Back
Kisselevia stellata
Charlesdowniea stellata (Damassa, 1979a, p.834,837, pl.7, figs.1-7) Lentin and Vozzhennikova, 1989, p.227.
NOW Vallodinium. Originally Kisselevia, subsequently Charlesdowniea, thirdly (and now) Vallodinium.
Holotype: Damassa, 1979a, pl.7, figs.1-2.
Paratypes: Damassa, 1979
Locus typicus: Costal Belt, Franciscan Complex, California, USA
Age: Early-Mid Eocene.
Original diagnosis: Damassa, 1979, p. 834
Cornucavate peridinioid cyst having penitabular arrangement of processes and trabeculae. Paracingulum indicated by a single row of processes partially interconnected by trabeculae. Trabecular connections between processes commonly interrupted. Parasulcus devoid of ornamentation or processes.
Original description: Damassa, 1979, p. 834
A species of Kisselovia characterized by penitabular arrangement of processes and trabeculae. Pericyst, length 132-170 Ám, mean = 156 Ám, width 121-157 Ám, mean = 140 Ám; endocyst, length 92-119 Ám, mean= 106 Ám, width 84-108 Ám, mean = 96 Ám; 13 specimens measured. Periphragm and endophragm rhomboidal in outline, horns distinct but not large. Periphragm and endophragm closely appressed over most of their surfaces, but tending to separate near horns, thus forming five pericoels. Parasulcus devoid of ornamentation or processes. Connection of trabeculae between processes commonly interrupted, and process tops then may be forked. Processes distally solid and cylindrical, with hollow flared bases, up to 20 Ám in height and approximately 1 Ám in thickness. Trabeculae solid, about half the diameter of the processes. Periphragm and endophragm generally without surface texture, except for slight irregularities such as small pits. Processes and trabeculae also smooth. Paracingulum indicated by a single row of processes partially interconnected by trabeculae. In well preserved specimens. paraplates 1', 1", 7", 1''', 5''', 1'''', and 2'''' are distinctly visible in ventral view; on the dorsal surface paraplates 3''', 1'''', and 2'''' are generally well defined. Due to dorsoventral compression, 2', 4', 2", and 6" seldom are clearly visible, and paraplates adjacent to the archeopyle (1a, 3a, 3', 4") commonly are poorly delineated. Endo- and periarcheopyle of similar shape and size, both with rounded corner, slightly greater in width than in height. Endo- and periopercula simple, free; perioperculum bears processes and trabeculae along its perimeter (pl 7, fig. 1). The lateral (paracingular) horns may be notched at their distal ends. The apical and antapical horns are well developed, with the right antapical horn distinct but consistently smaller than the left. Paratabulation.--4', 7", xc, 5''', 2''''. Inferred thecal tabulation.--4', 7", xc, 3-4s, 5''', 2''''.
Affinities:
Damassa, 1979, p. 834: Kisselovia stellata is most slmllar to K. clathrata (Eisenack) Lentin & Williams, 1976, but K. clathrata is more rounded in outline, whereas K. stellata tends to be pentagonal. In addition, the relative sizes of the endocyst and pericyst and the pericoel they enclose are different in the two species. The available illustrations of K. clathrata (e. g., Eisenack, 19~8, 1954; Morgenroth, 1966; Davey et al., 1966; Evitt, 1961) indicate that this species is circumcavate, having a pericoel which extends completely around the endophragm as seen in dorsal or ventral view. In K. stellata, however, the endophragm is in continuous contact with the periphragm along the lateral margins of the cyst, thus it is cornucavate (pl. 7, fig. 2). K. stellata also resembles K. coleothrypta Williams & Downie) Lentin & Williams, 1976 in general process structure and arrangement; however, K. coleothrypta is characterized by a more extensive development of the ectophragm. In K. stellata, the ectophragm is restricted to slender trabecular connections between processes, whereas in K. coleothrypta the ectophragm extends across the paraplates as a thin continuous membrane, and is suported by the processes below it.
