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Edwardsiella sexispinosa
Edwardsiella sexispinosum Versteegh and Zevenboom, 1995
Originally (and now) Edwardsiella, subsequently Novedwardsiella (generic name illegitimate).
Holotype: Versteegh and Zevenboom, 1995, pl. II, fig. 1,4
Type Locality: Singa Section, Calabria, S Italy
Type stratum: Chattian-mid Piacenzian.
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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.
Edwardsiella sexispinosum Versteegh and Zevenboom in Versteegh, 1995. According to Versteegh and Zevenboom in Versteegh (1995), this species has six processes of the same length and shape and an apical and antapical protrusion. Two processes are on the dorsal epicyst near the upper right and upper left corner of the archeopyle. Four processes are on the hypocyst of which two occur on the lower half of the dorsal epicyst, one right and one left. Of both remaining processes, one is present on the middle left ventral hypocyst and the other on the lower right ventral hypocyst. The processes consist of three membranous lists which pass into septa on the cyst surface. These septa decrease in height rapidly away from the base of the processes. Archeopyle probably 3". Size height 49-55 µm, maximum diameter 44-56 µm, spine length 39-49 µm, apical horn 5-11um, antapical horn 3-16 µm, height of membranes on upper half of spine 3-6 µm
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Original diagnosis: Versteegh and Zevenboom, 1995, p. 220-221
A species of Edwardsiella with six processes of the same length and shape, and an apical as well as an antapical protrusion. Two processes are present on the dorsal epicyst near the upper right and upper left corner of the archaeopyle respectively. Four processes are present on the hypocyst of which two occur on the lower half of the dorsal epicyst, one right and one left. Of both remaining processes, one is present on the middle left ventral hypocyst and the other on the lower right ventral hypocyst. The processes consist of three membraneous lists of which the bases are connected along their total length. The processes are truncated distally. From a process tip to its base the height of the membraneous lists (and thus the process diameter) increases only slightly. Only for the basal part of processes, where the lists pass into septa on the cyst surface, the list height increases more rapidly. The height of the septa decreases rapidly with increasing distance from the process base, and septa become indiscernible at short distance from the process base. Apart from spines and their extensions, ornamentation is absent on the cyst surface.
Description: Versteegh and Zevenboom, 1995, p. 221
The position of the spines is derived from Edwards (1984). In that study a specimen similar to the form described here, but with tabulation fully reflected by low septa was figured (Edwards, 1984; p.592, pl. 3, fig. 8). On that specimen the spines are located on the following triple junctions between plates: 2'/1''/2'', 3'/3''/4'', 1p/2'''/3''', 3'''/4'''/1'''', 4'''/5'''/1'''' and 5'''/6'''/1'''' (L. Edwards pers. commun, 1993). Since these locations fit well with those on the non-tabulated form described here, the same spine locations are proposed for the latter. The archaeopyle is probably formed by the loss of plate 3".
Dimensions: Holotype: height: 55 µm; maximum diameter: 55 µm; spine length: 39 µm; apical horn: 11 µm; antapical horn 16 µm; height of membranes on upper half of spine: 5 µm. Range: height: 49-55 µm; maximum diameter: 44-56 µm; spine length: 39-49 µm; apical horn: 5-11 µm; antapical horn 3-16 µm; 3 µm height of membranes on upper half of spine: 3-6 µm; specimens measured: 6.
Affinities:
Versteegh and Zevenboom, 1995, p. 221
In Miocene sediments specimens occur with septa on most of the plate margins occur (Edwards, 1984, plate 2, fig 12; and pers. obs.). Although these forms resemble Impagidinium aculeatum (Wall, 1967) Lentin and Williams, 1981, they differ by having truncated processes rather than expanded septa on triple junctions and could therefore be included in Edwardsiella but not in E. sexispinosum since E. sexispinosum has only six and much longer processes and it lacks sutural septa.
Stratigraphy:
Chattian, NP25 (Zevenboom subm.) to Middle Piacenzian, middle NN16 (Zevenboom and Versteegh, in prep).
