Description of lectotype: The fairly large test (approaching one millimeter in diameter) consists of about 10 chambers arranged in a very low trochospire of about 2 whorls, with 5 chambers present in the last whorl. The chambers are little, if at all, inflated; they are strongly compressed dorso-ventrally and uniformly enlarging. The equatorial profile is subcircular and the equatorial periphery is lobulate. In axial profile, the dorsal and ventral surfaces are only very slightly convex and the axial periphery is sharply acute. The dorsal intercameral and spiral sutures are weakly depressed but are limbate, being thickened by clear shell material which bears short blunt spines. The dorsal intercameral sutures are smoothly re-curved, meeting the spiral suture almost at right angles. The chambers do not embrace on their dorsal sides and the clear shell material present in the sutures appears to be continuous with the imperforate peripheral carina. The ventral intercameral sutures are depressed and nearly radial. The peripheral carina is characteristically furnished with an abundance of strongly developed spines arranged in nearly radial directions.

The umbilicus is small but open, with the relict parts of theprimary apertures of some of the later chambers visible within it. The primary aperture is interiomarginal, umbilical-extraumbilical, a low elongate opening furnished with a distinct lip. A trace of the lip of the penultimate chamber can be seen within the umbilicus. The wall is uniformly and fairly finely perforate, except for the imperforate peripheral carina and the dorsal sutural thickenings. The surfaces of the chambers are smooth except where these thickenings occur and no secondary deposits are apparent on the ventral side. [Banner & Blow 1960]

FROM BANNER & BLOW 1960

Taxonomic remarks: In 1884, Brady illustrated and described this species his original specimens are present in a slide registered in the British Museum (Natural History) as number ZF. 2227. These specimens, four in number, came from Challenger Station 24, depth 390 fathoms, off Culebra Island, West Indies. Brady's handwriting on the reverse of the slide confirmed that his illustrated specimen was present and this specimen has now been isolated and re-registered as British Museum (Natural History) number 1959.7.1.2. The work by Brady's illustrator, A. T. Hollick, was very accurate and we consider no useful purpose would be served in redrawing the specimen. The original illustration is reproduced here (pl. 5, fig. 2). [Banner & Blow 1960]

Remarks: The typical form of this species appears only to range from Pliocene to Recent, but some primitive forms have been observed in sediments of Fiji and Papua which may be of Uppermost Miocene age. These primitive forms show a relationship with Globigerina in/lata d'Orbigny auct. and it may be that the latter form is ancestral to P. obliquiloculata (Parker and Jones). The form figured by Stainforth (1948, p. 125, pl. 26, figs. 21-23) from the supposed Upper Miocene of Ecuador appears similar to the forms seen by us rom Papua and Fiji. These early forms are not so strongly streptospiral in late ontogeny as are the typical forms of the species. The form recorded by Germeraad in 1946 as Pulleniatina? semi-involuta is of unknown taxonomic position and needs further study. [Banner & Blow 1960]

References: