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Fibrocysta deflandrei
From Fensome et al., 2019:
Fibrocysta deflandrei (Lejeune-Carpentier, 1941, p.B84, fig.6) Lejeune-Carpentier and Sarjeant, 1981, p.14. Emendation: Lejeune-Carpentier and Sarjeant, 1981, p.14, as Fibrocysta? deflandrei. Holotype: Lejeune-Carpentier, 1941, fig.6; Lejeune-Carpentier and Sarjeant, 1981, pl.4, figs.5–6; text-fig.8. Originally Hystrichosphaeridium spinosum var. deflandrei, subsequently Baltisphaeridium spinosum var. deflandrei (Appendix A), thirdly Cordosphaeridium spinosum var. deflandrei (combination not validly published), fourthly Exochosphaeridium spinosum var. deflandrei, fifthly Exochosphaeridium spinosum subsp. deflandrei, sixthly Exochosphaeridium? spinosum subsp. deflandrei, seventhly (and now) Fibrocysta? deflandrei. Questionable assignment: Lejeune-Carpentier and Sarjeant (1981, p.14). Age: Late Cretaceous.
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Original description (Lejeune-Carpentier, 1941) (translated from French):
Another interesting case of fine shell sculpture is provided by our H. cf. spinosum var. Deflandrei. In this form (fig. 6), the topography of the spines is easy to visualize: apart from a few irregularities, it is a quincunx arrangement.
Towards the equatorial region, some appendages are attached along two parallel transverse lines; there is therefore a "belt," but it is not very visible since the fields that compose it are no smaller than the others.
Most of the polygonal fields of H. var. Deflandrei are only poorly delineated. Since their cocavity is smaller than that of the polygons of H. hirsutum, the fine shell sculpture is more accessible to observation. However, it did not reveal itself to us immediately; many specimens only reveal the fine punctuation" observed by G. Deflandre (1937; p. 78). At most, we see here and there a few lines of "dots," but they are not very long and quickly become entangled with each other.
This fine structure only became clear to us following the discovery of the remarkable fragment represented by our figure 7. This time again, it is a piece whose surface relief has become more visible due to the persistence of a little air inside. Upon immersion, we see lines of irregular grains that stand out in dark gray against an almost uniformly light background. And these lines radiate all around the spines in a fairly even manner. The appearance reproduces in short - by means of coarser and less tightly packed elements - that shown to us (1940) by the shell of certain Tubifera. The spines of this species are also less widely depressed than those of H. hirsutum. And since the crests are almost all equally weak, the "striated" territories are more apparent than the fields they compose. On the latter, most of which are triangular, the central meeting point of three different systems is often well marked. Moreover, in the most favorable places, we see that the two dark lines between which each of the crests is inscribed are doubly curved: they do not only rise in the immediate vicinity of the two spines they unite, but even more weakly, in the interval. We must therefore distinguish two segments, each of which belongs to a single radiating system. Under these conditions, the various systems are to be considered as entities no less distinct than the "striated" plates whose existence was obvious to us when we studied the Tubifera.
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Emended Diagnosis: Lejeune-Carpentier and Sarjeant 1981, p. 14, 15: Fibrocysta? deflandrei
Cyst broadly ellipsoidal, with a short, strong apical horn and a much less prominent, rather flattened antapical mamelon. Surface of phragma irregularly areolate, the elongation of the areolations around some processes suggesting a root-like structure. Processes non-tabular (or apparently so) and thornlike, broad and flattened at the base but tapering to an acute point their length shows some variation, but is always between one-third and one-half the shortest cyst diameter. Archaeopyle single-plate precingular (type P).
Dimensions Holotype: overall length of cyst 48 µm, length of apical horn 5 µm, height of antapical mamelon c. 2 µm, breadth of cyst 39 µm, length of processes up to 19 µm. Range of Dimensions: Overall length of cyst 36-49 µm, length of processes 14-21 µm.
Description: Lejeune-Carpentier and Sarjeant 1981, p. 14, 15: Fibrocysta? deflandrei
Our restudy showed that, instead of exhibiting the convergent web of rootlike extensions from process bases that the original figures (Lejeune~arpentier, 1941) suggest, the surface of the phragma has an irregular overall areolation with meshes of very variable size and shape. In some instances, these are indeed elongate and seem to converge on particular processes, so that their boundaries simulate roots; but in other instances, the meshes surrounding a process show no such relation to it, their shape instead appearing random.
The flattened bases of the spines are noteworthy, suggesting possible alignment along a reflected suture; but no pattern of process distribution could be elucidated and they must for the moment be regarded as non-tabular. The spines arising on and about the apical horn give a bifid appearance to that structure in some specimens: but this varies according to position.
Remarks: Lejeune-Carpentier and Sarjeant 1981, p. 14, 15
White's illustrations of Xanthidium (now Exochosphaeridium) spinosum (1842) depict a more rotund form, with processes of dissimilar morphology and without apical or antapical protuberances. Our restudy makes it evident that the Belgian forms are certainly not conspecific, and indeed not even congeneric, with White's specimens. Since a survey of the literature has brought to light no species that is exactly comparable, the former variety deflandrei is here elevated to specific status.
In its overall shape, polar protrusions and possession of hollow, non tabular processes, this species accords with the diagnosis of Fibrocysta and in particular resembles F. Iappacea (Drugg, 1970) Stover and Evitt, 1978. However, it lacks the fibrous processes, with expanded or branching tips, characteristic of that genus, instead having pointed processes that are not evidently fibrous. Moreover, though the overall shape is strikingly similar to that of F. Iappacea, the processes are much longer and slimmer and the single-plate precingular archaeopyle appears less broad (though this may be a result of orientation). The species deflandrei is thus placed only tentatively into Fibrocysta and may shortly merit transfer to another genus yet undescribed.
