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Batioladinium paeminosum
Batioladinium paeminosum, Riding and Helby, 2001g, p.187,189, figs.4A-P.
Holotype: Riding and Helby, 2001g, figs.4N-P.
Stratigraphical distribution: B. paeminosum is confined to the Tithonian Pseudoceratium iehiense Zone (subzones 4ciiib to 4cib) (Foster, this volume; Helby & Partridge, in prep).
Age: Tithonian.
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Original description: [Riding and Helby, 2001g]:
Description:
An intermediate to large species of Batioladinium which is slightly dorsoventrally flattened with a thick, robust autophragm is about 2 µm thick and is covered with dense, nontabular rugulate to verrucate ornamentation. The rugulae comprise relatively short, undulose ridges, mostly 2 to 3 µm wide, which may break up into irregular nature of the verrucae. The high density and irregular nature of the verrucae, particularly on the hypocyst, may give rise to a "scrollwork" pattern of ornamentation. The ornamentation varies in height from about 0.5 to 1 µm and becomes markedly more prominent towards the antapical area. The paracingulum is slightly indented, has reduced ornamentation and may bear low, discontinuous, parasutural ridges and reduced ornamentation. The epicyst is longer than the hypocyst. The anterior part of the parasulcus lies in the area between the offset ends of the paracingulum and below the ventral notch (6"/1') of the principal archeopyle suture. The single apical and paired antapical horns are variable in length, typically have solid distal portions and are rounded to pointed distally. The left antapical horn is larger than the right and both anatapical horns may be markedly reduced.
Dimensions:
(µm, n=30): Min. (Mean) Max.
Length of entire cyst incl. horns: 82 (109) 146
Length of loisthocyst incl. horns: 55 (72) 93
Length of operculum: 44 (66) 81
Maximum width: 25 (33) 45
Length of apical horn: 10 (30) 55
Length of the left antapical horn: 4 (11) 22
The measured specimens are from conventional core samples in Lambert-2 well at 3101.00m, Lorikeet-1 well at 1761.20 m and 1759.10 m, Mutineer-1B well at 3132.25m, Wanaea-2 well at 2880.50m and 2875.30m and sidewall cores from Avocet-1A well at 1780.00 m, 1778.00m, 1777.00m and 1771.50m, Scafell-1 well at 1418.00m and Zeewulf-1 well at 3085.00m.
Remarks/Comments:
Batioladinium paeminosum is characterised by the prominent rugulate-verrucate autophragm, especially on the hypocyst, the size of ornament elements diminishing towards the apex (Fig. 4). The ornamentation may be slightly irregular, variable in height and/or reduced in some specimens (Fig. 4). Many forms have relatively short antapical horns and the length of the apical horn is extremely variable (see above). In most specimens, the horns are distally rounded and in some individuals the outline of the antapical horns is disrupted by the ornamentation. Individuals with highly reduced antapical horns and in which the archaeopyle has not opened could be misidentified as Pareodinia resembling B. paeminosum occur throughout the stratigraphical range of the latter. Rarely, morphotypes similar to Batioladinium paeminosum, but with a microreticulate autophragm have been observed.
Affinities/Comparison:
Necrobroomea sp. of Below (1990, pl.13, fig. 20), from the Volgian of the Russian Platform, closely resembles Batioladinium paeminosum, and is indistinguishable form some end members of the species. The ornamentation of the specimens of Necrobroomea micropoda (Eisenack & Cookson 1960) Wiggins 1975 emend. Below 1990, as figured by Below (1990, pl. 13, figs 17-19) closely resembles that of B. paeminosum. Batioladinium paeminosum differs from the other species of the genus by the rugulate/verrucate ornamentation which diminishes in size apically. The majority of species of this genus, including the genotype Batioladinium jaegeri (Alberti 1961) Brideaux 1975, are psilate or have extremely low relief ornamentation (Alberti, 1961). Batioladinium daviesii Lentin & Vozzhennikova 1990, B. matyjae Poulsen 1996 and B. micropodum, however, have a granulate autophragm. The early Cretaceous species Batioladinium? gochtii (Alberti 1961) Lentin & Williams 1977 has a tuberculate autophragm, is pareodinioid in outline, has only a single antapical horn and is normally more squat than B. paeminosum. Batioladinium? pelliferum (Alberti 1961) Brideaux 1975 is also relatively squat and has an autophragm which is densely covered in short, slender spines and ornament that Alberti (1961) referred to as 'fur-like'. The lower Neocomian soecies, B. reticulatum Stover & Helby 1987, is holocavate and has a reticulate ectophragm (Stover & Helby, 1987).
