Catalog - Globorotalia puncticulata puncticuloides

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Globorotalia puncticulata puncticuloides

Citation: Globorotalia puncticulata puncticuloides Hornibrook 1981

Type specimens: TF1590.: Register TF1590. Holotype and 22 paratypes,Topotypes will be deposited in the British Museum (Natural History) London, and the National Museum of Natural History, Smithsonian Institution, Washington.

Type age (chronostrat): Late Pliocene or Early Pleistocene.

Type locality: DSDP Site 284, core 6, section 4, 120 cm

Type repository: Lower Hutt; New Zealand Geological Survey

Test hispid, usually compressed in juvenile stage, becoming progressively more inflated with growth, usually 4 chambers in final whorl, final chamber variable, usually strongly inflated and semicircular in end view but often compressed and reduced in size; sutural depressions shallow, moderately strongly recurved, periphery broadly rounded, lacking a distinct keel. Aperture opens in the plane of coiling and is moderately stongly arched with a distinct lip. Preferred coiling direction is dominantly sinistral in all populations seen.

1973 Globorotalia miozea conoidea, G. miozea sphericomiozea, G. puncticulata puncticulata, G. puncticulata padana; Theyer, F. in: Nature Physical Science, Vol. 241: pp. 142-5, fig. 3, nos 5-15 (in part).
1975 Globorotalia puncticulata; Kennett & Vella in: Initial Reports of the Deep Sea Drilling Project, Vol. 29: table 2, p. 772, (in part).

Remarks: The taxonomic treatment of populations induded in Globorotalia puncticulata puncticuloides is a difficult problem. In the East Coast Basin and in DSDP Site 284, such populations occupy similar biostratigraphic intervals and are characterised by varying proportions of rather compressed and strongly inflated individuals. The more compressed forms might be regarded as a different species if it were not for intermediate forms which show a complete gradation within many populations.

Comparison of populations from a neritic environment in the East Coast Basin (Fig. 8, 9v-dd) with populations from the oceanic environment in DSDP Site 284 (Fig. 7) is made difficult because the oceanic individuals are much larger and tend to produce more inflated adults with larger apertures.

Globorotalia puncticulata puncticuloides is presumably derived from the more typical form of G. puncticulata (inflated chambers in both adults and juveniles, a very wide, highly arched aperture, usually lacking a distinct lip) which occupies a lower biostratigraphic interval.

Theyer (1973a, fig. 3, nos 5-15; 1973b) identified similar populations from the Tasman Sea as Globorotalia miozea conoidea, G. miozea sphericomiozea, G. puncticulata puncticulata, and G. puncticulata padana from a normally polarised interval which he identified as Gauss. Watkins et al. (1973) argued, however, that the paleomagnetic data were unreliable and that a simple Brunhes Matuyama stratigraphy was a likely alternative. They commented that these forms fall within the subantarctic G. puncticulata populations. Kennett (pers. comm.) has confirmed that populations from DSDP Site 284 were included in the records of G. puncticulata by Kennett & Vella (1975).

Because of the differences in typical populations of G. puncticulata and their different biostratigraphic range, it is proposed that G. puncticuloides populations be given the taxonomic status of a subspecies of G. puncticulata. G. puncticuloides is separable from G. crassula by greater inflation of the chambers without a broad triangular shape, and also by having an arched aperture with a more distinct lip. G. crassaformis is distinguished by having a narrow slit-like aperture, a more quadrate shape, and different ratios dextrally and sinistrally coiling individuals.

References:

Hornibrook, N. d. B. (1981). Globorotalia in the late Pliocene and early Pleistocene of New Zealand. New Zealand Journal of Geology and Geophysics. 24: 263-292. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Globorotalia puncticulata puncticuloides Hornibrook 1981

Globorotalia puncticulata puncticuloides

References:

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