The generic revision of the Reussellids (Foraminiferida)

The study of the apertural complex in the type species of the reussellid genera leads to a reassessment of the classification of these taxa. The genus Reussella has so many characteristics in common with Bulimina that it is reclassified in the Buliminidae. The family Trimosinidae is retained and redescribed to contain the genera Trimosina, Mimosina and Fijiella only. Pyramidina is retained in the Turrilinidae on account of the praebulimine toothplate. The absence of an internal toothplate and the very un-bulimine apertural face in Bifarinella, Chrysalidinella, Cifellia, Finlayina, Orthocerina, Pavonina and Valvohifarina species is the main argument to remove these genera from the Buliminacea and reclassify them in the superfamily Pavoninacea herein proposed. The genus Orthocerina d’Orbigny, 1839 is reinstated and shown to be closely related to Chrysalidinella and Cifellia. The genus Compressigerina is reclassified in the Uvigerinidae, close to Trifarina because of the presence of an apertural neck with toothplate.


INTRODUCTION
The genus Reussella was created by Schwager ( 1 877) (under the preoccupied name Reussia), for high trochospiral Foraminifera easily distinguished from other forms by a remarkable triangular, almost pyramidal form, with Verneuilina spinulosa Reuss, 1850 as the type species. Although some years passed before the genus became generally accepted, it was finally incorporated in the systematic schemes, always more or less closely allied to Buliminn. Cushman (1927) created a separate subfamily for Rms.sia, changing its name to Reussellinae when the synonymy of Reu.rsia was shown (Cushman, 1933). Throughout his publications he maintained the Reussellinae as a distinct subfamily in the Buliminidae (Cushman, 1948). In 1929. Cushman discussed the position of s o m e of the reussellid g e n e r a , including Chi:vsnlidinella Schubert, 1907, Trimosina Cushman, 1927and Mimosinu Millett, 1900. R r u s s e l l u w a s described a s a development of Buliminu, differing by being triangular but with the same kind of aperture. Galloway ( 1933) proposed the name Reu.ssella to replace the preoccupied Re~/.s.sia and classified i t in the Turrilininae, Buliminidae. It was kept separate from the Bulimininae, partly on account of the absence of 'an internal ribbon or pillar' as present in Bulimina (Galloway, 1933, p.357).
The restudy of all known reussellid taxa by Cushman (1945) resulted in redescriptions and a systematic arrangement which set the scene for all subsequent classifications. He classified h'rirssclla, Trimosina, Mimosina, Paivnina and Chr~salidinellm in the Reussellinae, Buliminidae.
Despite the thorough study of the Buliniina, U~,igerina and Boliitinu-like taxa, Hofker (195 1 ) devoted little attention to Rei4.ssella. He described and briefly discussed two new species and classified Reussella in the Buliminidae, discussed the status of Chrysalidina, and erected V a l v o p a i~w~i n a and Vali~ohifarinu. Later, he discussed in great detail the relation between the different, for the Cretaceous important, buliminid genera (Hofker. 1957). He concluded that Reussella showed distinct affinities to Praehulimincr and Birlimina. but regarded Pyramidinu Brotzen. 1948 as nothing but an ontogenetic development of Reu.ssella. Loeblich & Tappan (1964) classified Reussrllu in the Pavonininae, reducing the Reussellinae to synonymy. They figured two specimens from the Vienna Basin and reproduced Hotker's drawing (Hofker, 1951, p.143) of the toothplate of Reussella spinulosa. Besides Rrussrlla, they included Pawnina. Acostina, Chi-ysalidinella, the synonymised Chrysalidinoidcs, Fijiellu, Mimosina, Trimosina, Tithulogrnerina and Vnlvohifurino in the Pavonininae. It was mentioned in passing that the more primitive, true toothplate-bearing forms might be separately classified in the Reussellinae, while the more advanced form\ would be kept in the Pavonininae (Loeblich & Tappan, 1964, p.562).
In their latest classification, Loeblich & Tappan (1987) presented a considerable number of changes. For the Bulirninacea, they propose the recognition of the Reussellidae alongside the Siphogenerinoididae, Buliminidae, Buliminellidae, Uvigerinidae, Trimosinidae, Pavoninidae and Millettiidae. They reduced the Re u s s e I I id a e to in c I u d e R e u ss e Ila , A cost in a r y sa l i d ; n c l l t i .
