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Dichadogonyaulax brennerii
Dichadogonyaulax brennerii Poulsen 1996
Mendicodinium? sp. B, Brenner, 1988, p. 65, pl. 13, figs. 2a-b, 4.
Holotype: Poulsen 1996, pl. 14, figs. 1; DGU catalogue no.: 1991-NEP-13; from Trojanow borehole at 50.3 m, (Poland), Leczno Beds (lower part), Kimmeridgian.
Poulsen 1996, p. 66
Dichadogonyaulax brenneri sp. nov.
Diagnosis. Proximate, spherical cyst, which may be slightly compressed in the apical-antapical direction. Autophragm with low, external reticulate sculpture. Paratabulation, when discernible, vaguely indicated by low ridges, which may be obscured by the reticulum, gonyaulacoid. Epicystal archeopyle, operculum attached ventrally. Epicyst and hypocyst of equal size and shape.
Description. The body is spherical or with slightly flattened poles, with no indications of horns or protrusions. Paratabulation generally is not indicated or is vaguely reflected as low ridges on a uniformly reticulate surface, the reticulum is closely appressed to autophragm. There are no paracingular or parasulcal depressions. The archeopyle is epicystal, type (tAtP)a; the epicyst and the hypocyst are connected on the ventral side, the opening never being complete. The archeopyle divides the cyst into two almost equal halves. The size is intermediate.
Dimensions. German specimens, length 55-70 Ám, width 70-85 Ám (Brenner, 1988); Polish specimens, length 58-65 Ám, width 63-71 Ám. 26 specimens measured. Dimensions of holotype: length 60 Ám, width 69 Ám.
Comparison. Dichadogonyaulax? brenneri differs from Mendicodinium reticulatum Morgenroth 1970 in having a more coarse-meshed reticulum and a vague indication of tabulation. It differs from Mendicodinium microreticulatum Kumar 1986 in having the reticulum on the exterior of the autophragm. Dichadogonyaulax? brenneri most closely resembles Dichadogonyaulax chondra (Drugg 1978) Courtinat 1989 which, however, has a much less distinct reticulum.
Age: Germany, Oxfordian to Early Kimmeridgian; Poland, Early Kimmeridgian; Denmark, earliest Volgian.
Recorded occurrences. Poland: Szadkowice borehole (98-116 m) (Divisum-Mutabilis Zones), and Trojanow 83 borehole (50-81 m) (Hypselocyclum-Divisum Zones). Denmark: Sound- 1 A borehole (49.35 m) Glossodinium dimorphum Zone, Subzone a.
Remarks. Brenner (1988) considered this species to be related to Ctenidodinium. This form most closely resembles D. chondra, but since an exact dichadogonyalacoid tabulation has not been established, it is only provisionally referred to Dichadogonyaulax. Here it is proposed as a separate species, but it may prove to be a subspecies of D. chondra.
Mendicodinium? sp. B, Brenner, 1988, p. 65, pl. 13, figs. 2a-b, 4.
Holotype: Poulsen 1996, pl. 14, figs. 1; DGU catalogue no.: 1991-NEP-13; from Trojanow borehole at 50.3 m, (Poland), Leczno Beds (lower part), Kimmeridgian.
Poulsen 1996, p. 66
Dichadogonyaulax brenneri sp. nov.
Diagnosis. Proximate, spherical cyst, which may be slightly compressed in the apical-antapical direction. Autophragm with low, external reticulate sculpture. Paratabulation, when discernible, vaguely indicated by low ridges, which may be obscured by the reticulum, gonyaulacoid. Epicystal archeopyle, operculum attached ventrally. Epicyst and hypocyst of equal size and shape.
Description. The body is spherical or with slightly flattened poles, with no indications of horns or protrusions. Paratabulation generally is not indicated or is vaguely reflected as low ridges on a uniformly reticulate surface, the reticulum is closely appressed to autophragm. There are no paracingular or parasulcal depressions. The archeopyle is epicystal, type (tAtP)a; the epicyst and the hypocyst are connected on the ventral side, the opening never being complete. The archeopyle divides the cyst into two almost equal halves. The size is intermediate.
Dimensions. German specimens, length 55-70 Ám, width 70-85 Ám (Brenner, 1988); Polish specimens, length 58-65 Ám, width 63-71 Ám. 26 specimens measured. Dimensions of holotype: length 60 Ám, width 69 Ám.
Comparison. Dichadogonyaulax? brenneri differs from Mendicodinium reticulatum Morgenroth 1970 in having a more coarse-meshed reticulum and a vague indication of tabulation. It differs from Mendicodinium microreticulatum Kumar 1986 in having the reticulum on the exterior of the autophragm. Dichadogonyaulax? brenneri most closely resembles Dichadogonyaulax chondra (Drugg 1978) Courtinat 1989 which, however, has a much less distinct reticulum.
Age: Germany, Oxfordian to Early Kimmeridgian; Poland, Early Kimmeridgian; Denmark, earliest Volgian.
Recorded occurrences. Poland: Szadkowice borehole (98-116 m) (Divisum-Mutabilis Zones), and Trojanow 83 borehole (50-81 m) (Hypselocyclum-Divisum Zones). Denmark: Sound- 1 A borehole (49.35 m) Glossodinium dimorphum Zone, Subzone a.
Remarks. Brenner (1988) considered this species to be related to Ctenidodinium. This form most closely resembles D. chondra, but since an exact dichadogonyalacoid tabulation has not been established, it is only provisionally referred to Dichadogonyaulax. Here it is proposed as a separate species, but it may prove to be a subspecies of D. chondra.