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Operculodinium spinigerum
Operculodinium? spinigerum Brideaux, 1977
Originally Operculodinium?, subsequently Protoellipsodinium.
Taxonomic senior synonym: Protoellipsodinium clavulus, according to Duxbury (1983, p.53).
Brideaux, 1977, questionably included this species in Operculodinium.
Holotype: Brideaux, 1977, pl.12, figs.8-9, pl.13, figs.14
Locus typicus: Richardson Mountains, District of Mackenzie, Canada
Stratum typicum: Barremian
Original diagnosis: Brideaux, 1977, p. 30
Shape: Pericyst longitudinally elongate, the length about one and one-half times the width, maximum width at the mid-latitude of the pericyst; apex and antapex rounded, apical and antapical prominences absent.
Endocyst closely appressed to the pericyst except at the loci of processes arising from the pericyst. Pericoel not developed; slight lateral compression.
Phragma: Periphragm less than 1.0 Ám thick; surface sculpture smooth; periphragm produced to form follow, smooth-columned, tubiform to cylindrical, distally closed processes; distal margins of processes highly variable, bifid, trifurcate with distal bifid tips, or quadrifurcate to multifurcate, the furcations produced into aculeate extensions of variable length, which may branch in a complex manner; periphragm also forms acicular or stout, spiny processes; distally complex processes 4-16 Ám long and 1-2 Ám wide; acicular and spiny processes, 4-8 Ám long and 0.5-1.0 Ám wide basally. Endophragm less than 0.5 Ám thick, smooth; closed beneath loci of processes arising from the periphragm.
Paratabulation: Process formula and paratabulation details indeterminate; process position apparently related to paratabulation as evidenced by the operculum, which bears three to four ?penesutural aculeate processes; processes interpreted as representing other paraplates variable in number and location. Five to seven aculeate processes and two aciculate processes are associated with the apical part of the epicyst; using the archeopyle to orient the presumed position of the precingular paraplates, the interpretation may be made that each precingular paraplate bears from one to three aculeate processes; scattered spinose processes mark the position of the pericingulum; epipericyst bears, therefore, from 13 to 25 aculeate processes and two aculeate processes and up to four stout spines in the pericingular region. Hypopericyst bearing from ten to fifteen aculeate processes and one to three reduced aculeate processes or aciculate processes; processes apparently related to paratabulation, often occurring in pairs, but varying from one to three per paraplate; exact process formula and paratabulation not determinable.
Archeopyle/operculum: Archeopyle formed by the loss of a single precingular paraplate; operculum free, occasionally lying in the archeopyle, and simple, consisting of a single horseshoe-shaped paraplate interpreted as the third precingular paraplate; operculum bearing three to four aculeate processes.
Pericingulum/perisulcus: General position of pericingulum at the mid-latitude of the pericyst; indicated by the absence of processes or by the presence of scattered aciculate processes or stout spines, up to four in number, exact pericingular course not delineated. Perisulcus represented by one to three reduced aculeate processes or aciculate processes; exact perisulcal course not determinable. Dimensions - Pericyst length, 44-57 Ám; pericyst depth (5 specimens), 29-38 Ám; pericyst width, 32-42 Ám (15 specimens); all measurements excluding processes.
Affinities:
Brideaux, 1977, p. 30: Operculodinium? spinigerum differs from all previously described species of Operculodinium in possessing smooth-columned processes which are not commonly situated penesuturally; 0.? spinigerum differs from 0.
centrocorpum (Deflandre and Cookson) Wall in possessing processes with complexly furcate distal margins which are much less numerous and not located
penesuturally. The genus Bourkidinium Morgan, 1975 possesses an apical archeopyle and cannot accomodate this species.
Originally Operculodinium?, subsequently Protoellipsodinium.
Taxonomic senior synonym: Protoellipsodinium clavulus, according to Duxbury (1983, p.53).
Brideaux, 1977, questionably included this species in Operculodinium.
Holotype: Brideaux, 1977, pl.12, figs.8-9, pl.13, figs.14
Locus typicus: Richardson Mountains, District of Mackenzie, Canada
Stratum typicum: Barremian
Original diagnosis: Brideaux, 1977, p. 30
Shape: Pericyst longitudinally elongate, the length about one and one-half times the width, maximum width at the mid-latitude of the pericyst; apex and antapex rounded, apical and antapical prominences absent.
Endocyst closely appressed to the pericyst except at the loci of processes arising from the pericyst. Pericoel not developed; slight lateral compression.
Phragma: Periphragm less than 1.0 Ám thick; surface sculpture smooth; periphragm produced to form follow, smooth-columned, tubiform to cylindrical, distally closed processes; distal margins of processes highly variable, bifid, trifurcate with distal bifid tips, or quadrifurcate to multifurcate, the furcations produced into aculeate extensions of variable length, which may branch in a complex manner; periphragm also forms acicular or stout, spiny processes; distally complex processes 4-16 Ám long and 1-2 Ám wide; acicular and spiny processes, 4-8 Ám long and 0.5-1.0 Ám wide basally. Endophragm less than 0.5 Ám thick, smooth; closed beneath loci of processes arising from the periphragm.
Paratabulation: Process formula and paratabulation details indeterminate; process position apparently related to paratabulation as evidenced by the operculum, which bears three to four ?penesutural aculeate processes; processes interpreted as representing other paraplates variable in number and location. Five to seven aculeate processes and two aciculate processes are associated with the apical part of the epicyst; using the archeopyle to orient the presumed position of the precingular paraplates, the interpretation may be made that each precingular paraplate bears from one to three aculeate processes; scattered spinose processes mark the position of the pericingulum; epipericyst bears, therefore, from 13 to 25 aculeate processes and two aculeate processes and up to four stout spines in the pericingular region. Hypopericyst bearing from ten to fifteen aculeate processes and one to three reduced aculeate processes or aciculate processes; processes apparently related to paratabulation, often occurring in pairs, but varying from one to three per paraplate; exact process formula and paratabulation not determinable.
Archeopyle/operculum: Archeopyle formed by the loss of a single precingular paraplate; operculum free, occasionally lying in the archeopyle, and simple, consisting of a single horseshoe-shaped paraplate interpreted as the third precingular paraplate; operculum bearing three to four aculeate processes.
Pericingulum/perisulcus: General position of pericingulum at the mid-latitude of the pericyst; indicated by the absence of processes or by the presence of scattered aciculate processes or stout spines, up to four in number, exact pericingular course not delineated. Perisulcus represented by one to three reduced aculeate processes or aciculate processes; exact perisulcal course not determinable. Dimensions - Pericyst length, 44-57 Ám; pericyst depth (5 specimens), 29-38 Ám; pericyst width, 32-42 Ám (15 specimens); all measurements excluding processes.
Affinities:
Brideaux, 1977, p. 30: Operculodinium? spinigerum differs from all previously described species of Operculodinium in possessing smooth-columned processes which are not commonly situated penesuturally; 0.? spinigerum differs from 0.
centrocorpum (Deflandre and Cookson) Wall in possessing processes with complexly furcate distal margins which are much less numerous and not located
penesuturally. The genus Bourkidinium Morgan, 1975 possesses an apical archeopyle and cannot accomodate this species.