Cornpressigerinu, Fijiella and Vali~oh(farina only. Mimosina and Trirnosina are the sole genera in the Trimosinidae, while P avonina, Bifarinella and Finlayina make up the Pavoninidae. The instability in the classification of the Reussellidae sensu lato indicates the need for a detailed study of the taxa in question, in order to obtain all the necessary comparative data afresh. Order Foraminiferida Eichwald, 1835Suborder Rotaliina Lankester, 1885Superfamily Buliminacea Jones, 1875 Family Buliminidae Jones, 18751875Buliminida Jones, in Griffith & Henfrey: 320 1927Reussiinae Cushman: 68, nom. rej. 1933 Genus Reussella Galloway, 1933 Reussella spinulosa (Reuss, 1850) (PI. 1, figs 1-4) 1850 Verneuilina spinulosa Reuss: 374, p1.47, fig. 12 1933 Reussella spinulosa (Reuss); Galloway: 360, p1.33, fig.4 1964 Reussella spinulosa (Reuss) Description. Test free, pyramidal, sharply triangular in crosssection, regularly increasing in size, 4 whorls, triserial; chambers low tetrahedral, wider than high, edges rather sharp, may slightly overhang the previous whorl, marked by a short spine at the very edge, in regular series, almost flush with the surface; intercameral sutures arched, spiral suture almost straight, distinct; aperture central at the apex of the test, apertural face almost terminal, formed by the top of the two previous chambers and for v3 by the ultimate chamber, aperture a large elliptical opening lying along the basal suture, bordered by a low lip which descends into the lumen to form the top of the toothplate; toothplate an elegant thin plate with a free, curved border, fuses with the foraminal lip at its topmost, peripheral side; wall calcareous, optically distinctly radial, distinctly perforate, with larger pores tending to seam the sutures. Remarks. Reussella differs from Bulimina in the pronounced angularity of the test; the chambers are tetrahedral rather than spherical and the aperture is more ovate and oriented in a Turrilina-like fashion. Although the preservational state of the available topotypes hinders critical observation of the relation between toothplate and foramen, the attachment seems to be intermediary between the very simple turriline and more extensive bulimine one. Observations of modem Reussella species show that most have a toothplate more akin to Bulimina, rather than Turrilina.

SYSTEMATIC DESCRIPTIONS
The study of material from the Vienna Basin shows that more than one species of Reussella is present in the Badenian. A revision of the genus is clearly needed to clarify the taxonomic status of most of its species.
Specimens from 'Galathea' St.376, 4O30'N 103"28'E, off Kerteh, Trengganu, -1 Om. Description. Test free, elongate, triangular in section, gradually tapering, chambers arranged in regular triserial series throughout ontogeny, 3 to 4 whorls; chambers subtetrahedral to subspherical, distinctly inflated, drawn-out peripherally into a pointed projection bearing one strong spine; sutures distinct, narrow, depressed, gently arched; aperture double, apertural face not delimited, superior aperture subtriangular, staying below the apex of the chamber, separated from the lower aperture by a fairly narrow thickened band of usually imperforate chamber wall, lower aperture an elongate slit with a denticulate upper edge, parallel to the basal suture, apertures not bordered by an everted lip, toothplate in one part, multiple attachments to the inside of the chamber at the upper aperture; wall calcareous, hyaline, finely and densely perforate, optically distinctly radial, earlier part of the test appears to be ornamented by numerous fine, low ridges running between the pores.
Genus Fijiella Loeblich & Tappan 1962 Type species. Trimosina simplex Cushman, 1929, original designation. Fijiella simplex (Cushman, 1929) (P1. Description. Test free, pyramidal to sub-pyramidal, triangular in section, early part regularly increasing in size, later part constant width, 6 whorls, triserial; chambers low tetrahedral, in regular series, flush with the test surface, the outer edge may tie slightly spinose; sutures distinct, intercameral ones curved, spiral suture gently undulate; apertural face terminal, apical, triangular and slightly convex, commonly bordered by thickened imperforate rims, ornamented with numerous small upright spines, aperture slit-like, partially covered by a low-lying extensively curved lip, lip divided into two pieces, a larger sigmoidally wrapped denticulate plate and a smaller less denticulate one curved into the hollow left by the larger one; toothplate large, perforated by a few large holes, fuses partly with the foraminal spines, partly with the foraminal lips; wall calcareous, optically distinctly radial, perforate, pores tending to seam the edges of the individual chambers, often slightly produced on low mounds. Remarks. Although superficially similar to Rrussella, the peculiar apertural face and especially the toothplate show it to be Explanation of Plate 2   a distinct genus. The apertural face is covered with spines and tubercles which may deceive one into believing that a supplementary cribrate aperture is present. If extra openings are at all present then it is due to subsequent damage or perhaps reproduction.
