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Stephanelytron tabulophorum
Stephanelytron tabulophorum Stover et al., 1977
Holotype: Stover et al. 1977: Plate 1, figures 12-13
Locus typicus: Reutlingen, Germany.
Stratum typicum: Middle of Dogger Zeta (Callovian; Peltoceras athleta Zone).
Age: Callovian
Original description: Stover et al. 1977, p. 333
Cysts proximochorate, ellipsoidal, outline in dorsal-ventral view roundly hexagonal, longitudinally elongate. Body two-layered; autophragm thin (<1 µm), smooth to faintly granulate, and bears relatively short, closely spaced, tubiform, parasutural and penitabular processes. Processes smooth, expanded slightly distally, 2 µm to 4 µm long, and 0.5 µm to 1 µm wide at midlength. Entire cyst enclosed by a thin, slightly folded or crumpled ectophragm. Paratabulation indicated by parasutural penitabular features, formula: ?1", 5", 6c, 5"", 1"", 1 p, 2s. Outline of apical and antapical paraplates unknown; outlines of most precingular and postcingular paraplates subrectangular and longitudinally elongate, first postcingular paraplate generally smaller than others and trapezoidal; posterior intercalary paraplate also trapezoidal and smaller than first postcingular paraplate. Paracingulum clearly indicated by six rectangular, transversely elongate paraplates. Antapical corona smooth-walled, length about the same as that of the processes, base thicker than autophragm, and occupies a major part of the anterior surface, Overall length 47 µm to 67 µm.
Comparison. Stephanelytron tabulophorum is similar to S. redcliffense and S. caytonense in having the paratabulation indicated by parasutural and penitabular features, and differs from both species in having a well-developed paracingulum. The new species differs from S. scarburghense in having parasutural and penitabular rather than nontabular processes. The corona on S. tabulophorum is generally less prominent than on the other species of Stephanelytron.
Remarks: Specimens of Stephanelytron tabulophorum exhibit a tendency to develop penitabular rows of processes near the longitudinal boundaries of precingular and postcingular paraplates, and especially on the dorsal surface. Single parasutural rows of processes occur along and within the paracingulum and bordering the parasulcus. Longitudinal splits may occur on the epicyst and extend between the closely spaced rows of penitabular processes, if such rows are present.
Holotype: Stover et al. 1977: Plate 1, figures 12-13
Locus typicus: Reutlingen, Germany.
Stratum typicum: Middle of Dogger Zeta (Callovian; Peltoceras athleta Zone).
Age: Callovian
Original description: Stover et al. 1977, p. 333
Cysts proximochorate, ellipsoidal, outline in dorsal-ventral view roundly hexagonal, longitudinally elongate. Body two-layered; autophragm thin (<1 µm), smooth to faintly granulate, and bears relatively short, closely spaced, tubiform, parasutural and penitabular processes. Processes smooth, expanded slightly distally, 2 µm to 4 µm long, and 0.5 µm to 1 µm wide at midlength. Entire cyst enclosed by a thin, slightly folded or crumpled ectophragm. Paratabulation indicated by parasutural penitabular features, formula: ?1", 5", 6c, 5"", 1"", 1 p, 2s. Outline of apical and antapical paraplates unknown; outlines of most precingular and postcingular paraplates subrectangular and longitudinally elongate, first postcingular paraplate generally smaller than others and trapezoidal; posterior intercalary paraplate also trapezoidal and smaller than first postcingular paraplate. Paracingulum clearly indicated by six rectangular, transversely elongate paraplates. Antapical corona smooth-walled, length about the same as that of the processes, base thicker than autophragm, and occupies a major part of the anterior surface, Overall length 47 µm to 67 µm.
Comparison. Stephanelytron tabulophorum is similar to S. redcliffense and S. caytonense in having the paratabulation indicated by parasutural and penitabular features, and differs from both species in having a well-developed paracingulum. The new species differs from S. scarburghense in having parasutural and penitabular rather than nontabular processes. The corona on S. tabulophorum is generally less prominent than on the other species of Stephanelytron.
Remarks: Specimens of Stephanelytron tabulophorum exhibit a tendency to develop penitabular rows of processes near the longitudinal boundaries of precingular and postcingular paraplates, and especially on the dorsal surface. Single parasutural rows of processes occur along and within the paracingulum and bordering the parasulcus. Longitudinal splits may occur on the epicyst and extend between the closely spaced rows of penitabular processes, if such rows are present.