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Microhedbergella albiana


Classification: pf_mesozoic -> Hedbergellidae -> Microhedbergella -> Microhedbergella albiana
Sister taxa: M. albiana, M. intermedia, M. miniglobularis, M. praeplanispira, M. pseudodelrioensis, M. pseudoplanispira, M. pseudotrocoidea, M. renilaevis, M. rischi, M. sp.,

Taxonomy

Citation: Microhedbergella albiana (Boudagher-Fadel et al., 1996)
Rank: Species
Basionym: Blefuscuiana albiana

Type images:

Original description: Test about 0.22-0.29 mm at its maximum diameter. This taxon comprises at least two whorls of subglobular chambers coiled in a low trochospire, and a slightly concave spiral side. It has five chambers in the last whorl. The chambers are high throughout the test. The wall is smooth; the microperforations of B. albiana are irregularly spaced and about 2 pm in diameter (twice as large as those of B. aptiana but half the size of those of true H edbergella - see BouDagher-Fadel et al., in press). The umbilicus is small (as in B. infracretacea), and is about 18 to 20% of the ventral test diameter. The apertu re is a narrow slit bordered by a thin porticus.



Later Redescrption (copied from Chronos webste): B. albiana has five subglobular chambers in the last whorl, which enlarge rapidly with growth, so that the addition of a new whorl increases the dorsal test diameter by almost twice. The umbilicus is small, as in B. infracretacea and is about 18 to 20% of the ventral test diameter. The aperture is slit-like with a thin porticus. The wall is smooth; the microperforations are irregularly spaced and are about 2 microns in diameter (twice as large as those of B. aptiana (Bartenstein) s.l. but about half the size as those of a true Hedbergella). There appears to be a slight but progressive increase in test size from B. aptiana (Bartenstein) s.s. (190-270 microns) and B. aptiana (Bartenstein) orientalis BouDagher-Fadel et al. (210-270 microns) in the Aptian to B. albiana (220-290 microns) in the Albian. It has already been suggested that B. albiana evolved from B. aptiana s.s. above the base of the Albian (BouDagher-Fadel et al., 1996).

Entries in the Catalog of original descriptions: Blefuscuiana albiana

Geological Range:
Last occurrence (top): within P. appenninica zone (100.50-101.92Ma, top in Albian stage). Data source: [copied from Chronos database]
First occurrence (base): within H. planispira zone (111.84-113.26Ma, base in Aptian stage). Data source: [copied from Chronos database]

Plot of occurrence data:

Dec 2017 - Plotting of Neptune data has been re-enabled on the Mesozoic pages following revision of the age-models in Neptune. The data is, however, still very sparse for the Early Cretaceous

  • (NB There is no histogram as there are no occurrence records for the taxon in the Neptune database) Parent: Microhedbergella

    Character matrix

    test outline:Lobatechamber arrangement:Trochospiraledge view:Inequally biconvexaperture:Umbilical-extraumbilical
    sp chamber shape:Inflatedcoiling axis:Lowperiphery:N/Aaperture border:Thin porticus
    umb chbr shape:Inflatedumbilicus:Narrowperiph margin shape:Broadly roundedaccessory apertures:None
    spiral sutures:Strongly depressedumb depth:Shallowwall texture:Finely pustuloseshell porosity:Finely Perforate: 1-2.5µm
    umbilical or test sutures:Strongly depressedfinal-whorl chambers:4.5-5.5 N.B. These characters are used for advanced search. N/A - not applicable

    References:

    BouDagher-Fadel, M. K., Banner, F. T., Gorbachik, T. N., Simmons, M. D. & Whittaker, J. E. (1996). Evolution in the Early Cretaceous planktonic foraminiferal genus Blefuscuiana. Neues Jahrbuch für Geologie und Palaeontologie Abhandlungen. 201(2): 243-258. gs

    BouDagher-Fadel, M. K., Banner, F. T. & Whittaker, J. E. (1997). The Early Evolutionary History of Planktonic Foraminifera. Chapman and Hall, London. -. gs


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    Microhedbergella albiana compiled by the pforams@mikrotax project team viewed: 13-11-2019

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    Short stable page link: http://mikrotax.org/pforams/index.php?id=110347 Go to Archive.is to create a permanent copy of this page - citation notes



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