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Morkallacysta pyramidalis
Morkallacysta pyramidalis Harris, 1974
Originally (and now) Morkallacysta, subsequently Palaeoperidinium.
Lentin and Williams, 1976, transferred this species to Palaeoperidinium Deflandre, 1935. Stover and Evitt, 1978, retained it in Morkallacysta.
Holotype: Harris, 1974, pl.1, fig.5
Locus typicus: Renmark Beds, Victoria
Stratum typicum: Palaeocene
Original diagnosis: Harris, 1974, p.163
A Morkallacysta of strongly peridinioid form, The epitract is protruded into a rounded horn and the antapex into two subequal horns. Cyst smooth to scabrate. Strongly marked and helicoid girdle. Archeopyle triangular, with operculum.
Description: Harris, 1974, p.163
Epitract 0.5 µm thick, strongly triangular in outline and larger than hypotract. Antapical bulges variable in degree but usually formed by a deep depression in the mid-line. Girdle about 8 µm wide and often deeply depressed, 2-4 µm deep, strongly helicoid and laevorotatory. Vertical area depressed in the hypotract. Archeopyle large, approximately 30 µm wide and 10-12 µm high; probably formed by loss of a precingular plate. Operculum attached near margin of the cingulum.
Dimensions: Length 55-68 µm, breadth 48-55 µm.
Affinities:
Harris, 1974, p.163: This species is similar to that described from the Princetown Member as Deflandrea obliquipes Deflandre and Cookson, 1955, but differs from that species in lacking an endocorpus.
Originally (and now) Morkallacysta, subsequently Palaeoperidinium.
Lentin and Williams, 1976, transferred this species to Palaeoperidinium Deflandre, 1935. Stover and Evitt, 1978, retained it in Morkallacysta.
Holotype: Harris, 1974, pl.1, fig.5
Locus typicus: Renmark Beds, Victoria
Stratum typicum: Palaeocene
Original diagnosis: Harris, 1974, p.163
A Morkallacysta of strongly peridinioid form, The epitract is protruded into a rounded horn and the antapex into two subequal horns. Cyst smooth to scabrate. Strongly marked and helicoid girdle. Archeopyle triangular, with operculum.
Description: Harris, 1974, p.163
Epitract 0.5 µm thick, strongly triangular in outline and larger than hypotract. Antapical bulges variable in degree but usually formed by a deep depression in the mid-line. Girdle about 8 µm wide and often deeply depressed, 2-4 µm deep, strongly helicoid and laevorotatory. Vertical area depressed in the hypotract. Archeopyle large, approximately 30 µm wide and 10-12 µm high; probably formed by loss of a precingular plate. Operculum attached near margin of the cingulum.
Dimensions: Length 55-68 µm, breadth 48-55 µm.
Affinities:
Harris, 1974, p.163: This species is similar to that described from the Princetown Member as Deflandrea obliquipes Deflandre and Cookson, 1955, but differs from that species in lacking an endocorpus.