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Protobatioladinium elatmaensis
Protobatioladinium elatmaense Riding and Ilyina, 1996, p.150, figs.1a–d.
Holotype: Riding and Ilyina, 1996, fig.1a.
Age: early-middle Bathonian.
Original description (Riding & Ilyina, 1996):
Derivation of name. From the town of Elatma, central Russia, from which region the type material was found [Fig. 2).
Diagnosis. Proximate, acavate, longitudinally elongate dinoflagellate cysts, small to intermediate in size (of Stover & Evitt, 1978). The ambitus is ovoidal with a large apical horn and a smaller antapical horn or protrusion. The horns and protrusions are hollow, evenly distally tapering and have simple, rounded extremities. Normally the antapical horn protrusion is offset ventrally. The cyst is no, significantly dorsoventrally flattened and the equatorial portion of the hypocyst may form a distinctive shoulder in oblique views. The epicyst and hypocyst are similar in height and the presumed paracingular area is normally the broadest part of the cyst. Autophragm thin, smooth to occasionally microgranulate. Archaeopyle combination, type (tA) + (21). The two opercular pieces comprise Kofoidian paraplates 1a plus 2a and the entire apical paraplate series. Both portions of the oparculum are potentially free, however the apical paraplates frequently remain attached or partially attached to the loisthocyst. The archaeopyle is the only indicator of paratabulation; the paracingulum and parasulcus are not indicated.
Holotype. Figure la-specimen MPK 10134. Sample VII 3592. a Lower-Middle Bathonian siltstonc [bed 21), taken from core at 75.50m in Borehole 132, near Elatma in the River Oka Basin, central Russia (Fig. 2). Housed in the palynological collections of the British Geological Survey, Keyworth, Nottingham, UK.
Dimensions. Based on measurements of 30 specimens, the average maximum (entire) cyst height is 69 µm: this parameter varies from 64.0 µm 10 82.1 µm. The maximum cyst width varies from 32.7 µm to 41.4 µm; the average is 36.0 µm. The height and width respectively of the holotype are 79.2 µm and 39.0 µm.
Stratigraphic and geographical distribution. Prorobarioladinium elatmaensis sp. nov. is present, frequently abundantly, in the Lower and Middle Bathonian of the Moscow Syncline, the Voronezh Anticline and the Timan-Pechora Basin, Russia (Ilyina, 1991).
Comparison. Protobatioladinium elatmaensis sp. nov. differs from the genotype, Protobatioladinium weshriensk NØhr-Hansen 1986 in having a shorter and distally tapering apical horn which is not constricted and has a broad base and a single antapical horn/protrusion. Protobatioladinium imbatodinense (Vouhennikova 1967) Lentin & Vozzhennikova 1990 is relatively large, has a densely granulate/verrucate autophragm and two prominent, short antapical lobes. Protobatioladinium lunare Monteil 1992 is relatively large, has short, broad horns, is punctate and has a type (tA) + 21 archaeopyle. The relatively small Protobatioladinium rossicum (losifova 1992) losifova 1996 possesses a small apical horn and two small antapical horns, has typically granulate autophragm and is possibly cornucavate.
Remarks. In the Russian Platform, the Lower and Middle Bathonian dinoflagellate cyst associations are of low species diversity. It is normally associated with rare Ctenidodinium sellwoodii (Sarjeant 1975) Stover & Evitt 1978. However, in the Voronezh Anticline Western Russia, Protobatioladinium elatmaensis sp. nov. is relatively rare and Ctenidodinium sellwoodii dominates the dinoflagellate cyst assemblages (Ilyina. 1991). The common presence of Protobatioladinium elatmaensis sp. nov. in the Lower-Middle Bathonian of Russia and its absence from northwest Europe is typical of the highly provincial marine palynofloras of the Bathonian Stage (Riding el al., 1985). Protobatioladinium elatmaensis sp. nov. is by far the oldest representative of the genus. The other four validly described species are confined to the Upper Jurassic-lowermost Cretaceous interval (Kimmeridgian, Volgian/Tithonian and Ryazanian).
