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Apteodinium corticatum
From Fensome et al., 2019:
Apteodinium corticatum (Norris and Jux, 1984, p.162–163, pl.2, figs.5–16; pl.3, figs.6–7; pl.6, figs.1–5) Lucas-Clark, 1987,
p.176. Holotype: Norris and Jux, 1984, pl.2, figs.7–8. Originally Aldorfia, subsequently (and now) Apteodinium.
Age: late Kimmeridgian–Portlandian.
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Original description: [Norris and Jux, 1984]:
Aldorfia corticata sp. nov
PI. 2, figs. 5-16; Pl. 3, figs. 6-7; Pl. 6, figs. 1-5
Holotype: Slide No. 1451-4 G+40; 53.9 x 101.4, Palynology collection, University of Toronto, PI. 2, figs. 7-8.
Diagnosis: An ovidal to polygonal cyst with an apical horn, feeble cingulum, indented sulcus, gonyaulacacean tabulation, and distinctively spongey wall. Precingular archeopyle large, trapezoidal. Periphragm and pericoel rather expanded and cavernous, consisting of felty fibrils without major projections other than granules but with slightly raised, more solid sutural ornament. Endophragm composed of relatively thin porous layer.
Name: corticatum (Latin) provided with a barky outside.
Dimensions: (equatorial diameter): 30-58 μm; length (including horn) 50-90 μm.
Distribution: Upper Kimmeridgian and Portlandian, Dorset and Sussex, Southern England (Norris, 1963).
Description: Light microscopy (Pl. 2, figs. 5-16): The subspherical to polygonal proximate cyst has an apical horn 10-20 um long, a weakly developed cingulum (width 4-6 μm), an indented sulcus (6-10 μm wide), and faint sutural ornament.
No prominent projections arise from the periphragm. The sculpture is coarsely granular (Ø 0.2-0.5 μm) to vermiculate (width ca. 0.5 μm; length 2-3 μm) except on the sulcus which is almost smooth. There are, however, wart-like tubercles, 1-2 μm apart from each other, which project slightly above the microgranular surface. The pattern of the sculpture is rather irregular tending towards a subreticulate arrangement. Sutural ornament is in the form of raised crests (or occasionally pandasutural sub-parallel raised crests) doubling or trebling the intratabular cyst wall thickness. Some cysts show intra-tabular rectilinear features, probably reflecting growth features. These are not not consistantly present. The apical horn is solid above the outbulging endophragm, usually bluntly terminated, and may be ornamented by one or two crest-like "shoulders" at the base or near the top. The posterior archeopyle margin encroaches on the anterior edge of the mid-dorsal cingulum. The hypocystal wall is up to twice as thick as the epicystal wall, leading to the development of a fold in the equatorial region close to but not necessarily coincident with the cingulum.
Scanning electron microscopy (PI. 3, figs. 6-7): Interwoven fibrils comprise a bark-like covering to the outside of the cyst. Cingulum and sulcus are less sculptured than other parts of the outside, but, the latter is bordered by a ridge of interconnected either vermiculate or granulate elements (Pl. 3, fig. 7b). Wherever the phragma is torn open, or when the trapezoidal operculum (Ø ca. 30 μm) is missing the smooth inner surface of the thick double layered cavernous phragma (thickness 1.4-1.8 μm) can be seen (PI. 3, fig. 7 a), with a spongy pericoel
separating endophragm from sculptured periphragm.
Transmission electron microscopy (Pl. 6, figs. 1-5): Sections through several cysts provide information about the structure and the arrangement of the sculpturing elements of the wall. Inner and outer layers are well defined. A thin endophragm (thickness 0.1-0.2 um) surrounds the endocoel (PI. 6, figs 1, 2). Its inner surface is smooth but minutely perforated (Pl. 6, fig. 3). The pores connect with tiny cavities (Ø ca. 0.05 μm) within the endophragm. They are arranged in a peripheral zone, ca. 0.1 μm apart from each other (Pl. 6, fig. 3 d). There is no sharp contact between the two layers, because the trabecular framework of the periphragm emerges from protruding zones of the endophragm (Pl. 6, figs. 3 G, 4g). Fibres and septa are interwoven to a meshy, relatively thick (0.7-1.5 μm) layer, including irregularly shaped and partly interconnected cavities (Ø 0.5-2.0 μm), forming a spongy pericoel.
