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Belodinium obsoletum
Belodinium obsoletum, Dodekova, 1975
Originally (and now) Belodinium, subsequently Clathroctenocystis.
Stover and Helby, 1987 transferred this species to Clathroctenocystis Wiggins, 1972. Dodekova, 1990, retained it in Belodinium.
Holotype: Dodekova, 1975, pl.4, figs.1-4
Locus typicus: NE Bulgaria
Stratum typicum: Late Bathonian
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Original description: [Dodekova, 1975, p. 24]:
Description:
Bicavate cyst with polyhedral periblast and ellipsoidal endoblast inside. It is divided by a slightly laevo-rotatorv spiral cingulum, located in the anterior half of the body. The apical pericoel is conic with strongly broadened base, dorsally projected. The apex terminates with subpyramidal horn inclined to the ventral side. The antapical pericoel is larger, ventrally projected.
Tabulation formula: ?6", 6"", 6c, 5""", 1p, 1pv, 1"""". The sutures are marked by thin, short membranous septa, very fine and difficult to observe. This hampers the complete clarification of the tabulation, especially in the area of the apex. While by the precingular and the postcingular belt, by the cingulum and by the antapex, the number, the form and the interrelation of the plates are clear (text-fig.5, a--c), by the apical part the scheme given is assumed. The antapical plate is inclined towards the ventral side.
The endophragm is thick, covered with rare, irregular small granules. The periphragm is very thin, smooth, easy deformable.
The cingulum is slightly helicoidal. It is divided into 6 elongated plates, from which 1c is the smallest.
The sulcus is broad and short. In the middle of the sulcus, near to 1""" a flagellar mark is seen, indicated by an elongated pit (text-fig.5,a).
The archaeopyle is apical, the operculum typically remaining attached ventrally (Pl. IV, figs. 9--12). Incomplete accessory sutures appear on the endoblast (textfig. 5, a--c).
Affinities:
Belodinium obsoletum resembles B. dysculum in general form, archaeopyle formation, apical pericoel with ventrally inclined apical horn, antapical pericoel with ventrally inclined antapical plate, fine sutures, and hardly noticeable tabulation. B. dysculum has relatively larger dimensions, smaller apical pericoel, which by B. obsoletum is wing-like broadened, smaller antapical pericoel, periphragm more closely nearing the endophragm and better expressed ornamentation of the endophraom. A comparison of the tabulation is not to be made on account of the unspecified tabulation of B. dysculum. The cingulum by B. obsoletum is located higher in comparison to the location of the cingulum by B. dysculum.
Originally (and now) Belodinium, subsequently Clathroctenocystis.
Stover and Helby, 1987 transferred this species to Clathroctenocystis Wiggins, 1972. Dodekova, 1990, retained it in Belodinium.
Holotype: Dodekova, 1975, pl.4, figs.1-4
Locus typicus: NE Bulgaria
Stratum typicum: Late Bathonian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Dodekova, 1975, p. 24]:
Description:
Bicavate cyst with polyhedral periblast and ellipsoidal endoblast inside. It is divided by a slightly laevo-rotatorv spiral cingulum, located in the anterior half of the body. The apical pericoel is conic with strongly broadened base, dorsally projected. The apex terminates with subpyramidal horn inclined to the ventral side. The antapical pericoel is larger, ventrally projected.
Tabulation formula: ?6", 6"", 6c, 5""", 1p, 1pv, 1"""". The sutures are marked by thin, short membranous septa, very fine and difficult to observe. This hampers the complete clarification of the tabulation, especially in the area of the apex. While by the precingular and the postcingular belt, by the cingulum and by the antapex, the number, the form and the interrelation of the plates are clear (text-fig.5, a--c), by the apical part the scheme given is assumed. The antapical plate is inclined towards the ventral side.
The endophragm is thick, covered with rare, irregular small granules. The periphragm is very thin, smooth, easy deformable.
The cingulum is slightly helicoidal. It is divided into 6 elongated plates, from which 1c is the smallest.
The sulcus is broad and short. In the middle of the sulcus, near to 1""" a flagellar mark is seen, indicated by an elongated pit (text-fig.5,a).
The archaeopyle is apical, the operculum typically remaining attached ventrally (Pl. IV, figs. 9--12). Incomplete accessory sutures appear on the endoblast (textfig. 5, a--c).
Affinities:
Belodinium obsoletum resembles B. dysculum in general form, archaeopyle formation, apical pericoel with ventrally inclined apical horn, antapical pericoel with ventrally inclined antapical plate, fine sutures, and hardly noticeable tabulation. B. dysculum has relatively larger dimensions, smaller apical pericoel, which by B. obsoletum is wing-like broadened, smaller antapical pericoel, periphragm more closely nearing the endophragm and better expressed ornamentation of the endophraom. A comparison of the tabulation is not to be made on account of the unspecified tabulation of B. dysculum. The cingulum by B. obsoletum is located higher in comparison to the location of the cingulum by B. dysculum.