Genus Mimosina Millett, 1900Millett, 1900 Mimosina Millett: 547 Type species. Mimosina histrix Millett, 1900, subsequent designation by Cushman, 1927. Mimosina histrix Millett, 1900  Description. Test free, elongate, tapering, slowly but regularly increasing in width, triserial in juvenile stage, later chambers arranged in biserial series; chambers very inflated, spherical, with an outwards projecting spine arising in the middle of the chamber; sutures distinct, depressed, gently arcuate; aperture double, no delineated apertural face, aperture turned towards the coiling axis, upper aperture almost terminal, rounded, bordered by a thickened low lip, separated from the lower aperture by a small ridge of perforated chamber wall, lower aperture more ovate, also bordered by a low, thickened lip; toothplate starts from the upper end of the topmost aperture and curves towards the toothplate bending downwards from the ridge between the two apertures, the lower toothplate continues towards the foramina and fuses with the foramen sitting over the top foramina1 opening; wall calcareous, hyaline, distinctly and densely perforate, the wall may be ornamented with thin, short ridges running parallel to each other. Remarks. The description covers the majority of specimens. apparently belonging to the microspheric generation. A few specimens were found which appear to be megalospheric. These differ from the microspheric ones in being biserial throughout, having more spherical chambers with much reduced projecting spines, and in having more prominent and larger apertural openings. It seems that the aperture becomes double only later in ontogeny as observation of some of the earliest chambers shows only a single aperture.
Family Turrilinidae Cushman, 19271927  Description. Test free, elongate, broadly ellipsoid in outline, periphery slightly lobulate, bluntly triangular in endview, triserial. 2 to 3 whorls; chambers moderately inflated, regularly increasing in size, somewhat angular but broadly rounded; sutures indistinct, slightly depressed, gently curved; aperture subterminal, elliptical, bordered by a low, thickened lip, clearly separated from the basal suture; a straight, narrow toothplate runs from aperture towards the foramen where it is apparently attached adjacent to the top of the foramen, running over a short distance as the plate narrows during its descent; wall calcareous, perforate. opaque. Remarks. All    Description. Test free, fan-shaped, compressed, initial stage hiserial, after about 8 chambers apparently becoming uniserial, due to the embracing of the successive chambers; chambers initially rounded, then laterally compressed and quickly becoming semi-lunar and more and more embracing; sutures distinct, arched; primary aperture appears to be absent but larger pores occur between the tubercles on the side rim of the chamber, chamber interior simple; wall calcareous, hyaline, optically distinctly radial, a septal flap is present, perforate, pores very large, on low raised mounds, arranged in a single row bordering the chamber edges, sometimes with a supplementary row. Remarks. The presence of a septal flap in this species adds weight to the calls for relinquishing this characteristic for taxonomic purposes above the species level. The absence of a well defined primary aperture makes this an unusual taxon. The ridges present in some specimens indicate that the earliest part may be twisted biserial, but it is never truly triserial.

Hayward.
Description. Test free, irregularly fan-shaped, laterally very compressed, first 14 chambers biserial, then uniserial, producing a central zigzag pattern in the lower part of the test; chambers numerous, semi-lunar. very much drawn-out and very low, almost lint-like, regularly increasing in length, except when changing from biserial to uniscrial coiling, not embracing; sutures indistinct, flush with the surface; aperture at the outer upper edge of the chamber, composed of multiple irregular openings, internal structures absent; wall calcareous, perforate, opaque. Remarks. Differs from Pavoninu in lacking the characteristic 'tubulopores' and the low tubercles sown all over the outer chamber edge, in being distinctly biserial for some 14 chambers, and in lacking the discrete costulation in the earlier part of the test. All available specimens show the effects of heavy diagenesis, thus making critical observations impossible.
This species appears to be related to Quasiholivinellu tuylori Quilty, 1981. Although the latter is reported to be biserial throughout, it shows the same disposition of the earliest chambers, and both the surface and outline are remarkably similar.
