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Occisucysta tentorium
Occisucysta tentorium Duxbury, 1977; emend. Jan du Chene et al., 1986
Holotype: Duxbury, 1977, pl.3, figs.8-9; Jan du Chene et al., 1986(a), pl.79, figs.1-3; Jan du Chene et al., 1986(b), pl.11, figs.1-5
Locus typicus: Speeton, England
Stratum typicum: Berriasian-Barremian
Translation Jan du Chene et al., 1986: LPP
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Occisucysta tentorium Duxbury, 1977, emend. Jan du Chêne et al., 1986b. Diagnosis from Duxbury (1977, p.44-45). A proximate cyst with a long (about one-third the main body diameter), broad-based, distally closed apical projection. The periphragm is thin and finely granular and the endophragm is fairly thick. The tabulation is 4', 2a, 6", 6"’, 1p, 1"” outlined on the periphragm by generally low, distally denticulate crests. Cingulum laevorotatory and bordered by high crests giving the impression in optical section of lateral extensions to the periphragm. In contrast, the crests on the apical projection are particularly low. Archeopyle large, precingular, formed from the loss of plates 2" and 3". The species is distinguished on its large apical prominence and distinctly polygonal outline. Jan du Chêne et al (1986b, p.20) emended the diagnosis as follows. Cyst proximate, cornucavate, to suturocavate, subspherical to largely polyhedral. Surmounted by an apical horn formed only from the periphragm. The endophragm and periphragm are relatively thick. The tabulation (4', 2a, 6", 6"’, 1p, 1"”) is delimited on the periphragm by low crests which are distally denticulate. The cingulum is sinistral, and delimited by high crests giving the impression of lateral extensions of the periphragm in optical section. In contrast the septa of the apical projection are very low. The archeopyle is large, precingular and formed from the loss of the plates 2" and 3". Size: overall 57-83 x 61-87 µm.
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Original description: Duxbury 1977, p. 44-45
Diagnosis: A proximate cyst with a long (about one-third the main body diameter), broad-based, distally closed apical projection. The periphragm is thin and finely granular and the endophragm is fairly thick. The tabulation 4', 2a, 6'', 6''', 1p, 1'''' is outlined by generally low, distally denticulate crests. Cingulum laevo-rotatory and bordered by high crests giving the impression in optical section of lateral extensions to the periphragm. In contrast, the crests on the apical projection are particularly low. Archeopyle large, precingular and formed by loss of plates 2'' and 3''.
Dimensions: Overall: 57-83 x 61-87 µm. Specimens measured: 11.
Emended diagnosis: Jan du Chene et al.,1986, p. 20
Cyst proximate, cornucavate to suturocavate, subspherical to largely polyhedrical, surmounted by an apical horn, formed solely by the periphragm. The periphragm and endophragm are relatively thick. The gonyaulacoid paratabulation (2pr, 4', 6'', 6c, 5s, 6''', 1'''') is indicated by low and complete parasutural septa with finely denticulate crests. The paracingular fringes, stemming from the endophragm, are regularly fenestrate between endophragm and periphragm. The paracingular fringes are irregularly denticulate (erymnate, Sarjeant, 1984, p.940, fig.6). The periphragm is grossly granulate and ornamented with intratabular verrucae, regularly arranged but more numerous on the hypocyst than on the epicyst. Archaeopyle is precingular, formed by the loss of paraplates 2'' and 3''. Operculum composite, free.
Description: Cyst proximate, cornucavate, partially suturocavate, subspherical to largely polyhedrical. Cyst surmounted by an apical horn formed solely by the periphragm. This horn is relatively long, shaped like a robust pyramid. It emerges from the central body, generally forming a marked angle where the periphragm detaches from the endophragm. The latter is clearly thicker than the periphragm. The paratabulation is gonyaulacoidal: 2pr, 4', 6'', 6c, 5s, 6''', 1p, 1''''. A porychnion is visible on the parasuture delimiting paraplates 1' and 4'. The parasutural septa are continuous, solid and their crests are ornamented with delicate and serrate spines.The septa delimiting the hypocystal paraplates are relatively higher than those delimiting the epicystal paraplates. The paracingular fringes stem from the endophragm. They are high and fenestrate between the endophragm and the periphragm. The crests of the fringes are irregularly denticylate (erymnate). The periphragm is grossly granulate and ornamented with intratabular verrucae, clearly more numerous on the pre- and post-cingulars than on the apical paraplate. The paracingulum is slightly helicoidal, laevorotatory. The parasulcus consists of five sulcal plates, generally vaguely delimited by low and irregular parasutural septa. The archaeopyle is precingular, formed by the loss of paraplates 2'' and 3''. Like in O. duxburyi, the parasutures of the archaeopyle delimiting paraplates 1''-2'' and 3''-4'' clearly show separation of the endophragm and periphragm. the operculum is free, composite.
Dimensions: Holotype (deformed): Length 76 µm, width 86 µm. Other specimens: Length 96-57 µm, width 100-67 µm.
