CATALOG OF ORIGINAL DESCRIPTIONS: Globorotalia crozetensis Thompson 1973

This page provides data from the catalog of type descriptions. The catalog is sorted alphabetically. Use the current identification link to go back to the main database.


Higher levels: pf_cat -> G -> Globorotalia -> Globorotalia crozetensis
Other pages this level: << < G. collactea, G. conica, G. conicotruncata, G. conomiozea, G. conomiozea mons, G. convexa, G. crassacarina, G. crassaconica, G. crassacrotonensis, G. crassaformis ronda, G. crassata aequa, G. crassula, G. crater, G. crosswicksensis, G. crotonensis, G. crozetensis, G. crystalriverensis, G. cushmani, G. dalii, G. decorata, G. dehiscens, G. delrioensis, G. denseconnexa, G. dolabrata, G. dominicana, G. edgari, G. ehrenbergi, G. emilei, G. extans, G. faragi, G. flabelliformis, > >>

Globorotalia crozetensis

Citation: Globorotalia crozetensis Thompson 1973
Rank: species
Type locality: western Crozet Basin (text-figure 1) of the southwest Indian Ocean, latitude 42° 53' S., longitude 42° 21' E., at a depth of 4330 meters.
Type sample and level: core RC8-39, 70cm
Holotype Repository: Washington; USNM
Type & figured specimens: Holotype, USNM 187704 (plate 2, figure 1 a-c), & figured paratypes, USNM 187705-187706 (plate 2, figures 2a-c, 3a-c)

Linked specimens: USNM-187704 USNM-187705 USNM-187706

Current identification/main database link: Globorotalia cavernula Bé, 1967


Original Description
Test large, coiling in a low trochospire; 14-17 chambers arranged in 3 whorls in adult; 5 chambers in final whorl; height of spire increasing moderately; chamber size increasing rapidly; axial profile biconvex, slightly convex on spiral side, strongly vaulted and obtusely conical on umbilical side; axial periphery angular, becoming keeled with ontogeny; chambers angulo-conical, tangentially larger than radially, slightly inflated on spiral side, much inflated on umbilical side; final chamber often same size as or smaller than penultimate one; sutures on both spiral and umbilical sides curved and slightly depressed; aperture interiomarginal, umbilicalextraumbilical, a low arch beneath a prominent umbilical shoulder and with a thick lip varying from a rim to a broad flap extending across umbilicus; umbilicus small and deep; wall calcareous and finely perforate; surface smooth, giving test a shiny appearance; small pustules dotting surface of early chambers near umbilicus and marking sutures on spiral side.

Size: Maximum diameter of the holotype 0.5 mm.

Etymology: The name of the species, G. crozetensis, is proposed because of the type locality in the Crozet Basin.

Extra details from original publication
Remarks: G. crozetensis occurs in this core only between 30 and 110 em. As this form has not been reported from recent surface tows taken in the same area (Be and Tolderlund, 1971), the upper limit of 20-30 em. may represent the extinction level of this species. If this is the case, G. crozetensis may become a useful biostratigraphic indicator for the Pleistocene-Holocene boundary at this latitude, as radiocarbon data suggest that the boundary lies close to 20 em. (J. D. Hays, personal communication). Until an ancestral form can be determined, the lower limit, 100 em., may be taken to approximate the initial appearance of this species. No ancestral form was recognized in core RC8-39. Although initially rare in the older samples from the core, G. crozetensis possesses all of its typical characteristics when it first appears, suggesting that the form had evolved elsewhere at an earlier time and was later introduced to this cored area.
In the core, G. truncatulinoides is the only other abundant form resembling G. crozetensis, but the latter differs by having finer perforations, a weakly developed keel, and a rounder equatorial profile. The large, circular to oval holes visible in several of the specimens examined, including the holotype, are probably due to predation rather than to the morphology of the test or its preservation.

References:

Thompson, P. R. (1973). Two new late Pleistocene foraminifera from a core in the southwest Indian Ocean. Micropaleontology. 19: 469-474. gs


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Globorotalia crozetensis compiled by the pforams@mikrotax project team viewed: 16-12-2019

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