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Bitubericysta boroujiana
Bitubericysta boroujiana, Soncini, 1992
Holotype: Soncini, 1992, pl.1, figs.1-3
Paratype: Soncini, 1992
Locus typicus: Al Borouj, Oulad Abdoun Phosphate Basin, Morocco
Stratum typicum: Ypresian
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Original description: [Soncini, 1992, p. 327, 329]:
Diagnosis:
Spheroidal, skolochorate, two-layered cyst. Thin endophragm closely appressed to fibropitted periphragm variable in thickness.
Processes well developed, hollow and fibrous, arising from periphragm only; simple buccinate (precingular and II, III, VI postcingular) to complexely divided (IV and V postcingular), distally expanding and recurving in an irregular spinous margin. One process per paraplate, reflecting a complete gonyaulacacean paratabulation with a Danea-type organization. Paracingular processes tubular to latispinous, simple or divided, parasulcal ones simple and slender. Bifurcate or trifurcate apical protrusion, short, broad and solid, made by periphragm only. Annular to soleate antapical complex surrounding a solid periphragmal protrusion variable in length.
Archeopyle type P(4), operculum free.
Description:
Bitubericysta cysts are typically spheroidal. The polar features are very distinctive but variable. The apical protrusion is solid and exclusively periphragmal: endocoele is not involved in this feature and less than 1% of the population show the endophragm slightly protruding into one or both polar projections; it is bifid or trifid, massive, and typically linked to the proximal part of the process from apical paraplate B (Plate 1, 3-6, Plate II, 1). The antapical pole is also highly distinctive by the periphragmal protrusion, shorter than processes but variable in length (7 to 18.5 µm), commonly with a rounded tip, associated with a soleate complex of long and loosely fibrous projections, more or less linked laterally and distally (Plate 1, 2, 7, 8, 10). This complex is open on ventral side (Plate 1, 2, 10). Other processes are clearly intratabular, tubular, hollow, open distally. In paracingular area, processes are tubular or slightly flattened to latispinous on dorsal side (Plate 1, 3), i.e. they are elliptical in cross-section, perpendicularly to the polar axis. They are simple, distally expanded in a paintbrush-like fashion. They can also be divided more or less close to their proximal part (bifurcate, trifurcate, complex...), particularly on dorsal side, but they clearly reflect 6 paracingular paraplates (Fig.4). In parasulcal area, li, ai, fu, li, Im, lu, X and Z processes are discernible (Plate 1, 1). Processes are hollow, slender and buccinate, with a spinous slightly recurved margin, densely fibrous, only lu possibly showing distal branching. Process of paraplate 11 is also smaller than pre- and postcingulars and can be incorporated in a parasulcal group in which processes depict faint alignments as follows: li and ai equal medium size, parallel to paracingulum organization; fu, lu, II in a growing size order, not parallel to paracingulum but bending towards antapical pole; li, Im, X in a growing size order, in a diagonal arrangement; and Z slightly offset on the right side, below the large process of postcingular paraplate Vl (Fig.4). Apical and precingular processes are larger (A and li smaller than B and C, 2 and 5 smaller than 3 and 6), densely to loosely fibrous, sometimes fenestrate. They are commonly simple tubular, largely expanded distally in paintbrush-like fashion. Distal margin is irregularly recurved and spinous. Postcingulars are comparable to precingulars on ventral side (Ill, Vl) but larger, proximally tubular, more or less divided and largely expanded distally. On dorsal side (IV, V), processes are complexly divided, proximally arranged in an arcuate to soleate feature, opened towards the apex (Plate 1, 3, 9). The plate boundary between IV and V complexes is then situated in a middorsal position, facing the archeopyle (Fig.4).
Dimensions:
holotype maximum diameter: 123.5 µm,
maximum processes length: 39.5 µm
antapical protrusion: 14 µm
range maximum diameter: 103 (126) 152 µm
maximum processes length: 32.5 (41) 54 µm
antapical protrusion: 7 (13) 18.5 µm
periphragm thickness (without polar protrusion and process): 2.5-5.5 µm endophragm thickness: 1.5-2 µm 15 specimens measured.
Affinities:
At first sight, Bitubericysta is similar to Cordosphaeridium (Eisenack) Davey 1969: spheroidal shape, fibro-pitted to fibrous periphragm, intratabular position of processes reflecting a gonyaulacacean paratabulation pattern. Global aspect of processes compares well with C. exilimurum Davey and Williams in Davey et al. 1966. However, solid, periphragmal projections have never been described by authors on Cordosphaeridium: "not distinctive" apical and antapical processes are depicted by Davey (1969), or a slightly distinctive antapical process (longer) is mentioned by Sarjeant (1981). In fact, there are always small to great differences (polar features for example) between Bitubericysta and the few other fibrous dinocysts which seem to show some morphological resemblance with it (Table 1): Amphoro.sphaeridium Davey 1969 or Fibrocysta Stover and Evitt 1978, for example. As regards the paraplates organization, Bitubericysta proves close affinities with Danea (Morgenroth) Drugg, 1970, in spite of important morphological differences between the two genera (penitabular or intratabular septa frequent to dominant among projections on Danea dinocysts for example). As there are also morphological differences between Bituhericysta and the other "Danea-type" dinocysts (Damassa, 1984) like Turbiosphaera Archangelsky 1969 (Table 1), Bitubericysta will, perhaps, be considered as a new member of the Danea-group (Damassa, 1984)?
