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Trimuridinium
From Fensome et al., 2019:
Fensome et al., 2019a, p.50. Type: Prince et al. 2008, pl. 1, figs 11–12, as Senoniasphaera whitenessensis.
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Original description Fensome et al., 2019a:
Type. Prince et al. 2008, pl. 1, figs 11–12, as Senoniasphaera whitenessensis.
Derivation of name. The name is derived from the Latin prefix “tri” for three, the Latin “murus” for wall, and “dinium”, the common suffix for dinoflagellates. Trimurodinium is thus the “three-walled dinoflagellate cyst”.2992
Diagnosis. Areoligeraceans in which the wall is constructed of three layers, the inner two of which are typically interconnected.
Comments. This genus is distinctive in having three wall layers. The presence of three wall layers is extremely unusual among dinoflagellate cysts, and, to our knowledge, previously unknown among areoligeraceans, even among gonyaulacineans. The best-known dinoflagellate cysts with three wall layers are perhaps the forms described by Evitt et al. (1998) and assigned to Palaeoperidinium. Evitt et al. (1998) referred to the outermost layer as the exophragm, a term that we favour here, retaining the terms endophragm and periphragm for the innermost and middle layers respectively. The two inner, interconnected, layers in Trimuridinium are clearly homologous with the endophragm and periphragm of Canningia. For Palaeoperidinium, Evitt et al. (1998) reasoned that the exophragm was formed outside the theca, and it would be of interest to examine Trimuridinium whitecliffense using the scanning electron microscope to see if any clues regarding the origin of the exophragm in this species might be revealed. Trimuridinium differs from Canningia in the presence of a third wall layer. Duxbury (1983) erected the genus Cepadinium, which has four wall layers. However, Cepadinium is an ovoidinioidean peridinioid dinoflagellate cyst.
Fensome et al., 2019a, p.50. Type: Prince et al. 2008, pl. 1, figs 11–12, as Senoniasphaera whitenessensis.
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Original description Fensome et al., 2019a:
Type. Prince et al. 2008, pl. 1, figs 11–12, as Senoniasphaera whitenessensis.
Derivation of name. The name is derived from the Latin prefix “tri” for three, the Latin “murus” for wall, and “dinium”, the common suffix for dinoflagellates. Trimurodinium is thus the “three-walled dinoflagellate cyst”.2992
Diagnosis. Areoligeraceans in which the wall is constructed of three layers, the inner two of which are typically interconnected.
Comments. This genus is distinctive in having three wall layers. The presence of three wall layers is extremely unusual among dinoflagellate cysts, and, to our knowledge, previously unknown among areoligeraceans, even among gonyaulacineans. The best-known dinoflagellate cysts with three wall layers are perhaps the forms described by Evitt et al. (1998) and assigned to Palaeoperidinium. Evitt et al. (1998) referred to the outermost layer as the exophragm, a term that we favour here, retaining the terms endophragm and periphragm for the innermost and middle layers respectively. The two inner, interconnected, layers in Trimuridinium are clearly homologous with the endophragm and periphragm of Canningia. For Palaeoperidinium, Evitt et al. (1998) reasoned that the exophragm was formed outside the theca, and it would be of interest to examine Trimuridinium whitecliffense using the scanning electron microscope to see if any clues regarding the origin of the exophragm in this species might be revealed. Trimuridinium differs from Canningia in the presence of a third wall layer. Duxbury (1983) erected the genus Cepadinium, which has four wall layers. However, Cepadinium is an ovoidinioidean peridinioid dinoflagellate cyst.