NOW Vallodinium. Originally Kisselevia, subsequently Charlesdowniea, thirdly (and now) Vallodinium.
Holotype: Damassa, 1979a, pl.7, figs.1-2.
Paratypes: Damassa, 1979
Locus typicus: Costal Belt, Franciscan Complex, California, USA
Age: Early-Mid Eocene.
Original diagnosis: Damassa, 1979, p. 834
Cornucavate peridinioid cyst having penitabular arrangement of processes and trabeculae. Paracingulum indicated by a single row of processes partially interconnected by trabeculae. Trabecular connections between processes commonly interrupted. Parasulcus devoid of ornamentation or processes.
Original description: Damassa, 1979, p. 834
A species of Kisselovia characterized by penitabular arrangement of processes and trabeculae. Pericyst, length 132-170 Ám, mean = 156 Ám, width 121-157 Ám, mean = 140 Ám; endocyst, length 92-119 Ám, mean= 106 Ám, width 84-108 Ám, mean = 96 Ám; 13 specimens measured. Periphragm and endophragm rhomboidal in outline, horns distinct but not large. Periphragm and endophragm closely appressed over most of their surfaces, but tending to separate near horns, thus forming five pericoels. Parasulcus devoid of ornamentation or processes. Connection of trabeculae between processes commonly interrupted, and process tops then may be forked. Processes distally solid and cylindrical, with hollow flared bases, up to 20 Ám in height and approximately 1 Ám in thickness. Trabeculae solid, about half the diameter of the processes. Periphragm and endophragm generally without surface texture, except for slight irregularities such as small pits. Processes and trabeculae also smooth. Paracingulum indicated by a single row of processes partially interconnected by trabeculae. In well preserved specimens. paraplates 1', 1", 7", 1''', 5''', 1'''', and 2'''' are distinctly visible in ventral view; on the dorsal surface paraplates 3''', 1'''', and 2'''' are generally well defined. Due to dorsoventral compression, 2', 4', 2", and 6" seldom are clearly visible, and paraplates adjacent to the archeopyle (1a, 3a, 3', 4") commonly are poorly delineated. Endo- and periarcheopyle of similar shape and size, both with rounded corner, slightly greater in width than in height. Endo- and periopercula simple, free; perioperculum bears processes and trabeculae along its perimeter (pl 7, fig. 1). The lateral (paracingular) horns may be notched at their distal ends. The apical and antapical horns are well developed, with the right antapical horn distinct but consistently smaller than the left. Paratabulation.--4', 7", xc, 5''', 2''''. Inferred thecal tabulation.--4', 7", xc, 3-4s, 5''', 2''''.
Affinities:
Damassa, 1979, p. 834: Kisselovia stellata is most slmllar to K. clathrata (Eisenack) Lentin & Williams, 1976, but K. clathrata is more rounded in outline, whereas K. stellata tends to be pentagonal. In addition, the relative sizes of the endocyst and pericyst and the pericoel they enclose are different in the two species. The available illustrations of K. clathrata (e. g., Eisenack, 19~8, 1954; Morgenroth, 1966; Davey et al., 1966; Evitt, 1961) indicate that this species is circumcavate, having a pericoel which extends completely around the endophragm as seen in dorsal or ventral view. In K. stellata, however, the endophragm is in continuous contact with the periphragm along the lateral margins of the cyst, thus it is cornucavate (pl. 7, fig. 2). K. stellata also resembles K. coleothrypta Williams & Downie) Lentin & Williams, 1976 in general process structure and arrangement; however, K. coleothrypta is characterized by a more extensive development of the ectophragm. In K. stellata, the ectophragm is restricted to slender trabecular connections between processes, whereas in K. coleothrypta the ectophragm extends across the paraplates as a thin continuous membrane, and is suported by the processes below it.