Genus Nuttallides n.gen.
Genotype: Eponides trümpyi Nuttall 1930 (Journ. Pal., vol. 4, no. 3, p. 287, pl. 24, figs. 9, 13, 14. Eocene, Mexico).
Test rotaliform, more or less planoconvex, with a strong tendency to develop a peripheral flange. Sutures sloping back at sharp angle dorsally, somewhat markedly sinuous basally. Umbilical area usually with a prominent boss of clear material. Aperture a linear slit with a sharp, projecting outer edge, extending from plug almost to periphery, where it suddenly turns backwards into the flange, like Pulvinulinella.
The discovery of abundant specimens in the New Zealand Eocene of a species closely related to the Mexican Eocene Eponides trümpyi is very interesting. The Mexican form was recorded by Nuttall as frequent in the Chapapote (upper) and Aragon (lower) members of the Eocene, but not outside this age. In New Zealand, specimens are common in the Upper Bortonian and apparently less so in the Lower Bortonian. It has not occurred in the Tahuian (Uppermost Eocene) but a closely related form is present in the lower and middle Rakauroa (Upper Cretaceous). The New Zealand Eocene form is best described by comparison with trümpyi as follows.
Nuttallides subtrumpyi n.sp.
Shell of entirely the same build and general features as trümpyi, with similar dorsal and ventral sutures. The flange is much sharper; Nuttall described and figured “a rounded peripheral flange,” but New Zealand specimens have a fairly acute, bevelled, translucent peripheral border. They are distinctly planoconvex, the dorsal side being mostly flat or slightly raised medially, while trümpyi is apparently biconvex. This feature varies somewhat, but the New Zealand shell as a whole presents a recognisably different shape from Nuttall's figures. An immediate distinction is the character of the ventral boss; this, in trümpyi, is mentioned and figured as rounded, and does not disturb the basal outline; in subtrümpyi it is almost always quite flat over its whole area, the basal outline being thus sharply truncated. The dorsal surface and to some extent the ventral has a heavy layer of translucent shell material evenly spread all over, through which the sutures are visible, the central ones indistinctly where the layer becomes thickest. This feature is not mentioned by Nuttall, who figures the central portion as clearly as the rim.
Diameter, up to 1 mm. (trümpyi averages 0.7 mm.); width, two-thirds to three-quarters diameter.
The figures prepared for this description did not show the essential details clearly, and illustrations will be given in a later paper.
Type from locality 3310, greasy marl, Matakohe Survey District, Auckland, 1 mile north-west of Pahi, Paparoa Arm. This is interbedded with greensands of the Pahi series, contains also Zeauvigerina and Hantkenina and is definitely Upper Bortonian. Elsewhere the species extends throughout the Bortonian (but not above), with a few rare specimens, possbily a distinct species, from the uppermost Cretaceous.
The reference of this type of shell to Eponides can hardly be upheld. Nautilus repandus, the genotype of Eponides, is a common Indo-Pacific shell, and its lineage is continued well back in our Tertiary. Fairly typical specimens extend down to the Lower Miocene, but in the Lower (and perhaps Upper) Ototaran a distinct ancestor occurs. This differs in having a less-pointed base, a distinctly open umbilical area formed by the great spread of the aperture ventrally, and especially in having fewer chambers; regularly five to a whorl, instead of seven to ten as in repandus. This form is especially common in the Waiarekan tuffs of Lorne (G.S. locality 1100) and
may take the name of Eponides lornensis, new species. Chapman, Parr and Collins (1934, p. 565, pl. 9, figs. 18a–c) have recorded and figured repandus from the Australian Tertiary as far down as the Oligocene Balcombian; as they say, Muddy Creek examples seem inseparable from typical Recent shells, and the same applies to N.Z. examples from the Miocene onwards. Waitematan specimens occasionally look like lornensis, but adults always have six or more chambers.
All these true representatives of Eponides show the typical generic aperture, a widely open space entirely confined to the straight contact between the last whorl and base; its outer margin notably convex and with a wider gape ventrally before the umbilical union of the sutures is reached. In the ancestral lornensis it spreads into this area; in all forms there is a definite end at the periphery with no tendency to invade that area at a new angle. The apertural face in typical Eponides is usually more or less cribrate. Other species of Eponides, such as the American Tertiary guayabalensis Cole and the European Miocene to Recent schreibersii d'Orb., keep this type of aperture with not a great transition in shell features.
This is totally unlike the apertural features of trümpyi and its allies, with the angled lateral extension into the peripheral face, and as several diverse species are known with this type of aperture it is here made the principle basis for generic segregation, though general habit of shell and type of chambers are not without significance also.
