CATALOG OF ORIGINAL DESCRIPTIONS: Heterohelix navarroensis Loeblich 1951

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 -> H -> Heterohelix -> Heterohelix navarroensis
Other pages this level: H. (Chiloguembelina) pseudotessera directa, H. (Heterohelix) planeobtusa, H. dentata, H. fayose, H. ivandeklaszi, H. labellosa, H. navarroensis, H. nkporoensis, H. olssoni, H. orientalis, H. pachymarginata, H. pseudoglobulosa, H. pseudoreussi, H. robusta, H. rumseyensis, H. sphenoides, H. stenopos, H. striata aegyptiaca, H. suwalkensis, H. varsoviensis, H. virgata, H. vistulaensis

Heterohelix navarroensis

Citation: Heterohelix navarroensis Loeblich 1951
Rank: Species
Type locality: a pit of the Seguin Tile and Brick Company at McQueeney, Guadalupe County, Texas.
Type age (chronostrat): Late Cretaceous
Type sample (& lithostrat): Navarro (Kemp clay); 6 to 8 feet above the base of the pit
Type specimens: Plate 12, figures l-3b; Text figure 1; Holotype (USNM P. 33), figured paratypes (USNM P. 32a-c) and unfigured paratypes (USNM P. 37); Desc p.107-108
Type repository: Washington; USNM

Linked specimens: USNM-37 USNM-32 USNM-32 USNM-37 USNM-37 USNM-37 USNM-37 USNM-37 USNM-37 USNM-33

Current identification/main database link: Spiroplecta americana Ehrenberg 1844

See also: Spiroplecta americana ;


Original Description
Test minute and subtriangular in side view, the bi- serial portion flaring widely from the tiny planispiral coil, periphery broadly rounded; the five to six cham- bers of the coil are low and not much inflated, the later 6 to 11 biserially arranged chambers increasing rapidly in height so that later ones are inflated and subglobular; sutures distinct, straight, somewhat oblique, depressed ; wall calcareous, hyaline, surface faintly striate, finely perforate; aperture a low arch at the inner margin of the final chamber, sometimes with a slight lip.

Size: Length of holotype 0.23 mm, greatest breadth of coil 0.04 mm, greatest breadth of biserial portion 0.13 mm, greatest thickness 0.05 mm. Other specimens range between 0.13 and 0.29 mm in length.

Extra details from original publication
Remarks: In an attempt to duplicate Ehrenberg's conditions of observation, specimens of the present species were mounted in balsam and drawn with a camera lucida. One is shown in text figure 2 and a copy of Ehrenberg's Plate 32, II, figure 25, is reproduced for comparison in text figure 1. This is the specimen designated as "genotype" by Cushman (1927 a, p. 190). A striking difference is apparent in the pattern of the ornamentation. Ehrenberg's illustration of H. americana shows faint vertical striae crossing the chambers, with occasional pores, but the Texas specimens show broadly curved striae, generally paralleling the upper surface of the chambers. In addition the early coil in H. americana is much more lobulate, the early biserial chambers are much more nearly globular and the aperture is much less prominent than in H. navarroensis.

The present species may possibly be conspecific with H. americana, if Ehrenberg's drawings should later be proved inaccurate, as the two are of approximately the same size and outline. However, it is difficult to compare abundant free specimens with diagramatic illustrations and with a meager description. Ehrenberg's types have not been available for study and because of the very generalized horizon and locality data no topotype material could be collected. For these reasons, the writer feels it reasonable to consider as new the present species, unless and until a study of Ehrenberg's original material proves otherwise.

Types and occurrence- From the type sample, 6 to 8 feet above the base of the pit, 329 specimens were examined. Heterohelix navarroensis is also common in the basal Navarro strata exposed in a steep slope on the right bank of Onion Creek just east of the bridge (known as Jones Crossing) on the Austin-Bastrop highway, Travis County, Texas. All material collected by the writer.

References:

Loeblich, A. R. (1951). Coiling in the Heterohelicidae. Contributions from the Cushman Foundation for Foraminiferal Research. 2: 106-110. gs V O

Montanaro Gallitelli, E. (1957). A revision of the foraminiferal family Heterohelicidae. In: Studies in foraminifera; Part 1 - Planktonic foraminifera. In, Loeblich, A. R. , Jr., Tappan, H., Beckmann, J. P., Bolli, H. M., Montanaro Gallitelli, E. & Troelsen, J. C. (eds) Studies in Foraminifera. U.S. National Museum Bulletin. 215: 133-154. gs V O


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Heterohelix navarroensis compiled by the pforams@mikrotax project team viewed: 13-4-2021

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