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Membranilarnacia compressa
Membranilarnacia compressa Bujak, 1994
Holotype: Bujak, 1994, pl.4, fig.4
Paratypes: Bujak, 1994
Locus typicus: North Sea, UK16/28-15z well
Stratum typicum: Ypresian
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Membranilarnacia compressa Bujak, 1994. Diagnosis from Bujak (1994, p.127), Endocyst subspherical to ovoidal, periphragm smooth to chagrinate, in contact with the endophragm except beneath the processes. Processes intratabular, solid or hollow, proximally and distally expanded less than 15 µm in length. Processes supporting a continuous smooth, entire, or occasionally perforate ectophragm. Tabulation gonyaulacoid delimited formula 4', 6", 0c, 5"’, 1p, 1"”, 0s. Archeopyle apical, tetraplacoid and contiguous. M.compressa has shorter processes than those on M.glabra Agelopoulos, which are typically 15-21 µm long. Species of Eatonicysta differ from M.compressa in possessing an ectophragm that is reticulate, fenestrate or irregularly net-like. Size: central body length (without operculum) 37-50 µm, width 36-52 µm, maximum process length 6-11 µm.
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Original diagnosis: Bujak, 1994, p.???
Endocyst subspherical to ovoidal; periphragm smooth to chagrinate, in contact with the endophragm except beneath the processes. Processes intratabular, solid or hollow, proximally and distally expanded, less than 15 Ám in length. Processes supporting a continuous, smooth, entire, or occasionally perforate ectophragm. Paratabulation gonyaulacoid, delimited formula 4', 6", 0c, 5''', 1p, 1'''', 0s. Archeopyle apical; tetraplacoid and contiguous.
Dimensions. Central body length (without operculum) 37-50 Ám, breadth 36-52 Ám, maximum process length 6-11 Ám.
Affinities:
Bujak, 1994, p.???: The ectophragm on M. compressa is generally entire, but rare specimens have been observed in the North Sea with a perforate ectophragm. These have the same stratigraphic range as specimens with an entire ectophragm, and they are included in M. compressa.
M. compressa has shorter processes than those on Membranilarnacia glabra Agelopoulos, which are typically 15-21 Ám in length M. glabra last occurs in the North Sea at the top of Ypresian Subzone E3c of Bujak and Mudge, whereas M. compressa last occurs at the top of Ypresian Subzone E3a of Bujak and Mudge. Species of Eatonicysta Stover and Evitt differ from M. compressa in possessing an ectophragm that is reticulate, fenestrate or irregularly net-like.
M. compressa is considered to be conspecific with Membranilarnacia sp. A, which De Coninck (1975) illustrated from the Argile de Merelbeke in the Kallo borehole, Belgium, assigned to MP13 by Verbeek (1988). Heilmann-Clausen and Costa (1989) also recorded Membranilarnacia sp. A sensu De Coninck (1975) from the Ypresian Heiligen-Hafen Formation of the Wursterheide research well, northwest Germany, between sections assigned to NP12 and NP14.
Holotype: Bujak, 1994, pl.4, fig.4
Paratypes: Bujak, 1994
Locus typicus: North Sea, UK16/28-15z well
Stratum typicum: Ypresian
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Membranilarnacia compressa Bujak, 1994. Diagnosis from Bujak (1994, p.127), Endocyst subspherical to ovoidal, periphragm smooth to chagrinate, in contact with the endophragm except beneath the processes. Processes intratabular, solid or hollow, proximally and distally expanded less than 15 µm in length. Processes supporting a continuous smooth, entire, or occasionally perforate ectophragm. Tabulation gonyaulacoid delimited formula 4', 6", 0c, 5"’, 1p, 1"”, 0s. Archeopyle apical, tetraplacoid and contiguous. M.compressa has shorter processes than those on M.glabra Agelopoulos, which are typically 15-21 µm long. Species of Eatonicysta differ from M.compressa in possessing an ectophragm that is reticulate, fenestrate or irregularly net-like. Size: central body length (without operculum) 37-50 µm, width 36-52 µm, maximum process length 6-11 µm.
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Original diagnosis: Bujak, 1994, p.???
Endocyst subspherical to ovoidal; periphragm smooth to chagrinate, in contact with the endophragm except beneath the processes. Processes intratabular, solid or hollow, proximally and distally expanded, less than 15 Ám in length. Processes supporting a continuous, smooth, entire, or occasionally perforate ectophragm. Paratabulation gonyaulacoid, delimited formula 4', 6", 0c, 5''', 1p, 1'''', 0s. Archeopyle apical; tetraplacoid and contiguous.
Dimensions. Central body length (without operculum) 37-50 Ám, breadth 36-52 Ám, maximum process length 6-11 Ám.
Affinities:
Bujak, 1994, p.???: The ectophragm on M. compressa is generally entire, but rare specimens have been observed in the North Sea with a perforate ectophragm. These have the same stratigraphic range as specimens with an entire ectophragm, and they are included in M. compressa.
M. compressa has shorter processes than those on Membranilarnacia glabra Agelopoulos, which are typically 15-21 Ám in length M. glabra last occurs in the North Sea at the top of Ypresian Subzone E3c of Bujak and Mudge, whereas M. compressa last occurs at the top of Ypresian Subzone E3a of Bujak and Mudge. Species of Eatonicysta Stover and Evitt differ from M. compressa in possessing an ectophragm that is reticulate, fenestrate or irregularly net-like.
M. compressa is considered to be conspecific with Membranilarnacia sp. A, which De Coninck (1975) illustrated from the Argile de Merelbeke in the Kallo borehole, Belgium, assigned to MP13 by Verbeek (1988). Heilmann-Clausen and Costa (1989) also recorded Membranilarnacia sp. A sensu De Coninck (1975) from the Ypresian Heiligen-Hafen Formation of the Wursterheide research well, northwest Germany, between sections assigned to NP12 and NP14.