Catalog - Praegublerina

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Praegublerina

Citation: Praegublerina Georgescu, Saupe and Huber 2009

Type species: Gublerina acuta robusta de Klasz 1953

Diagnosis. Tests are biserial throughout or with a multiserial chamber stage in the adult portion; a chamber proliferation stage follows the biaperturate progressive chamber; maximum of three multiserial chamber sets that gradually increase their number by one; test ornamentation costate or reticulate throughout, or a combination of the two kinds.

Description. Test is biserial throughout in earlier species of the lineage with chamber proliferation in the adult stage in the more highly evolved forms. Test outline is subtriangular to flaring due to the addition of chambers in the proliferation stage. The earlier biserial stage presents a central nonseptate area bounded by two rows of divergent chambers. The chamber proliferation stage initiates with the progressive chamber, which is the first biaperturate chamber of the test, and is followed by up to three multiserial chamber sets, the latter increasing the chamber number by one as new sets are added (i.e., two, then three, then four additional chambers in successive multiserial chamber sets). The test periphery is broadly rounded without peripheral structures. The aperture is single at the base of the last-formed chamber in the biserial stage and multiple due to the presence of both monoand biaperturate chambers in the multiserial stage. Apertures are bordered by wide flanges that are occasionally rimmed. Transverse biaperturate walls can be developed between the chambers in the multiserial portion of the test. Chamber surface is costate or reticulate or a combination of the two. The reticulate ornamentation occurs later in the genus history, being derived from costate forms. Test wall is calcareous, hyaline, and microperforate to finely perforate.

The prefix “Prae-” (= before, anterior to) is added to the pre-existing genus name Gublerina.

Remarks. Praegublerina nov. gen. differs from Heterohelix in having (i) a central nonseptate area between the two rows of diverging chambers, (ii) a chamber proliferation stage in the evolved taxa (e.g., P. acuta, P. robusta) and (iii) coarser costae than in H. planata, its ancestral species, and reticulate ornamentation, the latter being present either on distinct parts of the test or all over the test surface.

Praegublerina differs from Gublerina in having (i) a multiserial stage with chamber sets increasing their number by one chamber at a time rather than three chambers with each successive chamber set, (ii) finer costae (when present) and reticulate ornamentation without smooth sutures and unornamented portions and (iii) transverse biaperturate walls between the chambers of the multiserial chamber stage (text-figure 4).

Species included.

Praegublerina pseudotessera (Cushman) 1938, p. 14, pl. 2, figs. 19-20.
Praegublerina robusta (de Klasz) 1953, p. 247, pl. 8, figs. 4-5.
Praegublerina acuta (de Klasz) 1953, p. 246, pl. 8, fig. 3.

Phylogenetic relationships. Praegublerina nov. gen. is the oldest gublerinid genus and it evolved from Heterohelix through development of (i) a central nonseptate area between the two rows of divergent chambers and (ii) coarsening of costae. These trends are apparent in the Heterohelix planata-Praegublerina pseudotessera lineage.

Stratigraphic range. Campanian-Maastrichtian (from the Globotruncanita elevata Biozone to and throughout the Pseudoguembelina hariaensis Biozone).

Geographic distribution. Cosmopolitan.

References:

Georgescu, M. D., Saupe, E. E. & Huber, B. T. (2009). Morphometric and stratophenetic basis for phylogeny and taxonomy in Late Cretaceous gublerinid planktonic foraminifera. Micropaleontology. 54(5): 397-424. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Praegublerina Georgescu, Saupe and Huber 2009

Praegublerina

References:

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