Back
Occisucysta duxburyi
Occisucysta duxburyi Jan du Chêne et al. 1986
Holotype: Jan du Chêne et al., 1986(b), pl.4, figs.4-7; Jan du Chêne et al., 1986(a), pl.78, fig.4
Locus typicus:
Stratum typicum: Early Aptian
Remarks: A most striking species with very distinctive microreticulate pitting on the distal surface of the periphragm (which is--0.3 µm thick). This sculpture extends over the surface of the intratabular tubercles (which are most prominent on paraplates B, Y and the postcingulars). The endophragm is thicker (--0.75 µm), granular in cross section and has a rough rugulate/pitted surface sculpture. Cavation is restricted to the region of the apical horn and the paracingulum. Paratabulation pattern as cited by Jan du Chêne et al., 1986 consists of asymmetrical-oblong antapical, P/C apical and lu/li (with paraplate ai contacting paraplate 2) ventral arrangements. Parasutural septa (up to 10 µm high) delineate a paratabulation formula of 2pr, 4", 6"", 6c, 6""",1"""", 1p, 5s. A and lu are very elongated, the latter plate being very narrow. Porichnion lies on Q/A/lu triple junction. Reduced Type 2P archaeopyle involving paraplates 3 and 4 as a compound biplacoid operculum (Plate 16, Fig. 1). Parasulcus is deeply indented.
In contrast to the description given in Jan du Chêne et al., 1986, this species has been found to be the sole species of the genus present in Barremian time. Fenestration of the paracingular septa have been noted in some specimens.
Holotype: Jan du Chêne et al., 1986(b), pl.4, figs.4-7; Jan du Chêne et al., 1986(a), pl.78, fig.4
Locus typicus:
Stratum typicum: Early Aptian
Remarks: A most striking species with very distinctive microreticulate pitting on the distal surface of the periphragm (which is--0.3 µm thick). This sculpture extends over the surface of the intratabular tubercles (which are most prominent on paraplates B, Y and the postcingulars). The endophragm is thicker (--0.75 µm), granular in cross section and has a rough rugulate/pitted surface sculpture. Cavation is restricted to the region of the apical horn and the paracingulum. Paratabulation pattern as cited by Jan du Chêne et al., 1986 consists of asymmetrical-oblong antapical, P/C apical and lu/li (with paraplate ai contacting paraplate 2) ventral arrangements. Parasutural septa (up to 10 µm high) delineate a paratabulation formula of 2pr, 4", 6"", 6c, 6""",1"""", 1p, 5s. A and lu are very elongated, the latter plate being very narrow. Porichnion lies on Q/A/lu triple junction. Reduced Type 2P archaeopyle involving paraplates 3 and 4 as a compound biplacoid operculum (Plate 16, Fig. 1). Parasulcus is deeply indented.
In contrast to the description given in Jan du Chêne et al., 1986, this species has been found to be the sole species of the genus present in Barremian time. Fenestration of the paracingular septa have been noted in some specimens.