New species of unilocular calcareous foraminifera from the Holocene of the southwest Pacific Ocean

Four new species of unilocular calcareous foraminifera are described from Holocene sediments of the southwest Pacific Ocean. Vasicostella cranimorpha sp. nov. is distinguished by a lenticular tubule that pierces each margin of the peripheral carina. Globofissurella pattersoni sp. nov. is characterized by a large, produced circular apertural area ornamented in part by costae continuing from the chamber surface. Palliolatella peponisema sp. nov. bears a strong resemblance to a pumpkin seed, and has quite variable development of its central keel. Parafissurina thryptica sp. nov. is distinctly teardrop-shaped, with its greatest diameter near the base, and a mildly acute apertural end.


INTRODUCTION
Unilocular foraminifera from the southwest Pacific Ocean have been the subject of some significant studies, chief among them being F.W.O. Rymer Jones (1874), Millett (1901a. b, c). and Sidebottom (1912Sidebottom ( , 1913. In the present study, the benthic foraminifera in a suite of 62 Holocene sediment samples were examined. The sites are widely distributed across the tropical southwest Pacific Ocean, and span a range of water depths from 110-8900m. A total of 141 species of unilocular calcareous foraminifera were identified in the course of the study. Of these, 109 were referable to known species, while most of the remaining 32 species were represented by single or poorly preserved specimens. However, four of these species are represented by several excellent specimens with consistent features, and are described and named herein.

MATERIALS
All samples examined in this study were from the core collections of Scripps Institution of Oceanography, La Jolla, California. Information concerning the samples yielding the new species described herein is given in Table 1.

TYPE SPECIMENS
All holotype and paratype specimens denoted by the GSC prefix are deposited in the collections of the Geological Survey of Canada, Ottawa. Paratypes denoted by the RTP prefix are deposited in the collections of the Department of Earth Sciences, Carleton University, Ottawa.  surf.

SYSTEMATIC DESCRIPTIONS
Chocolate brown ooze. Grey-brown ooze. Light brown ooze. Light brown ooze. Light tan ooze.
Light cream-tan ooze. Grey-tan oozc. Tan Jones (1984). This may represent an extreme development of the absence of tubuli, which has been noted in the description, or merely reflect the fact that coating of specimens for SEM work hides the tubuli in lateral view (see PI. 1, figs 1, 5 this paper). The form wherein the outer costa encircles the chamber face is similar to that described as Lagena clathrata by Brady (1884: 485, pl. 60, fig. 4). However, that form lacks a tubular apertural neck, having a crescentic neck or lip instead. The present species is assigned to Vasicostella Patterson & Richardson, 1987 on the basis of its coarse costae, as opposed to the fine striae or ribs which characterize Lagnea Popescu, 1983. This latter genus often has a tubulated keel, however, and the present species, with its large tubuli, may represent a transition between the two genera.
Subfamily Ellipsolageninae A. Silvestri, 1923 Genus Globofssurella Patterson, 1986 Remarks. This genus is barely if at all compressed, the peripheral plane being defined by one pair out of several costae that is more completely developed. In contrast, Fissurina Reuss, 1850 lacks costae and is distinctly compressed. Derivation of name. In honour of R. T. Patterson's extensive work on unilocular foraminifera. Diagnosis. A species of Globofissurella in which the costae run well up onto the produced apertural area, which is also nearly circular rather than strongly compressed in section.   Fig. 19, lateral view, X315; fig. 20, oral view, X310. Figs 21,22. Parafissurinu fhrypticu sp. nov., paratype GSC 104632. Fig. 21 Description. Test pyriform in outline, 1.3 to 1.7 times as long as broad, barely compressed, base and apertural end well rounded, chamber somewhat ovate, with constriction before heavy broad convex apertural neck or collar that is hyaline imperforate and almost half as large in outline dimensions as the chamber. Surface with numerous sharp costae, fifteen in the holotype, with one set distinctly continuous across the base, forming a narrow carina. Each face with six to eight costae, not all reaching as far toward base, and none contacting the carina, becoming lower as they pass up chamber onto neck, eventually disappearing over halfway up the neck. Aperture terminal, a small oval opening, with entosolenian tube which appears to be attached to one side, there being no other asymmetrical elements to the test. Dimensions. Length of figured holotype GSC 104621 211 pm, width 124pm; length of figured paratype GSC 104622 176 pm, width 135 pm. Remarks. This species differs from G. bulabrum Patterson, 1986, in which the costae terminate at the base of the neck, and anastomose at the base, forming a zigzag keel or ridge where they meet. Lagena gratiosa Buchner, 1940 has a longer, constricted, straight neck with a slightly flared lip, all of which is embraced by broad carinal flanges. Boltovskoy & de Kahn's form clearly does not belong in that species, but it cannot be referred confidently to the present species without a basal view.
Genus Palliolatella Patterson & Richardson, 1987 Remarks. This genus is distinguished by the peripheral carina which embraces an elongate apertural neck, and iy expanded at the apertural end to form a so-called hood.