CATALOG OF ORIGINAL DESCRIPTIONS: Globigerinoita morugaensis Brönnimann 1952

This page provides data from the catalog of type descriptions. The catalog is sorted alphabetically. Use the current identification link to go back to the main database.


Higher levels: pf_cat -> G -> Globigerinoita -> Globigerinoita morugaensis
Other pages this level: G. morugaensis

Globigerinoita morugaensis

Citation: Globigerinoita morugaensis Brönnimann 1952
Rank: species
Type locality: Globorotalia menardii Zone, Lengua formation, Basal Miocene, Moruga area, Trinidad,B.W.1.
Type age (chronostrat): Basal Miocene
Type specimens: PR3913
Type repository: Washington; USNM

Linked specimens: USNM-3913 USNM-3212

Current identification:


Original Description
The  trochoidal test  is three  chambered in  the  adult. The small  initial portion is  indistinct,coarsely  cancellated, and  it  is almost  impossible to recognize  the  individual  early  chambers  and  the details  of  arrangement.  The subglobular  chambers  are  rapidly increasing  in  size  and the ultimate  chamber  is  peripherally  slightly flattened.  The large semicircular  umbilical main  aperture  lies  at  the  intersection of  the three sutures  of the end  chambers.  In addition, a  small rounded auxiliary  Globigerinoides  aperture  exists,  almost opposite the main aperture,  in  the  corner  between the  initial portion  and  the  two last chambers. Due to  the masking  effect of adhering matrix,  the  smalI  Globigerinoides  aperture  is not  always  visible.  Occasionally, and  only discernible under  higher  magnification,  a minute covering  plate across  the  Globigerinoides  aperture  can  be seen.  In  grown  up  individuals, this plate  develops into a  low chamberlike  growth. 

All the  investigated  specimens are characterized  by  low  to  slightly  inflated supplementary  chamberlike  growths. The following  types of  arrangement  can  be  distinguished: 
a)  Across  umbilicus,  covering  the  main  aperture  with 3  small  semicircular openings  situated  at  the  sutures. Present  in ail  individuals. 
b)  Across  umbilicus  as  described  above,  and  additional  similarly  structured  growth  issuing  from the  Globigerinoides aperture. 
The  normal  adult  test  shows  this  dual growth  across  umbilicus and  over the  Globigerinoides  aperture.  It is the  pre-dominant type  of  arrangement. 
c)  Two  chamberlike growths as  described  in b.  The  one  over  the  umbilicus  is  spreading  along  the  sutures  forming  3  small,  low  "chamberlets,"  separated  from  the  main growth  by straight incisions.  Each of the  new  "chamberlets" carries  three  small  semicircular  openings. This type  is only  rarely  encountered. 

The aperture of  the adult Globigerinoita is multiple  and  in  the typical  case  with maximum  6  small  semicircular  openings.  In  individuals  with complex  growths  as  described  above, the maximum  number of openings  is 12.  The  openings have minute  liplike  borders. The  walls  of  the  preceding Globigerinoides  chambers are  thicker  and  the pores coarser  than  those  of  the  supplementary "chambers,"  which  occasionally  are  transparent.

The  proportion  of  left  and  right  hand  coiling  specimens  is  about 2:1 (19 specimens counted).  The  species  has  been  encountered  in  only one  sample.  The  specimens  are common  and  well  preserved.

Size: The maximum diameter of the test, including the chamberlike growth, was measured in 10 individuals. It varies from 220µ to 315µ

Etymology: The species is named after the district of Moruga, South Trinidad.

References:

Brönnimann, P. (1952a). Globigerinoita and Globigerinatheka, new genera from the Tertiary of Trinidad, B.W.I. Contributions from the Cushman Foundation for Foraminiferal Research. 3(1): 25-28. gs V O


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Globigerinoita morugaensis compiled by the pforams@mikrotax project team viewed: 23-7-2021

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