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Muiriella
From Williams et al., 2017:
[Muiriella, Churchill and Sarjeant, 1962, p.36; Emendation: Harland and Sarjeant, 1970, p. 226-227
Type species: Muiriella plioplax, Churchill and Sarjeant, 1962 (pl.1, figs.20–21)]
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Original description: [Churchill and Sarjeant, 1962]:
Shell of sphaeroidal, or other, shape and with characteristic tabulation: 4`, 4a, 9-?10``, 7```, 3p, ?1````.
Remarks:
This new genus is characterised by its tabulation; variation in other characters is to be anticipated, should further species be attributed to it. The high number (17-?18) of epitheca plates is noteworthy; the structure of the hypotheca is less well established, but the number of plates is again certainly high (10 +). On the basis of general form, Muiriella is tentatively assigned to the family Peridiniaceae.
The most anterior end of the epitheca of the type species has been treated, in establishing the tabulation, as apex; this lies on mid-point of the crest separating plates 1` and 3`. Dr. Dorothy Ballantine has suggested (in litt.) that the apex might be better regarded as the point of conjunction of plates 1`, 2` and 3`, in which case plate 4` would be regarded as an additional intercalary and the epithecal tabulation would become 3`, 5a, 9-?10". However, it is felt that displacement of the apex can only be certainly determined when the relationships of a genus, or species, are known, and that in absence of such knowledge, the tabulation is better formulated as in the diagnosis.
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Emended description:
Harland and Sarjeant, 1970:
Diagnosis:
Proximate dinoflagellate cyst of spherical to ovoidal shape, with the tabulation ?`, 3a, 6-?7", ?6c, 8```, 2p, 4p.c., 1````, 3-?4s.
Archaeopyle apical.
[Muiriella, Churchill and Sarjeant, 1962, p.36; Emendation: Harland and Sarjeant, 1970, p. 226-227
Type species: Muiriella plioplax, Churchill and Sarjeant, 1962 (pl.1, figs.20–21)]
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Original description: [Churchill and Sarjeant, 1962]:
Shell of sphaeroidal, or other, shape and with characteristic tabulation: 4`, 4a, 9-?10``, 7```, 3p, ?1````.
Remarks:
This new genus is characterised by its tabulation; variation in other characters is to be anticipated, should further species be attributed to it. The high number (17-?18) of epitheca plates is noteworthy; the structure of the hypotheca is less well established, but the number of plates is again certainly high (10 +). On the basis of general form, Muiriella is tentatively assigned to the family Peridiniaceae.
The most anterior end of the epitheca of the type species has been treated, in establishing the tabulation, as apex; this lies on mid-point of the crest separating plates 1` and 3`. Dr. Dorothy Ballantine has suggested (in litt.) that the apex might be better regarded as the point of conjunction of plates 1`, 2` and 3`, in which case plate 4` would be regarded as an additional intercalary and the epithecal tabulation would become 3`, 5a, 9-?10". However, it is felt that displacement of the apex can only be certainly determined when the relationships of a genus, or species, are known, and that in absence of such knowledge, the tabulation is better formulated as in the diagnosis.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Harland and Sarjeant, 1970:
Diagnosis:
Proximate dinoflagellate cyst of spherical to ovoidal shape, with the tabulation ?`, 3a, 6-?7", ?6c, 8```, 2p, 4p.c., 1````, 3-?4s.
Archaeopyle apical.