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Scriniodinium kempiae
Scriniodinium kempiae Stover and Helby, 1987
Now Endoscrinium. Originally Scriniodinium, subsequently (and now) Endoscrinium.
Holotype: Stover and Helby, 1987, fig.15A-F
Paratypes: Stover and Helby, 1987
Locus typicus: Papuan Basin, Australia
Stratum typicum: Callovian
Original description: Stover and Helby, 1987, p. 114
Cysts proximate, generally circumcavate, compressed dorsoventrally. Endocyst subcircular to roundly quadrate; endophragm thin (usually less than 1 µm thick), smooth and frequently folded peripherally. Pericyst broadly elliptical to pentagonal in outline, usually with a conspicuous, relatively wide, posteriorly truncated, middorsal antapical projection. Periphragm 0.5-1.5 µm thick, scabrate, fibroid, to locally fenestrate and/or minutely reticulate. Rarely more than 2 types of ornamentation present on individual specimens. Paratabulation expressed incompletely by low parasutural ridges discernible most frequently in the midventral and middorsal areas and indistinct or undeveloped elsewhere. Ventrally, paraplates usually delineated (Fig. 14A), whereas only 2 middorsal paraplates distinguishable dorsally (Fig. 14B). Paracingulum indicated on the pericyst by 2 transverse, subparallel, parasutural ridges offset ventrally by about the width of the paracingulum and almost always undivided longitudinally. Arch-like anterior margin of the parasulcus usually discernible on epicyst; indications of parasulcus on hypocyst commonly less distinct and rarely complete, especially in the posterior area. Archeopyle precingular, type P, 3 " only- operculum free. Specimens 108-135 µm long and 110-128 µm wide; endocysts 82-100 µm long and 84-92 µm wide.
Comment. Scriniodinium kempiae does not display complete paratabulation but, from what is discernible, the paratabulation pattern is similar to that of Leptodinium Klement emend. Stover & Evitt 1978. Posteroventrally, the relationship between parasulcus and adjacent paraplates, as well as features within the parasulcus, were determined by piecing together information from several specimens. The exact configuration of the antapical paraplate is still uncertain. In contrast, we are reasonably certain that the antapical protrusion opens posteriorly and, therefore, is a hollow box-like structure as in S. Iuridum (Deflandre) Klement 1960 (see Gocht 1970, p.144, fig. 15; pl.28, fig.5) and in species of Tubotuberella Vozzhennikova 1967. The anterior ventral margin of this box-like structure forms a distinctive collar (Figs 14A,15A). The fibrous nature of the periphragm is evident, albeit occasionally faint, on all specimens. Parts of the periphragm, usually those along or near the lateral edges, may be finely fenestrate on some specimens, whereas on others the periphragm may be locally reticulate. Parasutural ridges are seemingly smooth in bright field illumination but in phase contrast, fine hairlike structures (about 1 µm in length) appear to extend from some parasutural ridges.
Affinities:
Stover and Helby, 1987, p.114: Scriniodinium kempiae differs from S. attadalense (Cookson & Eisenack) Eisenack 1967 in having parasutural ridges delineating some paraplates, a fibrous periphragm, and a more sharply differentiated posterior projection. Other Australian species including S. parvimarginatum (Cookson & Eisenack) Eisenack 1967, S. playfordii Cookson & Eisenack 1960b and S.? ceratophorum Cookson & Eisenack 1960b, lack parasutural ridges and an antapical protrusion. Scriniodinium luridum, is smaller than S. kempiae and has a smooth pericyst.
Now Endoscrinium. Originally Scriniodinium, subsequently (and now) Endoscrinium.
Holotype: Stover and Helby, 1987, fig.15A-F
Paratypes: Stover and Helby, 1987
Locus typicus: Papuan Basin, Australia
Stratum typicum: Callovian
Original description: Stover and Helby, 1987, p. 114
Cysts proximate, generally circumcavate, compressed dorsoventrally. Endocyst subcircular to roundly quadrate; endophragm thin (usually less than 1 µm thick), smooth and frequently folded peripherally. Pericyst broadly elliptical to pentagonal in outline, usually with a conspicuous, relatively wide, posteriorly truncated, middorsal antapical projection. Periphragm 0.5-1.5 µm thick, scabrate, fibroid, to locally fenestrate and/or minutely reticulate. Rarely more than 2 types of ornamentation present on individual specimens. Paratabulation expressed incompletely by low parasutural ridges discernible most frequently in the midventral and middorsal areas and indistinct or undeveloped elsewhere. Ventrally, paraplates usually delineated (Fig. 14A), whereas only 2 middorsal paraplates distinguishable dorsally (Fig. 14B). Paracingulum indicated on the pericyst by 2 transverse, subparallel, parasutural ridges offset ventrally by about the width of the paracingulum and almost always undivided longitudinally. Arch-like anterior margin of the parasulcus usually discernible on epicyst; indications of parasulcus on hypocyst commonly less distinct and rarely complete, especially in the posterior area. Archeopyle precingular, type P, 3 " only- operculum free. Specimens 108-135 µm long and 110-128 µm wide; endocysts 82-100 µm long and 84-92 µm wide.
Comment. Scriniodinium kempiae does not display complete paratabulation but, from what is discernible, the paratabulation pattern is similar to that of Leptodinium Klement emend. Stover & Evitt 1978. Posteroventrally, the relationship between parasulcus and adjacent paraplates, as well as features within the parasulcus, were determined by piecing together information from several specimens. The exact configuration of the antapical paraplate is still uncertain. In contrast, we are reasonably certain that the antapical protrusion opens posteriorly and, therefore, is a hollow box-like structure as in S. Iuridum (Deflandre) Klement 1960 (see Gocht 1970, p.144, fig. 15; pl.28, fig.5) and in species of Tubotuberella Vozzhennikova 1967. The anterior ventral margin of this box-like structure forms a distinctive collar (Figs 14A,15A). The fibrous nature of the periphragm is evident, albeit occasionally faint, on all specimens. Parts of the periphragm, usually those along or near the lateral edges, may be finely fenestrate on some specimens, whereas on others the periphragm may be locally reticulate. Parasutural ridges are seemingly smooth in bright field illumination but in phase contrast, fine hairlike structures (about 1 µm in length) appear to extend from some parasutural ridges.
Affinities:
Stover and Helby, 1987, p.114: Scriniodinium kempiae differs from S. attadalense (Cookson & Eisenack) Eisenack 1967 in having parasutural ridges delineating some paraplates, a fibrous periphragm, and a more sharply differentiated posterior projection. Other Australian species including S. parvimarginatum (Cookson & Eisenack) Eisenack 1967, S. playfordii Cookson & Eisenack 1960b and S.? ceratophorum Cookson & Eisenack 1960b, lack parasutural ridges and an antapical protrusion. Scriniodinium luridum, is smaller than S. kempiae and has a smooth pericyst.