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Protobatioladinium elongatum
Protobatioladinium elongatum Riding and Ilyina, 1998, p.86, figs.1a–d.
Holotype: Riding and Ilyina, 1998, fig.1a.
Age: late Bathonian.
Original description (Riding & Ilyina, 1998):
Derivation of name. From the longitudinally elongate nature of this species.
Diagnosis. Proximate, acavate, slender, markedly longitudinally elongate dinoflagellate cysts, questionably attributed to Protobatioladinium and intermediate to large in size (of Stover & Evitt, 1978). The ambitus is elongate ovoidal with a large, prominent, elongate apical horn (up to 41.4 µm in length) and normally a smaller antapical horn . The horns are hollow and evenly distally tapering. The apical horn has a sharply pointed, simple distal extremity; the distal portion of the antapical horn is either sharply pointed or rounded. The antapical horn is consistently offset toward the ventral side of the cyst. The species is not significantly dorso-ventrally flattened and the dorsal portion of the hypocyst may form a distinctive protrusion or bulge in lateral or oblique lateral views. The epicyst is normally longer than the hypocyst, assuming that the broadest part of the cyst is the paracingular area. The epicyst and hypocyst may be of similar lengths in certain specimens however. Autophragm thin and smooth. Archaeopyle anterior intercalary, apparently type (21). The apparently single opercular piece comprises Kofoidian paraplates la and 2a and is free. No archaeopyle sutures have been observed within the apical paraplate series. The archaeopylc is the only manifestation of paratabulation, as the paracingulum and parasulcus are not indicated.
Holotype. Figure la, specimen MPK 10143. Sample VII 3953, an Upper Bathonian muds tone (bed 18), taken from core at 74.00m in Borehole 132, near Elatma in the River Oka Basin , Moscow Syncline, central Russia (Riding & llyina, 1996, fig. 2). Housed in the palynological collections of the British Geological Survey, Keyworth, Notlingham, UK.
Dimensions (µm).
Overall length or cyst 87.1(103.4)120.7
Overall maximum width of cyst 24.1(29.3)34.5
34 specimens measured
The length and maximum width of the holotype are 102.1 µm and 31.6 μm respectively.
Stratigraphical and geographical distribution. Protobatioladinium? elongatum sp. nov. is present, frequently abundantly, in the Upper Bathonian strata of the Moscow Syncline and the the Ryazan- Saratov Trough of the central Russian Platform and in the Upper Bathonian sediments of the Timan- Pechora Basin, northern Russia (llyina , 199 1). The species has been observed to atta in 75% of the dinoflagellate cyst association; the average figure, however, is 31.6% .
Comparison. Protobatioladinium? elongate sp. nov. is similar in overall morphology and geographical/stratigraphical distribution to the morphologically similar Protobatioladinium elatmaensis Riding & llyina, 1996. The length and width of Protobatioladinium elatmaensis are, however, significantly lesser and greater, respectively, than these parameters in Protobatioladinium elongatum sp. nov. Furthermore, the archaeopyle of Protobatioladinium elatmaensis is combination, type (tA) +(21). Riding & llyina (1996) gave comparisons of Protobatioladinium elatmaensis and the remaining four Upper Jurassic- lowermost Cretaceous species in this genus. These comparisons are also applicable to Protobatioladinium? elongatum.
