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Operculodinium centrocarpum
Operculodinium centrocarpum (Deflandre and Cookson, 1955) Wall, 1967
Originally Hystrichosphaeridium centrocarpum, subsequently Baltisphaeridium centrocarpum, thirdly Cordosphaeridium centrocarpum, fourthly Cordosphaeridium tiara ssp. centrocarpum, fifthly (and now) Operculodinium centrocarpum, sixthly Cordosphaeridium? microtriainum ssp. centrocarpum, seventhly Cleistosphaeridium centrocarpum. Lentin and Williams (1973, p.102) retained this taxon as Operculodinium centrocarpum.
Taxonomic junior synonyms: Operculodinium? echigoense, according to Matsuoka et al. (1997, p.22); Membranilarnacia delicata, according to Jain (1980, p.140) — however, Membranilarnacia delicata is now considered to be a taxonomic junior synonym of Hystrichosphaeridium (now Polysphaeridium) zoharyi.
Motile equivalent: Peridinium (now Protoceratium) reticulatum Claparède and Lachmann, 1859 (as Gonyaulax grindleyi Reinecke, 1967), according to Wall and Dale (1966, p.1025–1026) — however, see Head (1996b, p.1211).
Head in Head and Wrenn (1992, p.24) considered this species to be the possible taxonomic senior synonym of Operculodinium wallii. See also Hystrichosphaeridium westii.
Holotype: Deflandre and Cookson, 1955, pl.8, figs.3-4
Locus typicus: Balcombe Bay, Victoria, Australia
Stratum typicum: Middle Miocene
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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.
Operculodinium centrocarpum (Deflandre and Cookson, 1955) Wall, 1967. The cyst stage of Protoceratium reticulatum According to Deflandre and Cookson (1955), this has a globular shell, covered with numerous straight, slender processes placed irregularly or with a certain alignment. Processes solid, showing radiating fibrils at their point of insertion on the shell which is clearly ornamented with a fine reticulum. The slightly widened apices of the processes are fringed with 10 or more small curved spines. Dale (in Head and Wrenn, 1992) believes that the modern forms included in this species are smaller than the type material. Matsuoka et al. (1997) restudied the holotype of O.centrocarpum. According to Matsuoka et al. (1997), the periphragm is 2 µm thick. The surface is microreticulate, and coarser around the base of the processes. The process shafts are solid, smooth. Distal terminations may be either recurved or patulate. Size: diameter of shell 54-80 µm, process length 13-18 µm, total diameter 97-115 µm. Operculodinium centrocarpum sensu Wall 1967 has a subspherical body, whose surface is microgranular and densely covered with radiating processes. The solid processes are slender and have conical bases bearing minute striations. The distal extremities of the processes bear small hooklets or minute platforms. Size of modern cysts of Protoceratium reticulatum, cyst diameter 28-50 µm, process length 4-16 µm.
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Original description: Deflandre and Cookson, 1955, p. 273: Hystrichosphaeridium centrocarpum
Shell globular, more or less ellipsoidal (probably by deformation), covered with numerous straight, slender processes placed irregulary or with a certain alignment. Processes solid, showing radiating fibrils at their point of insertion on the shell, which is clearly ornamented with a fine reticulum. The slightly widened apices of the processes are fringed with 10 or more small curved spines (this structure is only visible with a high-powered objective).
Dimensions: Diameter of shell 54-80 Ám, length of processes 13-18 Ám, total diameter c. 97-115 Ám.
As a result of the relative thinness of the shell membrane none of the specimens has been completely intact. Most of the examples have a large irregular or more or less angular opening.
Supplemental description: Wall, 1967, p. 111
The test is almost sphaerical and densely ornamented with slender radiating spines whose length (8-16 Ám) varies between approximately one-fifth and one-quater of the cell diameter. The dorsal precingular archaeopyle is large and subtrapezoidal. The outer cell wall is microgranular and the immediate spine bases are conical with minute striations. The spine tips bear small hooklets wich are visible only at high magnifications. The spines are aligned in the girdle region but there is no distinct ventral sulcus. The spine arrangement is intratabular, most spines lying alongside the sutural lines.
Dimensions: Caribbean specimens vary from 40 to 56 Ám for the test alone. Miocene specimens may be much larger, with diameters approching 90 Ám.
Affinities:
Deflandre and Cookson, 1955, p. 273: Hystrichosphaeridium centrocarpum
H. centrocarpum, in spite of its generally similar appearance, does not belong to the species group of H. recurvatum Delf. - H. major Lej.-Carp. known from the European Cretaceous flints. In these species the hollow processes have a quite different structure.
