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Cyclonephelium chabaca
Cyclonephelium chabaca Below, 1981
Holotype: Below, 1981, pl.4, figs.9,11; Fensome et al., 1991, figs.1-2-p.607
Paratypes: Below, 1981, pl.4, fig.l0 and pl.9, fig.3; pl.9, fig.2
Locus typicus: Section KV between Imi Ouadder and Assif Oumaine, SW Morocco
Stratum typicum: Aptian-Cenomanian
Translation Below, 1981: Fensome, 1991, p. 608-609
Original diagnosis: Below, 1981, p. 12
Proximate, nontabulate, lenticular central body of approximately rounded outline. Apically rounded or with very low bulge. Low, broad scaffold-like apical horn formed from appendages of the periphragm. Hypocyst asymmetrical with a left antapical horn and a marginally displaced bulge, or more rarely rounded. The ornamentation consists of a delicate, fine-meshed reticulum borne by numerous, thin appendages, and covers the entire cyst with the exception of a broad, ventral area which
corresponds to the parasulcal zone. Archeopyle of type (A); the zigzag archeopyle margin indicates six precingular paraplates and an as [anterior sulcal] paraplate in place. Occasionally pandasutural bands are partially developed.
Original description: Below, 1981, p. 12-13
The form of the cyst varies from elongate-oval to rounded. Development of the antapical lobe, and consequently the shape, is variable. Specimens range from forms with a rounded antapical pole, through transitional forms with an antapical and a laterally displaced bulge, to forms with a prominent, conical, distally rounded left antapical protuberance. The protuberances of the central body may be further emphasized by the ornamentation, which is particularly well developed on the antapex. However, if this [antapical] pole is rounded, the respective appendages may be scaffold-like, formed from the appendages of the ?periphragm.
The apical archeopyle has a simple, "free" operculum and is of type (A)- Notches along the archeopyle margin indicate six precingulars and one as [anterior sulcal]. Pandasutural bands very rarely separate paraplates, as in Cyclonephelium paucimarginatum Cookson and Eisenack 1962 (see [Below, 1981a] p.15). Whereas the paracingulum is never indicated, the parasulcus is always visible as a broad unornamented zone, slightly indented and extending from the archeopyle margin to the antapex. The cyst surface here is smooth, weakly vermiculate or shows different stages in the disintegration of the reticulum, which in part may be reduced to short stumps. In contrast, the dorsal surface only rarely shows an area with reduced or absent ornamentation which is typical for species of the genus Cyclonephelium. The rest of the cyst surface is covered with numerous, thin, solid appendages fusing distally to form a fine-meshed reticulum. Incipient development of an ectophragmal membrane supported by the appendages and developed by infilling of the lumina, was occasionally observed. On the other hand, breakdown of the reticulum by reduction of the distal trabeculi leads to representatives of the species Cyclonephelium uannophorum Davey 1969, but this is rare in the Cenomanian population.
Size.
Holotype: length 74 Ám (without operculum), width 74 Ám, length of processes up to 7.5 Ám.
Range of other specimens: length 54(57)68 Ám (without operculum), width 60(69)78 Ám, length of processes 4 - 8 Ám.
Holotype: Below, 1981, pl.4, figs.9,11; Fensome et al., 1991, figs.1-2-p.607
Paratypes: Below, 1981, pl.4, fig.l0 and pl.9, fig.3; pl.9, fig.2
Locus typicus: Section KV between Imi Ouadder and Assif Oumaine, SW Morocco
Stratum typicum: Aptian-Cenomanian
Translation Below, 1981: Fensome, 1991, p. 608-609
Original diagnosis: Below, 1981, p. 12
Proximate, nontabulate, lenticular central body of approximately rounded outline. Apically rounded or with very low bulge. Low, broad scaffold-like apical horn formed from appendages of the periphragm. Hypocyst asymmetrical with a left antapical horn and a marginally displaced bulge, or more rarely rounded. The ornamentation consists of a delicate, fine-meshed reticulum borne by numerous, thin appendages, and covers the entire cyst with the exception of a broad, ventral area which
corresponds to the parasulcal zone. Archeopyle of type (A); the zigzag archeopyle margin indicates six precingular paraplates and an as [anterior sulcal] paraplate in place. Occasionally pandasutural bands are partially developed.
Original description: Below, 1981, p. 12-13
The form of the cyst varies from elongate-oval to rounded. Development of the antapical lobe, and consequently the shape, is variable. Specimens range from forms with a rounded antapical pole, through transitional forms with an antapical and a laterally displaced bulge, to forms with a prominent, conical, distally rounded left antapical protuberance. The protuberances of the central body may be further emphasized by the ornamentation, which is particularly well developed on the antapex. However, if this [antapical] pole is rounded, the respective appendages may be scaffold-like, formed from the appendages of the ?periphragm.
The apical archeopyle has a simple, "free" operculum and is of type (A)- Notches along the archeopyle margin indicate six precingulars and one as [anterior sulcal]. Pandasutural bands very rarely separate paraplates, as in Cyclonephelium paucimarginatum Cookson and Eisenack 1962 (see [Below, 1981a] p.15). Whereas the paracingulum is never indicated, the parasulcus is always visible as a broad unornamented zone, slightly indented and extending from the archeopyle margin to the antapex. The cyst surface here is smooth, weakly vermiculate or shows different stages in the disintegration of the reticulum, which in part may be reduced to short stumps. In contrast, the dorsal surface only rarely shows an area with reduced or absent ornamentation which is typical for species of the genus Cyclonephelium. The rest of the cyst surface is covered with numerous, thin, solid appendages fusing distally to form a fine-meshed reticulum. Incipient development of an ectophragmal membrane supported by the appendages and developed by infilling of the lumina, was occasionally observed. On the other hand, breakdown of the reticulum by reduction of the distal trabeculi leads to representatives of the species Cyclonephelium uannophorum Davey 1969, but this is rare in the Cenomanian population.
Size.
Holotype: length 74 Ám (without operculum), width 74 Ám, length of processes up to 7.5 Ám.
Range of other specimens: length 54(57)68 Ám (without operculum), width 60(69)78 Ám, length of processes 4 - 8 Ám.