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Dingodinium harsveldtii
Dingodinium harsveldtii Herngreen et al., 1984
Holotype: Herngreen et al., 1984, pl.1, figs.4-5
Age: Middle Callovian-?Portlandian
Diagnosis: subspherical cyst with a short apical horn. Wall two-layered, camocavate, endophragm and periphragm in contact or closely spaced except, most likely, ventrally and in the antapical region where a relatively small pericoel is observed.
The periphragm forms an apical horn, the endophragm is spherical. Endophragm thicker than periphragm, densely spaced flat granulate-verrucate ornamentation, sometimes irregularly rounded triangular. Periphragm very thin, it is easily distorted and torn, psilate/smooth. SEM observation reveals a faint microstructure of the periphragm consisting of granulate and verrucate elements. Paratabulation expressed only by the archaeopyle, rarely an indistinct paracingulum is present. Other linear structures most likely represent folds of the thin periphragm; they do not show a consistent pattern and they are generally indistinct. In SEM observation no plate boundaries could be observed. Archaeopyle apical, type tA, with free operculum. Principal archaeopyle suture zigzag.
Accessory archaeopyle sutures are frequently present, their position denoting the anterior boundaries between six precingular plates. The operculum is composed of one piece only. The apical horn remains in some specimens attached.
Dimensionsholotype Ámrange (Ám) 10 specimens
overall length5142-51 (archaeopyle developed)
overall width3939-54
diameter endophragm3939-54
apical horn length87 (one specimen only)
antapical pericoel33
thickness endophragm
including ornamentation3/4-1+3/4-1¢
thickness periphragm<¢<¢ 3/4 in one specimen
size of ornamentation1 (1¢-2) 33/4 (1-2) 4
Affinities:
Dingodinium harsveldtii differs from other species of this genus by the combination of: absence of any tabulation other than archaeopyle, small apical horn and narrow antapical pericoel, and granulate-verrucate ornamentation only.
The Early Cretaceous D. cerviculum Cookson & Eisenack 1958 has a much wider pericoel, a generally clearly defined cingulum, a well developed higher apical horn and coarser ornamentation of the endophragm.
D. jurassicum Cookson & Eisenack 1958 was recorded from the Late Jurassic of Australia. The original description of this species mentioned numerous small irregularly disposed spines. Moreover, judging from the illustrations, D. jurassicum has a wider periphragm.
"D. jurassicum" was recorded by Raynaud 1978 from the Late Callovian-Portlandian of NW Europe. Raynaud (in litteris October 21st, 1983) confirmed that his specimens are verrucate and have generally a narrow pericoel. His specimens are somewhat larger than our specimens of Klomps.
D. cf. albertii in loannides et al. 1976 has an inner body covered with ornament consisting of grana and conical to tuberculate elements.
Dingodmium sp. A in loannides et al. 1976 is close to D. harsveldtii sp. nov. It has a comparable size range; it differs from D. harsveldtii by the minute tuberculate elements not exceeding 1 Ám in height.
D. cooksoniae Pocock 1972 has much coarser conical processes.
D. tuberosum (Gitmez 1970) Fisher & Riley 1980 was described from the Kimmeridgian. This species has a tabulation and a hole at the top of the apical horn.
D. spinosum (Duxbury 1977) Davey 1979, Late Portlandian-Ryazanian of NW Europe, has sutural crests bearing numerous spines.
The overall shape and the details of the wall structure of this new species are characteristic of Dingodinium Cookson & Eisenack 1958.
Particularly the cavate nature and the ornamentation of the endophragm are diagnostic features. The authors agree with Davey 1979 who regarded Parvocavatus Gitmez as a junior synonym of Dingodinium.
Chlamydophorella Cookson & Eisenack 1958 is holocavate. The ectophragm is approximately equidistant from the autophragm and supported by processes. D. harsveldtii sp. nov. has a superficial resemblance to some representatives of Escharisphaeridla Sarjeant 1980 and Sentusidmium Sarjeant & Stover 1978 in view of the granulate-verrucate sculpture. Both genera are single-layered proxim(ochor)ate and lack an apical horn.
Specimens in which the periphragm is damaged and partly torn off may easily be confused under low magnification (objective less than 63x) with E. pococki (Sarjeant 1968) Sarjeant 1980 or S. verrucosum (Sarjeant 1968) Sarjeant & Stover 1978.
Occurrence. Dmgodmium harsveldtll sp. nov. was mentioned by Herngreen & de Boer 1978: dinoflagelle sp. 5 from the Dogger, jason-lamberti Zones (Middle-Late Callovian) in the SW Netherlands. This species occurs consistently, although in low numbers, in the samples of the boreholes Klomps (Middle Callovian). It was also found in the Upper Kimmeridge Clay (Upper Kimmeridgian sensu anglico, ?Portlandian) of borehole F11-2 (see N.A.M. & R.G.D. 1980). Recently it was found in the Early Kimmeridgian of borehole Sehensand, Bavaria, FRG (Herngreen in press).
D. harsveldtii sp. nov. is the oldest species of Dingodinium described to date from W. Europe. D. tuberosum (Gitmez 1970) Fisher & Riley 1980 is restricted to the Kimmeridgian (sensu anglico), according to Woollam & Riding 1980. "D. jurassicum" was recorded by Raynaud 1978 from the Late Callovian-Portlandian of NW Europe, but unfortunately poorly illustrated.
Poulsen 1996, p. 82
Dingodinium harsveldtii Herngreen et al. 1984, Pl. 16, Fig. 1
Remarks. This species may be better treated as a subspecies of Dingodinium minutum (see discussion under D. minutum and Table 3).
