Back
Toenisbergia
From Fensome et al., 2019:
Toenisbergia Benedek et al., 1982, p.279.
Taxonomic senior synonym: Pentadinium, according to Lentin and Williams (1985, p.356; 1993, p.498).
Type: Benedek, 1972, pl.6, figs.12a–b, as Pentadinium taeniagerum subsp. imaginatum.
---------------------------------------------------------------------------------------------------
Original description: [Benedek et al., 1982]:
Description:
Cyst circumcavate. Periblast spheroidal to broadly ovoidal or rounded polygonal in ambitus, spheroidal to rounded-polygonal in polar view, with or without an indentation along the line of the sulcus. Endoblast spheroidal to ovoidal, broadly ellipsoidal or rounded-subpolygonal. Horns lacking; crests and processes lacking; cingulum marked by a slight indentation, faint lines, or not at all. Paratabulation otherwise normally indicated by archaeopyle only.
Archaeopyle intercalary (type l/l), of standard to broad hexa form.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Stover and Williams, 1987, p. 215:
Affinities:
The archeopyle in the type specimens of Toenisbergia is precingular (3" only), and not intercalary as stated above. The photomicrograph (Benedek et al. 1982, fig. 6C) and the drawing (ibid, fig. 8A) show that the posterior archeopyle margin extends to the paracingulum. This condition precludes the archeopyle being intercalary. Since the archeopyle on the type species of Toenisbergia, T. imaginata, is precingular, the species or its components may be retained in Pentadinium or Toenisbergia may be re-described. Basically, the only difference between Pentadinium and Toenisbergia is the occurrence of parasutural features on the former, and the absence or the reduction of such features on the latter. For forms whose only apparent difference is the presence or absence of features denoting paratabulation, the practice in the past was to establish two genera: one for forms possessing such features, and one for forms lacking them. Because transitional forms are being discovered more frequently, reasons for separating genera solely on the presence or absence of features indicating paratabulation (i.e. features other than the archeopyle and paracingulum) are becoming less and less compelling. Accordingly, we prefer to regard Toenisbergia as being within the generic circumscription of Pentadinium.
Toenisbergia Benedek et al., 1982, p.279.
Taxonomic senior synonym: Pentadinium, according to Lentin and Williams (1985, p.356; 1993, p.498).
Type: Benedek, 1972, pl.6, figs.12a–b, as Pentadinium taeniagerum subsp. imaginatum.
---------------------------------------------------------------------------------------------------
Original description: [Benedek et al., 1982]:
Description:
Cyst circumcavate. Periblast spheroidal to broadly ovoidal or rounded polygonal in ambitus, spheroidal to rounded-polygonal in polar view, with or without an indentation along the line of the sulcus. Endoblast spheroidal to ovoidal, broadly ellipsoidal or rounded-subpolygonal. Horns lacking; crests and processes lacking; cingulum marked by a slight indentation, faint lines, or not at all. Paratabulation otherwise normally indicated by archaeopyle only.
Archaeopyle intercalary (type l/l), of standard to broad hexa form.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Stover and Williams, 1987, p. 215:
Affinities:
The archeopyle in the type specimens of Toenisbergia is precingular (3" only), and not intercalary as stated above. The photomicrograph (Benedek et al. 1982, fig. 6C) and the drawing (ibid, fig. 8A) show that the posterior archeopyle margin extends to the paracingulum. This condition precludes the archeopyle being intercalary. Since the archeopyle on the type species of Toenisbergia, T. imaginata, is precingular, the species or its components may be retained in Pentadinium or Toenisbergia may be re-described. Basically, the only difference between Pentadinium and Toenisbergia is the occurrence of parasutural features on the former, and the absence or the reduction of such features on the latter. For forms whose only apparent difference is the presence or absence of features denoting paratabulation, the practice in the past was to establish two genera: one for forms possessing such features, and one for forms lacking them. Because transitional forms are being discovered more frequently, reasons for separating genera solely on the presence or absence of features indicating paratabulation (i.e. features other than the archeopyle and paracingulum) are becoming less and less compelling. Accordingly, we prefer to regard Toenisbergia as being within the generic circumscription of Pentadinium.