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Species Globorotalia puncticulata Deshayes 1832 | ||||||
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| Discussion / Comments: | ||||||
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Iaccarino (1985): An extensive description and discussion of this species was made by Banner & Blow (1960) who carried out an accurate revision of the taxonomy of Globigerina puncticulata and, following the description of Deshayes, designated a lectotype selected from the material preserved in the d'Orbigny collection. Barbieri (1971), in agreement with Banner & Blow, considered G. puncticulata Deshayes as valid but stated that the lectotype chosen by Banner & Blow did not correspond to the original description given by Deshayes and did not solve the taxonomic problem of the species. The controversy raised by Barbieri mainly concerns the form of the aperture which in the lectotype of Banner & Blow is a fairly high arch set into a slightly concave part of the apertural face, while according to Deshayes' description it is small 'apertura rotunda'. Within any population of G. puncticulata there exists a great variability in the shape of the aperture, from rounded to arched. Stainforth et at. (1975), who consider the lectotype of Banner & Blow a form morphologically distinct enough for biostratigraphic use, give a wide documentation of the species and point out the variability of the aperture. The G. puncticulata concept adopted by Barbieri restricts it to forms having rounded peripheries and rounded apertures, while forms having rounded peripheries and elongated apertures extending from the umbilicus towards the peripheral margin are included by Barbieri in G. crassaformis. It follows that G. crassaformis sensu Barbieri (1967, 1971), Barbieri & Petrucci (1967) and Iaccarino (1967) has to be referred to G. puncticulata because it shows features consistent with the description of the lectotype and with the variability of the species. Many divergencies of opinion concern the evolutionary ancestors of G. puncticulata. According to Kennett (1973), G. puncticulata is a form which has derived from G. conomiozea by reduction in the axial angularity and loss of the peripheral keel. Such a trend is extremely rare within the planktic foraminifera and was doubted by Blow. Blow (1969), in turn, interpreted G. puncticulata as developing from G. subscitula Conato (1964) within the interval of the upper part of N 19 and/or the early part of N 20. Berggren's (1977b) opinion was that the earliest forms of G. puncticulata are morphologically similar to forms referred to as G. praeoscitans Akers (1972) but are markedly smaller and generally lack the arched semicircular aperture of G. praeoscitans. In the Early Pliocene of the Rio Grande Rise the earliest forms of G. puncticulata are associated with G. cibaoensis into which it appears to grade imperceptibly. Berggren suggested that G. puncticulata evolved in the Early Pliocene from 6. cibaoensis. This lineage is, however, not sufficiently supported by the arguments put forward by him, such as the narrow sulcus near the peripheral margin of the last chamber above the aperture present in G. cibaoensis and in some early individuals of G. puncticulata. G. cibaoensis in fact has a sharp angular peripheral margin, limbate intercameral sutures on the spiral side and a less convex ventral side. In the Mediterranean area G. puncticulata appears within the Early Pliocene, well after the re establishment of open marine conditions which mark the Mio Pliocene boundary. The possible ancestors G. conomiozea, and G. cibaoensis suggested by Kennett and Berggren respectively did not occur in the early Pliocene of the Mediterranean. The only one of the above mentioned species which occurs in the Mediterranean Early Pliocene is G. subscitula. A gradual evolution from this species into G. puncticulata has so far not been documented. According to Conato & Follador (1967), G. subscitula appears later than G. puncticulata and therefore cannot he its evolutionary ancestor. The first appearance of G. puncticulata in the Mediterranean Basin could reflect a later migration into warmer waters after its initial evolutionary appearance in the cooler waters of the nearby Atlantic Ocean. If this suggestion, already emphasized by Kennett (1973) for New Zealand, is right, the possibility that G. puncticulata evolved from G. sphaericomiozea cannot he excluded. Kennett (1973) on the other hand included G. puncticulata in G. sphaericomiozea and Walters (1965) stated that G. sphaericomiozea appears to grade into G. inflata; therefore, G. puncticulata could represent an intermediate form between the two extreme taxa. G. puncticulata padana Dondi & Papetti (1968), which is not considered here, differs from G. puncticulata in having less depressed sutures, less globular and more appressed chambers and only 31, chambers in the final whorl. Its distribution extends higher than that of the type species. |
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| Systematics: | ||||||
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1 Superregnum Eukaryota Regnum Protoctista Phylum Ciliophora Subphylum Postciliodesmatophora Ordo Globigerinida Superfamilia Globorotaliaceae Superfamilia Nonionacea Familia Globorotaliidae Genus Globorotalia Species Globorotalia puncticulata |
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| Synonym list: | ||||||
| Iaccarino (1985): 1832 Globigerina puncticulata Deshayes. - Deshayes : p.170 figures in Fornasini, 1899, p. 210, text-fig. 5
1960 Globigerina puncticulata Deshayes. - Banner & Blow : p.15 pl. 5, figs. 7a-c (=Globorotalia (Turborotalia) puncticulata (Deshayes))
1985 Globorotalia puncticulata Deshayes. - Iaccarino : p.305 fig. 6.12a-c; 4
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| Stratigraphy - absolute ages: | ||||||
| DAP: 3.55 ± 0 [Ma], Berggren et al. (1995) Mediterranean RAP: 3.31 ± 0 [Ma], Berggren et al. (1995) Mediterranean LAD: 2.41 ± 0 [Ma], Berggren et al. (1995) |
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| References: | ||||||
Deshayes,G.P. (1832): Banner,F.T. and Blow,W.H. (1960): Iaccarino,S. (1985): Berggren,W.A.; Hilgen,F.J.; Langereis,C.G.; Kent,D.V.; Obradovich,J.D.; Raffi,I.; Raymo,M.E. and Shackleton,N.J. (1995): |
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| Anonymous: Unedited TaxonConcept data | ||||||
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