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Leptodinium asymmetricum
Leptodinium asymmetricum Morgan, 1980
Holotype: Morgan, 1980, pl.17, fig.1-3; Jan du Chêne et al., 1986, pl.75, figs.5-6, pl.152, figs.1-3
Locus typicus: Bellfield, New South Wales, Australia
Stratum typicum: Aptian-Middle Albian
Original descrpition: Morgan, 1980, p. 25-26
Periphragm ambitus elliptical, with high parasutural crests, endophragm ambitus elliptical; wall layers closely appressed except beneath hollow parasutural crests, especially on ventral surface; pericoels small, limited to inflaled crests; periphragm thin, psilate, or finely granulate, endophragm thin, psilate; paratabulation clearly defined by parasutural crests which are always about half as high at the apex (3-7 Ám high) than at the antapex (8-13 Ám); paracingulum defined by parasutural crests, six individual paraplates discernible parasulcus outlined by parasutural crests about 6 Ám broad, individual paraplates not visible; paraplate 1p discernible at antapical end of sulcus: paratabulation gonyaulacean 4", 6", 6c, 5""", 1p, 1""""; archeopyle precingular (3" only), wall layers closely appressed in vicinity of archeopyle, operculum free.
Affinities:
Morgan, 1980, p. 26: Leptodinium asymmetricum is characterized by its ellipsoidal ambitus, and asymmetrical development of parasutural crests, which are about twice as high at the antapex than at the apex. All other species of Leptodinium have parasutural crests of similar height all over the cyst.
Holotype: Morgan, 1980, pl.17, fig.1-3; Jan du Chêne et al., 1986, pl.75, figs.5-6, pl.152, figs.1-3
Locus typicus: Bellfield, New South Wales, Australia
Stratum typicum: Aptian-Middle Albian
Original descrpition: Morgan, 1980, p. 25-26
Periphragm ambitus elliptical, with high parasutural crests, endophragm ambitus elliptical; wall layers closely appressed except beneath hollow parasutural crests, especially on ventral surface; pericoels small, limited to inflaled crests; periphragm thin, psilate, or finely granulate, endophragm thin, psilate; paratabulation clearly defined by parasutural crests which are always about half as high at the apex (3-7 Ám high) than at the antapex (8-13 Ám); paracingulum defined by parasutural crests, six individual paraplates discernible parasulcus outlined by parasutural crests about 6 Ám broad, individual paraplates not visible; paraplate 1p discernible at antapical end of sulcus: paratabulation gonyaulacean 4", 6", 6c, 5""", 1p, 1""""; archeopyle precingular (3" only), wall layers closely appressed in vicinity of archeopyle, operculum free.
Affinities:
Morgan, 1980, p. 26: Leptodinium asymmetricum is characterized by its ellipsoidal ambitus, and asymmetrical development of parasutural crests, which are about twice as high at the antapex than at the apex. All other species of Leptodinium have parasutural crests of similar height all over the cyst.