Originally (and now) Edwardsiella, subsequently Novedwardsiella (generic name illegitimate).
Holotype: Versteegh and Zevenboom, 1995, pl. II, fig. 1,4
Type Locality: Singa Section, Calabria, S Italy
Type stratum: Chattian-mid Piacenzian.
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Edwardsiella sexispinosum Versteegh and Zevenboom in Versteegh, 1995. According to Versteegh and Zevenboom in Versteegh (1995), this species has six processes of the same length and shape and an apical and antapical protrusion. Two processes are on the dorsal epicyst near the upper right and upper left corner of the archeopyle. Four processes are on the hypocyst of which two occur on the lower half of the dorsal epicyst, one right and one left. Of both remaining processes, one is present on the middle left ventral hypocyst and the other on the lower right ventral hypocyst. The processes consist of three membranous lists which pass into septa on the cyst surface. These septa decrease in height rapidly away from the base of the processes. Archeopyle probably 3". Size height 49-55 µm, maximum diameter 44-56 µm, spine length 39-49 µm, apical horn 5-11um, antapical horn 3-16 µm, height of membranes on upper half of spine 3-6 µm
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Original diagnosis: Versteegh and Zevenboom, 1995, p. 220-221
A species of Edwardsiella with six processes of the same length and shape, and an apical as well as an antapical protrusion. Two processes are present on the dorsal epicyst near the upper right and upper left corner of the archaeopyle respectively. Four processes are present on the hypocyst of which two occur on the lower half of the dorsal epicyst, one right and one left. Of both remaining processes, one is present on the middle left ventral hypocyst and the other on the lower right ventral hypocyst. The processes consist of three membraneous lists of which the bases are connected along their total length. The processes are truncated distally. From a process tip to its base the height of the membraneous lists (and thus the process diameter) increases only slightly. Only for the basal part of processes, where the lists pass into septa on the cyst surface, the list height increases more rapidly. The height of the septa decreases rapidly with increasing distance from the process base, and septa become indiscernible at short distance from the process base. Apart from spines and their extensions, ornamentation is absent on the cyst surface.
Description: Versteegh and Zevenboom, 1995, p. 221
The position of the spines is derived from Edwards (1984). In that study a specimen similar to the form described here, but with tabulation fully reflected by low septa was figured (Edwards, 1984; p.592, pl. 3, fig. 8). On that specimen the spines are located on the following triple junctions between plates: 2'/1''/2'', 3'/3''/4'', 1p/2'''/3''', 3'''/4'''/1'''', 4'''/5'''/1'''' and 5'''/6'''/1'''' (L. Edwards pers. commun, 1993). Since these locations fit well with those on the non-tabulated form described here, the same spine locations are proposed for the latter. The archaeopyle is probably formed by the loss of plate 3".
Dimensions: Holotype: height: 55 µm; maximum diameter: 55 µm; spine length: 39 µm; apical horn: 11 µm; antapical horn 16 µm; height of membranes on upper half of spine: 5 µm. Range: height: 49-55 µm; maximum diameter: 44-56 µm; spine length: 39-49 µm; apical horn: 5-11 µm; antapical horn 3-16 µm; 3 µm height of membranes on upper half of spine: 3-6 µm; specimens measured: 6.
Affinities:
Versteegh and Zevenboom, 1995, p. 221
In Miocene sediments specimens occur with septa on most of the plate margins occur (Edwards, 1984, plate 2, fig 12; and pers. obs.). Although these forms resemble Impagidinium aculeatum (Wall, 1967) Lentin and Williams, 1981, they differ by having truncated processes rather than expanded septa on triple junctions and could therefore be included in Edwardsiella but not in E. sexispinosum since E. sexispinosum has only six and much longer processes and it lacks sutural septa.
Stratigraphy:
Chattian, NP25 (Zevenboom subm.) to Middle Piacenzian, middle NN16 (Zevenboom and Versteegh, in prep).