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Operculodinium eirikianum var. eirikianum
Operculodinium eirikianum var. eirikianum
Autonym.
Holotype: Head et al., 1989b, pl.4, figs.11,15–16.
Original description: Head et al. 1989, p. 459
Diagnosis: Cysts skolochorate, having a spherical body and nontabular processes. Cyst wall apparently single layered; solid and nonfibrous and has a prominently microreticulate surface. Processes are solid, circular in cross section, nonfibrous and taper gradually to an acuminate tip. They are often sinuous towards the tips and may have scattered fine granules over their surface. Archeopyle precingular Type P (presumably by loss of paraplate 3''). Operculum free.
Dimensions: Range: diameter: 33-42 Ám; process length: 5-10 Ám; wall thickness up to 1.5 Ám, usually 1Ám or less. 17 specimens were measured.
Supplemental description: Head, 1993, p.27
Cyst skolochorate. Processes non-tabular, about 8 Ám long, characteristically solid, with granulate surface, and tapering to sinuous points. Processes arise from circular bases up to about 2.6 Ám wide but some thinner processes with bases of about 1.3 Ám also observed. Wall thickness less than 1 Ám. Periphragm distinctly microreticulate with lumina about 0.5 Ám wide or less and muri about 0.3 Ám wide. A single torn specimen seen.
Affinities:
Head et al. 1989, p. 459: The long acuminate solid, nonfibrous processes and nonfibrous microreticulate surface distinguish this species from 'typical' Operculodinium taxa, including the type species. These characters possibly reflect a fundamentally different structural pattern between O.?eirikianum and typical species of Operculodinium. O. longispinigerum Matsuoka, 1983 from the Miocene of Japan has a smooth to granulate wall surface, rather than a microreticulate wall surface, as found in O. ?eirikianum. Both O. echigoense Matsuoka, 1983 and O. walli Matsuoka, 1983 have capitate or bifid process terminations, compared to the tapering, acuminate process terminations of O. ?eirikianum.
Autonym.
Holotype: Head et al., 1989b, pl.4, figs.11,15–16.
Original description: Head et al. 1989, p. 459
Diagnosis: Cysts skolochorate, having a spherical body and nontabular processes. Cyst wall apparently single layered; solid and nonfibrous and has a prominently microreticulate surface. Processes are solid, circular in cross section, nonfibrous and taper gradually to an acuminate tip. They are often sinuous towards the tips and may have scattered fine granules over their surface. Archeopyle precingular Type P (presumably by loss of paraplate 3''). Operculum free.
Dimensions: Range: diameter: 33-42 Ám; process length: 5-10 Ám; wall thickness up to 1.5 Ám, usually 1Ám or less. 17 specimens were measured.
Supplemental description: Head, 1993, p.27
Cyst skolochorate. Processes non-tabular, about 8 Ám long, characteristically solid, with granulate surface, and tapering to sinuous points. Processes arise from circular bases up to about 2.6 Ám wide but some thinner processes with bases of about 1.3 Ám also observed. Wall thickness less than 1 Ám. Periphragm distinctly microreticulate with lumina about 0.5 Ám wide or less and muri about 0.3 Ám wide. A single torn specimen seen.
Affinities:
Head et al. 1989, p. 459: The long acuminate solid, nonfibrous processes and nonfibrous microreticulate surface distinguish this species from 'typical' Operculodinium taxa, including the type species. These characters possibly reflect a fundamentally different structural pattern between O.?eirikianum and typical species of Operculodinium. O. longispinigerum Matsuoka, 1983 from the Miocene of Japan has a smooth to granulate wall surface, rather than a microreticulate wall surface, as found in O. ?eirikianum. Both O. echigoense Matsuoka, 1983 and O. walli Matsuoka, 1983 have capitate or bifid process terminations, compared to the tapering, acuminate process terminations of O. ?eirikianum.