Catalog - Helvetiella

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Helvetiella

Citation: Helvetiella Longoria & Gamper 1984

Type species: Helvetiella helvetia Longoria and Gamper 1984

Type age (chronostrat): Maastrichtian

Diagnosis: Globotruncanids with hispid (roughened) tro· chospire, chambers inflated; periphery round to angled, lacking keel or imperforate peripheral band.

Definition: Test trochospiral, generally planoconvex to biconvex, umbilicate. Peripheral outline circular, periphery rounded, lacking keel or imperforate peripheral band, but ephebic individuals may have poorly developed rim, formed by aggregation of papillae. Chambers spherical to ovate, strongly inflated. Sutures depressed, straight on both spirai and umbilical sides. Wall calcareous, radiai in section, coarsely perforate, surface spinosopapillate (hispid). Primary aperture covered by tegilla. Umbilicus wide, deep.

Helvetiella derives its name from Switzerland (Confederatia Helvetica) to honor its geologists and their pioneer contributions to Cretaceous planktonic foraminiferal biostratigraphy

Remarks: Helvetiella differs from Rugoglobigerina by lacking rugosities arranged in a meridional pattern. lt differs from Globotruncana and Globotruncanita by 1) lacking truncate periphery; 2) having spherical to ovoid chambers; 3) lacking keels; 4) having depressed rather than raised sutures; and 5) showing umbilically inflated chambers.

Helvetiella is somewhat similar to Archaeoglobigerina, as both genera have spherical chambers and lack a truncate or angle periphery. Helvetiella differs from Archaeoglobigerina by 1) lacking imperforate peripheral band; 2) always having depressed sutures both umbilically and spirally; and 3) having spinosopapillate (hispid) rather than smooth or slightly pustulose surface ornamentation. The development of the latitudinally arranged surface ornamentation displayed by helvetiellids is rather difficult to understand. Neanic individuals seem to develop a papillate test whose ornament consists of massive papillae; some of the papillae in these neanic individuals may be axially elongated. However, gerontic specimens tend to develop a heavily ornamented test, becoming hispid. The ornamentation in these gerontic specimens consists of triangular massive spines and elongated papillae. The papillae are often restricted to the earlier chambers and rapidly are replaced by massive spines. The helvetiellids are characterized by their spinosopapillate ornamentation (pl. 2).

The "hispid" surface ornamentation displayed by helvetiellids is morphologically similar to the muricae described by Blow (1979) from the Tertiary genera Morozovella McGowran, Muricoglobigerina Blow and Acarinina Subbotina. However, the lack of comparative studies on the wall structure and surface ornamentation of both Cretaceous and Tertiary planktonic foraminifera impedes speculation at this time on the possible relationship between them. For the moment, the gross similarities between the surface ornamentation of helvetiellids and that of the Tertiary planktonic foraminifera is regarded as unrelated, perhaps phyletically unrelated.

The specimens illustrated by Berggren (1962, pl. X) most likely belong to Helvetiella. They were regarded by Berggren (op. cit.) as Rugoglobigerina rugosa Plummer, lacking typical meridional rugosities. lt is also likely that the specimens illustrated by Hanslikova (1972) and Cita and Gartner (1971) as Rotundina rotundata (Bronnimann) are assignable to Helvetiella, as they show the papillate surface ornamentation and lack rugosities meridionally oriented.

Range: Maastrichtian.

Occurrence: We have observed species of Helvetiella in Late Maastrichtian sediments recovered during DSDP Legs 12, 32, 39 and 40, and in the Late Maastrichtian of Poland, Austria, Mexico and Trinidad.

References:

Berggren, W. A. (1962a). Some planktonic foraminifera from the Maestrichtian and type Danian stages of southern Scandinavia. Stockholm Contributions in Geology. 9(1): 1-106. gs

Blow, W. H. (1979). The Cainozoic Globigerinida: A study of the morphology, taxonomy, evolutionary relationships and stratigraphical distribution of some Globigerinida (mainly Globigerinacea). E. J. Brill, Leiden. 2: 1-1413. gs

Cita, M. b. . & Gartner, S (1971). Deep sea Upper Cretaceous from the western North Atlantic. In, Farinacci, A (ed.) Proceedings of the Second Planktonic Conference, Roma 1970. Edizioni Tecnoscienza 287-319. gs

Hanzlíková, E. (1972). Carpathian Upper Cretaceous Foraminiferida of Moravia (Turonian-Maestrichtian). Rozpravy Ustredniho ustavu geologickeho. 39: 1-160. gs

Longoria, J. F. & Gamper, M. A. (1984). Subfamily Helvetiellinae, a new group of Late Cretaceous (Maastrichtian) planktonic foraminifera. Micropaleontology. 30: 171-179. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Helvetiella Longoria & Gamper 1984

Helvetiella

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			Helvetiella atlantica Longoria&Gamper 1984 = Kuglerina rotundata
			Helvetiella helvetia Longoria&Gamper 1984