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Echinidinium lucidum
Echinidinium lucidum Heilmann-Clausen and Van Simaeys, 2005, p.163–164, pl.4, figs.1–6; text-fig.5.
Questionable assignment: Heilmann-Clausen and Van Simaeys (2005, p.163).
Holotype: Heilmann-Clausen and Van Simaeys, 2005, pl.4, figs.1–2.
Age: late Eocene.
Original description (Heilmann-Clausen and Van Simaeys, 2005):
Echinidinium? lucidum sp. nov. Plate 4, figs. 1–6, Text-Figure 5
Description. A small, subspherical, proximochorate dinoflagellate cyst. The thin, smooth, hyaline wall and especially the numerous short processes are colorless and strongly refractive. The processes are rigid, massive, and of unequal length. The process morphology is variable (Text-Figure 5). Most processes are conical, or cylindrical with pointed tips. Some processes have a more irregular shape; they may be distally expanded and bifurcate, rarely irregularly branched. The distribution of the processes is mostly nontabular. Locally, processes may be aligned in short rows and can be fused in the lower part, forming a denticulate septum. An archeopyle is rarely visible, and its type has not been identified. It seems to be theropylic, with an operculum consisting of at least two adnate paraplates.
Derivation of name. From Latin lucidus,meaning sending out light, with reference to the strong refractivity of the cyst wall.
Designation of holotype. Plate 4, figs. 1, 2, Slide 1930 G2, England Finder coordinates H51. MGUH 27772. Kysing-3 borehole, sample 1930, Upper Eocene. Specimen dimensions: Total cyst diameter 51 µm; central body diameter 37 µm.
Designation of paratype. Plate 4, fig. 3, Slide 1928 G1, England Finder coordinates P46/4-P47/3. MGUH 27773. Kysing-3 borehole, sample 1928, Upper Eocene.
Dimensions of measured specimens. Total cyst diameter 45 (49) 53 µm. Central body diameter 33 (39) 45 µm. Maximum length of spines 6 (7) 8 µm. (9 specimens measured).
Comparison. Within this genus, this species especially resembles Echinidinium delicata Zonneveld 1997, which however has hollow and more uniform processes. There is also some similarity with the Recent genus Islandinium Head et al. 2001, especially with Islandinium minutum (Harland & Reid in Harland et al. 1980) Head et al. 2001. However, Islandinium minutum differs by having a saphopylic archeopyle, simpler processes and being pigmented. Echinidinium? lucidum sp. nov. differs from Selenopemphix quanta (Bradford 1975) Matsuoka 1985 in lacking two rows of paracingular processes, and by its more complex processes.
Remarks. The allocation of this species with the Recent genus Echinidinium is provisional since the archeopyle type is not well known. Furthermore, species of the genus Echinidinium are normally pigmented.
Questionable assignment: Heilmann-Clausen and Van Simaeys (2005, p.163).
Holotype: Heilmann-Clausen and Van Simaeys, 2005, pl.4, figs.1–2.
Age: late Eocene.
Original description (Heilmann-Clausen and Van Simaeys, 2005):
Echinidinium? lucidum sp. nov. Plate 4, figs. 1–6, Text-Figure 5
Description. A small, subspherical, proximochorate dinoflagellate cyst. The thin, smooth, hyaline wall and especially the numerous short processes are colorless and strongly refractive. The processes are rigid, massive, and of unequal length. The process morphology is variable (Text-Figure 5). Most processes are conical, or cylindrical with pointed tips. Some processes have a more irregular shape; they may be distally expanded and bifurcate, rarely irregularly branched. The distribution of the processes is mostly nontabular. Locally, processes may be aligned in short rows and can be fused in the lower part, forming a denticulate septum. An archeopyle is rarely visible, and its type has not been identified. It seems to be theropylic, with an operculum consisting of at least two adnate paraplates.
Derivation of name. From Latin lucidus,meaning sending out light, with reference to the strong refractivity of the cyst wall.
Designation of holotype. Plate 4, figs. 1, 2, Slide 1930 G2, England Finder coordinates H51. MGUH 27772. Kysing-3 borehole, sample 1930, Upper Eocene. Specimen dimensions: Total cyst diameter 51 µm; central body diameter 37 µm.
Designation of paratype. Plate 4, fig. 3, Slide 1928 G1, England Finder coordinates P46/4-P47/3. MGUH 27773. Kysing-3 borehole, sample 1928, Upper Eocene.
Dimensions of measured specimens. Total cyst diameter 45 (49) 53 µm. Central body diameter 33 (39) 45 µm. Maximum length of spines 6 (7) 8 µm. (9 specimens measured).
Comparison. Within this genus, this species especially resembles Echinidinium delicata Zonneveld 1997, which however has hollow and more uniform processes. There is also some similarity with the Recent genus Islandinium Head et al. 2001, especially with Islandinium minutum (Harland & Reid in Harland et al. 1980) Head et al. 2001. However, Islandinium minutum differs by having a saphopylic archeopyle, simpler processes and being pigmented. Echinidinium? lucidum sp. nov. differs from Selenopemphix quanta (Bradford 1975) Matsuoka 1985 in lacking two rows of paracingular processes, and by its more complex processes.
Remarks. The allocation of this species with the Recent genus Echinidinium is provisional since the archeopyle type is not well known. Furthermore, species of the genus Echinidinium are normally pigmented.