Holotype: Soncini, 1992, pl.1, figs.1-3
Paratype: Soncini, 1992
Locus typicus: Al Borouj, Oulad Abdoun Phosphate Basin, Morocco
Stratum typicum: Ypresian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Soncini, 1992, p. 327, 329]:
Diagnosis:
Spheroidal, skolochorate, two-layered cyst. Thin endophragm closely appressed to fibropitted periphragm variable in thickness.
Processes well developed, hollow and fibrous, arising from periphragm only; simple buccinate (precingular and II, III, VI postcingular) to complexely divided (IV and V postcingular), distally expanding and recurving in an irregular spinous margin. One process per paraplate, reflecting a complete gonyaulacacean paratabulation with a Danea-type organization. Paracingular processes tubular to latispinous, simple or divided, parasulcal ones simple and slender. Bifurcate or trifurcate apical protrusion, short, broad and solid, made by periphragm only. Annular to soleate antapical complex surrounding a solid periphragmal protrusion variable in length.
Archeopyle type P(4), operculum free.
Description:
Bitubericysta cysts are typically spheroidal. The polar features are very distinctive but variable. The apical protrusion is solid and exclusively periphragmal: endocoele is not involved in this feature and less than 1% of the population show the endophragm slightly protruding into one or both polar projections; it is bifid or trifid, massive, and typically linked to the proximal part of the process from apical paraplate B (Plate 1, 3-6, Plate II, 1). The antapical pole is also highly distinctive by the periphragmal protrusion, shorter than processes but variable in length (7 to 18.5 µm), commonly with a rounded tip, associated with a soleate complex of long and loosely fibrous projections, more or less linked laterally and distally (Plate 1, 2, 7, 8, 10). This complex is open on ventral side (Plate 1, 2, 10). Other processes are clearly intratabular, tubular, hollow, open distally. In paracingular area, processes are tubular or slightly flattened to latispinous on dorsal side (Plate 1, 3), i.e. they are elliptical in cross-section, perpendicularly to the polar axis. They are simple, distally expanded in a paintbrush-like fashion. They can also be divided more or less close to their proximal part (bifurcate, trifurcate, complex...), particularly on dorsal side, but they clearly reflect 6 paracingular paraplates (Fig.4). In parasulcal area, li, ai, fu, li, Im, lu, X and Z processes are discernible (Plate 1, 1). Processes are hollow, slender and buccinate, with a spinous slightly recurved margin, densely fibrous, only lu possibly showing distal branching. Process of paraplate 11 is also smaller than pre- and postcingulars and can be incorporated in a parasulcal group in which processes depict faint alignments as follows: li and ai equal medium size, parallel to paracingulum organization; fu, lu, II in a growing size order, not parallel to paracingulum but bending towards antapical pole; li, Im, X in a growing size order, in a diagonal arrangement; and Z slightly offset on the right side, below the large process of postcingular paraplate Vl (Fig.4). Apical and precingular processes are larger (A and li smaller than B and C, 2 and 5 smaller than 3 and 6), densely to loosely fibrous, sometimes fenestrate. They are commonly simple tubular, largely expanded distally in paintbrush-like fashion. Distal margin is irregularly recurved and spinous. Postcingulars are comparable to precingulars on ventral side (Ill, Vl) but larger, proximally tubular, more or less divided and largely expanded distally. On dorsal side (IV, V), processes are complexly divided, proximally arranged in an arcuate to soleate feature, opened towards the apex (Plate 1, 3, 9). The plate boundary between IV and V complexes is then situated in a middorsal position, facing the archeopyle (Fig.4).
Dimensions:
holotype maximum diameter: 123.5 µm,
maximum processes length: 39.5 µm
antapical protrusion: 14 µm
range maximum diameter: 103 (126) 152 µm
maximum processes length: 32.5 (41) 54 µm
antapical protrusion: 7 (13) 18.5 µm
periphragm thickness (without polar protrusion and process): 2.5-5.5 µm endophragm thickness: 1.5-2 µm 15 specimens measured.
Affinities:
At first sight, Bitubericysta is similar to Cordosphaeridium (Eisenack) Davey 1969: spheroidal shape, fibro-pitted to fibrous periphragm, intratabular position of processes reflecting a gonyaulacacean paratabulation pattern. Global aspect of processes compares well with C. exilimurum Davey and Williams in Davey et al. 1966. However, solid, periphragmal projections have never been described by authors on Cordosphaeridium: "not distinctive" apical and antapical processes are depicted by Davey (1969), or a slightly distinctive antapical process (longer) is mentioned by Sarjeant (1981). In fact, there are always small to great differences (polar features for example) between Bitubericysta and the few other fibrous dinocysts which seem to show some morphological resemblance with it (Table 1): Amphoro.sphaeridium Davey 1969 or Fibrocysta Stover and Evitt 1978, for example. As regards the paraplates organization, Bitubericysta proves close affinities with Danea (Morgenroth) Drugg, 1970, in spite of important morphological differences between the two genera (penitabular or intratabular septa frequent to dominant among projections on Danea dinocysts for example). As there are also morphological differences between Bituhericysta and the other "Danea-type" dinocysts (Damassa, 1984) like Turbiosphaera Archangelsky 1969 (Table 1), Bitubericysta will, perhaps, be considered as a new member of the Danea-group (Damassa, 1984)?