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Egmontodinium diminutum
Egmontodinium? diminutum Davies, 1983
Davies, 1983, questionably included this species in Egmontodinium.
Holotype: Davies, 1983, pl.2, figs.6-7
Locus typicus: Central Amund Ringnes Dome, Amund Ringnes Island, District of Franklin, Canada
Stratum typicum: Late Bathonian-Oxfordian
Original diagnosis: Davies, 1983, p. 15
Ellipsoidal proximate dinoflagellate cyst without apical or antapical horns. Ornament granulate to spinate. sutures marked by aligned and coalescent granules and spines usually larger than the fine intratabular ornament.
Tabulation: 4", 3a-5a, 6", 6c, 6""", 5p, 2"""", 3s with geniculate 2a plate boundaries.
Archeopyle: (4A31) + 6Pa.
Size: length - 25(34)45 Ám; breadth - 22(25)33 Ám.
Original description: Davies, 1983, p.15
The posterior intercalary series is a circlet of plates with the dorsal 3p relatively large. The anterior intercalaries are variable with three, four or, infrequently, five which remain attached to the apical operculum. The operculum hinges on plate 1" at the sulcal notch but usually is found detached. Often the precingular plates develop accessory archeopyle sutures. The cingulum is slightly laevo-rotary, variable in width and often greater than one-fifth of the total length of the cyst. Sutural spines (less than 1.2 Ám) are present.
Affinities:
Davies, 1983, p. 16: Egmontodinium polyplacophorum differs by its larger
size (60-80 Ám), lack of granulatiom and the development of delicate sutural crests. The archeopyle of this species develops by splitting through the intercalary plates whereas in E. diminutum the intercalaries are removed entirely with the operculum. ?E. diminutum is tentatively placed in Egmontodinium because it possesses a fewer number of anterior and posterior intercalary plates than the type species E. polyplacophorum.
Davies, 1983, questionably included this species in Egmontodinium.
Holotype: Davies, 1983, pl.2, figs.6-7
Locus typicus: Central Amund Ringnes Dome, Amund Ringnes Island, District of Franklin, Canada
Stratum typicum: Late Bathonian-Oxfordian
Original diagnosis: Davies, 1983, p. 15
Ellipsoidal proximate dinoflagellate cyst without apical or antapical horns. Ornament granulate to spinate. sutures marked by aligned and coalescent granules and spines usually larger than the fine intratabular ornament.
Tabulation: 4", 3a-5a, 6", 6c, 6""", 5p, 2"""", 3s with geniculate 2a plate boundaries.
Archeopyle: (4A31) + 6Pa.
Size: length - 25(34)45 Ám; breadth - 22(25)33 Ám.
Original description: Davies, 1983, p.15
The posterior intercalary series is a circlet of plates with the dorsal 3p relatively large. The anterior intercalaries are variable with three, four or, infrequently, five which remain attached to the apical operculum. The operculum hinges on plate 1" at the sulcal notch but usually is found detached. Often the precingular plates develop accessory archeopyle sutures. The cingulum is slightly laevo-rotary, variable in width and often greater than one-fifth of the total length of the cyst. Sutural spines (less than 1.2 Ám) are present.
Affinities:
Davies, 1983, p. 16: Egmontodinium polyplacophorum differs by its larger
size (60-80 Ám), lack of granulatiom and the development of delicate sutural crests. The archeopyle of this species develops by splitting through the intercalary plates whereas in E. diminutum the intercalaries are removed entirely with the operculum. ?E. diminutum is tentatively placed in Egmontodinium because it possesses a fewer number of anterior and posterior intercalary plates than the type species E. polyplacophorum.