I suggest as a congeneric species Discorbina alata Marsson, which has been figured and described as a Pulvinulinella by Cushman (1931, p. 311, pl. 36, figs. 5a–c). Specimens extremely similar to those there figured from the Saratoga chalk occur at locality 3250A, Tuparoa Stream, Waipiro S.D., Poverty Bay, in marls of mid-Rakauroa age. The aperture in Cushman's figures is not altogether distinct, but the New Zealand specimens show exactly the Nuttallides aperture. The basal knob of clear callus is prominent only in juveniles, adult examples tending to surround this below with a basal ridge, forming a pseudo-umbilicus. The later figures of this species given by Cushman and Jarvis (1932, p. 48, pl. 15, figs. 1, 2) are less like the Tuparoa and Saratoga specimens and more resemble in shape another species occurring in the New Zealand Rakauroa.
The devolpment of the basal characteristics in alata lead me to suggest that the characteristic Upper Cretaceous species recorded by authors as Gyroidina or Globorotalia micheliniana d'Orb. also belongs to Nuttalides. Cushman's figures of Annona chalk and Antigua specimens show clearly the sinuous suture and flange development and the characteristic aperture. Also the pseudoumbilicus, as in alata, is quite different from the pervious one of Gyroidina. Two other Cretaceous species certainly to be grouped with micheliniana are Gyroidina alabamensis Sandidge (Alabama Ripley) and Globorotalia subconica Morrow (Kansas).
Another genus which must necessarily be brought into the discussion is Pulvinulinella Cushman. The genotype of this is P. subperuviana Cushman, the description and figures of which show an
elongate aperture just below the periphery and entirely in the plane of coiling, without prolongation along the basal margin towards umbilicus. The aperture was originally described as “somewhat loop shaped,” with the remark that the type species “does not show the apertural characters as definitely as do the Recent species.” This was evidently overlooked by Chapman, Parr and Collins (1934, p. 569, pl. 9, figs. 19a–c) when describing the Australian Oligocene tenuimarginata as doubtfully belonging to this genus. In shell features it is quite like the genotype except for the straight aperture, which, however, is seen in Recent species such as pacifica Cushman. The Balcombian form, which can be taken as gencrically typical, is abundant also in New Zealand, where is has an extended range from at least Lower Oligocene to Upper Miocene.
A series of such typical species shows that the Pulvinulinella aperture is well defined and not really much like that of Nuttallides, where the lateral extension, though definite, is merely an adjunct to the main aperture, and it is stretching the limits of the genus too much to include alata and similar types. The recently described P. gyroidinaformis Cushman and Gaudkoff (1938, p. 2, pl 1, figs. 1, 2) has some unusual shell features but apparently a fairly typical aperture. Another type of aperture, however, which is decidedly atypical is that shown by Planorbulina culter Parker and Jones. This has been very generally referred to Pulvinulinella but some writers have questioned this, and Nuttall (1930, p. 293) has stated that the appertures are very different. The good figures given by Brady (Chall., pl. 96, fig. 3c) and Schwager (1866, pl. 7, fig. 111; as bengalensis) clearly show that the striking feature of this aperture is an oblique slit in the end face, well below the periphery, opening out from the contact slit between base and last chamber, and descending well into the face at an angle about midway between basal and peripheral margins. A number of similar forms are known, including mexicana Cole, velascoensis Cushman and probably the lately described texana Cushman (1938, p. 49), which, though compared with alata, seems to have more the culter type of aperture and shell coiling. This kind of shell is common practically throughout the Tertiary succession in New Zealand, and the lineage extends into the Upper Cretaceous. The apertural and shell distinctions from Pulvinulinella and Nuttallides are here emphasised by the proposal of the new genus Parrella, with Anomalina begalensis Schwager as genotype. This form is chosen for the type instead of Parker and Jones' culter on account of the ambiguity associated with the latter. Chapman and Parr (1937, p. 119) have noted that the true culter differs from Brady's interpretation, which probably was equivalent to Schwager's species; since my remarks on apertures have been based on shells like Brady's and Schwager's figures, it is plain that bengalensis must typify the genus. These remarks were written before Chapman and Parr's were seen; their independent suggestion that a new genus is probably needed is much wiser than their unsatisfactory location in Cibicides.
Cushman has figured (Contrib. Cush. Lab., vol. 14, pt. 3, pl. 11, figs. 4, 5) as Pulvinulinella two species which show very clearly indeed the characteristics of the two apertures, glabrata being a typical Pulvinulinella, while navarroana is plainly a Parrella.
It is fitting that the genus name should mark the independent research of Mr. W. J. Parr into this matter.