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Cyclonephelium tabulatum
Cyclonephelium tabulatum Davey and Verdier, 1974
Originally Cyclonephelium, subsequently Canninginopsis, thirdly Cerbia.
Tax. jr. synonym of Tenua hystrix Eisenack, 1958, according to Sarjeant, 1985, 1990. Stover and Williams, 1987, and Lentin and Williams, 1989, retained Cyclonephelium (as Cerbia) tabulatum as a separate species.
Holotype: Davey and Verdier 1974, pl.92, fig.1,4; Sarjeant, 1992, figs.3-4
Locus typicus: La BÚdoule, SE France
Stratum typicum: Aptian
Original diagnosis: Davey and Verdier, 1974, p. 630:
The cyst is subcircular in outline and possesses a thin, smooth to lightly tuberculate wall. The processes are predominantly peritabular in position and clearly define the precingular and postcingular plates and the cingulum. The central part of the plates and the sulcal region are practically devoid of processes. The processes are short, stout, and capitate; they rarely branch distally or are joined proximally. The archaeopyle is apical and has a strongly zigzag margin and a sulcal notch; the operculum is typically detached.
Original description: Davey and Verdier, 1974, p.630-631
Since all the identified specimens possessed an apical archaeopyle and only rarely detached opercula were identified, it is difficult to precisely define the shape of the apical region. It is surmised, however, that it is of similar shape to that found in related species. That is, the cyst is rounded apically or has a reduced apical boss.
The main part of the cyst is subcircular, or rarely slightly angular, in outline. The processes are neatly aligned just within the plate margins and hence clearly define the tabulation in the precingular and postcingular regions. In each case five or six plates appear to be present. The parallel lines of processes, either side of a plate boundary, are 3-4 Ám apart. Rare processes on the cingulum may indicate the position of plate boundaries; a distinct cingular tabulation, however, is not present. Two to three antapical and four apical plates appear to be present.
Affinities:
Davey and Verdier, 1974, p. 631: The shape of the cyst and its processes are identical to that of C. distinctum Deflandre and Cookson 1955. C. tabulatum differs significantly from C. distinctum, and other members of Cyclonephelium, by the possession of peritabular processes and an encircling cingulum; the processes of C. distinctum are concentrated towards the circumferential region. The two species are clearly closely related, and although C. tabulatum does not conform exactly with the generic diagnosis of Cyclonephelium it is considered best placed in this genus at present.
Originally Cyclonephelium, subsequently Canninginopsis, thirdly Cerbia.
Tax. jr. synonym of Tenua hystrix Eisenack, 1958, according to Sarjeant, 1985, 1990. Stover and Williams, 1987, and Lentin and Williams, 1989, retained Cyclonephelium (as Cerbia) tabulatum as a separate species.
Holotype: Davey and Verdier 1974, pl.92, fig.1,4; Sarjeant, 1992, figs.3-4
Locus typicus: La BÚdoule, SE France
Stratum typicum: Aptian
Original diagnosis: Davey and Verdier, 1974, p. 630:
The cyst is subcircular in outline and possesses a thin, smooth to lightly tuberculate wall. The processes are predominantly peritabular in position and clearly define the precingular and postcingular plates and the cingulum. The central part of the plates and the sulcal region are practically devoid of processes. The processes are short, stout, and capitate; they rarely branch distally or are joined proximally. The archaeopyle is apical and has a strongly zigzag margin and a sulcal notch; the operculum is typically detached.
Original description: Davey and Verdier, 1974, p.630-631
Since all the identified specimens possessed an apical archaeopyle and only rarely detached opercula were identified, it is difficult to precisely define the shape of the apical region. It is surmised, however, that it is of similar shape to that found in related species. That is, the cyst is rounded apically or has a reduced apical boss.
The main part of the cyst is subcircular, or rarely slightly angular, in outline. The processes are neatly aligned just within the plate margins and hence clearly define the tabulation in the precingular and postcingular regions. In each case five or six plates appear to be present. The parallel lines of processes, either side of a plate boundary, are 3-4 Ám apart. Rare processes on the cingulum may indicate the position of plate boundaries; a distinct cingular tabulation, however, is not present. Two to three antapical and four apical plates appear to be present.
Affinities:
Davey and Verdier, 1974, p. 631: The shape of the cyst and its processes are identical to that of C. distinctum Deflandre and Cookson 1955. C. tabulatum differs significantly from C. distinctum, and other members of Cyclonephelium, by the possession of peritabular processes and an encircling cingulum; the processes of C. distinctum are concentrated towards the circumferential region. The two species are clearly closely related, and although C. tabulatum does not conform exactly with the generic diagnosis of Cyclonephelium it is considered best placed in this genus at present.