Originally Hystrichosphaeridium centrocarpum, subsequently Baltisphaeridium centrocarpum, thirdly Cordosphaeridium centrocarpum, fourthly Cordosphaeridium tiara ssp. centrocarpum, fifthly (and now) Operculodinium centrocarpum, sixthly Cordosphaeridium? microtriainum ssp. centrocarpum, seventhly Cleistosphaeridium centrocarpum. Lentin and Williams (1973, p.102) retained this taxon as Operculodinium centrocarpum.
Taxonomic junior synonyms: Operculodinium? echigoense, according to Matsuoka et al. (1997, p.22); Membranilarnacia delicata, according to Jain (1980, p.140) — however, Membranilarnacia delicata is now considered to be a taxonomic junior synonym of Hystrichosphaeridium (now Polysphaeridium) zoharyi.
Motile equivalent: Peridinium (now Protoceratium) reticulatum Claparède and Lachmann, 1859 (as Gonyaulax grindleyi Reinecke, 1967), according to Wall and Dale (1966, p.1025–1026) — however, see Head (1996b, p.1211).
Head in Head and Wrenn (1992, p.24) considered this species to be the possible taxonomic senior synonym of Operculodinium wallii. See also Hystrichosphaeridium westii.
Holotype: Deflandre and Cookson, 1955, pl.8, figs.3-4
Locus typicus: Balcombe Bay, Victoria, Australia
Stratum typicum: Middle Miocene
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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.
Operculodinium centrocarpum (Deflandre and Cookson, 1955) Wall, 1967. The cyst stage of Protoceratium reticulatum According to Deflandre and Cookson (1955), this has a globular shell, covered with numerous straight, slender processes placed irregularly or with a certain alignment. Processes solid, showing radiating fibrils at their point of insertion on the shell which is clearly ornamented with a fine reticulum. The slightly widened apices of the processes are fringed with 10 or more small curved spines. Dale (in Head and Wrenn, 1992) believes that the modern forms included in this species are smaller than the type material. Matsuoka et al. (1997) restudied the holotype of O.centrocarpum. According to Matsuoka et al. (1997), the periphragm is 2 µm thick. The surface is microreticulate, and coarser around the base of the processes. The process shafts are solid, smooth. Distal terminations may be either recurved or patulate. Size: diameter of shell 54-80 µm, process length 13-18 µm, total diameter 97-115 µm. Operculodinium centrocarpum sensu Wall 1967 has a subspherical body, whose surface is microgranular and densely covered with radiating processes. The solid processes are slender and have conical bases bearing minute striations. The distal extremities of the processes bear small hooklets or minute platforms. Size of modern cysts of Protoceratium reticulatum, cyst diameter 28-50 µm, process length 4-16 µm.
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Original description: Deflandre and Cookson, 1955, p. 273: Hystrichosphaeridium centrocarpum
Shell globular, more or less ellipsoidal (probably by deformation), covered with numerous straight, slender processes placed irregulary or with a certain alignment. Processes solid, showing radiating fibrils at their point of insertion on the shell, which is clearly ornamented with a fine reticulum. The slightly widened apices of the processes are fringed with 10 or more small curved spines (this structure is only visible with a high-powered objective).
Dimensions: Diameter of shell 54-80 Ám, length of processes 13-18 Ám, total diameter c. 97-115 Ám.
As a result of the relative thinness of the shell membrane none of the specimens has been completely intact. Most of the examples have a large irregular or more or less angular opening.
Supplemental description: Wall, 1967, p. 111
The test is almost sphaerical and densely ornamented with slender radiating spines whose length (8-16 Ám) varies between approximately one-fifth and one-quater of the cell diameter. The dorsal precingular archaeopyle is large and subtrapezoidal. The outer cell wall is microgranular and the immediate spine bases are conical with minute striations. The spine tips bear small hooklets wich are visible only at high magnifications. The spines are aligned in the girdle region but there is no distinct ventral sulcus. The spine arrangement is intratabular, most spines lying alongside the sutural lines.
Dimensions: Caribbean specimens vary from 40 to 56 Ám for the test alone. Miocene specimens may be much larger, with diameters approching 90 Ám.
Affinities:
Deflandre and Cookson, 1955, p. 273: Hystrichosphaeridium centrocarpum
H. centrocarpum, in spite of its generally similar appearance, does not belong to the species group of H. recurvatum Delf. - H. major Lej.-Carp. known from the European Cretaceous flints. In these species the hollow processes have a quite different structure.