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Biconidinium
From Fensome et al., 2019:
Biconidinium, Islam, 1983c, p.84.
Type: Islam, 1983c, pl.1, fig.3, as Biconidinium longissimum.
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Original diagnosis: [Islam, 1983]:
Pericyst fusiform with one long apical and one long antapical horn; endocyst ellipsoidal to biconical; bicavate to circumcavate; phragma ornamented; surface ornamentation or linear thickenings in periphragm define paratabulation as 4`, 3a, 7", ?6c, 5```, 2````, xs; archeopyle intercalary type 3I/3I.
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Modified description:
Stover and Williams, 1987, p. 39:
Synopsis:
Cysts proximochorate, cornucavate, pericyst fusiform, epipericyst and hypopericyst of approximately equal size; endocyst ellipsoidal- pericyst paratabulation gonyaulacacean, delineated in varying degrees by parasutural ridges; formula: 3`, 7", 6c, 6```, lp, 1````, xs; archeopyle apical, operculum free.
Description:
Shape: Fusiform with one apical and one antapical horn of more or less equal length and rounded distally. Epipericyst and hypopericyst of approximately equal size.
Wall relationships: Cysts cornucavate or narrowly circumcavate, endocyst ellipsoidal. Periphragm and endophragm usually appressed except at the bases of horns.
Wall features: Parasutural ridges developed to variable degree on pericyst. Periphragm may be scabrate, granulate or pitted; endophragm thinner than periphragm, smooth.
Archeopyle: Apical, type [3A] with simple free operculum consisting of paraplates 1`-3`. Peri- and endoperculum may remain attached on ventral surface.
Paratabulation: Indicated by parasutural ridges; gonyaulacacean, formula 3`, 7", 6c, 6```,1 p, 1````.
Paracingulum: Consists of six transversely elongate paraplates indicated by parasutural ridges, slightly helicoidal.
Parasulcus: Large, mainly restricted to the hypocyst; where determinable, consists of five paraplates.
Size: Large, length of pericyst about 110-165 µm.
Affinities:
Biconidinium differs from other fusiform genera in its paratabulation and archeopyle type. Palaeocystodinium Albert 1961 and Svalbardella Manum 1960 have simple intercalary 2a archeopyles, indicating a peridiniacean tabulation. Biconidinium, following the Kofoidian system of series designation, has 3 apical and 7 precingular paraplates, a tabulation known in no other fusiform cyst.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Biconidinium Islam, 1983c. According to Islam (1983c) has an intercalary archeopyle. However, Goodman in Fensome et al. (1991) re-interpreted it as an apical archeopyle with a free operculum. Further, he gave the tabulation as 4`, 6", 6c, 6"' , 1p, 1"'' , xs, believing it to be pyrodinioid.
Biconidinium, Islam, 1983c, p.84.
Type: Islam, 1983c, pl.1, fig.3, as Biconidinium longissimum.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original diagnosis: [Islam, 1983]:
Pericyst fusiform with one long apical and one long antapical horn; endocyst ellipsoidal to biconical; bicavate to circumcavate; phragma ornamented; surface ornamentation or linear thickenings in periphragm define paratabulation as 4`, 3a, 7", ?6c, 5```, 2````, xs; archeopyle intercalary type 3I/3I.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Williams, 1987, p. 39:
Synopsis:
Cysts proximochorate, cornucavate, pericyst fusiform, epipericyst and hypopericyst of approximately equal size; endocyst ellipsoidal- pericyst paratabulation gonyaulacacean, delineated in varying degrees by parasutural ridges; formula: 3`, 7", 6c, 6```, lp, 1````, xs; archeopyle apical, operculum free.
Description:
Shape: Fusiform with one apical and one antapical horn of more or less equal length and rounded distally. Epipericyst and hypopericyst of approximately equal size.
Wall relationships: Cysts cornucavate or narrowly circumcavate, endocyst ellipsoidal. Periphragm and endophragm usually appressed except at the bases of horns.
Wall features: Parasutural ridges developed to variable degree on pericyst. Periphragm may be scabrate, granulate or pitted; endophragm thinner than periphragm, smooth.
Archeopyle: Apical, type [3A] with simple free operculum consisting of paraplates 1`-3`. Peri- and endoperculum may remain attached on ventral surface.
Paratabulation: Indicated by parasutural ridges; gonyaulacacean, formula 3`, 7", 6c, 6```,1 p, 1````.
Paracingulum: Consists of six transversely elongate paraplates indicated by parasutural ridges, slightly helicoidal.
Parasulcus: Large, mainly restricted to the hypocyst; where determinable, consists of five paraplates.
Size: Large, length of pericyst about 110-165 µm.
Affinities:
Biconidinium differs from other fusiform genera in its paratabulation and archeopyle type. Palaeocystodinium Albert 1961 and Svalbardella Manum 1960 have simple intercalary 2a archeopyles, indicating a peridiniacean tabulation. Biconidinium, following the Kofoidian system of series designation, has 3 apical and 7 precingular paraplates, a tabulation known in no other fusiform cyst.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Biconidinium Islam, 1983c. According to Islam (1983c) has an intercalary archeopyle. However, Goodman in Fensome et al. (1991) re-interpreted it as an apical archeopyle with a free operculum. Further, he gave the tabulation as 4`, 6", 6c, 6"' , 1p, 1"'' , xs, believing it to be pyrodinioid.