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Alisogymnium deflandrei
From Fensome et al., 2019:
Alisogymnium deflandrei, (Boltenhagen, 1977, p.67–68, pl.9, figs.1b–c,2a–b,3a–b,4a–b) Lentin and Vozzhennikova, 1990, p.28.
Holotype: Boltenhagen, 1977, pl.9, figs.1b–c; Lentin and Vozzhennikova, 1990, Appendix A, fig.31.
Originally Dinogymnium, subsequently (and now) Alisogymnium.
Age: late Senonian.
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Original description: [Boltenhagen, 1977] (translated from French):
Dinogymnium deflandrei nov. sp.
DIAGNOSIS
Inframicroreticulate or microgranular theca, formed by a conical epitheca with an ogival apex and not a hemispherical hypotheca, a wide cingulum shifted towards the antapex, a sulcus extending halfway down the hypotheca; ribs only on the epitheca and in small numbers; apical archaeopyle "wedge-shaped".
DESCRIPTION
The roughly pear-shaped theca of our specimens is more or less oval in outline, depending on whether the specimen is spread out or laterally compressed; the ratio of the polar axis to the diameter is thus between 1.1 and 1.4. The resistant wall of the theca appears smooth or punctuated at 320x magnification. At 800x magnification, depending on the specimen, infrareticularity or infragranulation appears. Small corpuscles are also visible on the surface of one of the specimens studied. The theca is divided by a wide, circular cingulum into two unequal portions, such that the cingulum coefficient (CI) is between 52 and 59 (based on measurements of 9 specimens). The sulcus extends halfway down the hypotheca and forms a notch on the epitheca above the cingulum. The archaeopyle located on the apex has zigzagging edges.
OBSERVATIONS
This species is fairly common and generally well preserved.
DIMENSIONS
Holotypes: theca L x W = 44 x 39μ.
cingulum W = 51; CI = 52
Paratypes (in order of appearance):
L x W = 46 x 35 μ; 53 x 37 μ; 53 x 33 μ
cingulum W = 5 - 6 μ - 5 - 6 μ - 5 μ
CI = 59 - 53 - 53
Other specimens:
theca L = 46 to 52 μ - 1 = 36 to 44 μ
COMPARISON
By the presence of ribs only on the epithecium, this species resembles D. evittii described above. It is distinguished by its general shape, the hypotheca being smaller than the epitheca, the deeper cingulum, the resistant wall, and the larger size.
Alisogymnium deflandrei, (Boltenhagen, 1977, p.67–68, pl.9, figs.1b–c,2a–b,3a–b,4a–b) Lentin and Vozzhennikova, 1990, p.28.
Holotype: Boltenhagen, 1977, pl.9, figs.1b–c; Lentin and Vozzhennikova, 1990, Appendix A, fig.31.
Originally Dinogymnium, subsequently (and now) Alisogymnium.
Age: late Senonian.
---------------------------------------------------------------------------------------------------
Original description: [Boltenhagen, 1977] (translated from French):
Dinogymnium deflandrei nov. sp.
DIAGNOSIS
Inframicroreticulate or microgranular theca, formed by a conical epitheca with an ogival apex and not a hemispherical hypotheca, a wide cingulum shifted towards the antapex, a sulcus extending halfway down the hypotheca; ribs only on the epitheca and in small numbers; apical archaeopyle "wedge-shaped".
DESCRIPTION
The roughly pear-shaped theca of our specimens is more or less oval in outline, depending on whether the specimen is spread out or laterally compressed; the ratio of the polar axis to the diameter is thus between 1.1 and 1.4. The resistant wall of the theca appears smooth or punctuated at 320x magnification. At 800x magnification, depending on the specimen, infrareticularity or infragranulation appears. Small corpuscles are also visible on the surface of one of the specimens studied. The theca is divided by a wide, circular cingulum into two unequal portions, such that the cingulum coefficient (CI) is between 52 and 59 (based on measurements of 9 specimens). The sulcus extends halfway down the hypotheca and forms a notch on the epitheca above the cingulum. The archaeopyle located on the apex has zigzagging edges.
OBSERVATIONS
This species is fairly common and generally well preserved.
DIMENSIONS
Holotypes: theca L x W = 44 x 39μ.
cingulum W = 51; CI = 52
Paratypes (in order of appearance):
L x W = 46 x 35 μ; 53 x 37 μ; 53 x 33 μ
cingulum W = 5 - 6 μ - 5 - 6 μ - 5 μ
CI = 59 - 53 - 53
Other specimens:
theca L = 46 to 52 μ - 1 = 36 to 44 μ
COMPARISON
By the presence of ribs only on the epithecium, this species resembles D. evittii described above. It is distinguished by its general shape, the hypotheca being smaller than the epitheca, the deeper cingulum, the resistant wall, and the larger size.