nmn

Paracostellagerina


Classification: pf_mesozoic -> Hedbergellidae -> Paracostellagerina
Sister taxa: Asterohedbergella, Clavihedbergella, Costellagerina, Falsotruncana, Hedbergella, Helvetoglobotruncana, Liuenella, Microhedbergella, Muricohedbergella, Paracostellagerina, Paraticinella, Praeglobotruncana, Pseudoguembelitria, Whiteinella,
Daughter taxa (blue => in age window 0-300Ma)

Specimens which cannot be assigned to established species

Taxonomy

Citation: Paracostellagerina Georgescu and Huber 2006
Rank: Genus
Basionym: Hedbergella libyca
Type species: Hedbergella libyca Barr, 1972
Taxonomic discussion: The genus Paracostellagerina nov. gen. is proposed to accommodate hedbergellid taxa bearing asymmetrical test ornamentation, with meridional costellae on the umbilical side and costellae oriented parallel to the periphery on the spiral side. Test ornamentation is a peculiar feature of the genus, with transitional forms being recently placed in a new species Hedbergella praelibyca by Petrizzo and Huber (2006). The asymmetric test ornamentation and extraumbilicalumbilical primary aperture separate Paracostellagerina nov. gen. from the early Santonian-early Campanian genus Costellagerina. The latter generally has a meridional ornamentation pattern on both sides of the test, although variations in test ornamentation were observed by Huber (1994).
Differences in test ornamentation, position of the primary aperture, and nature of the periapertural structures provide the impetus to distinguish Hedbergella libyca and Rugoglobigerina pilula as the type species of the two monospecific genera Paracostellagerina nov. gen. and Costellagerina. The two species were considered congeneric in the past by Loeblich and Tappan (1988, p. 462) and Premoli Silva and Sliter (1995, pl. 1, fig. 8) under Costellagerina, and by El-Nakhal (2002) under his genus Meridionalla. Meridionalla was based on the figures of the holotype of Hedbergella murphyi, which was named by Douglas (1969). Re-examination of the SEM photographs of the Hedbergella murphyi holotype by Petrizzo and Premoli Silva (2000) showed that there is no meridional ornamentation as was illustrated in the original figure. Therefore Meridionalla lacks taxonomic significance. Separation of Costellagerina and Paracostellagerina nov. gen. is supported by absence of forms with similar test morphology between the extinction of Paracostellagerina libyca and the first occurrence of Costellagerina pilula. This stratigraphic interval ranges from the earliest Cenomanian to the earliest Santonian and spans approximately 13 myr.

Type images:

Original description: Paracostellagerina: Test low to moderate trochospiral, globular chambers with a broadly rounded periphery, lacking peripheral structures;
primary aperture extraumbilical-umbilical, bordered by a narrow, imperforate lip; test ornamentation asymmetrical with respect to the peripheral plane, rugosities and sharp costellae arranged following a meridional pattern on the umbilical side, and parallel to the periphery on the spiral side.

Entries in the Catalog of original descriptions: Paracostellagerina;

Short diagnosis: Test low to moderate trochospiral, globular chambers with a broadly rounded periphery, lacking peripheral structures; primary aperture extraumbilical-umbilical, bordered by a narrow, imperforate lip; test ornamentation asymmetrical with respect to the peripheral plane, rugosities and sharp costellae arranged following a meridional pattern on the umbilical side, and parallel to the periphery on the spiral side.

Geological Range:
Last occurrence (top): within Cenomanian Stage (93.90-100.50Ma, top in Cenomanian stage). Data source: Total of range of species in this database
First occurrence (base): within Albian Stage (100.50-112.95Ma, base in Albian stage). Data source: Total of range of species in this database

Plot of occurrence data:

NB Plotting of Neptune data has been disabled on the Mesozoic pages because the dataset is both small and badly affected by a few sites with erroneous age models (our obs Huber, Petrizzo, Young, Nov 2016). The data can still be viewed via the range plottertool - tools menu.

References:

Georgescu & Huber 2006 [sorry, not in our bibliography yet]


logo

Paracostellagerina compiled by the pforams@mikrotax project team viewed: 13-12-2017

Taxon Search:
Advanced Search

Go to Archive.is to create a permanent copy of this page - citation notes



Comments (0)

No comments yet. Be the first!

Add Comment

* Required information
1000
Captcha Image
Powered by Commentics