Catalog - Hastigerinopsis digitiformans

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Hastigerinopsis digitiformans

Citation: Hastigerinopsis digitiformans Saito & Thompson, in Saito et al. 1976

Type repository: Washington, USNM

Test free, initially a low trochospire later becoming a streptospire; usually 6 chambers per whorl; first whorl covered by later chambers; chambers rapidly enlarging; initial chambers globular; later chambers becoming radially elongate and slightly bulbous at distal end; frequently becoming bifurcate or trifurcate (lobes usually of unequal sizes) in mature specimens; sutures on both spiral and umbilical sides radial to slightly curved, often becoming limbate due to an incomplete embracement of the previous apertural rim by the following chamber; aperture a high and broad arch, interiomarginal, equatorial, occasionally becoming spiroumbilical, bordered by an imperforate, raised rim; wall very thin, finely perforate, with spines and spine bases on distal ends of chambers; spines consistently triradiate in cross section from proximal to distal ends, having irregularly spaced, upward-pointing, two-pronged barbs along outer edge of each spine blade.

digitus-Latin, finger; + formans- Latin, forming.

Hastigerina digitata.-RHUMBLER, 1911. pp. 163-164, 202. 220. pl. 37. figs. 7-14.
Hasterigerina [sicl] digitata Rhumbler.-CUSHMAN. 1927, p. 87.
Hastigerinella digitata (Rhumbler) .-CUSHMAN. 1927, pl. 19. fig. 9 (after Rhumbler) .-BANNER and BLOW. 1960, pp. 24-26, text-fig. 598.-Bt:, JONGEBLOED and McINTYRE, 1969. p. 1388, pl. 161. fig. 2.-HEMLEBEN, 1969. pl. 8, figs. 4-6.
Hastigerinella rhumbleri GALLOWAY, 1933, p. 333, pl. 30, fig. 9 (after Rhumbler) (nomen nudum).-BRADSHAW, 1959, pp. 47, 49, pl. 8, fig. 16.-Bt:. 1959. p. 83 (list), pl. 2. fig. 23.-BE. 1965, p. 83. text-fig. 2B, right-hand specimen.
Hastigerina digitata (Brady), var. digitifera RHUMBLER, 1949, p. 40 (nomen nudum).
Hastigerina digitata (Brady), var. acuminata RHUMBLER, 1949, p. 40 (nomen nudum). Not Globigerina digitata Brady, 1879.-BRADY. 1884 (part), pl. 80, figs. 6-10 [=Beella digitata (Brady)]. Not Globigerina digitata Brady.-BRADY, 1884 (part), pl. 82, figs. 6-7 [= Globigerinella adamsi (Banner and Blow)].

Remarks: Aside from the greatly differing chamber shapes and arrangements of Hastigerina pelagica, H. parapelagica, and Hastigerinopsis digitiformans, the distribution of the barbed, triradiate spines is an important key to the separation of these genera and species. Banner and Blow (1960. pp. 25-26) noted that Hastigerinella digitata ( = Hastigerinopsis digitiformans) has "a higher concentration of finer spines upon the distal chamber surface than is seen in specimens of H. (Hastigerina) pelagica of comparable size". Furthermore. "the distribution of the spines in H. (Hastigerina) pelagica is symmetrical about the chamber. whereas the spinose area on an unmodified chamber of Hastigerinella digitata is asymmetrical, extending more on one side of the chamber than on the other."

The species is rare but has been figured by Rhumbler (1911. plate 37. figures 7-14). Bé (1959. plate 2. figure 23). Bradshaw (1959. plate 8. figure 16), Banner and Blow (1960. text-figs. 5-8). Bé (1965. text-fig. 2B. right-hand specimen). Bé Jongebloed and Mclntyre (1968. pl. 161. fig. 2) and Hemleben (1969. pl. 8. figs. 4-6). The reasons for this rarity are unclear. but it may result from a combination of the deep-water habitat of the species and its fragile test.

The holotype specimen is preserved in Canada balsam and appears to contain some original protoplasm giving the test an overall pink or salmon-pink coloration.

References:

Banner, F. T. & Blow, W. H. (1960b). The taxonomy, morphology and affinities of the genera included in the subfamily Hastigerininae. Micropaleontology. 6(1): 19-31. gs

Galloway, J. J. (1933). A manual of foraminifera. Principia Press, Bloomington (Indiana). -. gs

Hemleben, C. (1969). Zur morphogenese planktonischer Foraminiferen,. Zitteliana. 1: 91-133. gs

Rhumbler, L. (1911). Die Foraminiferen (Thalamophoren) der Plankton-Expedition: Teil 1. Die allgemeinen Organisations verhaltnisse der Foraminiferen, Plankton Expedition Humbold-Stiftung, Ergeben 3, L. C 1. . 1-331. gs

Saito, T., Thompson, P. R. & Breger, D. (1976). Skeletal ultra-microstructure of some elongate-chambered planktonic foraminifera and related species. In, Takayanagi, Y. & Saito, T. (eds) Progress in Micropaleontology, Special Publication. Micropaleontology Press, The American Museum of Natural History, New York 278-304. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Hastigerinopsis digitiformans Saito & Thompson, in Saito et al. 1976

Hastigerinopsis digitiformans

References:

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