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Athigmatocysta
From Fensome et al., 2019:
Athigmatocysta, Duxbury, 1977, p.23–24.
Taxonomic senior synonyms: Endoscrinium, according to Below (1981a, p.48); and Scriniodinium, according to Stover and Williams (1987, p.27), and Pestchevitskaya and Lebedeva (2017, p.106) -- however, Harding (1990b, p.28), Riding and Fensome (2002, p.23–24) and the present authors herein retained Athigmatocysta.
Type: Duxbury, 1977, pl.11, figs.1,6; text-fig.3, as Athigmatocysta glabra.
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Original description: [Duxbury, 1977]:
Diagnosis:
Proximo-cavate cysts, spheroidal to ellipsoidal with no apparent contact between the two body layers. Tabulation ?4`, 6``, 6c, 6```, 1p, 1pv, 1````, defined by poorly to well-developed sutural crests which are distinctly denticulate. A short apical horn is present.
Archaeopyle precingular, formed by loss of plate 3``.
Affinities:
The genus differs from Gonyaulacysta Deflandre 1964 emend. Sarjeant 1969 and Psaligonyaulax Sarjeant 1966 in the cavation between the body layers. Athigmatocysta is distinguished from Scriniodinium Klement 1957 in possessing a full tabulation and from Endoscrinium Klement 1960 emend. Vozzhennikova 1967 in having six postcingular plates and a plate 1````. Endoscrinium has only five postcingular plates and does not possess any antapical plates.
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Remarks Stover and Williams, 1987, p. 27:
"We see no taxonomically significant difference between Athigmatocysta and Scriniodinium, therefore, the former is regarded herein as a junior synonym of the latter. This position is essentially the same as that taken by Below (1981, p. 48) except that he considered Athigmatocysta as a junior synonym of Endoscrinium, which in turn was treated as a junior synonym of Scriniodinium by Stover and Evitt (1978, p. 182). The paratabulation depicted by Duxbury (1977, text-fig. 3) is not clearly discernible on the illustrations of the holotype (Duxbury, 1977, pl. 11, figs. 1, 6). Moreover, the paraplate designated as 6```, by its size, shape and location, is more likely a sulcal rather than a postcingular paraplate.
Athigmatocysta, Duxbury, 1977, p.23–24.
Taxonomic senior synonyms: Endoscrinium, according to Below (1981a, p.48); and Scriniodinium, according to Stover and Williams (1987, p.27), and Pestchevitskaya and Lebedeva (2017, p.106) -- however, Harding (1990b, p.28), Riding and Fensome (2002, p.23–24) and the present authors herein retained Athigmatocysta.
Type: Duxbury, 1977, pl.11, figs.1,6; text-fig.3, as Athigmatocysta glabra.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Duxbury, 1977]:
Diagnosis:
Proximo-cavate cysts, spheroidal to ellipsoidal with no apparent contact between the two body layers. Tabulation ?4`, 6``, 6c, 6```, 1p, 1pv, 1````, defined by poorly to well-developed sutural crests which are distinctly denticulate. A short apical horn is present.
Archaeopyle precingular, formed by loss of plate 3``.
Affinities:
The genus differs from Gonyaulacysta Deflandre 1964 emend. Sarjeant 1969 and Psaligonyaulax Sarjeant 1966 in the cavation between the body layers. Athigmatocysta is distinguished from Scriniodinium Klement 1957 in possessing a full tabulation and from Endoscrinium Klement 1960 emend. Vozzhennikova 1967 in having six postcingular plates and a plate 1````. Endoscrinium has only five postcingular plates and does not possess any antapical plates.
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Remarks Stover and Williams, 1987, p. 27:
"We see no taxonomically significant difference between Athigmatocysta and Scriniodinium, therefore, the former is regarded herein as a junior synonym of the latter. This position is essentially the same as that taken by Below (1981, p. 48) except that he considered Athigmatocysta as a junior synonym of Endoscrinium, which in turn was treated as a junior synonym of Scriniodinium by Stover and Evitt (1978, p. 182). The paratabulation depicted by Duxbury (1977, text-fig. 3) is not clearly discernible on the illustrations of the holotype (Duxbury, 1977, pl. 11, figs. 1, 6). Moreover, the paraplate designated as 6```, by its size, shape and location, is more likely a sulcal rather than a postcingular paraplate.