CATALOG OF ORIGINAL DESCRIPTIONS: Guembelitria sergipensis Koutsoukos 1994

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 -> Guembelitria -> Guembelitria sergipensis
Other pages this level: G. alabamensis, G. azzouzi, G. besbesi, G. blowi, G. columbiana, G. cretacea, G. dammula, G. harrisi, G. irregularis, G. kegeli, G. langparensis, G. ornata, G. oveyi, G. samwelli, G. sergipensis, G. stavensis, G. turrita, G. vivans, T. triseriata,

Guembelitria sergipensis

Citation: Guembelitria sergipensis Koutsoukos 1994
Rank: Species
Type locality: Holotype is from a cutting sample of well I-CA-I (latitude 10’ 54‘ 30”S, longitude 37” 07’ 45” W; Fig. I), depth 1245-1260 m (upper Aptian). Taquari Member, Riachuelo Formation, Sergipe Basin, northeastern Brazil.
Type age (chronostrat): Upper Aptian
Type specimens: 5791-I
Type repository: Rio de Janeiro, Departamento de Geologia e Paleontologia of the Museu Nacional

Linked specimens: USNM-534321 USNM-534323 USNM-534319 USNM-534320 USNM-534322

Current identification/main database link: Guembelitria sergipensis Koutsoukos 1994


Original Description
This species is characterized by having a minute trochoid test, triserial throughout, with a short, moderately high trochospire, and a slight variability during ontogeny in the maximum height/diameter (H/D) ratio (e.g., from H/D around 1.1, elongate-conical neanic to early ephebic morphotypes-Pl.1, figs.5, 6, 15, Pl.2, fig.2; and H/D close or equal to 1, nearly as broad as long, globular trochoid, early ephebic and gerontic morphotypes-Pl.1, figs.1-2, 8, 12, 13, Pl.2, figs.1, 3, 4). Three inflated, gradually enlarging globular chambers in the last whorl, distinct, differing little in size and comprising about 2/3 of the test size. Chambers of previous whorl are indistinct, mostly obscured by overgrowth of test surface calcification. Ultimate chamber in mature specimens has smoother ornamentation and partially covers the umbilicus (e.g., Pl.1, figs.1, 8, 12, 13). Umbilicus small, shallow; periphery rounded. Sutures distinct and depressed, in the last whorl; indistinct in the previous whorls. Aperture a low to medium sized umbilical arch at the base of the last formed chamber, slightly asymmetrical. The aperture is nearly completely obscured by overgrowths of test ornamentation and deposited calcite particles. Test surface covered with blunt rounded or elongate poreless pustules, some forming elongate imperforate quadrangles (= short ridges)-(Pl.1, figs.3, 4, 5, 7, 9-11 and Pl.2, figs.5, 9, 10), several pore mounds (pores of maximum diameter around 1.0 microns; see Pl.1, figs.11, 14, 16 and Pl.2, figs.7, 12), and sporadic presence of pores on edges of pustules (Pl.2, figs.5, 10). The specimens show an irregular development of the pore mounds on the first two chambers of the last whorl (Pl.1, figs.14, 16, and Pl.2, fig.5, 7). The ultimate chamber may be densely covered with small poreless pustules and totally lack pore mounds (Pl.2, fig.10), whereas these may have been sealed on the earlier chambers by shell overgrowths. Morphologically intermediate forms between G. sergipensis and G. cenomana (Keller), with a more elongate test (WD from around 1.2 to 1.3). higher trochospire, and more developed pore mounds surface texture, are recorded in the middle Albian to lowermost upper Albian (PI. 2, figs. 6-12). Thirteen paratypes are illustrated by the lateral views in PI. 1, figs. 5-16, and PI. 2, figs. 1-12. The overall morphological features are similar to that of the holotype, varying only slightly in the WD ratio, coarseness of the test surface ornamentation and in the density and regularity of pore mounds.

Size: 184/182 µm

Etymology: Guembelitria sergipensis derives its name from the type locality, the state of Sergipe.

Extra details from original publication

Remarks: The new species has a distinctive short, moderately high trochospire, triserial coiling throughout, a short, almost symmetrical, low intraumbilical apertural arch, often masked, and a test surface covered by small rounded or elongate pustules, with several pore mounds. The triserial chamber arrangement and the test surface ornamentation are consistent with placement of the species in the genus Guembelitria Cushman. However, it differs from the later species of Guembelitria (e.g., G . cenomana (Keller) uppermost Albian to uppermost Turonian; G. cretacea Cushman Coniacian to lower Danian) chiefly in having a trochoid test (WD close or equal to 1), coarser pustulose surface ornamentation with poreless pustules, sparse occurrence of pore mounds, sporadic presence of pores on edges of pustules and indistinct chambers in the earlier whorls.

Deposition of types. The holotype and figured paratypes of Guembelitria sergipensis n. sp. are deposited as follows

References:

Koutsoukos, E. A. M. (1994). Early stratigraphic record and phylogeny of the planktonic genus Guembelitria Cushman, 1933. Journal of Foraminiferal Research. 24: 288-295. gs


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Guembelitria sergipensis compiled by the pforams@mikrotax project team viewed: 20-10-2020

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