Chrysalidinella paczfica (Uchio, 1952 Description. Test free, elongate, at first triangular in section, but quickly becoming quadrangular, triangular part multiserial, then reduced to uniserial; chambers flush with the surface, tetrahedral to sub-cubic, not clearly delimited; primary aperture not observed, foramen pierced by relatively large rounded openings bordered by a low rim, scattered over the septa1 face; wall calcareous, distinctly perforate. Remarks. Chrysalidinoides was synonymised by Loeblich & Tappan (1964) with Chrysalidinella on the grounds that quadrangularity is known to be adventituous in many dominantly triangular forms. Specimens of the 'Challenger' material seen by me reinforce this conclusion, since some of them are quadrangular later in ontogeny. The species pacz~ca is maintained as it can be differentiated from C. dimorpha by the pores being barely produced and the openings on the apertural face being bordered by low rims (plate 4, fig.9).
Genus Cifellia Gibson, 19891989 Type species. Chrysalidina cosfafa Heron-Allen & Earland, 1924, original designation. Cifellia costata (  Figs 7-9, Close-ups of the tubular networks. Note especially the absence of contact between successive networks and the large, irregular holes in the test wall underlying the networks ( 5 0~) .
Valvohifurina mackinnonii (Millett), lectotype; Fig. 10, Habitus (200pn); Fig.1  Description. Test free, elongate, angular, width fairly uniform, later in ontogeny somewhat irregular outline, usually triangular in section, quadrangularity adventitious, early part triserial, then uniserial; chambers subtetrahedral, angular, lower than wide, at first flush with the test, later in ontogeny overlapping and irregularly arranged over the test; sutures distinct, flush with the surface, may be slightly raised, distinctly curved upwardly; apertural face apical, triangular, aperture multiple, composed of fairly large irregular openings, apertural face covered by a lowlying network of massive cylindroid structures apparently delimiting the apertural openings, no internal structures; wall calcareous, hyaline, distinctly perforate, pores usually arranged in rows parallel to the sutures, raised on low mounds, giving a 'tubu1opore'-like impression. Remarks. The tubular network on top of the apertural face very often has foreign material trapped in the gaps, obscuring the apertures. This may to some extent explain why the original description by d'Orbigny mentions only a single opening. Le Calvez (1977) states that the only available specimen, contrary to d'orbigny's description, actually possesses a multiple aperture: " ... alors qu'il s'agit de pores disskminks sur toute la face orale".
Due to curatorial policy, it is impossible to investigate the holotype of Orthocerina in full detail. However, specimens recovered from d'orbigny's original samples seem to fit the original description, bearing in mind the different degrees of resolving power of our respective instruments. I feel confident that the true nature of Orthocerina is here adequately presented.
The type specimen of Orthocerina is quadrangular in section, but all specimens recovered from the Cuba and Jamaica samples originally used by d'Orbigny are triangular. I maintain that triangular and quadrangular specimens are conspecific, as is indeed the case for Chrysalidinella (q.v.).
Remarks. The specimens of V. mackinnonii figured by Millett, supposedly from the Malay Archipelago, should be considered lost. Courtesy of Mr Hodgkinson (BMNH), the following details relevant to the Millett collection have come to light. The Millett collection was salvaged through effective action taken by Heron-Allen after Millett's death. Apparently, Heron-Allen found the collection in Millett's house in a very derelict state, with many of the slides open, quite damp, attacked by mould and buried under great piles of dust and rubbish. Heron-Allen tried to rescue as much as possible, but obviously losses were unavoidable. This also explains the precarious and fragile state of many of the specimens in the Millett collection.

Genera attributed to the Heussellidae
Genus Acostina Bermlidez, 1949Bermlidez, 1949  However, based on the drawings provided by Acosta, I wish to make the following suggestions. The triangular shape of the test and the form of the chambers seems to indicate some affinity to Tristix MacFadyen, 1941 or some other Nodosariid taxon. Until specimens become available for further investigation, I propose to remove Acostina from the reussellid taxa and to consider it as incertae sedis.

