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Sanshuia
From Williams et al., 2017:
[Sanshuia, Yu Jing-xian et al., 1981, p. 259
Tax. sr. syn.: Geiselodinium, according to Chen et al. (1988, p.27) and Saeptodinium, according to Lentin and Williams (1989, p.326) — however, Mao Shaozhi et al. (1995, p.50) retained Sanshuia.
Type species: Sanshuia sphaerica, Yu Jing-xian et al., 1981 (pl.1, fig.1)]
Age: Late Eocene to Early Oligocene.
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Original description: [Yu Jing-xian, 1981]: (Translation: Chen et al., 1988, p. 27):
Description:
Cysts proximate, spherical, ellipsoidal to pentagonal in outline with one apical and two antapical horns. Periphragm and endophragm appressed, separated only in the areas of the apical and antapical horns (cornucavate), cysts have only one wall layer. Surface smooth, finely granulate or finely rugulate. Paratabulation indicated by paracingulum and parasulcus only, former planar, bordered by low ridges. Parasulcus, when present, extends onto the epicyst. Archeopyle unknown.
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Chen et al., 1988, p. 27:
Comparison of the descriptions and illustrations of Sanshuia with those of Geiselodinium revealed no significant differences between the two genera. Accordingly, we consider them as congeneric and Geiselodinium, as the senior synonym, is retained.
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GSC: (Provisional translation: courtesy R. Fensome):
Proximate cysts, with circular to elliptical to pentagonal outlines. Periphragm closely appressed to endocyst, with separation only at apical and antapical horns, or endophragm lacking. Periphragm smooth, with fine granules or fine creases. No paratabulation. All specimens lack archeopyle. Cingulum developed, annular, decorated with narrow ridge, and dividing cyst into upper and lower tests. When sulcus developed, apex reaches upper test or does not show.
Discussion:
The new genus has an annular cingulum that distinguishes it from the helical Lejeunia. Although Palaeoperidinium also has proximate cysts, with an endophragm that is distinct or inconspicuous, an annular cingulum and developed apical and antapical horns, it is distinguished from this new genus by its epitractal archaeopyle and sulcus which, when developed, is limited to the lower test. In "Early Tertiary Dinoflagellates and Acritarchs in the Coastal Region of the Bo Hai", there are plates of certain Deflandrea species which have an indistinct boundary between the periphragm and endocyst and display no archeopyle. Assigning them to Deflandrea with its cavate cysts and intercalary archeopyle is inappropriate, and the authors feel that they should be assigned to Sanshuia.
[Sanshuia, Yu Jing-xian et al., 1981, p. 259
Tax. sr. syn.: Geiselodinium, according to Chen et al. (1988, p.27) and Saeptodinium, according to Lentin and Williams (1989, p.326) — however, Mao Shaozhi et al. (1995, p.50) retained Sanshuia.
Type species: Sanshuia sphaerica, Yu Jing-xian et al., 1981 (pl.1, fig.1)]
Age: Late Eocene to Early Oligocene.
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Original description: [Yu Jing-xian, 1981]: (Translation: Chen et al., 1988, p. 27):
Description:
Cysts proximate, spherical, ellipsoidal to pentagonal in outline with one apical and two antapical horns. Periphragm and endophragm appressed, separated only in the areas of the apical and antapical horns (cornucavate), cysts have only one wall layer. Surface smooth, finely granulate or finely rugulate. Paratabulation indicated by paracingulum and parasulcus only, former planar, bordered by low ridges. Parasulcus, when present, extends onto the epicyst. Archeopyle unknown.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Chen et al., 1988, p. 27:
Comparison of the descriptions and illustrations of Sanshuia with those of Geiselodinium revealed no significant differences between the two genera. Accordingly, we consider them as congeneric and Geiselodinium, as the senior synonym, is retained.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
GSC: (Provisional translation: courtesy R. Fensome):
Proximate cysts, with circular to elliptical to pentagonal outlines. Periphragm closely appressed to endocyst, with separation only at apical and antapical horns, or endophragm lacking. Periphragm smooth, with fine granules or fine creases. No paratabulation. All specimens lack archeopyle. Cingulum developed, annular, decorated with narrow ridge, and dividing cyst into upper and lower tests. When sulcus developed, apex reaches upper test or does not show.
Discussion:
The new genus has an annular cingulum that distinguishes it from the helical Lejeunia. Although Palaeoperidinium also has proximate cysts, with an endophragm that is distinct or inconspicuous, an annular cingulum and developed apical and antapical horns, it is distinguished from this new genus by its epitractal archaeopyle and sulcus which, when developed, is limited to the lower test. In "Early Tertiary Dinoflagellates and Acritarchs in the Coastal Region of the Bo Hai", there are plates of certain Deflandrea species which have an indistinct boundary between the periphragm and endocyst and display no archeopyle. Assigning them to Deflandrea with its cavate cysts and intercalary archeopyle is inappropriate, and the authors feel that they should be assigned to Sanshuia.