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Subspecies Hastigerina (Hastigerina) siphonifera praesiphonifera Blow 1969 | ||||||
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| Diagnosis / Definition: | ||||||
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Blow (1969): Description of holotype: Test trochospirally coiled in the early stages but becoming planispirally coiled for the last three chambers of the final whorl. Chambers strongly inflated, subglobular, not embracing but well separated one from the other. Coiling evolute and the two "umbilical "depressions are widely open. Aperture not fülly symmetrical about the peripheral midplane, the "ventral" extension of the aperture is a less open arch and is more slit like than the peripheral part of the arch. "Dorsal" extension of the aperture less slit like than the "ventral" extension and retains the characters of an open arch. The dorsal spire of the earlier chambers can be seen as a slightly raised coil within the widely open "umbilical" cavity formed by the last convolution of the test. Intercameral sutures of the last whorl of chambers deeply incised, radially disposed. Intercameral sutures of the earlier chambers slightly recurved. Aperture bordered by rim like lip. The relict aperture of the penultimate chamber can be seen "ventrally" but not "dorsally". Wall calcareous, radial hyaline [62a], hispid with distinct spine bases, comparatively coarsely perforate with small pore pits. Maximum diameter of holotype 0.62 mm. |
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| Discussion / Comments: | ||||||
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Blow (1969): Remarks: Since Hastigerina (H.) siphonifera praesiphonifera retains a distinct early trochospiral coiling and the early spire is still visible in the concavity form by the last whorl of chambers it is still possible to discuss the morphology in terms of a "ventral" and "dorsal" side. The planispiral coiling is only adopted in the last whorl and it is only possible to say that planispiral coiling is present when at least three consecutively arranged chambers show the coiling mode. In some forms of Globorotalia (Turborotalia) obesa, the final chamber possesses an aperture which extends over the dorsal peripheral margin of the preceeding whorl but it is not possible to say whether this chamber is arranged in the coil planispirally or not until the disposition of the preceeding chamber is noted and until the disposition of any subsequently added chamber is known. Thus, before the coiling mode can be unambiguously analysed the disposition of at least three chambers needs to be known. For this reason the writer separates forms referable to Globorotalia (T.) obesa from forms referable to Hastigerina (H.) siphonifera Praesiphonifera on the criteria that three consecutive chambers must be planispirally disposed, at least, in the latter form. Hastigerina (H.) siphonifera Praesiphonifera differs from H. (H.) siphonifera siphonifera in that the dorsal trochospiral coil is still visible within the concavity of the later whorl of chambers and that the planispirality is confined to the final convolution of the test. H. (H.) siphonifera Praesiphonifera gives rise to siphonifera (s.s.) in the middle to later parts of Zone N.i2. Stratigraphical Range: Ranges from within Zone N.7 to within Zone N.13. Occurs commonly in the Indo Pacific Province but is rare in the Caribbean/Atlantic Province. Holotype from a sample collected at Aguide, Venezuela (ex P. J. BERMUDEZ); Zone N.8 (see also plate and figure explanations). |
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| Synonym list: | ||||||
| Blow (1969): 1969 Hastigerina n spp. (Hastigerina) siphonifera praesiphonifera Blow. - Blow : p.408 pl. 54, figs. 7-9
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| Was used in synonym list of: | ||||||
| References: | ||||||
Blow,W.H. (1969): |
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| Anonymous: Unedited TaxonConcept data | ||||||
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