The cingulum and sulcus have a different wall structure, with the periphragm condensed to a relatively solid and much less spongy sheet, considerably thinner and almost fusing with the endophragm (Pl. 6, fig. 2, 3 d). Somewhat larger wall chambers are arranged along the margins connected by endophragmatic pores with the endocoel and topped by wart-like projections (PI. 6, figs. 3 b, 5).
The outer part of the periphragm is strengthened by scaly elements, corresponding with similar structures of the endophragm (Pl. 6, fig. 3 d). Fibrous extensions may also converge to warty or vermiculate tips from the expanded cavernous outer wall. In the sections these appear either as stout spongy cones (P1. 6, fig. 3 c) of 1-2 μm length, or as rather solid rod-like spines (Pl. 6, fig. 4 a) of 1.0-1.5 μm length and ca. 0.5 μm diameter.
Comparison: Aldorfia spongiosa (McINTYRE & BRIDAUX) DAVEY 1982 differs from Aldorfia corticata sp. nov. by its larger size, lack of tabular features, and the coarser, rugulate "scrollwork" elements in the pericoel and periphragm compared with the reticulate aspect in ligth microscopy of the phragma of A. corticata.
The wall structure compares well with Apteodinium spirioides BENEDEK. There is almost no difference between the endophragm of this Tertiary species and Aldorfia corticata sp. nov, but the periphragms - though basically alike - exhibit some distinct differences. A. spirioides has only a few but relatively large interwall chambers, functionally replacing a pericoel. Furthermore, the Tertiary cyst does not have either warty or spiny projections. BENEDEK (1972) has figured rather similar TEM-sections from Leiosphaeridia sp. cf. L. deflandrei MÄDLER and other, unidentified spherical cysts with thin, compact inner and relatively thick spongy outer walls. These patterns combined with a precingular archeopyle suggest affinities with Aldorfia corticata sp. nov.
Apteodinium corticatum (Norris and Jux, 1984, p.162–163, pl.2, figs.5–16; pl.3, figs.6–7; pl.6, figs.1–5) Lucas-Clark, 1987,
p.176. Holotype: Norris and Jux, 1984, pl.2, figs.7–8. Originally Aldorfia, subsequently (and now) Apteodinium.
Age: late Kimmeridgian–Portlandian.
---------------------------------------------------------------------------------------------------
Original description: [Norris and Jux, 1984]:
Aldorfia corticata sp. nov
PI. 2, figs. 5-16; Pl. 3, figs. 6-7; Pl. 6, figs. 1-5
Holotype: Slide No. 1451-4 G+40; 53.9 x 101.4, Palynology collection, University of Toronto, PI. 2, figs. 7-8.
Diagnosis: An ovidal to polygonal cyst with an apical horn, feeble cingulum, indented sulcus, gonyaulacacean tabulation, and distinctively spongey wall. Precingular archeopyle large, trapezoidal. Periphragm and pericoel rather expanded and cavernous, consisting of felty fibrils without major projections other than granules but with slightly raised, more solid sutural ornament. Endophragm composed of relatively thin porous layer.
Name: corticatum (Latin) provided with a barky outside.
Dimensions: (equatorial diameter): 30-58 μm; length (including horn) 50-90 μm.
Distribution: Upper Kimmeridgian and Portlandian, Dorset and Sussex, Southern England (Norris, 1963).
Description: Light microscopy (Pl. 2, figs. 5-16): The subspherical to polygonal proximate cyst has an apical horn 10-20 um long, a weakly developed cingulum (width 4-6 μm), an indented sulcus (6-10 μm wide), and faint sutural ornament.
