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Epelidosphaeridia spinosa
Epelidosphaeridia spinosa (Cookson and Hughes 1964) Davey 1979
Originally Palaeoperidinium, subsequently (and now) Epelidosphaeridia.
Holotype: Cookson and Hughes, 1964, pl.8, fig.8
Locus typicus: Bradfortshire, England
Stratum typicum: Early Cenomanian
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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.
Epelidosphaeridia spinosa (Cookson and Hughes, 1964) Davey, 1969a, has a shallow circular cingulum, and short longitudinal furrow. The phragma is covered with short, blunt, hollow spines, ca 2 µm long. The tabulation is peridinioid and the archeopyle (4A3I), resulting from the loss of all four apicals and the three anterior intercalaries. Size: overall length 55-67 µm, width 38-50 µm.
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Original diagnosis: Cookson and Hughes 1964, p. 49: Palaeoperidinium spinosum
Shell with convex sides, an arched apex with a slight central prominence, a slanting antapex, a shallow, circular, equatorial girdle, and a short, rather ill-defined longitudinal furrow. A capsule is not developed. Shell-membrane thin, covered with short, blunt, hollow outgrowths c. 2 Ám long which usually give the wall a scalloped appearance. The shell opens by the detachment of the distal portion of the epitheca.
Dimensions: Range: 55-67 Ám long; 38-50 Ám broad.
Supplemental description: Davey 1969, p. 143
The shell possesses convex sides, conical epitract and a hypotract which is more or less truncated posteriorly. A small apical prominence is commonly present.
The periphragm is smooth or lightly granular and forms a moderate number of small, stout spines. The spines appear to be hollow, closed proximally, parallel sided, and are oblate distally or terminate with a small fork. The spines widen slightly before joining the shell and they are sometimes joined proximally. This is particularly well developed in the antapical region where the processes are joined medially and form a slight projection on one side of the shell. The cingulum is clearly delimited by two parallel lines of closely set spines and is 5 to 8 Ám in width. It is only slightly helicoid and it bears few spines on its surface. The sulcus in most specimens is clearly defined, being slightly hollowed and almost devoid of spines.
The spines on the remainder of the shell surface are usually randomly arranged, but occasionally a vague alignment is present suggesting a tabulation. An apical archaeopyle is constantly developed, the margin being only slightly angular.
Dimensions: Range of observed specimens: shell length: 32-56 Ám; width: 27-57 Ám; maximum length of spines: 2.5-5 Ám.
Affinities:
Cookson and Hughes, 1964, p. 49-50: Palaeoperidinium spinosum
The genus Palaeoperidinium has been used for this species in the general sense in which it was created by Deflandre. P.spinosum resembles P.caulleryi Deflandre (1934) in its small size, the type of its ornament, the scalloped shell outline, and the development of a slight projection on one side of the antapex. It differs, however, in having a denser ornamentation, a circular instead of helicoid girdle, and a less pronounced apical prominence. The mode of opening of the shell in P.caulleryi was not specified by Deflandre. Palaeoperidinium spinosum has not been generically associated with Spinidinium Cookson and Eisenack 1962, to the description of which it conforms in several respects, on account of its different mode of opening. In the type species S.styloniferum a pylome is present in the epitheca, in contrast to the detachment of the apex in P.spinosum.
Originally Palaeoperidinium, subsequently (and now) Epelidosphaeridia.
Holotype: Cookson and Hughes, 1964, pl.8, fig.8
Locus typicus: Bradfortshire, England
Stratum typicum: Early Cenomanian
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Epelidosphaeridia spinosa (Cookson and Hughes, 1964) Davey, 1969a, has a shallow circular cingulum, and short longitudinal furrow. The phragma is covered with short, blunt, hollow spines, ca 2 µm long. The tabulation is peridinioid and the archeopyle (4A3I), resulting from the loss of all four apicals and the three anterior intercalaries. Size: overall length 55-67 µm, width 38-50 µm.
--------------------------------------------------
Original diagnosis: Cookson and Hughes 1964, p. 49: Palaeoperidinium spinosum
Shell with convex sides, an arched apex with a slight central prominence, a slanting antapex, a shallow, circular, equatorial girdle, and a short, rather ill-defined longitudinal furrow. A capsule is not developed. Shell-membrane thin, covered with short, blunt, hollow outgrowths c. 2 Ám long which usually give the wall a scalloped appearance. The shell opens by the detachment of the distal portion of the epitheca.
Dimensions: Range: 55-67 Ám long; 38-50 Ám broad.
Supplemental description: Davey 1969, p. 143
The shell possesses convex sides, conical epitract and a hypotract which is more or less truncated posteriorly. A small apical prominence is commonly present.
The periphragm is smooth or lightly granular and forms a moderate number of small, stout spines. The spines appear to be hollow, closed proximally, parallel sided, and are oblate distally or terminate with a small fork. The spines widen slightly before joining the shell and they are sometimes joined proximally. This is particularly well developed in the antapical region where the processes are joined medially and form a slight projection on one side of the shell. The cingulum is clearly delimited by two parallel lines of closely set spines and is 5 to 8 Ám in width. It is only slightly helicoid and it bears few spines on its surface. The sulcus in most specimens is clearly defined, being slightly hollowed and almost devoid of spines.
The spines on the remainder of the shell surface are usually randomly arranged, but occasionally a vague alignment is present suggesting a tabulation. An apical archaeopyle is constantly developed, the margin being only slightly angular.
Dimensions: Range of observed specimens: shell length: 32-56 Ám; width: 27-57 Ám; maximum length of spines: 2.5-5 Ám.
Affinities:
Cookson and Hughes, 1964, p. 49-50: Palaeoperidinium spinosum
The genus Palaeoperidinium has been used for this species in the general sense in which it was created by Deflandre. P.spinosum resembles P.caulleryi Deflandre (1934) in its small size, the type of its ornament, the scalloped shell outline, and the development of a slight projection on one side of the antapex. It differs, however, in having a denser ornamentation, a circular instead of helicoid girdle, and a less pronounced apical prominence. The mode of opening of the shell in P.caulleryi was not specified by Deflandre. Palaeoperidinium spinosum has not been generically associated with Spinidinium Cookson and Eisenack 1962, to the description of which it conforms in several respects, on account of its different mode of opening. In the type species S.styloniferum a pylome is present in the epitheca, in contrast to the detachment of the apex in P.spinosum.