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Striatodinium
From Williams et al., 2017:
[Striatodinium, Riding and Helby, 2001f, p. 166, 168.
Type species: Striatodinium ottii, Riding and Helby, 2001f (figs.15O-P)]
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Original description: [Riding and Helby, 2001f]:
Diagnosis:
Small to intermediate, proximate, acavate dinoflagellate cysts, which are elongate ellipsoidal in outline. The autophragm is smooth or has low relief, non-parasultural ornamentation. The autophragm also bears numerous, prominent, largely longitudinal ridges or crests, which may be nontabular or penitabular. These nontabular elements may be discontinuous. The paratabulation is gonyaulacalean. Paraplates are enormally outlined by smooth, narrow, pandasultural bands. The archaeopyle is apical; operculum simple and free. Parasutures surrounding the paracingulum and parasulcus indicated by the absence of ornamentation of by penitabular ridges or crests; the parasulcus is slightly indented. The paracingulum is laevorotatory and is displaced at the parasulcus by as much as its entire height.
Remarks:
Striatodinium is a small, distinctive genus. The longitudinal alignment of the nontabular or penitabular ridges or crests, coupled with the elongate shape of this genus, are characteristic. In forms with penitabular ornamentation, lateral features are present, for example on the paracingular paraplates. However, in the markedly more elongate precingular and postcingular paraplate series, the apical and antapical sides of the penitabular fields are particularly narrow. Nontabular elements commonly occur within the fields marked by the penitabular rigdes; the dominant lineation of these elements is longitudinal.
Affinities:
Dinogymnium Evitt et al. 1967 and Ellipsodinium Clarke & Verdier 1967 both have longitudinal ornamentation and thus resemble Striatodinium. However, Dinogymnium is biconical, has extremely small, apical archaeopyle and a unique wall structure (May, 1967; Evitt, 1985). Ellipsodinium lacks parasultural features and has a precingular archaeopyle. Hemiplacophora Cookson & Eisenack 1965 has penitabular ornamentation, but these elements are incomplete and polar in position. Alisocysta Stover and Evitt 1978 is subspherical and penitabular crests or septa are consistently present. Laterna Dodekova 1969 is ellipsoidal, has an apical archaeopyle and penitabular ornamentation. However, this Jurassic genus completely lacks longitudinal ornamentation characteristic of Striatodinium The genera Eisenackia Deflandre & Cookson 1955 and Cassidium Drugg 1967 have linear parasultural features, but these are depressions, which are surrounded by raised intratabular areas. Gerdiocysta Liengjarern et al. 1980 is proximate, has an apical archaeopyle and penitabular ornament, but is holocavate. This new genus resembles several other proximate genera with apical archaeopyles such as Ellipsoidyctum Klement 1960 and Valensiella Eisenack 1963, but differs in its penitabular and pandasutural paraplate delineation. Isolated endocysts of some cavate genera including Belodinium Cookson & Eisenack 1960 and Gardodinium Alberti 1961 may be elongate and exhibit similar penitabular and pandasutural features to Striatodinium.
[Striatodinium, Riding and Helby, 2001f, p. 166, 168.
Type species: Striatodinium ottii, Riding and Helby, 2001f (figs.15O-P)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Riding and Helby, 2001f]:
Diagnosis:
Small to intermediate, proximate, acavate dinoflagellate cysts, which are elongate ellipsoidal in outline. The autophragm is smooth or has low relief, non-parasultural ornamentation. The autophragm also bears numerous, prominent, largely longitudinal ridges or crests, which may be nontabular or penitabular. These nontabular elements may be discontinuous. The paratabulation is gonyaulacalean. Paraplates are enormally outlined by smooth, narrow, pandasultural bands. The archaeopyle is apical; operculum simple and free. Parasutures surrounding the paracingulum and parasulcus indicated by the absence of ornamentation of by penitabular ridges or crests; the parasulcus is slightly indented. The paracingulum is laevorotatory and is displaced at the parasulcus by as much as its entire height.
Remarks:
Striatodinium is a small, distinctive genus. The longitudinal alignment of the nontabular or penitabular ridges or crests, coupled with the elongate shape of this genus, are characteristic. In forms with penitabular ornamentation, lateral features are present, for example on the paracingular paraplates. However, in the markedly more elongate precingular and postcingular paraplate series, the apical and antapical sides of the penitabular fields are particularly narrow. Nontabular elements commonly occur within the fields marked by the penitabular rigdes; the dominant lineation of these elements is longitudinal.
Affinities:
Dinogymnium Evitt et al. 1967 and Ellipsodinium Clarke & Verdier 1967 both have longitudinal ornamentation and thus resemble Striatodinium. However, Dinogymnium is biconical, has extremely small, apical archaeopyle and a unique wall structure (May, 1967; Evitt, 1985). Ellipsodinium lacks parasultural features and has a precingular archaeopyle. Hemiplacophora Cookson & Eisenack 1965 has penitabular ornamentation, but these elements are incomplete and polar in position. Alisocysta Stover and Evitt 1978 is subspherical and penitabular crests or septa are consistently present. Laterna Dodekova 1969 is ellipsoidal, has an apical archaeopyle and penitabular ornamentation. However, this Jurassic genus completely lacks longitudinal ornamentation characteristic of Striatodinium The genera Eisenackia Deflandre & Cookson 1955 and Cassidium Drugg 1967 have linear parasultural features, but these are depressions, which are surrounded by raised intratabular areas. Gerdiocysta Liengjarern et al. 1980 is proximate, has an apical archaeopyle and penitabular ornament, but is holocavate. This new genus resembles several other proximate genera with apical archaeopyles such as Ellipsoidyctum Klement 1960 and Valensiella Eisenack 1963, but differs in its penitabular and pandasutural paraplate delineation. Isolated endocysts of some cavate genera including Belodinium Cookson & Eisenack 1960 and Gardodinium Alberti 1961 may be elongate and exhibit similar penitabular and pandasutural features to Striatodinium.