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Bellatudinium
From Williams et al., 2017:
[Bellatudinium, Yu Jing-xian et al., 1981, p. 261
Type species: Bellatudinium conspicuum, Yu Jing-xian et al., 1981(pl.1, fig.20)]
Age: GSC, Late Cretaceous
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Original description: [Yu Jing-xian, 1981]: (Translation: Chen et al., 1988, p. 6):
Description:
Cysts proximate, outline pentagonal to pear-shaped with a bent epicyst. Epicyst larger than hypocyst. An apical horn is present and may or may not be dominent. Two unequal antapical horns are strongly or weakly developed. Autophragm thin, ornamented with numerous, fine, irregular folds.
Paratabulation indicated by the paracingulum, which is wide and planar, and by the parasulcus, which extends onto the epicyst.
Archeopyle not discernible.
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Modified description:
Chen et al., 1988, p.4-5
Synopsis:
Cysts proximate, peridinioid; outline pentagonal to pear-shaped; epicyst longer than hypocyst and with or without a prominent apical horn; antapical horns present; autophragm thin and ornamented with irregular features of low relief; paratabulation reflected by paracingulum and parasulcus; archaeopyle not discernible.
Description:
Shape: Peridinioid, outline pentagonal to pear-shaped; epicyst widely to narrowly triangular and with or without a prominent apical horn; antapical horns strongly or weakly developed.
Wall Relationships: Autophragm only.
Wall Features: Surface finely and irregularly folded.
Archeopyle: Not discernible.
Paratabulation: Expressed by paracingulum and parasulcus.
Paracingulum: Stated as being wide and planar; evidently indicated by transverse folds.
Parasulcus: Stated as extending onto the epicyst, mode of expression not indicated.
Size: Small to intermediate, about 40 µm to 60 µm in length.
Affinities:
According to Yu Jingxian et al. (1981, p. 261), Bellatudinium differs from Palaeoperidinium Deflandre 1935 emended Sarjeant 1967 in lacking an archeopyle and in having the parasulcus developed on the epicyst. The latter is of questionable value as a generic taxonomic character. Evidently, Bellatudinium differs from Apiculadinium Yu Jingxian et al. 1981 in having only one wall layer rather than two.
The recognition of Apiculadinium and Bellatudinium as separate genera is based on the generic descriptions, not on the illustrations. In our opinion, the illustrated specimens of Apiculadinium and Bellatudinium are virtually indistinguishable and those of the former are not clearly cavate. If our interpretation is correct, the two genera are synonymous.
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GSC: (Provisional translation GSC: courtesy R. Fensome):
Description:
Proximate cysts. Outline tripodal to pentagonal to asymmetrically pyriform . Only periphragm present. Surface has irregular sutural ridge. Endocyst indistinct. Upper test larger than lower test. No tabulation or archaeopyle. Cingulum broad, annular. Apex of sulcus reaches upper test. Apical horn conspicuous or inconspicuous. Two antapical horns unequal in size, conspicuously or slightly developed (Fig.2).
Affinities/Discussion:
This genus is distinguished from Sanshuia by the width and size of the sulcus which goes from the lower to the upper test and by the presence of only a periphragm which is often decorated along the edge with very fine crease lines. It is distinguished from Palaeoperidinium by the absence of an archaeopyle and by the development of its sulcus which reaches the upper test.
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Kurita and matsuoka, 1994, p. 146:
Remarks:
According to the original diagnosis by Yu et al. (1981), the genus Bellatudinium is characterized by a thin and transparent autophragm with apical and antapical horns which vary from almost absent to distinctly developed. The genus Apiculadinium which has a cavate cyst and generally lacks antapical horns was erected by Yu et al. (1981) from the same material as Bellatudinium. Chen et al. (1988) pointed out that Bellatudinium may be a junior synonym of Apiculadinium, because the cavation around the apex and antapex of the latter genus is not clear and its wall presumably consists of an autophragm only. We, however, prefer to keep the genus Bellatudinium until the wall relation in Apiculadinium is well demonstrated.
