Back
Achomosphaera pachyderma
From Fensome et al., 2019:
Achomosphaera pachyderma, Heilmann-Clausen in Heilmann-Clausen and Thomsen, 1995, p.287–288, pl.10, figs.5–10.
Holotype: Heilmann-Clausen and Thomsen, 1995, pl.10, figs.5–6.
Age: early Aptian.
Paratype: Heilmann-Clausen and Thomsen 1995: Pl. 10, fig. 9
Locus typicus: Ahlum I borehole
---------------------------------------------------------------------------------------------------
Original description: [Heilmann-Clausen and Thomsen, 1995]:
Diagnosis:
This is a skolochorate dinoflagellate cyst. The central body is ovoidal-subsphaerical, thickwalled and hyaline. Fine parasutural lines may, or may not, be visible. Occasionally the parasutures are developed as low ridges over parts of the dorsal surface. Parasutural and gonal massive processes are present. The process-stems are rather robust and short, cylindrical or tapering, often with one or a few vacuoles present. The process-bases are sometimes expanded, in which case they are fenestrate and may coalesce with neighbouring process-bases. The distal process-endings are bi- or trifurcate, usually with bifid tips. The distal ramification is short and blunt, often reduced.
The archaeopyle is precingular, type P (3").
Dimensions:
of holotype: Central body length 46 µm, breadth 40 µm, total length 59 µm, breadth 55 µm.
Dimensions of measured specimens: Central body length: 41 (44) 49 µm. Central body breadth: 40 (42) 47 µm. Total length: 56 (61) 70 µm.
Total breadth: 49 (59) 67 µm. Cyst-wall thickness: 1-2 µm. (7 specimens measured)
Affinities/Comparison:
This new species shows some resemblance to Achomosphaera linifera (COOKSON & EISENACK, 1967b) STOVER & EVITT, 1978 and A. regiensis CORRADINI, 1973. The two previously described species differ in having fewer (mainly gonal) processes which are longer. Furthermore, their central bodies are thinner walled.
Achomosphaera pachyderma, Heilmann-Clausen in Heilmann-Clausen and Thomsen, 1995, p.287–288, pl.10, figs.5–10.
Holotype: Heilmann-Clausen and Thomsen, 1995, pl.10, figs.5–6.
Age: early Aptian.
Paratype: Heilmann-Clausen and Thomsen 1995: Pl. 10, fig. 9
Locus typicus: Ahlum I borehole
---------------------------------------------------------------------------------------------------
Original description: [Heilmann-Clausen and Thomsen, 1995]:
Diagnosis:
This is a skolochorate dinoflagellate cyst. The central body is ovoidal-subsphaerical, thickwalled and hyaline. Fine parasutural lines may, or may not, be visible. Occasionally the parasutures are developed as low ridges over parts of the dorsal surface. Parasutural and gonal massive processes are present. The process-stems are rather robust and short, cylindrical or tapering, often with one or a few vacuoles present. The process-bases are sometimes expanded, in which case they are fenestrate and may coalesce with neighbouring process-bases. The distal process-endings are bi- or trifurcate, usually with bifid tips. The distal ramification is short and blunt, often reduced.
The archaeopyle is precingular, type P (3").
Dimensions:
of holotype: Central body length 46 µm, breadth 40 µm, total length 59 µm, breadth 55 µm.
Dimensions of measured specimens: Central body length: 41 (44) 49 µm. Central body breadth: 40 (42) 47 µm. Total length: 56 (61) 70 µm.
Total breadth: 49 (59) 67 µm. Cyst-wall thickness: 1-2 µm. (7 specimens measured)
Affinities/Comparison:
This new species shows some resemblance to Achomosphaera linifera (COOKSON & EISENACK, 1967b) STOVER & EVITT, 1978 and A. regiensis CORRADINI, 1973. The two previously described species differ in having fewer (mainly gonal) processes which are longer. Furthermore, their central bodies are thinner walled.