Holotype: Duxbury, 1977, pl.3, figs.8-9; Jan du Chene et al., 1986(a), pl.79, figs.1-3; Jan du Chene et al., 1986(b), pl.11, figs.1-5
Locus typicus: Speeton, England
Stratum typicum: Berriasian-Barremian
Translation Jan du Chene et al., 1986: LPP
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Occisucysta tentorium Duxbury, 1977, emend. Jan du Chêne et al., 1986b. Diagnosis from Duxbury (1977, p.44-45). A proximate cyst with a long (about one-third the main body diameter), broad-based, distally closed apical projection. The periphragm is thin and finely granular and the endophragm is fairly thick. The tabulation is 4', 2a, 6", 6"’, 1p, 1"” outlined on the periphragm by generally low, distally denticulate crests. Cingulum laevorotatory and bordered by high crests giving the impression in optical section of lateral extensions to the periphragm. In contrast, the crests on the apical projection are particularly low. Archeopyle large, precingular, formed from the loss of plates 2" and 3". The species is distinguished on its large apical prominence and distinctly polygonal outline. Jan du Chêne et al (1986b, p.20) emended the diagnosis as follows. Cyst proximate, cornucavate, to suturocavate, subspherical to largely polyhedral. Surmounted by an apical horn formed only from the periphragm. The endophragm and periphragm are relatively thick. The tabulation (4', 2a, 6", 6"’, 1p, 1"”) is delimited on the periphragm by low crests which are distally denticulate. The cingulum is sinistral, and delimited by high crests giving the impression of lateral extensions of the periphragm in optical section. In contrast the septa of the apical projection are very low. The archeopyle is large, precingular and formed from the loss of the plates 2" and 3". Size: overall 57-83 x 61-87 µm.
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Original description: Duxbury 1977, p. 44-45
Diagnosis: A proximate cyst with a long (about one-third the main body diameter), broad-based, distally closed apical projection. The periphragm is thin and finely granular and the endophragm is fairly thick. The tabulation 4', 2a, 6'', 6''', 1p, 1'''' is outlined by generally low, distally denticulate crests. Cingulum laevo-rotatory and bordered by high crests giving the impression in optical section of lateral extensions to the periphragm. In contrast, the crests on the apical projection are particularly low. Archeopyle large, precingular and formed by loss of plates 2'' and 3''.
Dimensions: Overall: 57-83 x 61-87 µm. Specimens measured: 11.
Emended diagnosis: Jan du Chene et al.,1986, p. 20
Cyst proximate, cornucavate to suturocavate, subspherical to largely polyhedrical, surmounted by an apical horn, formed solely by the periphragm. The periphragm and endophragm are relatively thick. The gonyaulacoid paratabulation (2pr, 4', 6'', 6c, 5s, 6''', 1'''') is indicated by low and complete parasutural septa with finely denticulate crests. The paracingular fringes, stemming from the endophragm, are regularly fenestrate between endophragm and periphragm. The paracingular fringes are irregularly denticulate (erymnate, Sarjeant, 1984, p.940, fig.6). The periphragm is grossly granulate and ornamented with intratabular verrucae, regularly arranged but more numerous on the hypocyst than on the epicyst. Archaeopyle is precingular, formed by the loss of paraplates 2'' and 3''. Operculum composite, free.
Description: Cyst proximate, cornucavate, partially suturocavate, subspherical to largely polyhedrical. Cyst surmounted by an apical horn formed solely by the periphragm. This horn is relatively long, shaped like a robust pyramid. It emerges from the central body, generally forming a marked angle where the periphragm detaches from the endophragm. The latter is clearly thicker than the periphragm. The paratabulation is gonyaulacoidal: 2pr, 4', 6'', 6c, 5s, 6''', 1p, 1''''. A porychnion is visible on the parasuture delimiting paraplates 1' and 4'. The parasutural septa are continuous, solid and their crests are ornamented with delicate and serrate spines.The septa delimiting the hypocystal paraplates are relatively higher than those delimiting the epicystal paraplates. The paracingular fringes stem from the endophragm. They are high and fenestrate between the endophragm and the periphragm. The crests of the fringes are irregularly denticylate (erymnate). The periphragm is grossly granulate and ornamented with intratabular verrucae, clearly more numerous on the pre- and post-cingulars than on the apical paraplate. The paracingulum is slightly helicoidal, laevorotatory. The parasulcus consists of five sulcal plates, generally vaguely delimited by low and irregular parasutural septa. The archaeopyle is precingular, formed by the loss of paraplates 2'' and 3''. Like in O. duxburyi, the parasutures of the archaeopyle delimiting paraplates 1''-2'' and 3''-4'' clearly show separation of the endophragm and periphragm. the operculum is free, composite.
Dimensions: Holotype (deformed): Length 76 µm, width 86 µm. Other specimens: Length 96-57 µm, width 100-67 µm.