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Rhombodinium pentagonum
Rhombodinium? pentagonum Vozzhennikova, 1967
Originally Rhombodinium, subsequently Wetzeliella, thirdly (and now) Rhombodinium?. Stover and Evitt (1978, p.121) retained this species in Rhombodinium. Questionable assignment: Lentin and Vozzhennikova (1990, p.79).
Taxonomic senior synonym: Wetzeliella articulata, according to Costa and Downie (1979, p.40) — however, Lentin and Williams (1981, p.244) retained Rhombodinium pentagonum. Lentin and Vozzhennikova (1990, p.79) provided an "expanded description" for this species.
Holotype: Vozzhennikova, 1967, pl.96, fig.2 (lost according to Lentin and Vozzhennikova, 1990)
Lectotype: Lentin and Vozzhennikova, 1990, pl.7, fig.4, text-fig.42; designated by Lentin and Vozzhennikova, 1990
Locus typicus: Western Siberia, Russia
Stratum typicum: Late Eocene-early Oligocene
Translation Vozzhennikova, 1967: Lentin and Vozzhennikova, 1990
Original description: Vozzhennikova, 1967, p.171-172
Theca pentagonal, strongly compressed with cornuate outgrowths of variable size. In some forms the lateral horns are barely discernible whereas in others they are quite distinct. Laterial horns slightly attenuated with blunt, indented ends. Apical horn conical, rounded at tbe tip. Antapical horn triangular; transverse furrow discernible on the lateral horns. Internal body oval-pentagonal, smooth or finely granular. Theca colored, its wall of variable thickness. On the sides of the theca and on the horns there are short processes which branch at the end, the branches sometimes uniting to give a characteristic form of ornamentation. These outgrowths occur less frequently or are completely absent from the dorsal and ventral sides of the theca. Pylome round to trapeziform.
Expanded description: Lentin and Williams, 1990, p.79
Cyst shape pentagonal with a low, conical apical horn, two equal, short pericingular horns ant one or two unequal symmetrically located antapical horns; strongly dorsoventrally flattened; endocyst roundly pentagonal; circumcavate to occasionally cornucavate. Periphragm smooth to finely granulose except on lateral margins of cyst where delicate processes arise which may branch at the ends to interconnect with fine trabeculae; endophragm smooth to finely granulose; paratabulation indicated by the archeopyle and paracingulum only, peridinioid Periarcheopyle is quatra 2a resulting from the loss or displacement of paraplate 2a or soleiform 2a, perioperculum ant endoperculum free or attached. Paracingulum indicated by indendations on extremities of the lateral horns and may occasionally be indicated by indistinct shallow depressions on the dorsal ans ventral surfaces. Parasulcus not indicated.
Originally Rhombodinium, subsequently Wetzeliella, thirdly (and now) Rhombodinium?. Stover and Evitt (1978, p.121) retained this species in Rhombodinium. Questionable assignment: Lentin and Vozzhennikova (1990, p.79).
Taxonomic senior synonym: Wetzeliella articulata, according to Costa and Downie (1979, p.40) — however, Lentin and Williams (1981, p.244) retained Rhombodinium pentagonum. Lentin and Vozzhennikova (1990, p.79) provided an "expanded description" for this species.
Holotype: Vozzhennikova, 1967, pl.96, fig.2 (lost according to Lentin and Vozzhennikova, 1990)
Lectotype: Lentin and Vozzhennikova, 1990, pl.7, fig.4, text-fig.42; designated by Lentin and Vozzhennikova, 1990
Locus typicus: Western Siberia, Russia
Stratum typicum: Late Eocene-early Oligocene
Translation Vozzhennikova, 1967: Lentin and Vozzhennikova, 1990
Original description: Vozzhennikova, 1967, p.171-172
Theca pentagonal, strongly compressed with cornuate outgrowths of variable size. In some forms the lateral horns are barely discernible whereas in others they are quite distinct. Laterial horns slightly attenuated with blunt, indented ends. Apical horn conical, rounded at tbe tip. Antapical horn triangular; transverse furrow discernible on the lateral horns. Internal body oval-pentagonal, smooth or finely granular. Theca colored, its wall of variable thickness. On the sides of the theca and on the horns there are short processes which branch at the end, the branches sometimes uniting to give a characteristic form of ornamentation. These outgrowths occur less frequently or are completely absent from the dorsal and ventral sides of the theca. Pylome round to trapeziform.
Expanded description: Lentin and Williams, 1990, p.79
Cyst shape pentagonal with a low, conical apical horn, two equal, short pericingular horns ant one or two unequal symmetrically located antapical horns; strongly dorsoventrally flattened; endocyst roundly pentagonal; circumcavate to occasionally cornucavate. Periphragm smooth to finely granulose except on lateral margins of cyst where delicate processes arise which may branch at the ends to interconnect with fine trabeculae; endophragm smooth to finely granulose; paratabulation indicated by the archeopyle and paracingulum only, peridinioid Periarcheopyle is quatra 2a resulting from the loss or displacement of paraplate 2a or soleiform 2a, perioperculum ant endoperculum free or attached. Paracingulum indicated by indendations on extremities of the lateral horns and may occasionally be indicated by indistinct shallow depressions on the dorsal ans ventral surfaces. Parasulcus not indicated.