No prominent projections arise from the periphragm. The sculpture is coarsely granular (Ø 0.2-0.5 μm) to vermiculate (width ca. 0.5 μm; length 2-3 μm) except on the sulcus which is almost smooth. There are, however, wart-like tubercles, 1-2 μm apart from each other, which project slightly above the microgranular surface. The pattern of the sculpture is rather irregular tending towards a subreticulate arrangement. Sutural ornament is in the form of raised crests (or occasionally pandasutural sub-parallel raised crests) doubling or trebling the intratabular cyst wall thickness. Some cysts show intra-tabular rectilinear features, probably reflecting growth features. These are not not consistantly present. The apical horn is solid above the outbulging endophragm, usually bluntly terminated, and may be ornamented by one or two crest-like "shoulders" at the base or near the top. The posterior archeopyle margin encroaches on the anterior edge of the mid-dorsal cingulum. The hypocystal wall is up to twice as thick as the epicystal wall, leading to the development of a fold in the equatorial region close to but not necessarily coincident with the cingulum.
Scanning electron microscopy (PI. 3, figs. 6-7): Interwoven fibrils comprise a bark-like covering to the outside of the cyst. Cingulum and sulcus are less sculptured than other parts of the outside, but, the latter is bordered by a ridge of interconnected either vermiculate or granulate elements (Pl. 3, fig. 7b). Wherever the phragma is torn open, or when the trapezoidal operculum (Ø ca. 30 μm) is missing the smooth inner surface of the thick double layered cavernous phragma (thickness 1.4-1.8 μm) can be seen (PI. 3, fig. 7 a), with a spongy pericoel
separating endophragm from sculptured periphragm.
Transmission electron microscopy (Pl. 6, figs. 1-5): Sections through several cysts provide information about the structure and the arrangement of the sculpturing elements of the wall. Inner and outer layers are well defined. A thin endophragm (thickness 0.1-0.2 um) surrounds the endocoel (PI. 6, figs 1, 2). Its inner surface is smooth but minutely perforated (Pl. 6, fig. 3). The pores connect with tiny cavities (Ø ca. 0.05 μm) within the endophragm. They are arranged in a peripheral zone, ca. 0.1 μm apart from each other (Pl. 6, fig. 3 d). There is no sharp contact between the two layers, because the trabecular framework of the periphragm emerges from protruding zones of the endophragm (Pl. 6, figs. 3 G, 4g). Fibres and septa are interwoven to a meshy, relatively thick (0.7-1.5 μm) layer, including irregularly shaped and partly interconnected cavities (Ø 0.5-2.0 μm), forming a spongy pericoel.
The cingulum and sulcus have a different wall structure, with the periphragm condensed to a relatively solid and much less spongy sheet, considerably thinner and almost fusing with the endophragm (Pl. 6, fig. 2, 3 d). Somewhat larger wall chambers are arranged along the margins connected by endophragmatic pores with the endocoel and topped by wart-like projections (PI. 6, figs. 3 b, 5).
The outer part of the periphragm is strengthened by scaly elements, corresponding with similar structures of the endophragm (Pl. 6, fig. 3 d). Fibrous extensions may also converge to warty or vermiculate tips from the expanded cavernous outer wall. In the sections these appear either as stout spongy cones (P1. 6, fig. 3 c) of 1-2 μm length, or as rather solid rod-like spines (Pl. 6, fig. 4 a) of 1.0-1.5 μm length and ca. 0.5 μm diameter.
Comparison: Aldorfia spongiosa (McINTYRE & BRIDAUX) DAVEY 1982 differs from Aldorfia corticata sp. nov. by its larger size, lack of tabular features, and the coarser, rugulate "scrollwork" elements in the pericoel and periphragm compared with the reticulate aspect in ligth microscopy of the phragma of A. corticata.
The wall structure compares well with Apteodinium spirioides BENEDEK. There is almost no difference between the endophragm of this Tertiary species and Aldorfia corticata sp. nov, but the periphragms - though basically alike - exhibit some distinct differences. A. spirioides has only a few but relatively large interwall chambers, functionally replacing a pericoel. Furthermore, the Tertiary cyst does not have either warty or spiny projections. BENEDEK (1972) has figured rather similar TEM-sections from Leiosphaeridia sp. cf. L. deflandrei MÄDLER and other, unidentified spherical cysts with thin, compact inner and relatively thick spongy outer walls. These patterns combined with a precingular archeopyle suggest affinities with Aldorfia corticata sp. nov.