Holotype: Riding and Ilyina, 1996, fig.1a.
Age: early-middle Bathonian.
Original description (Riding & Ilyina, 1996):
Derivation of name. From the town of Elatma, central Russia, from which region the type material was found [Fig. 2).
Diagnosis. Proximate, acavate, longitudinally elongate dinoflagellate cysts, small to intermediate in size (of Stover & Evitt, 1978). The ambitus is ovoidal with a large apical horn and a smaller antapical horn or protrusion. The horns and protrusions are hollow, evenly distally tapering and have simple, rounded extremities. Normally the antapical horn protrusion is offset ventrally. The cyst is no, significantly dorsoventrally flattened and the equatorial portion of the hypocyst may form a distinctive shoulder in oblique views. The epicyst and hypocyst are similar in height and the presumed paracingular area is normally the broadest part of the cyst. Autophragm thin, smooth to occasionally microgranulate. Archaeopyle combination, type (tA) + (21). The two opercular pieces comprise Kofoidian paraplates 1a plus 2a and the entire apical paraplate series. Both portions of the oparculum are potentially free, however the apical paraplates frequently remain attached or partially attached to the loisthocyst. The archaeopyle is the only indicator of paratabulation; the paracingulum and parasulcus are not indicated.
Holotype. Figure la-specimen MPK 10134. Sample VII 3592. a Lower-Middle Bathonian siltstonc [bed 21), taken from core at 75.50m in Borehole 132, near Elatma in the River Oka Basin, central Russia (Fig. 2). Housed in the palynological collections of the British Geological Survey, Keyworth, Nottingham, UK.
Dimensions. Based on measurements of 30 specimens, the average maximum (entire) cyst height is 69 µm: this parameter varies from 64.0 µm 10 82.1 µm. The maximum cyst width varies from 32.7 µm to 41.4 µm; the average is 36.0 µm. The height and width respectively of the holotype are 79.2 µm and 39.0 µm.
Stratigraphic and geographical distribution. Prorobarioladinium elatmaensis sp. nov. is present, frequently abundantly, in the Lower and Middle Bathonian of the Moscow Syncline, the Voronezh Anticline and the Timan-Pechora Basin, Russia (Ilyina, 1991).
Comparison. Protobatioladinium elatmaensis sp. nov. differs from the genotype, Protobatioladinium weshriensk NØhr-Hansen 1986 in having a shorter and distally tapering apical horn which is not constricted and has a broad base and a single antapical horn/protrusion. Protobatioladinium imbatodinense (Vouhennikova 1967) Lentin & Vozzhennikova 1990 is relatively large, has a densely granulate/verrucate autophragm and two prominent, short antapical lobes. Protobatioladinium lunare Monteil 1992 is relatively large, has short, broad horns, is punctate and has a type (tA) + 21 archaeopyle. The relatively small Protobatioladinium rossicum (losifova 1992) losifova 1996 possesses a small apical horn and two small antapical horns, has typically granulate autophragm and is possibly cornucavate.
Remarks. In the Russian Platform, the Lower and Middle Bathonian dinoflagellate cyst associations are of low species diversity. It is normally associated with rare Ctenidodinium sellwoodii (Sarjeant 1975) Stover & Evitt 1978. However, in the Voronezh Anticline Western Russia, Protobatioladinium elatmaensis sp. nov. is relatively rare and Ctenidodinium sellwoodii dominates the dinoflagellate cyst assemblages (Ilyina. 1991). The common presence of Protobatioladinium elatmaensis sp. nov. in the Lower-Middle Bathonian of Russia and its absence from northwest Europe is typical of the highly provincial marine palynofloras of the Bathonian Stage (Riding el al., 1985). Protobatioladinium elatmaensis sp. nov. is by far the oldest representative of the genus. The other four validly described species are confined to the Upper Jurassic-lowermost Cretaceous interval (Kimmeridgian, Volgian/Tithonian and Ryazanian).