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Species Hastigerina siphonifera d'Orbigny 1839 | ||||||
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| Discussion / Comments: | ||||||
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Bolli & Saunders (1985): D'Orbilgny's original illustration of siphonifera shows a small specimen, measuring only 0.33 mm. It consists of only 5 trochospirally arranged chambers, which increase more rapidly in size, particularly the last, than is usually observed in Hastigerina. Furthermore, the aperture of its last chamber is distinctly umbilical to umbilical extraumbilical and not equatorial as it should be to be classified as a Hastigerina. D'Orbigny's figured specimen could therefore represent a trochospiral juvenite, though not a typical stage of Hastigerina. It could also be interpreted as a small or juvenile Globigerina or Globorotalia. The lectotype chosen by Banner & Blow for H. siphonifera (Fig. 42.2) differs considerably from the specimen originally figured by d'Orbigny. It is larger, involute planispiral instead of trochospiral, with no trochospiral initial stage visible on the figures, with 41 instead of 31 inflated chambers forming the last whorl, and increasing fairly rapidly in size. The lectotype established by Banner & Blow for H. aequilateralis (Fig. 42.3) and placed by them in synonymy with H. siphonifera is virtually identical with Banner & Blow's lectotype of that species. It is also close to one of Brady's figured specimens (fig. 20 on his plate 80). As explained in the introduction, we maintain a distinction using H. siphonifera in the sense of Banner & Blow's closely coiled lectotype and H. aequilateralis in the sense of the wider coiled and evolute specimen illustrated by Brady as fig. 18 on his plate 80 (Fig. 42.6). The two taxa can readily be distinguished in Pleistocene to Recent low latitude sediments. This has been done for the Caribbean DSDP Site 147, used in the present evaluation. The involute H. siphonifera already occurs in the Middle and Late Miocene. The extent of pre Pleistocene occurrences of H. aequilateralis has still to be evaluated. |
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| Synonym list: | ||||||
| Bolli & Saunders (1985): 1839 Globigerina siphonifera d'Orbigny. - d'Orbigny : p.83 pl.4, figs.15-18
1960 Hastigerina siphonifera d'Orbigny. - Banner & Blow : p.22 figs. 2a-c
1960 Hastigerina aequilateralis Brady. - Banner & Blow : p.23 figs. 3a-b (lectotype designated by Banner &, Blow and placed by them in synonymy with H. siphonifera)
1985 Hastigerina siphonifera d'Orbigny. - Bolli & Saunders : 251, 252 figs. 42.1-4, 43.1-2,8; 7,10,11
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| References: | ||||||
d'Orbigny,A.D. (1839): Banner,F.T. and Blow,W.H. (1960): Bolli,H.M. and Saunders,J.B. (1985): |
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| Anonymous: Unedited TaxonConcept data | ||||||
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