Back
Alterbidinium varium
From Fensome et al., 2019:
Alterbidinium varium, Kirsch, 1991, p.98–99, pl.19, figs.1–10; text-figs.46a–h,47a–b.
Holotype: Kirsch, 1991, pl.19, figs.1–2; text-fig.46a.
Age: early Maastrichtian.
Locus typicus: Moos-Graben, Bavaria, Germany
---------------------------------------------------------------------------------------------------
Original description: [Kirsch, 1991, p. 98-99]: (Translation: LPP):
Diagnosis:
Circumcavate, smooth cyst with ovoidal, rounded to sphaeroidal pericyst habit, two irregular, weakly developed antapical horns and a subsphaerical to ellipsoidal endocyst. The variation of the overall habit metionable.
Archaeopyle intercalary (2a); Type standard hexa (according to Lentin and Williams, 1976); operculum posterior adnate.
Description:
The slightly larger, ovoidal epicyst is characterized by the rounded to weakly conical apex and the convex flanks. Apex may appear blunted or shows a trace of a developing protrusin. A distinct cingulum misses. It may by indicated by weak granulation or slightly extended lateral areas. Endo- and pericyst are smooth and very thin. The smaller hypocyst is characterized by a pointed, longer right antapical horn and a sometimes totally reduced second antapical horn. The cysts are usually folded ventrally.
An intercalary archaeopyle (2a) with standard hexa outline and a posterior adnate operculum is determinable. The length of the archaeopyle sides is variable.
Affinities:
Alterbidinium varium differs in the mainly ovoidal habit and the lack of apical horn and cingulum from Alterbidinium minus (Alberti 1959) which shows a very distinct pentagonal outline. Ascodinium parvum (Cookson and Eisenack 1958) consists of a combined archaeopyle. Isabelidinium cretaceum (Cookson 1956) is larger, lacks antapical processes and differs in the archaeopyle-form. Alterbidinium varium differs from Eurydinium saxoniense Marshall and Batten 1988 in the weakly developed cingulum and the reduction of the second antapical horn.
Alterbidinium varium, Kirsch, 1991, p.98–99, pl.19, figs.1–10; text-figs.46a–h,47a–b.
Holotype: Kirsch, 1991, pl.19, figs.1–2; text-fig.46a.
Age: early Maastrichtian.
Locus typicus: Moos-Graben, Bavaria, Germany
---------------------------------------------------------------------------------------------------
Original description: [Kirsch, 1991, p. 98-99]: (Translation: LPP):
Diagnosis:
Circumcavate, smooth cyst with ovoidal, rounded to sphaeroidal pericyst habit, two irregular, weakly developed antapical horns and a subsphaerical to ellipsoidal endocyst. The variation of the overall habit metionable.
Archaeopyle intercalary (2a); Type standard hexa (according to Lentin and Williams, 1976); operculum posterior adnate.
Description:
The slightly larger, ovoidal epicyst is characterized by the rounded to weakly conical apex and the convex flanks. Apex may appear blunted or shows a trace of a developing protrusin. A distinct cingulum misses. It may by indicated by weak granulation or slightly extended lateral areas. Endo- and pericyst are smooth and very thin. The smaller hypocyst is characterized by a pointed, longer right antapical horn and a sometimes totally reduced second antapical horn. The cysts are usually folded ventrally.
An intercalary archaeopyle (2a) with standard hexa outline and a posterior adnate operculum is determinable. The length of the archaeopyle sides is variable.
Affinities:
Alterbidinium varium differs in the mainly ovoidal habit and the lack of apical horn and cingulum from Alterbidinium minus (Alberti 1959) which shows a very distinct pentagonal outline. Ascodinium parvum (Cookson and Eisenack 1958) consists of a combined archaeopyle. Isabelidinium cretaceum (Cookson 1956) is larger, lacks antapical processes and differs in the archaeopyle-form. Alterbidinium varium differs from Eurydinium saxoniense Marshall and Batten 1988 in the weakly developed cingulum and the reduction of the second antapical horn.