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Rhombodinium
From Williams et al., 2017:
[Rhombodinium, Gocht, 1955, p. 85; Emendations: Bujak, 1979, p. 313–314 — however, see Lentin and Vozzhennikova (1989, p.218–219); Williams, Damassa, Fensome and Guerstein in Fensome et al., 2009, p.57.
Type species: Rhombodinium draco, Gocht, 1955 (text-fig.1c)]
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Original description: [Gocht, 1955]: (Translation: Stover and Evitt 1978, p. 120-121):
Dinoflagellates with an approximately rhomboidal, kite-shaped, or quadrate outline, well-developed apical and lateral horns. Shell untabulated, smooth, not ornamented with septae or spines (difference from Wetzeliella), without clearly recognizable transverse or longitudinal furrow. Shell always contains an inner capsule.
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Vozzhennikova 1967, p. 167: (Translation: Lees in Sarjeant (ed.), 1971):
Supplemental description:
Theca rhomboidal with well-developed apical and lateral horns; antapical horns small, of different size, and one is reduced. Transverse furrow well or poorly expressed, often discernible only on the lateral horns. Position of longitudinal furrow distinct. Internal body oval or ovalquadrangular, its surface sculptured, yellow, pale yellow, or pale brown. Theca light colored, its surface smooth to finely granular.
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Modified description:
Stover and Evitt 1978, p. 120-121:
Synopsis:
Cysts proximate, circumcavate, compressed peridinoid, with one apical, two lateral, and two antapical horns, of which some may be reduced or absent; periphragm smooth or with features of low relief; paratabulation quadra style, normally indicated by archeopyle only, occasionally also by paracingulum; archeopyle intercalary, Type I/I.
Description:
Shape: Typically compressed peridinoid, with apical, two antapical, and two lateral horns, of which some may be reduced or absent.
Wall relationships: Cysts circumcavate; endophragm circular to broadly elliptical in outline, occasionally approximating outline of pericyst.
Wall features: No parasutural features. Periphragm smooth or with features of low relief (granulae, coni, short spines); ornamentation generally sparse.
Paratabulation: Indicated by archeopyle or by archeopyle and paracingulum.
Archeopyle: Intercalary, Type I/I, (2a only); archeopyle index >0.5; opercula free or adherent apically; perioperculum may be longer than endoperculum.
Paracingulum: Generally indicated by faint parallel transverse folds of the periphragm; position may be emphasized by lateral horns.
Parasulcus: Indicated by shallow, poorly delimited depression on hypocyst; flagellar scar may be present; parasulcus not expressed on some forms.
Size: Large.
Affinities:
Rhombodinium differs from Wetzeliella in that its periphragm is smooth or ornamentated with features of low relief. Transitional forms are found with short spines or processes, which are somewhat longer (higher) than the ornamentation features on typical forms of Rhombodinium, and shorter (lower) than the processes normally present on forms of Wetzeliella. Assignment of the transitional specimens to either genus is subjective.
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Lentin and Williams 1976, p. 126-128:
Affinities:
Rhombodinium is characterised by having usually well developed pericingular horns, unequal antapical horns, a periphragm lacking processes, a clearly delineated endocyst and a quadra 2a archeopyle. This type of archeopyle is also present in Kisselovia, Wetzeliella and Wilsonidinium. Wezteliella and Kisselovia both differ in having processes. Wilsonidinium differs in possessing parasutural ornamentation.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Rhombodinium Gocht, 1955, emend. Bujak, 1979. Emendation by Bujak (1979), The periarcheopyle is quadra intercalary, soleiform, resulting from the displacement of the second anterior intercalary paraplate 2a. Perioperculum attached along the anterior margin Q1. Endoarcheopyle adjacent to the periarcheopyle and having same size and shape. Endooperculum attached along the anterior margin Q1.
[Rhombodinium, Gocht, 1955, p. 85; Emendations: Bujak, 1979, p. 313–314 — however, see Lentin and Vozzhennikova (1989, p.218–219); Williams, Damassa, Fensome and Guerstein in Fensome et al., 2009, p.57.
Type species: Rhombodinium draco, Gocht, 1955 (text-fig.1c)]
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Original description: [Gocht, 1955]: (Translation: Stover and Evitt 1978, p. 120-121):
Dinoflagellates with an approximately rhomboidal, kite-shaped, or quadrate outline, well-developed apical and lateral horns. Shell untabulated, smooth, not ornamented with septae or spines (difference from Wetzeliella), without clearly recognizable transverse or longitudinal furrow. Shell always contains an inner capsule.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Vozzhennikova 1967, p. 167: (Translation: Lees in Sarjeant (ed.), 1971):
Supplemental description:
Theca rhomboidal with well-developed apical and lateral horns; antapical horns small, of different size, and one is reduced. Transverse furrow well or poorly expressed, often discernible only on the lateral horns. Position of longitudinal furrow distinct. Internal body oval or ovalquadrangular, its surface sculptured, yellow, pale yellow, or pale brown. Theca light colored, its surface smooth to finely granular.
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Modified description:
Stover and Evitt 1978, p. 120-121:
Synopsis:
Cysts proximate, circumcavate, compressed peridinoid, with one apical, two lateral, and two antapical horns, of which some may be reduced or absent; periphragm smooth or with features of low relief; paratabulation quadra style, normally indicated by archeopyle only, occasionally also by paracingulum; archeopyle intercalary, Type I/I.
Description:
Shape: Typically compressed peridinoid, with apical, two antapical, and two lateral horns, of which some may be reduced or absent.
Wall relationships: Cysts circumcavate; endophragm circular to broadly elliptical in outline, occasionally approximating outline of pericyst.
Wall features: No parasutural features. Periphragm smooth or with features of low relief (granulae, coni, short spines); ornamentation generally sparse.
Paratabulation: Indicated by archeopyle or by archeopyle and paracingulum.
Archeopyle: Intercalary, Type I/I, (2a only); archeopyle index >0.5; opercula free or adherent apically; perioperculum may be longer than endoperculum.
Paracingulum: Generally indicated by faint parallel transverse folds of the periphragm; position may be emphasized by lateral horns.
Parasulcus: Indicated by shallow, poorly delimited depression on hypocyst; flagellar scar may be present; parasulcus not expressed on some forms.
Size: Large.
Affinities:
Rhombodinium differs from Wetzeliella in that its periphragm is smooth or ornamentated with features of low relief. Transitional forms are found with short spines or processes, which are somewhat longer (higher) than the ornamentation features on typical forms of Rhombodinium, and shorter (lower) than the processes normally present on forms of Wetzeliella. Assignment of the transitional specimens to either genus is subjective.
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Lentin and Williams 1976, p. 126-128:
Affinities:
Rhombodinium is characterised by having usually well developed pericingular horns, unequal antapical horns, a periphragm lacking processes, a clearly delineated endocyst and a quadra 2a archeopyle. This type of archeopyle is also present in Kisselovia, Wetzeliella and Wilsonidinium. Wezteliella and Kisselovia both differ in having processes. Wilsonidinium differs in possessing parasutural ornamentation.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Rhombodinium Gocht, 1955, emend. Bujak, 1979. Emendation by Bujak (1979), The periarcheopyle is quadra intercalary, soleiform, resulting from the displacement of the second anterior intercalary paraplate 2a. Perioperculum attached along the anterior margin Q1. Endoarcheopyle adjacent to the periarcheopyle and having same size and shape. Endooperculum attached along the anterior margin Q1.