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Canningia plera
From Fensome et al., 2019:
(Duxbury, 1983, p.22,25, pl.1, figs.7–8,11; pl.10, fig.3; text-figs.5–6) Fensome et al., 2019a, p.27.
Holotype: Duxbury, 1983, pl.1, fig.7; Fensome et al., 2019a, fig.13D. Originally Aptea, subsequently Pseudoceratium, thirdly (and now) Canningia.
Age: early Aptian.
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Pseudoceratium plerum (Duxbury, 1983) Bint, 1986
Originally Aptea, subsequently (and now) Pseudoceratium.
Holotype: Duxbury, 1983, pl.1, fig.7
Locus typicus: Atherfield section, Isle of Wight
Stratum typicum: Early Aptian
Original diagnosis: Duxbury, 1983, p. 22: Aptea plera
A large, dorso-ventrally flattened cyst with well-developed right lateral and left antapical horns. Poorly developed left lateral and right antapical horns may be present and the antapex may vary from convex to concave. Short, solid, distally and proximally flaring rods cover paraplate areas and these are distally united by a
fine reticulum. Parasutural areas are free of such ornament and a paratabulation pattern of the formula 4", 6", 6c, 6""", 1p, 1"""", 1a.s., 2s may be inferred. The "parasulcal" notch is offset to the left and the archeopyle is apical, formed by detachment of the whole apical series. Observed Dimensions: Holotype - 82 x 102 Ám. Complete specimens - 131 (125) 113 x 116 (99) 90 Ám. Operculum detached - 102 (84) 70 x 116 (96) 75 Ám.
Affinities:
Duxbury, 1983, p. 22-23: Aptea plera
The presence of well-defined areas of ornament which express paratabulation in A. plera allows comparisons to be made between this species and other, similar genera and species, particularly with the ceratiacean types described in Wall & Evitt, 1975. In their excellent drawings of Ceratium, Wall & Evitt have illustrated a tabulation of the formula 4", 6", 5-6c, 6""", 1p, 1"""", plus two or more sulcal platelets. The paratabulation pattern of A. plera is almost identical to this and its distribution is remarkably similar to that demonstrated for Ceratium carolinianum in Wall & Evitt, 1975. Their Text-Fig. 5 A and B is reproduced here (Text-Fig. 10) with the apical series deleted so that direct comparisons may be made between the morphology of C. carolinianum and that of A. plera. It is interesting to note that the sulcus in C. carolinianum occupies the comparative position of the two paraplates designated ls and 2s in A. plera. Paraplate ls is equivalent to that small paraplate frequently designated 1""" in gonyaulacacean paratabulation diagrams but its clear homology with part of the sulcus in Ceratium must dictate its being classed as a parasulcal paraplate. Similarly, 2s is probably equivalent to that paraplate frequently termed 1 p.v.
Davey & Verdier (1974, P. 641) have stressed the "typical and characteristic asymmetry" of Aptea which they consider distinguishes that genus from the similar genera Cyclonephelium, Canningia and Tenua. Such asymmetry has prompted the present author to include Aptea plera in that genus. However, that species termed Canningia cf. reticulata in Duxbury, 1977 has been re-examined by the author and, as well as possessing similar body ornament, distal reticular areas and ornament-free pandasutural regions to A. plera, it also has remarkably similar
paratabulation and paraplate distribution. In fact, the only relevant difference between A. plera and C. cf. reticulata is the absence in the latter of the "typical and characteristic asymmetry" of Aptea, largely because of its lack of horns or possession of generally shorter horns (see remarks under Cerbia below). The presence or absence of the Aptea asymmetry may prove a difficult criterion to maintain at generic level.
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Comments Fensome et al., 2019a:
Duxbury (Citation1983, p. 22) noted that ‘Short, solid, distally and proximally flaring rods cover paraplate areas and these are distally united by a fine reticulum. Parasutural areas are free of such ornament’. In ambital view, the reticulum appears as a more or less continuous periphragm similar to that in many species of Canningia, including the type, Canningia reticulata. Duxbury (Citation1983) also stated that the species has well-developed right lateral and left antapical horns, and more weakly developed left lateral and right antapical horns may be developed. However, especially in the holotype, the ‘horns’ are actually prominences produced by the ornament. Because of the presence of an outer wall layer (periphragm) and lack of a right lateral horn produced by the inner wall layer (endophragm), we reassign this species to Canningia.
Duxbury (Citation1983, p. 25) further commented that:
Davey & Verdier (Citation1974, p. 641) have stressed the ‘typical and characteristic asymmetry’ of Aptea which they consider distinguishes that genus from similar genera …. Such asymmetry has prompted the present author to include Aptea plera in that genus. However, that species termed Canningia cf. reticulata in Duxbury, Citation1977 has been re-examined … [and] the only relevant difference between A. plera and C. cf. reticulata is the absence in the latter of the ‘typical and characteristic asymmetry’ of Aptea, largely because of its lack of … or possession of … shorter horns …. The presence or absence of the Aptea asymmetry may prove a difficult criterion to maintain at generic level.
Thus, Duxbury (Citation1983) informally anticipated one of our major conclusions: that symmetry of the inner body is not a useful generic criterion within the Cyclonephelium group.
Stratigraphical occurrence. Duxbury (Citation1983) recorded this species from the lower Aptian of southern England.