Holotype: Riding and Helby, 2001g, figs.4N-P.
Stratigraphical distribution: B. paeminosum is confined to the Tithonian Pseudoceratium iehiense Zone (subzones 4ciiib to 4cib) (Foster, this volume; Helby & Partridge, in prep).
Age: Tithonian.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Riding and Helby, 2001g]:
Description:
An intermediate to large species of Batioladinium which is slightly dorsoventrally flattened with a thick, robust autophragm is about 2 µm thick and is covered with dense, nontabular rugulate to verrucate ornamentation. The rugulae comprise relatively short, undulose ridges, mostly 2 to 3 µm wide, which may break up into irregular nature of the verrucae. The high density and irregular nature of the verrucae, particularly on the hypocyst, may give rise to a "scrollwork" pattern of ornamentation. The ornamentation varies in height from about 0.5 to 1 µm and becomes markedly more prominent towards the antapical area. The paracingulum is slightly indented, has reduced ornamentation and may bear low, discontinuous, parasutural ridges and reduced ornamentation. The epicyst is longer than the hypocyst. The anterior part of the parasulcus lies in the area between the offset ends of the paracingulum and below the ventral notch (6"/1') of the principal archeopyle suture. The single apical and paired antapical horns are variable in length, typically have solid distal portions and are rounded to pointed distally. The left antapical horn is larger than the right and both anatapical horns may be markedly reduced.
Dimensions:
(µm, n=30): Min. (Mean) Max.
Length of entire cyst incl. horns: 82 (109) 146
Length of loisthocyst incl. horns: 55 (72) 93
Length of operculum: 44 (66) 81
Maximum width: 25 (33) 45
Length of apical horn: 10 (30) 55
Length of the left antapical horn: 4 (11) 22
The measured specimens are from conventional core samples in Lambert-2 well at 3101.00m, Lorikeet-1 well at 1761.20 m and 1759.10 m, Mutineer-1B well at 3132.25m, Wanaea-2 well at 2880.50m and 2875.30m and sidewall cores from Avocet-1A well at 1780.00 m, 1778.00m, 1777.00m and 1771.50m, Scafell-1 well at 1418.00m and Zeewulf-1 well at 3085.00m.
Remarks/Comments:
Batioladinium paeminosum is characterised by the prominent rugulate-verrucate autophragm, especially on the hypocyst, the size of ornament elements diminishing towards the apex (Fig. 4). The ornamentation may be slightly irregular, variable in height and/or reduced in some specimens (Fig. 4). Many forms have relatively short antapical horns and the length of the apical horn is extremely variable (see above). In most specimens, the horns are distally rounded and in some individuals the outline of the antapical horns is disrupted by the ornamentation. Individuals with highly reduced antapical horns and in which the archaeopyle has not opened could be misidentified as Pareodinia resembling B. paeminosum occur throughout the stratigraphical range of the latter. Rarely, morphotypes similar to Batioladinium paeminosum, but with a microreticulate autophragm have been observed.
Affinities/Comparison:
Necrobroomea sp. of Below (1990, pl.13, fig. 20), from the Volgian of the Russian Platform, closely resembles Batioladinium paeminosum, and is indistinguishable form some end members of the species. The ornamentation of the specimens of Necrobroomea micropoda (Eisenack & Cookson 1960) Wiggins 1975 emend. Below 1990, as figured by Below (1990, pl. 13, figs 17-19) closely resembles that of B. paeminosum. Batioladinium paeminosum differs from the other species of the genus by the rugulate/verrucate ornamentation which diminishes in size apically. The majority of species of this genus, including the genotype Batioladinium jaegeri (Alberti 1961) Brideaux 1975, are psilate or have extremely low relief ornamentation (Alberti, 1961). Batioladinium daviesii Lentin & Vozzhennikova 1990, B. matyjae Poulsen 1996 and B. micropodum, however, have a granulate autophragm. The early Cretaceous species Batioladinium? gochtii (Alberti 1961) Lentin & Williams 1977 has a tuberculate autophragm, is pareodinioid in outline, has only a single antapical horn and is normally more squat than B. paeminosum. Batioladinium? pelliferum (Alberti 1961) Brideaux 1975 is also relatively squat and has an autophragm which is densely covered in short, slender spines and ornament that Alberti (1961) referred to as 'fur-like'. The lower Neocomian soecies, B. reticulatum Stover & Helby 1987, is holocavate and has a reticulate ectophragm (Stover & Helby, 1987).