Cassigerinella


Classification: pf_cenozoic -> microperforate -> Cassigerinellidae -> Cassigerinella
Sister taxa: Cassigerinella, Tenuitella,
Daughter taxa (blue => in age window 0-300Ma)
Differs from C. eocaenica by having a broader and more globular test and a planispirally or pseudoplanispirally enrolled coiling mode rather than a biserially enrolled coiling mode.
Differs from C. chipolensis and C. boudecensis by its smaller size, more compressed test, less inflation of the chambers, slower chamber size increase, and lower and broader aperture.

Taxonomy

Citation: Cassigerinella Pokorny, 1955, emended Li, 1986
Rank: Genus
Type species: Cassigerinella boudecensis Pokorny, 1955
Synonyms:
Taxonomic discussion: The confused state of the taxonomy of species referred to Cassigerinella was thoroughly discussed by Li (1986). According to Pokorny (1955), the type species, C. boudecensis ( =chipolensis), is characterized by having an initial planispiral stage and presence of a continuously extended toothplate structure. However, Li (1986) demonstrated that the initial chambers of C. boudecensis Pokorny and Cassigerinella chipolensis (Cushman and Ponton) are biserially arranged on a rotating coiling plane, and that species included in the genus possess a variably developed apertural rim or flange rather than a true toothplate.
Li’s (1986) dissections of C. boudecensis and C. chipolensis reveal that their wall microstructure is composed of monolamellar, randomly arranged microgranules that may be optically radial. The wall surface texture of Cassigerinella may be smooth and/or with scattered perforation cones.
Evidence that Cassigerinella lived a planktonic mode of life is partly based on morphological features, such as its inflated test with globular chambers and presence of pore mounds, a feature not found in benthic species. Of the species included in this genus, only C. chipolensis has a distribution that is typical of planktonic species, as it is widespread and it is abundant in deep sea sediments. Boersma and Shackleton (1978) confirmed a near surface habitat for this species based on their oxygen and carbon isotope analyses.
SEM observation of the holotype of Cassigerinella winniana (Pl. 16.4, Figs. 13-15) reveals the presence of pustules concentrated only in the umbilicus, which is a common feature in benthic foraminifera but not characteristic of planktonic foraminifera. Dissection of specimens assigned to winniana reveals a blocky wall microstructure that is characteristic of rotaliid benthic foraminifera (Pl. 16.4, Fig. 17). For these reasons, and because of its restriction to nearshore paleoenvironments, winniana is now considered a benthic taxon and is assigned to the genus Cassidulina. [Huber et al. 2006]

Catalog entries: Cassigerinella; Riveroinella;

Type images:

NB The short diagnoses are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus. They have initially been copied from the diagnostic characters/distinguishing features sections of the Eocene and Paleocene Atlases, they will be edited as the site is developed.

Description


Wall type: wall calcareous, optically radial but granular in structure, sparsely pierced by small perforations; pores simple or surrounded by protruding rim-like pore-cones; [Huber et al. 2006]

Test morphology: “Test small, nearly planispiral or irregularly coiled in the first few chambers, becoming low trochospiral in adult; always biserial-enrolled with the chambers alternating in arrangement in the coiling plane (as in Cassidulina); chambers 6-8 per whorl, relatively compressed and compactly together in early ontogeny but usually becoming strongly inflated, ovate to semiglobular in last whorl; aperture interiomarginally alternating, asymmetrical, highly arched to virguline in shape, without toothplate structure, but often with apertural rims or laterally asymmetrical flanges more- or-less developed.” (Li, 1986, p. 60-61).
[Huber et al. 2006]

Biogeography and Palaeobiology


Phylogenetic relations: Because of the absence of a true umbilicus and an assumed planktonic mode of life, Blow (1979) suggested Cassigerinella should be placed in the Heterohelicidae. This proposal was later adopted by Kennett and Srinivasan (1983). Li (1986) included the Cassigerinellidae in the Heterohelicaceae based on the presence of the biserial enrolled test, microperforate wall microstructure, occasional presence of perforation cones, and high apertures with asymmetrical flanges. We follow Li’s (1986) classification rather than that of Loeblich of Tappan (1988), who placed the Cassigerinellidae along with normal perforate genera within the Hantkeninaceae. [Huber et al. 2006]

Biostratigraphic distribution

Geological Range:
Notes: Middle Eocene-middle Miocene (Zones E13-M13a). [Huber et al. 2006]
Last occurrence (top): within Messinian Stage (5.33-7.25Ma, top in Messinian stage). Data source: Total of range of species in this database
First occurrence (base): within Bartonian Stage (37.75-41.15Ma, base in Bartonian stage). Data source: Total of range of species in this database

Plot of occurrence data:

Primary source for this page: Huber et al. 2006 - Atlas of Eocene Planktonic Foraminifera, chapter 16, p. 484

References:

Blow, W.H., (1979). The Cainozoic Globigerinida: A study of the morphology, taxonomy, evolutionary relationships and stratigraphical distribution of some Globigerinida (mainly Globigerinacea). E. J. Brill, Leiden, 1413 pp.

Boersma, A. & Shackleton, N.J., (1978). Oxygen and carbon isotope record through the Oligocene, Site 366 (equatorial Atlantic). Initial Reports of the Deep Sea Drilling Project, 41: 957-962.

Huber, B.T.; Olsson, R.K. & Pearson, P.N., (2006). Taxonomy, biostratigraphy, and phylogeny of Eocene microperforate planktonic foraminifera (Jenkinsina, Cassigerinelloita, Chiloguembelina, Streptochilus, Zeauvigerina, Tenuitella, and Cassigerinella) and Problematica (Dipsidripella). In: Pearson, P.N. et al. (Editors), Atlas of Eocene Planktonic Foraminifera, Cushman Foundation Special Publication 41. Cushman Foundation Special Publication. Allen Press, Lawrence, Kansas, pp. 461-508.

Kennett, J.P. & Srinivasan, M.S., (1983). Neogene Planktonic Foraminifera. Hutchinson Ross Publishing Co., Stroudsburg, Pennsylvania, 1-265 pp.

Li 1986 [sorry, not in our bibliography yet]

Pokorny, V., (1955). Cassigerinella boudecensis, n. gen., n. s.p. (Foraminifera, Protozoa) from the Oligocene of the Zdanice Flych). Vestnik UUG, 30: 136-140.

Tappan 1988 [sorry, not in our bibliography yet]


Cassigerinella compiled by the pforams@mikrotax project team viewed: 30-5-2017

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