Planomalina cheniourensis Sigal 1952 from: Caron, M. (1985): Cretaceous planktic foraminifera. In: Plankton stratigraphy Eds: Bolli, H.M.Saunders, J.B.Perch-Nielsen, K. p. 17–86 . |
Notice: This catalogue page may contain unedited data.
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Species Planomalina cheniourensis Sigal 1952 |
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Discussion / Comments: |
Caron (1985):
It differs from P. buxtorfi in its more numerous chambers and absence of a peripheral keel in the last 3-4 chambers.
Bellier & Moullade (2002):
Our Leg 171B material permitted us to follow step
by step the direct evolutionary linkage from Globigerinelloides
algerianus (cf. PI. 3, fig. 1-3) to Planomalina
cheniourensis, as suggested by Caron (1985), by
the progressive acquisition of peripheral muricocarinae
on the earhest, and then most, chambers in the
last whorl. Conversely, BouDagher-Fadel et al.
(1997) assume that P. cheniourensis "according to
our phylogeny.., must have evolved from a macroperforate
AlanlordeUa...". Our observations show
that all Leg 171B specimens belonging to this species
are microperforate, as well as those of their phylogenetic
ancestor, G. algerianus. The type-species of the
genus Planomalina (P. apsidostroba, junior synonym
of the Vraconian P. buxtorfi) being macroperforate
(cf. P1. 3, fig. 8-10), the taxon P. cheniourensis
cannot belong to the same genus, according to the
pre-eminent taxonomic ranking given by BouDagher-
Fadel et al. (1997) using their microstructural
criterion. Planomalina cheniourensis cannot belong
to Globigerinelloides as well, since this genus is restricted
to globular-chambered forms, devoid of muricocarinae.
The taxonomic decisions which are needed
at the generic level will be detailed in a further
paper (Moullade et al., submitted).
Boudagher-Fadel et al. (1997):
Remarks: This species differs from P. buxtor-
(Gandolfi) by its more numerous chambers (twelve
chambers in the last whorl) and absence of peripheral
muricocarina on the last three chambers.
According to our phylogeny (Figure 5.2), this
species must have evolved from a macroperforate
Alanlordella (which, as we have seen, can have
muricocarina on the earliest chambers of the last
whorl), but presumably not from A. bentonensis,
from which the P. buxtor- lineage is thought to
have derived (see further discussion under A. praebuxtor-
(Wonders), pp. 214, 246). Although we
have retained this species in the fully muricocarinate
Planomalina, as we have said before
(p. 211), the transition between these genera is
essentially gradual and arbitrary. Nevertheless this
phylogeny is at variance with that suggested by
Caron (1985) who would derive P. cheniourensis
from Globigerinelloides algerianus Cushman
and Ten Dam by progressive acquisition of the
peripheral keel. |
Systematics: |
5 Classis Foraminifera
Familia Planomalinidae
Genus Planomalina
Species Planomalina cheniourensis
22 Superfamilia Globigerinaceae
Familia Planomalinidae
Genus Planomalina
Species Planomalina cheniourensis
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Synonym list: |
Caron (1985):
Bellier & Moullade (2002):
Boudagher-Fadel et al. (1997):
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Was used in synonym list of: |
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References: |
Sigal,J. (1952): Apercu stratigraphique sur la Micropaléontologie du Crétacé . XIXe Congrès Géologique International (Série 1), Alger Vol. 26 p. 3-47
Moullade,M. (1966): Etude stratigraphique et micropaléontologique du Crétacé inférieur de la "fosse vocontienne" . Documents des Laboratoires de Géologie de la Faculté des Sciences de Lyon Vol. 15 p. 1-369
Leckie,M.R. (1984): Mid-Cretaceous planktonic foraminiferal biostratigraphy off Morocco, Deep Sea Drilling Project Leg 79, Sites 545 and 547 . Initial Reports of the Deep Sea Drilling Project Vol. 79 p. 579–620
Caron,M. (1985): Cretaceous planktic foraminifera. In: Plankton stratigraphy Eds: Bolli, H.M.Saunders, J.B.Perch-Nielsen, K. p. 17–86
Boudagher-Fadel,M.K.; Banner,F.T. and Whittaker,J.E. (1997): The early evolutionary history of planktonic foraminifera. p. 296
Boudagher-Fadel,M.K.; Banner,F.T.; Whittaker,J.E. and Simmons,M.D. (1997): Early Evolutionary History of Planktonic Foraminifera. Vol. 1
Bellier,J.P. and Moullade,M. (2002): Lower Cretaceous Planktonik Foraminiferal Biostratigraphy Of The Western North Atlantic (ODP LEG 171B), And Taxonomic Clarification Of Key Index Species . Revue de Micropaleontologie Vol. 45(1) p. 9-26
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