Recorded occurrence. Poland: Kimmeridgian.
Holotype: Herngreen et al., 1984, pl.1, figs.4-5
Age: Middle Callovian-?Portlandian
Diagnosis: subspherical cyst with a short apical horn. Wall two-layered, camocavate, endophragm and periphragm in contact or closely spaced except, most likely, ventrally and in the antapical region where a relatively small pericoel is observed.
The periphragm forms an apical horn, the endophragm is spherical. Endophragm thicker than periphragm, densely spaced flat granulate-verrucate ornamentation, sometimes irregularly rounded triangular. Periphragm very thin, it is easily distorted and torn, psilate/smooth. SEM observation reveals a faint microstructure of the periphragm consisting of granulate and verrucate elements. Paratabulation expressed only by the archaeopyle, rarely an indistinct paracingulum is present. Other linear structures most likely represent folds of the thin periphragm; they do not show a consistent pattern and they are generally indistinct. In SEM observation no plate boundaries could be observed. Archaeopyle apical, type tA, with free operculum. Principal archaeopyle suture zigzag.
Accessory archaeopyle sutures are frequently present, their position denoting the anterior boundaries between six precingular plates. The operculum is composed of one piece only. The apical horn remains in some specimens attached.
Dimensionsholotype Ámrange (Ám) 10 specimens
overall length5142-51 (archaeopyle developed)
overall width3939-54
diameter endophragm3939-54
apical horn length87 (one specimen only)
antapical pericoel33
thickness endophragm
including ornamentation3/4-1+3/4-1¢
thickness periphragm<¢<¢ 3/4 in one specimen
size of ornamentation1 (1¢-2) 33/4 (1-2) 4
Affinities:
Dingodinium harsveldtii differs from other species of this genus by the combination of: absence of any tabulation other than archaeopyle, small apical horn and narrow antapical pericoel, and granulate-verrucate ornamentation only.
The Early Cretaceous D. cerviculum Cookson & Eisenack 1958 has a much wider pericoel, a generally clearly defined cingulum, a well developed higher apical horn and coarser ornamentation of the endophragm.
D. jurassicum Cookson & Eisenack 1958 was recorded from the Late Jurassic of Australia. The original description of this species mentioned numerous small irregularly disposed spines. Moreover, judging from the illustrations, D. jurassicum has a wider periphragm.
"D. jurassicum" was recorded by Raynaud 1978 from the Late Callovian-Portlandian of NW Europe. Raynaud (in litteris October 21st, 1983) confirmed that his specimens are verrucate and have generally a narrow pericoel. His specimens are somewhat larger than our specimens of Klomps.
D. cf. albertii in loannides et al. 1976 has an inner body covered with ornament consisting of grana and conical to tuberculate elements.
Dingodmium sp. A in loannides et al. 1976 is close to D. harsveldtii sp. nov. It has a comparable size range; it differs from D. harsveldtii by the minute tuberculate elements not exceeding 1 Ám in height.
D. cooksoniae Pocock 1972 has much coarser conical processes.
D. tuberosum (Gitmez 1970) Fisher & Riley 1980 was described from the Kimmeridgian. This species has a tabulation and a hole at the top of the apical horn.
D. spinosum (Duxbury 1977) Davey 1979, Late Portlandian-Ryazanian of NW Europe, has sutural crests bearing numerous spines.
The overall shape and the details of the wall structure of this new species are characteristic of Dingodinium Cookson & Eisenack 1958.
Particularly the cavate nature and the ornamentation of the endophragm are diagnostic features. The authors agree with Davey 1979 who regarded Parvocavatus Gitmez as a junior synonym of Dingodinium.
Chlamydophorella Cookson & Eisenack 1958 is holocavate. The ectophragm is approximately equidistant from the autophragm and supported by processes. D. harsveldtii sp. nov. has a superficial resemblance to some representatives of Escharisphaeridla Sarjeant 1980 and Sentusidmium Sarjeant & Stover 1978 in view of the granulate-verrucate sculpture. Both genera are single-layered proxim(ochor)ate and lack an apical horn.
Specimens in which the periphragm is damaged and partly torn off may easily be confused under low magnification (objective less than 63x) with E. pococki (Sarjeant 1968) Sarjeant 1980 or S. verrucosum (Sarjeant 1968) Sarjeant & Stover 1978.
Occurrence. Dmgodmium harsveldtll sp. nov. was mentioned by Herngreen & de Boer 1978: dinoflagelle sp. 5 from the Dogger, jason-lamberti Zones (Middle-Late Callovian) in the SW Netherlands. This species occurs consistently, although in low numbers, in the samples of the boreholes Klomps (Middle Callovian). It was also found in the Upper Kimmeridge Clay (Upper Kimmeridgian sensu anglico, ?Portlandian) of borehole F11-2 (see N.A.M. & R.G.D. 1980). Recently it was found in the Early Kimmeridgian of borehole Sehensand, Bavaria, FRG (Herngreen in press).
D. harsveldtii sp. nov. is the oldest species of Dingodinium described to date from W. Europe. D. tuberosum (Gitmez 1970) Fisher & Riley 1980 is restricted to the Kimmeridgian (sensu anglico), according to Woollam & Riding 1980. "D. jurassicum" was recorded by Raynaud 1978 from the Late Callovian-Portlandian of NW Europe, but unfortunately poorly illustrated.
Poulsen 1996, p. 82
Dingodinium harsveldtii Herngreen et al. 1984, Pl. 16, Fig. 1
Remarks. This species may be better treated as a subspecies of Dingodinium minutum (see discussion under D. minutum and Table 3).
Recorded occurrence. Poland: Kimmeridgian.