(Duxbury, 1983, p.22,25, pl.1, figs.7–8,11; pl.10, fig.3; text-figs.5–6) Fensome et al., 2019a, p.27.
Holotype: Duxbury, 1983, pl.1, fig.7; Fensome et al., 2019a, fig.13D. Originally Aptea, subsequently Pseudoceratium, thirdly (and now) Canningia.
Age: early Aptian.
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Pseudoceratium plerum (Duxbury, 1983) Bint, 1986
Originally Aptea, subsequently (and now) Pseudoceratium.
Holotype: Duxbury, 1983, pl.1, fig.7
Locus typicus: Atherfield section, Isle of Wight
Stratum typicum: Early Aptian
Original diagnosis: Duxbury, 1983, p. 22: Aptea plera
A large, dorso-ventrally flattened cyst with well-developed right lateral and left antapical horns. Poorly developed left lateral and right antapical horns may be present and the antapex may vary from convex to concave. Short, solid, distally and proximally flaring rods cover paraplate areas and these are distally united by a
fine reticulum. Parasutural areas are free of such ornament and a paratabulation pattern of the formula 4", 6", 6c, 6""", 1p, 1"""", 1a.s., 2s may be inferred. The "parasulcal" notch is offset to the left and the archeopyle is apical, formed by detachment of the whole apical series. Observed Dimensions: Holotype - 82 x 102 Ám. Complete specimens - 131 (125) 113 x 116 (99) 90 Ám. Operculum detached - 102 (84) 70 x 116 (96) 75 Ám.
Affinities:
Duxbury, 1983, p. 22-23: Aptea plera
The presence of well-defined areas of ornament which express paratabulation in A. plera allows comparisons to be made between this species and other, similar genera and species, particularly with the ceratiacean types described in Wall & Evitt, 1975. In their excellent drawings of Ceratium, Wall & Evitt have illustrated a tabulation of the formula 4", 6", 5-6c, 6""", 1p, 1"""", plus two or more sulcal platelets. The paratabulation pattern of A. plera is almost identical to this and its distribution is remarkably similar to that demonstrated for Ceratium carolinianum in Wall & Evitt, 1975. Their Text-Fig. 5 A and B is reproduced here (Text-Fig. 10) with the apical series deleted so that direct comparisons may be made between the morphology of C. carolinianum and that of A. plera. It is interesting to note that the sulcus in C. carolinianum occupies the comparative position of the two paraplates designated ls and 2s in A. plera. Paraplate ls is equivalent to that small paraplate frequently designated 1""" in gonyaulacacean paratabulation diagrams but its clear homology with part of the sulcus in Ceratium must dictate its being classed as a parasulcal paraplate. Similarly, 2s is probably equivalent to that paraplate frequently termed 1 p.v.
Davey & Verdier (1974, P. 641) have stressed the "typical and characteristic asymmetry" of Aptea which they consider distinguishes that genus from the similar genera Cyclonephelium, Canningia and Tenua. Such asymmetry has prompted the present author to include Aptea plera in that genus. However, that species termed Canningia cf. reticulata in Duxbury, 1977 has been re-examined by the author and, as well as possessing similar body ornament, distal reticular areas and ornament-free pandasutural regions to A. plera, it also has remarkably similar
paratabulation and paraplate distribution. In fact, the only relevant difference between A. plera and C. cf. reticulata is the absence in the latter of the "typical and characteristic asymmetry" of Aptea, largely because of its lack of horns or possession of generally shorter horns (see remarks under Cerbia below). The presence or absence of the Aptea asymmetry may prove a difficult criterion to maintain at generic level.
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Comments Fensome et al., 2019a:
Duxbury (Citation1983, p. 22) noted that ‘Short, solid, distally and proximally flaring rods cover paraplate areas and these are distally united by a fine reticulum. Parasutural areas are free of such ornament’. In ambital view, the reticulum appears as a more or less continuous periphragm similar to that in many species of Canningia, including the type, Canningia reticulata. Duxbury (Citation1983) also stated that the species has well-developed right lateral and left antapical horns, and more weakly developed left lateral and right antapical horns may be developed. However, especially in the holotype, the ‘horns’ are actually prominences produced by the ornament. Because of the presence of an outer wall layer (periphragm) and lack of a right lateral horn produced by the inner wall layer (endophragm), we reassign this species to Canningia.
Duxbury (Citation1983, p. 25) further commented that:
Davey & Verdier (Citation1974, p. 641) have stressed the ‘typical and characteristic asymmetry’ of Aptea which they consider distinguishes that genus from similar genera …. Such asymmetry has prompted the present author to include Aptea plera in that genus. However, that species termed Canningia cf. reticulata in Duxbury, Citation1977 has been re-examined … [and] the only relevant difference between A. plera and C. cf. reticulata is the absence in the latter of the ‘typical and characteristic asymmetry’ of Aptea, largely because of its lack of … or possession of … shorter horns …. The presence or absence of the Aptea asymmetry may prove a difficult criterion to maintain at generic level.
Thus, Duxbury (Citation1983) informally anticipated one of our major conclusions: that symmetry of the inner body is not a useful generic criterion within the Cyclonephelium group.
Stratigraphical occurrence. Duxbury (Citation1983) recorded this species from the lower Aptian of southern England.