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Angustidinium
From Fensome et al., 2019:
Angustidinium, Goodman and Evitt, 1981, p.47–48.
Taxonomic senior synonym: Moesiodinium, according to Below (1987a, p.129) -- however, Lentin and Williams (1989, p.17) retained Angustidinium.
Type: Davey and Verdier, 1971, pl.2, fig.10, as Deflandrea acribes.
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Original description: [Goodman and Evitt, 1981]:
Diagnosis:
Cavate peridiniacean cyst; apical horn present, antapical horns absent to moderately prominent; paratabulation expressed by parasutural features as 5`, 3a, 7", Xc, 5```, 2````. Archeopyle intercalary (2a only) and seven-sided.
Description:
Cyst weakly compressed dorso-ventrally, outline more or less peridinioid; one well-developed apical horn, and two antapical horns absent or variably developed.
Cavate, endocyst outline subcircular to elliptical- pericoels generally prominent apically and antapically, and lacking laterally. Periphragm ornamented with low parasutural features indicating paratabulation formula of 5`, 3a, 7", Xc, 5```, 2````; areas within parasutures smooth or ornamented with features of low relief.
Archeopyle intercalary, formed by detachment of seven-sided 2a paraplate.
Paracingulum and parasulcus variably expressed.
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Modified description:
Stover and Williams, 1987, p. 17:
Synopsis:
Cysts proximate, typically bicavate; apical horn present, antapical horns absent to moderately developed. Paratabulation expressed by parasutural features, formula: 2pr, 5`, 3a, 7", Xc, 5```, 2````, 5-6s. Archeopyle, type I/I, periarcheopyle 7-sided, anteriorly camerate
operculum free.
Description:
Shape: More or less peridinioid, slightly compressed dorso-ventrally; antapical horns variably developed or lacking.
Wall Relationships: Typically bicavate, rarely circumcavate; endocyst outline subcircular to elliptical.
Wall Features: Parasutural ridges generally low, may be lacking in rare cases; areas between parasutures smooth or faintly ornamented.
Archeopyle: Intercalary, type l/l (2a only); operculum free, 7-sided, anteriorly camerate; posteriorly planate.
Paratabulation: Expressed by parasutural features; peridiniacean, formula: 2pr, 5`, 3a, 7", Xc, 5```, 2```, 5-6s.
Paracingulum: Indicated by parallel, transverse, low parasutural ridges; not subdivided.
Parasulcus: Expressed by a relatively deep depression mainly on the hypocyst and a long, narrow region on the epicyst; 5 or 6 sulcal paraplates
may be differentiated.
Size: Small to intermediate, length about 25 to 55 µm, generally less than 50 µm.
Affinities:
Angustidinium differs from Phthanoperidinium Drugg and Loebich 1967 in being cavate and in having 5 apical paraplates and a 7-sided 2a paraplate rather than 4 apical paraplates and a 6-sided, biplanate 2a paraplate. Moesiodinium Antonescu 1974 resembles Angustidinium in shape and size, but the former lacks parasutural features and has a 6-sided, bicamerate 2a paraplate. Smolenskiella Vozzhennikova 1967 is most similar to Angustidinium in overall appearance, but uncertainties about the paratabulation of the former preclude further comparison.
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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.
Angustidinium Goodman and Evitt, 1981. According to Stover and Williams (1987, p.17): Cysts proximate, typically bicavate, apical horn present, antapical horns absent to moderately developed. Paratabulation expressed by parasutural features, formula 2pr, 5`, 3a, 7", xc, 5"' , 2"" , 5-6s. Archeopyle type I/I, periarcheopyle 7 sided, anteriorly camerate: operculum free.
Angustidinium, Goodman and Evitt, 1981, p.47–48.
Taxonomic senior synonym: Moesiodinium, according to Below (1987a, p.129) -- however, Lentin and Williams (1989, p.17) retained Angustidinium.
Type: Davey and Verdier, 1971, pl.2, fig.10, as Deflandrea acribes.
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Original description: [Goodman and Evitt, 1981]:
Diagnosis:
Cavate peridiniacean cyst; apical horn present, antapical horns absent to moderately prominent; paratabulation expressed by parasutural features as 5`, 3a, 7", Xc, 5```, 2````. Archeopyle intercalary (2a only) and seven-sided.
Description:
Cyst weakly compressed dorso-ventrally, outline more or less peridinioid; one well-developed apical horn, and two antapical horns absent or variably developed.
Cavate, endocyst outline subcircular to elliptical- pericoels generally prominent apically and antapically, and lacking laterally. Periphragm ornamented with low parasutural features indicating paratabulation formula of 5`, 3a, 7", Xc, 5```, 2````; areas within parasutures smooth or ornamented with features of low relief.
Archeopyle intercalary, formed by detachment of seven-sided 2a paraplate.
Paracingulum and parasulcus variably expressed.
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Modified description:
Stover and Williams, 1987, p. 17:
Synopsis:
Cysts proximate, typically bicavate; apical horn present, antapical horns absent to moderately developed. Paratabulation expressed by parasutural features, formula: 2pr, 5`, 3a, 7", Xc, 5```, 2````, 5-6s. Archeopyle, type I/I, periarcheopyle 7-sided, anteriorly camerate
operculum free.
Description:
Shape: More or less peridinioid, slightly compressed dorso-ventrally; antapical horns variably developed or lacking.
Wall Relationships: Typically bicavate, rarely circumcavate; endocyst outline subcircular to elliptical.
Wall Features: Parasutural ridges generally low, may be lacking in rare cases; areas between parasutures smooth or faintly ornamented.
Archeopyle: Intercalary, type l/l (2a only); operculum free, 7-sided, anteriorly camerate; posteriorly planate.
Paratabulation: Expressed by parasutural features; peridiniacean, formula: 2pr, 5`, 3a, 7", Xc, 5```, 2```, 5-6s.
Paracingulum: Indicated by parallel, transverse, low parasutural ridges; not subdivided.
Parasulcus: Expressed by a relatively deep depression mainly on the hypocyst and a long, narrow region on the epicyst; 5 or 6 sulcal paraplates
may be differentiated.
Size: Small to intermediate, length about 25 to 55 µm, generally less than 50 µm.
Affinities:
Angustidinium differs from Phthanoperidinium Drugg and Loebich 1967 in being cavate and in having 5 apical paraplates and a 7-sided 2a paraplate rather than 4 apical paraplates and a 6-sided, biplanate 2a paraplate. Moesiodinium Antonescu 1974 resembles Angustidinium in shape and size, but the former lacks parasutural features and has a 6-sided, bicamerate 2a paraplate. Smolenskiella Vozzhennikova 1967 is most similar to Angustidinium in overall appearance, but uncertainties about the paratabulation of the former preclude further comparison.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Angustidinium Goodman and Evitt, 1981. According to Stover and Williams (1987, p.17): Cysts proximate, typically bicavate, apical horn present, antapical horns absent to moderately developed. Paratabulation expressed by parasutural features, formula 2pr, 5`, 3a, 7", xc, 5"' , 2"" , 5-6s. Archeopyle type I/I, periarcheopyle 7 sided, anteriorly camerate: operculum free.