[Bellatudinium, Yu Jing-xian et al., 1981, p. 261
Type species: Bellatudinium conspicuum, Yu Jing-xian et al., 1981(pl.1, fig.20)]
Age: GSC, Late Cretaceous
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Original description: [Yu Jing-xian, 1981]: (Translation: Chen et al., 1988, p. 6):
Description:
Cysts proximate, outline pentagonal to pear-shaped with a bent epicyst. Epicyst larger than hypocyst. An apical horn is present and may or may not be dominent. Two unequal antapical horns are strongly or weakly developed. Autophragm thin, ornamented with numerous, fine, irregular folds.
Paratabulation indicated by the paracingulum, which is wide and planar, and by the parasulcus, which extends onto the epicyst.
Archeopyle not discernible.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Chen et al., 1988, p.4-5
Synopsis:
Cysts proximate, peridinioid; outline pentagonal to pear-shaped; epicyst longer than hypocyst and with or without a prominent apical horn; antapical horns present; autophragm thin and ornamented with irregular features of low relief; paratabulation reflected by paracingulum and parasulcus; archaeopyle not discernible.
Description:
Shape: Peridinioid, outline pentagonal to pear-shaped; epicyst widely to narrowly triangular and with or without a prominent apical horn; antapical horns strongly or weakly developed.
Wall Relationships: Autophragm only.
Wall Features: Surface finely and irregularly folded.
Archeopyle: Not discernible.
Paratabulation: Expressed by paracingulum and parasulcus.
Paracingulum: Stated as being wide and planar; evidently indicated by transverse folds.
Parasulcus: Stated as extending onto the epicyst, mode of expression not indicated.
Size: Small to intermediate, about 40 µm to 60 µm in length.
Affinities:
According to Yu Jingxian et al. (1981, p. 261), Bellatudinium differs from Palaeoperidinium Deflandre 1935 emended Sarjeant 1967 in lacking an archeopyle and in having the parasulcus developed on the epicyst. The latter is of questionable value as a generic taxonomic character. Evidently, Bellatudinium differs from Apiculadinium Yu Jingxian et al. 1981 in having only one wall layer rather than two.
The recognition of Apiculadinium and Bellatudinium as separate genera is based on the generic descriptions, not on the illustrations. In our opinion, the illustrated specimens of Apiculadinium and Bellatudinium are virtually indistinguishable and those of the former are not clearly cavate. If our interpretation is correct, the two genera are synonymous.
---------------------------
GSC: (Provisional translation GSC: courtesy R. Fensome):
Description:
Proximate cysts. Outline tripodal to pentagonal to asymmetrically pyriform . Only periphragm present. Surface has irregular sutural ridge. Endocyst indistinct. Upper test larger than lower test. No tabulation or archaeopyle. Cingulum broad, annular. Apex of sulcus reaches upper test. Apical horn conspicuous or inconspicuous. Two antapical horns unequal in size, conspicuously or slightly developed (Fig.2).
Affinities/Discussion:
This genus is distinguished from Sanshuia by the width and size of the sulcus which goes from the lower to the upper test and by the presence of only a periphragm which is often decorated along the edge with very fine crease lines. It is distinguished from Palaeoperidinium by the absence of an archaeopyle and by the development of its sulcus which reaches the upper test.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Kurita and matsuoka, 1994, p. 146:
Remarks:
According to the original diagnosis by Yu et al. (1981), the genus Bellatudinium is characterized by a thin and transparent autophragm with apical and antapical horns which vary from almost absent to distinctly developed. The genus Apiculadinium which has a cavate cyst and generally lacks antapical horns was erected by Yu et al. (1981) from the same material as Bellatudinium. Chen et al. (1988) pointed out that Bellatudinium may be a junior synonym of Apiculadinium, because the cavation around the apex and antapex of the latter genus is not clear and its wall presumably consists of an autophragm only. We, however, prefer to keep the genus Bellatudinium until the wall relation in Apiculadinium is well demonstrated.