DISCUSSION
The general habitus of the species studied falls in the category of the high trochospiral forms. The test is elongated along the coiling axis, and the seriality is reduced. Most of the species investigated exhibit a mixed seriality: the juvenile test is often tri-or biserial, but soon becomes reduced (Bifarinellu, Chrysalidinella, Cifellia, Finlayina, Mimosina. Orrhocer-ina, and Valivhifarina). It seems that this mixed seriality is linked in at least some of the genera to reproductive dimorphism. There are indications that a correlation exists between the size of the proloculus and the occurrence of a pluriserial juvenile part; i.e. the rnicrospheric generation seems to start a test pluriserially, while the megalospheric generation is rectilinear from the very beginning ( e . g . C h r y s a l i d i n e l l a , Cifelliu, m a y b e a l s o Orthocerina). Others remain triserial throughout their ontogeny (Fijiella, Mimosina, Pyr-amidina and Reu.ssella), irrespective of the generation.
The shape of the chamber is quite varied. Contrary to the other representatives 0 1 the Buliminacea, characterised by .;pherical or at least broadly rounded chambers, many of the 'reussellid' genera have tctragonal chambers with true triangular faces, sharp comers and edges. Others possess curiously modified chamber forms such as cuneate (Vul\~ohifurina), ribbon-shaped (Bifarinella), or reniform chambers (Pavonina, Fir~la.vina).
The pores in the wall of tests also show some interesting variety. In many cases the pores are arranged i n neat rows paralleling the sutures of the chambers. In some taxa (e.g. R$urinella, Valvohifarina), the pores are produced on small mounds, vaguely reminiscent of the t u b u l o p o r e s in fuhulogenrrina (see Gibson, 1987).
T h e habitus of the test in these genera has been uscd extensively to classify them more or less together on the family level. T h e apparent recurrency of early 'reussellid' coiling together with historic tradition are the main reasons behind this taxonomic arrangement. The use of internal anatomical features has never beforc been attempted for the genera here under study.
As was the case for some of the buliminid genera, the inclusion of these characteristics in the analysis is a great help in clarifying the true relations between the genera (Revets, 1989). The apertural complex in the taxa investigated is highly varied or e v e n u n k n o w n . Upon opening the specimens, a fundamental divide can be made immediately, depending on the presence or abscnce of a toothplate. The apertural complex i\ intimately related to the toothplate, so that a fairly large set of characters are available for systematic purposes. The apertural face ranges from a typical bulimine one (Reussella) to a simple p l a n e p i e r c e d by larger, irregularly arranged openings (Chry.sulidinella). Peculiar modifications do occur such as the tubular net in Orthocerina, or the heavily sculptured lips in Fijiella, and even the presence of more than one primary opening as in Mimosina and Trimosina.
As is the case for Bulirnina-like taxa, there is a clear relation between the apertural f a c e and the presence (and indeed morphology) of the toothplate. All taxa with an un-bulimine aperture lack any form of toothplate (Bifarinella, Chrysalidinella. Cifellia, Finlayinu, Orthocerina, Paimina, Val\h'fat-ina). The remaining genera possess a toothplate with varying degrees of complexity. The simplest toothplate is encountered in Reussella. in which a typically bulimine toothplate connects aperture with foramen, its relation to the apertural lip included. Complexity increases with Fijiella (with rather disturbing reminiscences to the apertural complex in Sagrina pulchellu, type species of Sqrinu d ' O r b i g n y , 1839 [study in p r o g r e s s ] ) , and finally a very convoluted morphology, quite different from the bulimine toothplates, is found in Trimosina and especially in Mimosina.
From early on in the endeavours towards classification. Reussella has been more or less allied to Bulimina. The perceived similarities between representatives of these two genera were based exclusively on the gross outer morphology. Before the work by Hofker (1951), all students seem to have been unaware of the presence of an internal toothplate in Reussella (e.g. Galloway. 1933, p.357-358;Cushman. 1927Cushman. , until the last re-edition in 1948. Surprisingly, Galloway (1933) (Hofker, 1951, p.143). Loeblich & Tappan (1964, also 1987 reproduced Hofker's drawing of the toothplate of Reu.s.selln spitiulosa sensu Hofker. and figured two specimens from the Miocene of the Vienna area. One of the specimens drawn agrees very well with the figures provided by Reuss, but the other specimen fits Reirssella pirlchrci Cushman, 1945, also from the Vienna Basin. The toothplate is similar to the one in Birliniiriu murgi~iuru (Revets. 1989. plates I & 2). This stands in sharp contrast to the toothplate depicted by Hofker (1951), and later reproduced in all major classifications. Since Hofker only used Recent representatives from the Pacific Province, it is almost certain that the specimens identified by Hofker as R. spinulosa belong in fact to quite a different species, and maybe even to Fijiella. Furthermore, the morphology of the apertural face and the coiling mode are the same as in Bulimina. The chief difference between the two genera is the form of the chambers, which is tetrahedral in Reussella and rounded in Bulimina, and the orientation of the aperture, lying in a Turrilinalike fashion in Reussella rather than running up the apertural face.
