Catalog - Pulleniatina praepulleniatina

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Pulleniatina praepulleniatina

Citation: Pulleniatina praepulleniatina Brönnimann & Resig 1971

Type locality: S W Pacific,Eauripik Ridge, Hole 62.1, Core 21, Sec.4, 15-17cm, Zone N.17

Type repository: Washington; USNM

The large-sized test is a dorsally flattened, ventrally more or less convex trochospire of about 14 chambers in about 2.5 whorls, with 6 chambers in the final whorl. The chambers of the earliest portion of the trochospire are not individually discernible. The three final chambers of the last whorl progressively show onlap onto the chambers of the previous whorl,suggesting the beginning of a dorsally involute coiling.
Simultaneously they become elongate in an axial direction as in Pulleniatina spectabilis spectabilis Parker, 1965, and in Pulleniatina spectabilis praespectabilis Brönnimann and Resig, n. subsp. However,they do not cover, through the cameral sutures, the well-defined angularly contoured deep umbilical cavity of about 50 microns maximum diameter. As in Pulleniatina spectabilis praespectabilis, also in the holotype of Pulleniatina praepulleniatina, the ultimate chamber does not extend as far ventrally as the penultimate and antepenultimate chambers. In spiral view, the outline of the test is somewhat lobate, at least in the portion formed by the last four chambers. The radial cameral and the spiral sutures of the final whorl are incised.
Those of the earliest portion of the trochospire are not discernible because they are masked by secondary shell material. The ventral cameral sutures are radial. In lateral view, the outline of the test is broadly rounded peripherally, flat to faintly depressed dorsally and asymmetrically convex-rounded ventrally.
In the beginning of the trochospire, the chambers are subglobular. During growth of the final whorl, they become more and more elongate in an axial direction, show onlap dorsally and extend ventrally. These ontogenetic modifications of chamber form and arrangement are accompanied by a slight change in the coiling direction of the test from a turborotaliid to a very slightly streptospiral trochospire. The aperture is an umbilical-extraumbilical slit-like opening of about 25 microns height which extends from the umbilicus up to the shoulder of the first chamber of the last whorl. The aperture of the holotype shows, in its peripheral portion, a strong rounded rim, reminiscent of that observed in Globorotalia (Turborotalia) acostaensis acostaensis Blow, 1959 (1969, pi. 9, fig. 13-15) and Globorotalia (Turborotalia) acostaensis humerosa
Takayanagi and Saito, 1962. The calcareous wall is perforate and the surface of the early chambers distinctly pustulate. The surface of the three last chambers, however, is progressively more finely pustulate and approaches the surface structure as seen on the early chambers of the last whorl of primitive pulleniatines, such as, Pulleniatina primalis Banner and Blow,1967. The pustules are composite and form through basal and lateral fusion a well-developed polygonal meshwork. Each funnel-shaped compartment surrounds a deeply set rounded wall pore. The holotype of Pulleniatina praepulleniatina coils to the right.

The maximum diameter of the holotype is 275 microns; its axial height is about 300 microns. The specimen is illustrated on Plate 20, Figures 2 and 3. It comes from Hole 62.1, Core 21, Section 4, 15-17 centimeters, Zone N. 17, basal portion.

Pulleniatina praepulleniatina, n. sp., is the most primitive pulleniatine described so far. It develops apparently from the Globorotalia (Turborotalia) acostaensis humerosa-Globorotalia (Turborotalia) acostaensis acostaensis group of forms at the base of Zone N. 17. In Hole 62.1, Globorotalia (Turborotalia) acostaensis humerosa starts in the middle of Zone N. 17, Globorotalia (Turborotalia) acostaensis acostaensis in the upper part of Zone N. 16 and intermediates between these subspecies, from which Pulleniatina praepulleniatina might evolve, are quite common. Transitional forms have been recorded in Hole 62.1, Core 15, Sections 1 to 3, in Core 14, Sections 1, 2, 5 and 6, in Core 13,Section 2 and in Core 12, Section 5. All the paratypes from Hole 62.1, Core 21, Section 4, 15-17 centimeters,Zone N. 17 coil to the right. Pulleniatina primalis Banner and Blow, 1967, recorded in Hole 62.1 from Core 20, Section 2 to Core 6, Section 4 is here interpreted either as a direct descendant of Pulleniatina praepulleniatina or as a parallel development from the
acostaensis acostaensis-acostaensis humerosa group of forms, independently of Pulleniatina praepulleniatina.
Pulleniatina primalis has a smoother surface and pustules on the ventral surface of the first chamber of the last whorl in front of the aperture. The chambers of the final whorl here extend much farther ventrally than in Pulleniatina praepulleniatina, where the umbilical cavity also remains open in the adult. Pulleniatina praepulleniatina is, in any case, more turborotaliid than Pulleniatina primalis. On the other hand Pulleniatina primalis is always evolute dorsally, whereas Pulleniatina praepulleniatina shows in the last chambers of the final whorl a slight tendency toward dorsal involution. In its general aspect, outline and wall surface, Pulleniatina primalis is closer to the later streptospiral typical pulleniatines than Pulleniatina praepulleniatina. Reference is made to Banner and Blow's (1967) description of the holotype of Pulleniatina primalis and their illustrations on Plate 1, Figures 3 through 8 and Plate 3, Figures 2a-c. We have illustrated several paratypes of Pulleniatina praepulleniatina on Plate 20, Figures 1 through 6 and 8; of the five individuals illustrated, four
coil to the right and one to the left. The ventral extension of the final chambers and their tendency to overlap dorsally is quite variable, as is also the strength of the lip-like imperforate rim. The placing of some of the individuals either in the Globorotalia (Turborotalia) acostaensis acostaensis-Globorotalia (Turborotalia) acostaensis humerosa group of forms or in Pulleniatina praepulleniatina will clearly depend on the observers taxonomic judgement.
The maximum diameter of paratypes varies from about 350 to 415 microns, the maximum height is from about 250 to 300 microns.

References:

Brönnimann, P. & Resig, J. (1971). A Neogene globigerinacean biochronologic time-scale of the southwestern Pacific. Initial Reports of the Deep Sea Drilling Project. 7(2): 1235-1469. gs O

CATALOG OF ORIGINAL DESCRIPTIONS: Pulleniatina praepulleniatina Brönnimann & Resig 1971

Pulleniatina praepulleniatina

References:

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