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Areosphaeridium michoudii
Areosphaeridium michoudii, Bujak, 1994, p. 121, pl.1, figs.1–3.
Holotype: Bujak, 1994
Locus typicus: North Sea, UK21 /28b-7 well
Stratum typicum: Lutetian, Middle Eocene
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Original description: [Bujak, 1994]:
Diagnosis:
Cysts skolochorate with subspherical bodies comprising an autophragm. Central body diameter typically greater than 50 µm.
Body typically with 17 intratabular processes, ten on the epicyst and seven on the hypocyst; areas between process bases smooth, or indistinctly ornamented, or finely and irregularly granulate. Process stems solid, with proximal fibrous ends expanded slightly and merging smoothly with the autophragm surface. Process stems expanded distally, and forming recurved or straight distal bifurcations. The distal margin of the bifurcations are digitate or bear completely or partially developed fenestrations which are restricted to a band lying along the bifurcations. The processes reflect a paratabulation of 4', 6", 0c, 5''', 1p, 1'''', 0s, with the hypocystal paratabulation following the standard sexiform pattern.
Paracingulum typically expressed by the absence of processes.
Parasulcal processes absent although a medial parasutural notch is frequently discernible.
Archeopyle apical; operculum tetraplacoid, contiguous.
Dimensions:
Central body length (without operculum) 50-58 µm, breadth 56-63 µm, maximum process length 35-40 µm.
Affinities:
A. michoudii is distinguished from all other species of Areosphaeridium by its distally bifid processes which lack fenestrate or reticulate process platforms. The process terminations on A. michoudii are similar to those on several species of Enneadocysta, including E. arcuata (Eaton) Stover and Williams and E. multicornuta (Eaton) Stover and Williams which are common in the North Sea. A. michoudii differs from all species of Enneadocysta in having a sexiform hypocystal paratabulation reflected by a processes on paraplates 5''', 1p and 1''''. Species of Enneadocysta have a partiform hypocystal partabulation reflected by processes on paraplates 6", 2'''' and ps.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Areosphaeridium michoudii Bujak, 1994, has 17 processes that are expanded distally and form recurved or straight distal bifurcations. The distal margin of the bifurcations are digitate or bear completely or partially developed fenestrations, which are restricted to a band lying along the bifurcations. This species is distinguished by its distally bifid processes which lack fenestrate or reticulate process platforms. The process terminations are similar to those in species of Enneadocysta. Size: Central body length (without operculum) 50-58 µm, width 56-63 µm. Maximum process length 35-40 µm.
Holotype: Bujak, 1994
Locus typicus: North Sea, UK21 /28b-7 well
Stratum typicum: Lutetian, Middle Eocene
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Bujak, 1994]:
Diagnosis:
Cysts skolochorate with subspherical bodies comprising an autophragm. Central body diameter typically greater than 50 µm.
Body typically with 17 intratabular processes, ten on the epicyst and seven on the hypocyst; areas between process bases smooth, or indistinctly ornamented, or finely and irregularly granulate. Process stems solid, with proximal fibrous ends expanded slightly and merging smoothly with the autophragm surface. Process stems expanded distally, and forming recurved or straight distal bifurcations. The distal margin of the bifurcations are digitate or bear completely or partially developed fenestrations which are restricted to a band lying along the bifurcations. The processes reflect a paratabulation of 4', 6", 0c, 5''', 1p, 1'''', 0s, with the hypocystal paratabulation following the standard sexiform pattern.
Paracingulum typically expressed by the absence of processes.
Parasulcal processes absent although a medial parasutural notch is frequently discernible.
Archeopyle apical; operculum tetraplacoid, contiguous.
Dimensions:
Central body length (without operculum) 50-58 µm, breadth 56-63 µm, maximum process length 35-40 µm.
Affinities:
A. michoudii is distinguished from all other species of Areosphaeridium by its distally bifid processes which lack fenestrate or reticulate process platforms. The process terminations on A. michoudii are similar to those on several species of Enneadocysta, including E. arcuata (Eaton) Stover and Williams and E. multicornuta (Eaton) Stover and Williams which are common in the North Sea. A. michoudii differs from all species of Enneadocysta in having a sexiform hypocystal paratabulation reflected by a processes on paraplates 5''', 1p and 1''''. Species of Enneadocysta have a partiform hypocystal partabulation reflected by processes on paraplates 6", 2'''' and ps.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Areosphaeridium michoudii Bujak, 1994, has 17 processes that are expanded distally and form recurved or straight distal bifurcations. The distal margin of the bifurcations are digitate or bear completely or partially developed fenestrations, which are restricted to a band lying along the bifurcations. This species is distinguished by its distally bifid processes which lack fenestrate or reticulate process platforms. The process terminations are similar to those in species of Enneadocysta. Size: Central body length (without operculum) 50-58 µm, width 56-63 µm. Maximum process length 35-40 µm.