Since the organisational principle of Reussella is shown to be matching that of Bulimina, Reussella is here reclassified in the Buliminidae. A difference in chamber form is useful to characterise genera, but does not constitute in itself a sufficient criterion to separate families. Recent specimens of Reussella only confirm this observation: although many of the species seen have a much larger aperture than R. spinulosa, it is still clearly of the bulimine type, albeit oriented more in a Turrilina-like fashion. However, the strict triseriality and the low, barely ornamented apertural lip shows the affinity to be bulimine, rather than tumline.
The genus Fijiella, originally separated from Trimosina, is very different from Reussella, anatomically speaking. The apertural face is much larger and flatter, ornamented by upwards projecting short spines, and the aperture itself is partially hidden by a heavily modified lip which has fragmented into a double, flap-like protrusion. The original description of the genus mentions the presence of supplementary openings in the central part of the apertural face (Loeblich & Tappan, 1962;also Cushman, 1929). These openings are found in some specimens but are lacking in the large majority of them, including the type specimens. These openings may be due either to taphonomical effects, or may be linked to reproduction. I do not consider them to be primary and therefore disregard them as being of any use for descriptive and taxonomic purposes. The toothplate is an intricate piece of calcite, rather large and perforated by a number of holes, which contacts the septum not only at the foraminal lips, but also at the foraminal spines. The construction of the toothplate differs from the Bulimina-like toothplate in Reussella, but is rather similar to the one in Trimosina. The similarity of the toothplate morphology to the one in Sagrina raises disturbing questions as to which grounds to use for taxonomic decisions. It has become increasingly difficult to argue the relative merits of characteristics used to define supraspecific (and especially suprageneric) taxa.
The analogy in toothplate anatomy and the resemblance of the apertural face between Trirnosina, Mimosina and Fijiella demonstrates affinities between these three genera extending beyond the more superficial resemblances of coiling and test shape. Fijiella can be regarded as the more primitive genus in this group: the aperture is not yet double, but the beginnings for it are present (witness the doubling of the apertural lip). Development is taken one step further with Trirnosina, in which the aperture has become double, but with the lower one still very narrow; the toothplate is still a single plate, but the multiple attachment sites clearly show the increasing complexity. The pinnacle is reached with Mirnosina, with two very prominent primary apertures and (especially) the convoluted toothplate. Therefore, the Trimosinidae are maintained and redefined to include Trimosina.
The status of Compressigerina remains still somewhat uncertain because of the state of preservation of the specimens. However, the apertural neck is a very strong indication for uvigerine affinities, and, together with the habitus of the test being reminiscent of Angulogerina, sufficient arguments are available to reclassify it in the Uvigerinidae.
The majority of genera studied deviate substantially from the reussellid or even buliminid concept, i.e. they lack a toothplate, possess a very uncharacteristic apertural face and have a mixed seriality. I therefore propose to recognise these fundamental differences by introducing the superfamily Pavoninacea.
The genera herein revised in the Pavoninacea fall into two groups. On the one hand there is the group centred round Pavonina, including Finlayina, Bifarinella and to a lesser extent Valvohifarina. They are characterised by the distinctly compressed nature of the test with a marked tendency towards flabelliformity, and an apertural face which is very elongate. On the other hand there is the group centred round Chrysalidinella, including Cifellia and Orthocerina. This second group is characterised by uniseriality in the adult stage, the non-compressed chambers and the apical, multiple aperture.
Other genera to be included in the superfamily are already known to lack internal structures, such as Loxostoma, Aragonia and Bolivinella.
Earlier revisions removed some genera from the Buliminacea, i.e. Buliminella and Buliminoides (Revets, 1990a, b) and Tosaia (Nomura, 1985). The large number of genera herein removed favours the cause for a separate superfamily even more. It is intriguing to note that all forms in the Pavoninacea are eminently shallow water forms. Perhaps this may be a first indiction towards solving the mystery of the function of the toothplate.
A rethinking of the classification of the Buliminacea sensu lato, based on generic revisions has become urgent in order to restore stability and increase the understanding of this group.