Chiloguembelina morsei

Classification: pf_cenozoic -> microperforate -> Chiloguembelinidae -> Chiloguembelina -> Chiloguembelina morsei
Sister taxa: C. cubensis, C. ototara, C. parallela, C. trinitatensis, C. wilcoxensis, C. crinita, C. subtriangularis, C. midwayensis, C. morsei, C. sp.,


Citation: Chiloguembelina morsei (Kline 1943)
Rank: Species
Basionym: Guembelina morsei
Taxonomic discussion: The gross morphology of Chiloguembelina morsei is very similar to that of Chiloguembelina midwayensis. Loeblich and Tappan (1957a) suggested that C. morsei can be distinguished from C. midwayensis sensu stricto by the former's narrower test, more globular chambers, and more deeply constricted sutures. The two taxa are most readily distinguished by the narrowness of their tests; the chambers of C. morsei expand less rapidly in breadth than those of C. midwayensis. Consequently, the periphery of the former defines a more acute angle (~50°) than that of the latter (~60°). Forms intermediate between C. morsei and C. midwayensis have been illustrated as C. midwayensis by D'Hondt (1991:173, pl. 2: figs. 13, 15). [Olsson et al. 1999]

Catalog entries: Guembelina morsei;

Type images:

Distinguishing features: The test biserial throughout. Sutures are distinct and depressed, initially sub-horizontal, oblique between later chambers. Successive chambers overlap, particularly in late ontogeny. Initial chambers sub-spherical, later chambers broader Wall surface with numerous small pustules, especially on early chambers. Aperture with a single distinct lateral flange.

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.


Diagnostic characters: The test is biserial throughout. Sutures are distinct and depressed. Basal sutures that separate the earliest chambers are sub-horizontal, whereas those that separate the later chambers are oblique. Successive chambers overlap, particularly in late ontogeny. The initial chambers are sub-spherical. As chamber breadth increases more rapidly than chamber depth, each successive chamber exhibits a greater breadth to depth ratio than its predecessor. Consequently, the maximum breadth of each late-stage chamber is greater than its maximum depth. The surface of the holotype test is marked by numerous small pustules. These pustules are less abundant on the final chambers. The aperture of each chamber exhibits only one distinct lateral flange. [Olsson et al. 1999]

Character matrix

test outline:Triangularchamber arrangement:Biserialedge view:Equally biconvexaperture:Terminal
umb chamber shape:Inflatedcoiling axis:N/Aperiphery:N/Aaperture border:Thick flange
sp chbr shape:N/Aumbilicus:N/Aperiph margin shape:Moderately roundedaccessory apertures:None
umbilical or test sutures:Strongly depressedumb depth:N/Awall texture:Spinoseshell porosity:
spiral sutures:N/Adiameter mm:width mm:-breadth mm:-
final-whorl chambers:2.0-2.0

Biogeography and Palaeobiology

Geographic distribution: Low and middle latitudes (Boersma, 1984b; D'Hondt and Keller, 1991). [Olsson et al. 1999]

Isotope paleobiology: No data available. [Olsson et al. 1999]

Phylogenetic relations: Chiloguembelian morsei evolved from a Woodringina species in Zone P a (D'Hondt, 1991; Liu and Olsson, 1992). [Olsson et al. 1999]

Most likely ancestor: Woodringina hornerstownensis - at confidence level 3 (out of 5). Data source: Olsson et al. 1999 fig6, Koutsoukos 2014, fig16.

Biostratigraphic distribution

Geological Range:
Notes: Zone P a (D'Hondt, 1991) to Subzone Pic (Boersma, 1984b). [Olsson et al. 1999]
Last occurrence (top): within P1c subzone (62.60-63.90Ma, top in Danian stage). Data source: Olsson et al. 1999
First occurrence (base): within Pa zone (65.72-66.00Ma, base in Danian stage). Data source: Olsson et al. 1999

Plot of occurrence data:

Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 91


Olsson, R.K.; Hemleben, C.; Berggren, W.A. & Huber, B.T., (1999). Atlas of Paleocene Planktonic Foraminifera. Smithsonian Contributions to Paleobiology, 85. Smithsonian Institution Press, Washington, DC, 1-252 pp.


Chiloguembelina morsei compiled by the pforams@mikrotax project team viewed: 22-3-2018

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