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Sinocysta
From Williams et al., 2017:
[Sinocysta, He Cheng-quan, 1984a, p. 769, 773
Type species: Sinocysta minuta, He Chengquan, 1984a (pl.1, fig.5; text-fig.1)]
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Original description: [He Cheng-quan, 1984]:
Diagnosis:
Cysts proximate, compressed, roundly peridinioid to nearly subcircular in outline, an apical horn typically short and two antapical horns more or less reduced or absent. Wall thin and single-layered; surface smooth or granulate, striate and rugose.
Paratabulation and inner body absent.
Cingulum clearly indicated by low, parallel and transverse equatorial ridges. Sulcus often present.
Archaeopyle combination, Type (tI3P)a, larger and arched in outline, occupying most of the dorsal surface of the epicyst and involving an intercalary area (1a-3a) and three precingular paraplates (3"-5"). Operculum probably attached along its cingulum margin.
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Chen et al., 1988, p. 28:
The description of Sinocysta is compatible with the original description of Laciniadinium, whose variability, as expressed by McIntyre, 1975, and reiterated by Stover and Evitt, 1978, readily encompasses the features attributed to Sinocysta.
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GSC: (GSC provisional translation: Courtesy R. Fensome):
Cysts proximate, with a compressed, pentagonal outline. One short apical horn (convex); two antapical horns in varying degrees of degeneration or missing. Cingulum annular. Sulcus present or missing. No inner body or conspicuous tabulation (apart from archaeopyle). Test walls thin, single-layered; surface smooth or with low-relief ornamentation (such as granules, striae or rugae). Combination archaeopyle; type tI3Pa.
Comparison:
The archaeopyle in Sinocysta gen. nov. may very possibly resemble those in Luxadinium and Laciniadinium, in that during its formation the archaeopyle contained no apical plates. However, the new genus is distinguished from the former in lacking an inner body and from the latter in having a peridinoid outline. The new genus differs from Palaeoperidinium in that its archaeopyle is type tI3Pa and its two antapical horns are in varying degrees of degeneration or completely missing. However, there may be a genetic relationship between the two genera, with both belonging to the modern Peridiniaceae. The new genus is similar to Soaniella in outer shape, but the latter has an intercalary archaeopyle. It differs from Subtilisphaera and Saeptodinium in its proximate rather than cavate cysts and in the nature of the archaeopyle.
[Sinocysta, He Cheng-quan, 1984a, p. 769, 773
Type species: Sinocysta minuta, He Chengquan, 1984a (pl.1, fig.5; text-fig.1)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [He Cheng-quan, 1984]:
Diagnosis:
Cysts proximate, compressed, roundly peridinioid to nearly subcircular in outline, an apical horn typically short and two antapical horns more or less reduced or absent. Wall thin and single-layered; surface smooth or granulate, striate and rugose.
Paratabulation and inner body absent.
Cingulum clearly indicated by low, parallel and transverse equatorial ridges. Sulcus often present.
Archaeopyle combination, Type (tI3P)a, larger and arched in outline, occupying most of the dorsal surface of the epicyst and involving an intercalary area (1a-3a) and three precingular paraplates (3"-5"). Operculum probably attached along its cingulum margin.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Chen et al., 1988, p. 28:
The description of Sinocysta is compatible with the original description of Laciniadinium, whose variability, as expressed by McIntyre, 1975, and reiterated by Stover and Evitt, 1978, readily encompasses the features attributed to Sinocysta.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
GSC: (GSC provisional translation: Courtesy R. Fensome):
Cysts proximate, with a compressed, pentagonal outline. One short apical horn (convex); two antapical horns in varying degrees of degeneration or missing. Cingulum annular. Sulcus present or missing. No inner body or conspicuous tabulation (apart from archaeopyle). Test walls thin, single-layered; surface smooth or with low-relief ornamentation (such as granules, striae or rugae). Combination archaeopyle; type tI3Pa.
Comparison:
The archaeopyle in Sinocysta gen. nov. may very possibly resemble those in Luxadinium and Laciniadinium, in that during its formation the archaeopyle contained no apical plates. However, the new genus is distinguished from the former in lacking an inner body and from the latter in having a peridinoid outline. The new genus differs from Palaeoperidinium in that its archaeopyle is type tI3Pa and its two antapical horns are in varying degrees of degeneration or completely missing. However, there may be a genetic relationship between the two genera, with both belonging to the modern Peridiniaceae. The new genus is similar to Soaniella in outer shape, but the latter has an intercalary archaeopyle. It differs from Subtilisphaera and Saeptodinium in its proximate rather than cavate cysts and in the nature of the archaeopyle.