Catalog - Nuttallides

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Nuttallides

Citation: Nuttallides Finlay, 1939

Type species: Nuttallides truempyi (Nuttall) = Eponides truempyi Nuttall, 1930

[Finlay 1939]: Test rotaliform, more or less planoconvex, with a strong tendency to develop a peripheral flange. Sutures sloping back at sharp angle dorsally, somewhat markedly sinuous basally. Umbilical area usually with a prominent boss of clear material. Aperture a linear slit with a sharp, projecting outer edge, extending from plug almost to periphery, where it suddenly turns backwards into the flange, like Pulvinulinella.

[Finlay 1939 emend. Belford 1958]: Test trochoid, evolute dorsally, involute ventrally, unequally biconvex, with the ventral surface the more strongly convex, periphery poreless. Umbilical area with a poreless boss. Test calcareous, chamber walls radiate hyaline, finely perforate on both dorsal and ventral surfaces; septal walls single, imperforate. Aperture ventral, at base of chamber, with a slight lip, extending from the umbilical boss to a small groove at the periphery, formed parallel to the plane of coiling and bordered marginally by a small fold of the apertural face. Each chamber with a toothplate extending from the septal foramen diagonally across the chamber towards the peripheral groove.

[Finlay 1939 emend. Belford 1958]: Remarks. – The generic description of Nuttallides given by Finlay [1939, loc. cit.] requires emending to include the internal structure and apertural characteristics. The details of the sutures given by Finlay are of specific and not generic significance.

The genus Nuttallides has some features suggesting a relationship with the genus Alabamina Toulmin, 1941, the type genus of the family Alabaminidae. The marginal groove of Nuttallides, formed parallel to the plane of coiling, is regarded by the writer as homologous with the groove in Alabamina, called by Brotzen (1948, Sver. Geol. Unders., Avh ser. C, no. 493, vol. 42, no. 2) the “scrobis septalis,” and the small forward fold of the chamber at the periphery as homologous with the “tectum” of Alabamina. According to the interpretation of Hofker (1951, Siboga-Exped., Monogr., no. 4b) the groove to which the reduced toothplate of Alabamina (“infundibulum” of Brotzen) is attached is a closed protoforamen. The same interpretation may be applied to the groove of Nuttallides; the aperture in this genus is therefore a deuteroforamen, and the genus belongs to Hofker’s suborder Biforaminata deuteroforaminata.

The toothplate of Nuttallides is more strongly developed than that of Alabamina, and extends the full width of the chamber from the septal foramen. The internal feature of Alabamina called by Brotzen the “foramen infundibulum” is absent from Nuttallides, and the poreless ventral boss and poreless margin of Nuttallides do not occur in Alabamina. Another difference is in the wall structure, which is granular in Alabamina and radiate in Nuttallides. In this respect, and in having a ventral boss, Nuttallides resembles the genus Epistomina [Terquem, 1883], but does not have as well developed or as complex a toothplate as that genus.

The genus Nuttallides is in its combination of characters intermediate between the genera Alabamina and Epistomina. The classification of these forms depends on the significance given to the different features. Brotzen (1948, op. cit.) suggested that the marginal groove of Alabamina is a reduced marginal aperture, and included this genus in the Epistominidae. Hofker (1951, op. cit.) considered the reduced marginal aperture (protoforamen) and the sutural aperture formed by the deuteroforamen to be significant, and proposed the family Alabaminidae. This view receives some support from the difference in wall structure between Alabamina and Epistomina, although Hofker did not consider this feature.

The taxonomic significance of the toothplate and the wall structure is not fully understood, but the writer prefers to place Nuttallides in the Epistominidae rather than in the Alabaminidae. The intermediate position of Nuttallides may indicate the origin of the Alabaminidae within the Epistominidae.

References:

Belford, D. J. (1958). The Genera Nuttallides Finlay 1939, and Nuttallina n. gen. Contributions from the Cushman Foundation for Foraminiferal Research. 9(4): 93-98. gs

Finlay, H. J. (1939a). New Zealand foraminifera: key species in stratigraphy – No. 1. Transactions of the Royal Society of New Zealand. 68(4): 504-543. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Nuttallides Finlay, 1939

Nuttallides

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			Nuttallides concentricus Mcneil, 1997 = Nuttallides concentricus
			Nuttallides rudis Todd 1970 = Nuttallides rudis
			Nuttallides subtruempyi Finlay, 1939 = Nuttallides truempyi