Remarks. The new dinoflagellate cyst species elongatum described herein is questionably attributed to the genus Protobatioladinium as the archaeopyle is apparently of anterior intercalary style, type (2 1). Protobatioladinium has a compound combination archaeopyle, type (tA) + 21 (N 0 hr-Hansen, 1986; Riding & llyina , 1996). However, the co-occurrence with Protobatioladinium elatmaensis means that elongatum almost certainly belongs in Protobatioladinium. Furthermore, P. elatmaensis often appears to have an anterior intercalary, type (2 1), achaeopyle (Riding & llyina, 1996, figs la, c). Protobatioladinium elongatum sp. nov. has never been previously figured. However, the species was erroneously referred to Kalyptea diceras Cookson & Eisenack, 1960 by llyina (1991), who erected the Upper Bathonian Kalvptea diceras dinoflagellate cyst zone. The species Protobatioladinium elongatum and P. elatmaensis are the oldest representatives of this genus; the four other species are confined to Upper Jurassic lowermost Cretaceous sediments. The endemism of this species is entirely consistent with the markedly provincial nature of Bathonian dinoflagellate cyst associations. Bathonian dinoflagellate cyst associations of the Russian Platform are of relatively low species diversity. In Lower and Middle Bathonian sediments, the assemblages are dominated by Ctenidodinium sellwoodii (Sarjeant, 1975) Stover & Evill, 1978 or Protobatiolaidinium elatmaensis (see Riding & llyina , 1996). P. elongatum is confined to the Upper Bathonian strata of the Moscow Syncline, the Ryazan- Saratov Trough (central western Russia) and the Upper Bathonian sediments of the Timan- Pechora Basin (northern Russia). Associated Upper Bathonian dinoflagellate cysts in Borehole 132 near Elatrna in the Moscow Syncline (mudstones with interbedded silt stones between 74.00 m a nd 62.80 m) compri se Batiacasphaera spp., Dissiliodinium sp., Mendicodinium groenlandicum (Pocock & Sarjeant, [ 972) Davey, 1979, Pareodinia ceratophora Defl andre, 1947 and Protobatioladinium elatmaensis. Similar associations were recovered from Upper Bathonian mudstones of the nearby Borehole 12 1, Lasicyi (Riding & llyina, 1996, fig. 2). In the Upper Balhonian mudstones
(Cadoceras variabile Zone) of the River Pizhma area, Timan- Pechora region, northern Russian Platform, Protobatioladinium? elongatum sp. nov. occurs together with slightly more diverse dinoflagellate cyst associations. These assemblages comprise Batiacasphaera spp., Chitroeisphaeridia hyalina (Raynaud, 1978) Lentin & Williams. 198 1, Dissiliodinum spp. , Fromea tornatilis (Drugg, 1978) Lentin & Williams, 1981, ?Korystocysta sp., Lithodinia spp. , Nannoceratopsis pellucida Defland re, 1938, Pareodinia ceratophora, Protobatioladinium elatmaensis, ?Sirmiodinium grossii Alberti, 1961 , Tubotuberella dangeardii (Sarj eant, 1968) Stover & Evitt , 1978 and Wanaea acollaris Dodekova, 1975. The Boreal latest Bathonian Cadoceras variabile (ammonite) Zone is approximately the correlative of the European latest Bathonian Clydoniceras discus Zone. References for the author citations or the dinoflagellate species mentioned herein may be found in Lentin & Williams (1993).
Holotype: Riding and Ilyina, 1998, fig.1a.
Age: late Bathonian.
Original description (Riding & Ilyina, 1998):
Derivation of name. From the longitudinally elongate nature of this species.
Diagnosis. Proximate, acavate, slender, markedly longitudinally elongate dinoflagellate cysts, questionably attributed to Protobatioladinium and intermediate to large in size (of Stover & Evitt, 1978). The ambitus is elongate ovoidal with a large, prominent, elongate apical horn (up to 41.4 µm in length) and normally a smaller antapical horn . The horns are hollow and evenly distally tapering. The apical horn has a sharply pointed, simple distal extremity; the distal portion of the antapical horn is either sharply pointed or rounded. The antapical horn is consistently offset toward the ventral side of the cyst. The species is not significantly dorso-ventrally flattened and the dorsal portion of the hypocyst may form a distinctive protrusion or bulge in lateral or oblique lateral views. The epicyst is normally longer than the hypocyst, assuming that the broadest part of the cyst is the paracingular area. The epicyst and hypocyst may be of similar lengths in certain specimens however. Autophragm thin and smooth. Archaeopyle anterior intercalary, apparently type (21). The apparently single opercular piece comprises Kofoidian paraplates la and 2a and is free. No archaeopyle sutures have been observed within the apical paraplate series. The archaeopylc is the only manifestation of paratabulation, as the paracingulum and parasulcus are not indicated.
Holotype. Figure la, specimen MPK 10143. Sample VII 3953, an Upper Bathonian muds tone (bed 18), taken from core at 74.00m in Borehole 132, near Elatma in the River Oka Basin , Moscow Syncline, central Russia (Riding & llyina, 1996, fig. 2). Housed in the palynological collections of the British Geological Survey, Keyworth, Notlingham, UK.
Dimensions (µm).
Overall length or cyst 87.1(103.4)120.7
Overall maximum width of cyst 24.1(29.3)34.5
34 specimens measured
The length and maximum width of the holotype are 102.1 µm and 31.6 μm respectively.
