate.
Dimensions: Shell 56-107 µm, appandages 5-36 µm long (majority between 13 and 23 µm).
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Emendation (Radmacher et al., 2003):
Synonyms:
1955 Hystrichosphaeridium heteracanthum (De flandre and Cookson): 276, pl. 2, figs. 5 –6, text figs. 40 –41.
1965 Baltisphaeridium heteracanthum (Downie and Sarjeant): 91 Table 1 Distribution of palynomorphs in well 7119/9-1. (not validly published).
1966 Cleistosphaeridium heteracanthum (Davey et al.): 168, pl. 2, figs. 6–7.
1971 Heterosphaeridium heteracanthum (Eisenack and Kjellström): 451, pl. 7, fig. 3.
1978 Heterosphaeridium? heteracanthum (Stover and Evitt): 52.
2004 Heterosphaeridium heteracanthum (Fauconnier and Begouën in Fauconnier and Masure): 269, pl. 35, figs. 7–8.
Emended diagnosis (based on original description and photograph of Deflandre and Cookson, 1955, pl. 2, figs. 5, 6): Large, gonyaulacacean, circular in outline, chorate to proximo-chorate cyst with an apical archaeopyle. Numerous, non-tabular processes are characterised by variable shape, length and width. All processes are solid, usually elongated and their endings differ significantly. They may be pointed, everted or irregularly branched, never “scythe-like” or distally connected. Wall structure is punctate.
Comparison to Heterosphaeridium bellii: Heterosphaeridium heteracanthum differs significantly from H. bellii sp. nov. by having solid processes of variable length and width, often strongly branched and furcated at the ends and never “scythe-shaped” terminations. The processes of H. bellii sp. nov. are rather constant in length and possess different, “scythe-shaped” types of terminations. They are solid and hollow on one specimen. Some of the processes may be solid in the middle and hollow at the ends. The endings are never branched as in H. heteracanthum. Additionally, crests observed in H. heteracanthum are much taller and more commonly observed than in H. bellii sp. nov.
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Originally Hystrichosphaeridium, subsequently Baltisphaeridium (acritarch), thirdly Cleistosphaeridium, fourthly (and now) Heterosphaeridium, fifthly Heterosphaeridium?Questionable assignment: Stover and Evitt (1978, p.52); however, Fauconnier and Begouën in Fauconnier and Masure (2004, p.269) considered that this species should be assigned to Heterosphaeridium without question.
Holotype: Deflandre and Cookson, 1955, pl.2, fig.5; Fauconnier and Masure, 2004, pl.35, figs.7–8
Locus typicus: Victoria, Australia
Stratum typicum: ?Late Cretaceous-Early Eocene
Original description: Deflandre and Cookson, 1955, p. 276: Hystrichosphaeridium heteracanthum
Shell large, approximately circular in outline, with numerous appandages of variable size, shape and form. Appandages solid, usually elongated, frequently filiform, sometimes as beoad as long, the apices either pointed, everted, or irregulary branched. Surface of shell punctate.
Dimensions: Shell 56-107 µm, appandages 5-36 µm long (majority between 13 and 23 µm).
---------------------------------------------
Emendation (Radmacher et al., 2003):
Synonyms:
1955 Hystrichosphaeridium heteracanthum (De flandre and Cookson): 276, pl. 2, figs. 5 –6, text figs. 40 –41.
1965 Baltisphaeridium heteracanthum (Downie and Sarjeant): 91 Table 1 Distribution of palynomorphs in well 7119/9-1. (not validly published).
1966 Cleistosphaeridium heteracanthum (Davey et al.): 168, pl. 2, figs. 6–7.
1971 Heterosphaeridium heteracanthum (Eisenack and Kjellström): 451, pl. 7, fig. 3.
1978 Heterosphaeridium? heteracanthum (Stover and Evitt): 52.
2004 Heterosphaeridium heteracanthum (Fauconnier and Begouën in Fauconnier and Masure): 269, pl. 35, figs. 7–8.
Emended diagnosis (based on original description and photograph of Deflandre and Cookson, 1955, pl. 2, figs. 5, 6): Large, gonyaulacacean, circular in outline, chorate to proximo-chorate cyst with an apical archaeopyle. Numerous, non-tabular processes are characterised by variable shape, length and width. All processes are solid, usually elongated and their endings differ significantly. They may be pointed, everted or irregularly branched, never “scythe-like” or distally connected. Wall structure is punctate.
Comparison to Heterosphaeridium bellii: Heterosphaeridium heteracanthum differs significantly from H. bellii sp. nov. by having solid processes of variable length and width, often strongly branched and furcated at the ends and never “scythe-shaped” terminations. The processes of H. bellii sp. nov. are rather constant in length and possess different, “scythe-shaped” types of terminations. They are solid and hollow on one specimen. Some of the processes may be solid in the middle and hollow at the ends. The endings are never branched as in H. heteracanthum. Additionally, crests observed in H. heteracanthum are much taller and more commonly observed than in H. bellii sp. nov.
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