Fibrocysta deflandrei (Lejeune-Carpentier, 1941, p.B84, fig.6) Lejeune-Carpentier and Sarjeant, 1981, p.14. Emendation: Lejeune-Carpentier and Sarjeant, 1981, p.14, as Fibrocysta? deflandrei. Holotype: Lejeune-Carpentier, 1941, fig.6; Lejeune-Carpentier and Sarjeant, 1981, pl.4, figs.5–6; text-fig.8. Originally Hystrichosphaeridium spinosum var. deflandrei, subsequently Baltisphaeridium spinosum var. deflandrei (Appendix A), thirdly Cordosphaeridium spinosum var. deflandrei (combination not validly published), fourthly Exochosphaeridium spinosum var. deflandrei, fifthly Exochosphaeridium spinosum subsp. deflandrei, sixthly Exochosphaeridium? spinosum subsp. deflandrei, seventhly (and now) Fibrocysta? deflandrei. Questionable assignment: Lejeune-Carpentier and Sarjeant (1981, p.14). Age: Late Cretaceous.
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Original description (Lejeune-Carpentier, 1941) (translated from French):
Another interesting case of fine shell sculpture is provided by our H. cf. spinosum var. Deflandrei. In this form (fig. 6), the topography of the spines is easy to visualize: apart from a few irregularities, it is a quincunx arrangement.
Towards the equatorial region, some appendages are attached along two parallel transverse lines; there is therefore a "belt," but it is not very visible since the fields that compose it are no smaller than the others.
Most of the polygonal fields of H. var. Deflandrei are only poorly delineated. Since their cocavity is smaller than that of the polygons of H. hirsutum, the fine shell sculpture is more accessible to observation. However, it did not reveal itself to us immediately; many specimens only reveal the fine punctuation" observed by G. Deflandre (1937; p. 78). At most, we see here and there a few lines of "dots," but they are not very long and quickly become entangled with each other.
This fine structure only became clear to us following the discovery of the remarkable fragment represented by our figure 7. This time again, it is a piece whose surface relief has become more visible due to the persistence of a little air inside. Upon immersion, we see lines of irregular grains that stand out in dark gray against an almost uniformly light background. And these lines radiate all around the spines in a fairly even manner. The appearance reproduces in short - by means of coarser and less tightly packed elements - that shown to us (1940) by the shell of certain Tubifera. The spines of this species are also less widely depressed than those of H. hirsutum. And since the crests are almost all equally weak, the "striated" territories are more apparent than the fields they compose. On the latter, most of which are triangular, the central meeting point of three different systems is often well marked. Moreover, in the most favorable places, we see that the two dark lines between which each of the crests is inscribed are doubly curved: they do not only rise in the immediate vicinity of the two spines they unite, but even more weakly, in the interval. We must therefore distinguish two segments, each of which belongs to a single radiating system. Under these conditions, the various systems are to be considered as entities no less distinct than the "striated" plates whose existence was obvious to us when we studied the Tubifera.
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Emended Diagnosis: Lejeune-Carpentier and Sarjeant 1981, p. 14, 15: Fibrocysta? deflandrei
Cyst broadly ellipsoidal, with a short, strong apical horn and a much less prominent, rather flattened antapical mamelon. Surface of phragma irregularly areolate, the elongation of the areolations around some processes suggesting a root-like structure. Processes non-tabular (or apparently so) and thornlike, broad and flattened at the base but tapering to an acute point their length shows some variation, but is always between one-third and one-half the shortest cyst diameter. Archaeopyle single-plate precingular (type P).
Dimensions Holotype: overall length of cyst 48 µm, length of apical horn 5 µm, height of antapical mamelon c. 2 µm, breadth of cyst 39 µm, length of processes up to 19 µm. Range of Dimensions: Overall length of cyst 36-49 µm, length of processes 14-21 µm.
Description: Lejeune-Carpentier and Sarjeant 1981, p. 14, 15: Fibrocysta? deflandrei
Our restudy showed that, instead of exhibiting the convergent web of rootlike extensions from process bases that the original figures (Lejeune~arpentier, 1941) suggest, the surface of the phragma has an irregular overall areolation with meshes of very variable size and shape. In some instances, these are indeed elongate and seem to converge on particular processes, so that their boundaries simulate roots; but in other instances, the meshes surrounding a process show no such relation to it, their shape instead appearing random.
The flattened bases of the spines are noteworthy, suggesting possible alignment along a reflected suture; but no pattern of process distribution could be elucidated and they must for the moment be regarded as non-tabular. The spines arising on and about the apical horn give a bifid appearance to that structure in some specimens: but this varies according to position.
Remarks: Lejeune-Carpentier and Sarjeant 1981, p. 14, 15
White's illustrations of Xanthidium (now Exochosphaeridium) spinosum (1842) depict a more rotund form, with processes of dissimilar morphology and without apical or antapical protuberances. Our restudy makes it evident that the Belgian forms are certainly not conspecific, and indeed not even congeneric, with White's specimens. Since a survey of the literature has brought to light no species that is exactly comparable, the former variety deflandrei is here elevated to specific status.
In its overall shape, polar protrusions and possession of hollow, non tabular processes, this species accords with the diagnosis of Fibrocysta and in particular resembles F. Iappacea (Drugg, 1970) Stover and Evitt, 1978. However, it lacks the fibrous processes, with expanded or branching tips, characteristic of that genus, instead having pointed processes that are not evidently fibrous. Moreover, though the overall shape is strikingly similar to that of F. Iappacea, the processes are much longer and slimmer and the single-plate precingular archaeopyle appears less broad (though this may be a result of orientation). The species deflandrei is thus placed only tentatively into Fibrocysta and may shortly merit transfer to another genus yet undescribed.