Stratigraphical and geographical distribution. Protobatioladinium? elongatum sp. nov. is present, frequently abundantly, in the Upper Bathonian strata of the Moscow Syncline and the the Ryazan- Saratov Trough of the central Russian Platform and in the Upper Bathonian sediments of the Timan- Pechora Basin, northern Russia (llyina , 199 1). The species has been observed to atta in 75% of the dinoflagellate cyst association; the average figure, however, is 31.6% .
Comparison. Protobatioladinium? elongate sp. nov. is similar in overall morphology and geographical/stratigraphical distribution to the morphologically similar Protobatioladinium elatmaensis Riding & llyina, 1996. The length and width of Protobatioladinium elatmaensis are, however, significantly lesser and greater, respectively, than these parameters in Protobatioladinium elongatum sp. nov. Furthermore, the archaeopyle of Protobatioladinium elatmaensis is combination, type (tA) +(21). Riding & llyina (1996) gave comparisons of Protobatioladinium elatmaensis and the remaining four Upper Jurassic- lowermost Cretaceous species in this genus. These comparisons are also applicable to Protobatioladinium? elongatum.
Remarks. The new dinoflagellate cyst species elongatum described herein is questionably attributed to the genus Protobatioladinium as the archaeopyle is apparently of anterior intercalary style, type (2 1). Protobatioladinium has a compound combination archaeopyle, type (tA) + 21 (N 0 hr-Hansen, 1986; Riding & llyina , 1996). However, the co-occurrence with Protobatioladinium elatmaensis means that elongatum almost certainly belongs in Protobatioladinium. Furthermore, P. elatmaensis often appears to have an anterior intercalary, type (2 1), achaeopyle (Riding & llyina, 1996, figs la, c). Protobatioladinium elongatum sp. nov. has never been previously figured. However, the species was erroneously referred to Kalyptea diceras Cookson & Eisenack, 1960 by llyina (1991), who erected the Upper Bathonian Kalvptea diceras dinoflagellate cyst zone. The species Protobatioladinium elongatum and P. elatmaensis are the oldest representatives of this genus; the four other species are confined to Upper Jurassic lowermost Cretaceous sediments. The endemism of this species is entirely consistent with the markedly provincial nature of Bathonian dinoflagellate cyst associations. Bathonian dinoflagellate cyst associations of the Russian Platform are of relatively low species diversity. In Lower and Middle Bathonian sediments, the assemblages are dominated by Ctenidodinium sellwoodii (Sarjeant, 1975) Stover & Evill, 1978 or Protobatiolaidinium elatmaensis (see Riding & llyina , 1996). P. elongatum is confined to the Upper Bathonian strata of the Moscow Syncline, the Ryazan- Saratov Trough (central western Russia) and the Upper Bathonian sediments of the Timan- Pechora Basin (northern Russia). Associated Upper Bathonian dinoflagellate cysts in Borehole 132 near Elatrna in the Moscow Syncline (mudstones with interbedded silt stones between 74.00 m a nd 62.80 m) compri se Batiacasphaera spp., Dissiliodinium sp., Mendicodinium groenlandicum (Pocock & Sarjeant, [ 972) Davey, 1979, Pareodinia ceratophora Defl andre, 1947 and Protobatioladinium elatmaensis. Similar associations were recovered from Upper Bathonian mudstones of the nearby Borehole 12 1, Lasicyi (Riding & llyina, 1996, fig. 2). In the Upper Balhonian mudstones
(Cadoceras variabile Zone) of the River Pizhma area, Timan- Pechora region, northern Russian Platform, Protobatioladinium? elongatum sp. nov. occurs together with slightly more diverse dinoflagellate cyst associations. These assemblages comprise Batiacasphaera spp., Chitroeisphaeridia hyalina (Raynaud, 1978) Lentin & Williams. 198 1, Dissiliodinum spp. , Fromea tornatilis (Drugg, 1978) Lentin & Williams, 1981, ?Korystocysta sp., Lithodinia spp. , Nannoceratopsis pellucida Defland re, 1938, Pareodinia ceratophora, Protobatioladinium elatmaensis, ?Sirmiodinium grossii Alberti, 1961 , Tubotuberella dangeardii (Sarj eant, 1968) Stover & Evitt , 1978 and Wanaea acollaris Dodekova, 1975. The Boreal latest Bathonian Cadoceras variabile (ammonite) Zone is approximately the correlative of the European latest Bathonian Clydoniceras discus Zone. References for the author citations or the dinoflagellate species mentioned herein may be found in Lentin & Williams (1993).