Planularia kintradwellensis sp. nov. (Foraminifera), a distinctive biostratigraphical marker species for the Lower Kimmeridgian of the U.K.

A foraminiferal species, Planularia kintradwellensis sp. nov., previously left in open nomenclature, is shown to have a useful short stratigraphical range. It has been recovered from several onshore sites within the UK and only from the Lower Kimmeridgian.


INTRODUCTION
After examination of several unpublished sources in conjunction with the author's research on foraminifera from Jurassic onshore outcrops of Scotland it has become apparent that a foraminiferid taxon previously left in opennomenclature as Plunuluriu sp. A (Gregory 1986(Gregory ,1989) has a useful and short stratigraphical range. Plunuluriu kintrudwellensis first appears and is restricted to the baylei -mutubilis Zones of the Lower Kimmeridgian. So far this particular taxon has been positively identified from several onshore Upper Jurassic UK sites ( Fig.  1) and recovery within this area is quite extensive ranging from separate basins of the North Sea and Hebrides in North East and North West Scotland respectively. Interestingly, this form was also recovered from the Dorset area (Lloyd, 1958), representing the Wessex Basin of Southern England.
One reason for publishing is to elicit further occurrences from other offshore Jurassic deposits of the North Sea, Hebridean and Irish Sea Basins. From the limited amount of data released from oil company offshore wells it is apparent that these deeper water deposits are dominated by agglutinated faunas (e.g. Nagy 1985a, b;Lerfaldi et al. 1983;Morris 1989;Morris & Dyer 1990and P.Copestake, pers.comm. 1986. However, calcareous forms do occur in these deeper water facies, but they are not as evident as in the shallower water deposits, represented by the onshore sections (Fig. 1). This transition from calcareous dominated to agglutinated dominated microfaunas is also apparent when examining the onshore Inner Moray Firth Basin sequences from Helmsdale to Eathie Haven in NE Scotland. Facies type indicates that these deposits represent at the former a shallow water, near shore shelf that was a fairly well oxygenated environment dominated by calcareous foraminifera (Gregory, 1986(Gregory, ,1989 grading to the latter which represents deeper water, occasionally anoxic, hemipelagic shale basinal deposits dominated by agglutinated foraminifera. This trend is also corroborated by an increase in the radiolaria (planktonic): foraminifera (benthonic) ratio basinwards. This simple quantitative method is used here in lieu of the usual water depth/distance from palaeo-shore indicator of the planktonic foraminifera to benthonic foraminifera ratio more usually used in Cretaceous and Recent sequences.

SYSTEMATIC DESCRIPTION
The monumental suprageneric classification of foraminiferids by Loeblich & Tappan (1988) is utilised here, which in turn is based on earlier exploratory works (Loeblich & Tappan, 1964, 1974,1984. The number of suprageneric groups have more than doubled in the period 1964-1988, with an increase from five to twelve suborders, including the elevation of Lagenina. Loeblich & Tappan (1988) continue to group all the foraminifera withinoneorder following the recommendations of the protozoan classification committee of Levine et al. (1980). However, various authors advocate the elevation of foraminifera to class or subclass ( e g Haynes, 1989), or even to phylum level (Margulis, 1974). In the absence of a consensus of opinion on this issue, the higher classificatory system of Levine et al. (1980)  Their stated purpose in following this practice is to allow evolutionary sequences to be more naturally defined; but, as environment is also observed to control the development of these features, such splitting must be viewed with caution. Also, splitting of genera tends to be somewhat cumbersome and confusing to non-specialists. Diagnosis. Planularia is characterised by its loose, flat uniserial coil. Initial 3-6 chambers in a fairly tight coil succeeded by an uncoiled uniserial section.
Remarks. This genus was recently involved in a proposed conservation to the Bulletin of Zoological Nomenclature by Hansen & Rogl(l986) who suggested suppression of its unused senior subjective synonym Linthuris de Montfort 1808.
Planularia appears to have beenvindicated as the correct name (Hansen pers. comm., 1991and Opinion 1571. Planularia kintradwellensis (Fig. 2 Material. HELMSDALE (typelocality): 109specimenscymodoce mutabilis Zones (Gregory 1986(Gregory ,1989. EATHIE HAVEN: 12 specimens baylei-cyrnodoce Zones (present work). FLODIGARRY: 6 specimens baylei Zone (Young, 1987 and present work). BLACKHEAD, Dorset: several specimens from the base of the rnutabilis Zone (Young, 1987 andLloyd, 1958 (Giimbel) 1862 and Planularia eugenii (Terquem) 1864. It differs from the former in having ornamentation and from the latter by its more irregular, but distinct ribbing. This species was previously recorded as Planularia curticostata by Lloyd (1958) in an unpublished Ph.D. thesis. Lloyd (1959Lloyd ( , 1962 published accounts on the distribution of agglutinated, miliolid, and polymorphinid foraminifera from the type Kimmeridgian in Dorset but did not include the diverse nodosariid faunas he had recovered. Under Rule 8a of the International Code of Zoological Nomenclature (Ride, 1985), a species name is invalid if it isnominated inapublicationthatisnotwidely disseminated or in a readily available format. Young (1987, unpublished Ph.D. thesis) recorded a few forms that were assigned to Snracenaria sp.2 from selected sites in the British Isles. Examination of his material indicates that this form is synonymous with Planularia kintrndzoellensis and represents forms that have a looser coiling mode. It is hypothesized here that coiling mode is perhaps an environmentally controlled feature and the triangular section, normally a saracenarid feature is also enhanced by the presence of the rather coarse keel.

STRATIGRAPHICAL OCCURRENCE
Plnnulnrin kintrndzoellensis has been recovered from several sequences of the Upper Jurassic in the United Kingdom (Figs 1 & 2). These sections are dealt with below, commencing with the type section of the Kintradwell Boulder Beds at Helmsdale, NE Sutherlandshire. Apparently a form Gregory (1986Gregory ( ,1989 for the Lower Kimmeridgian (cymodocemutabilis Zones). Further work on the entire sequence spaning the upper series of the Helmsdale Boulder Beds from the autissiodorensis to albani Zones has failed to recover any further specimens of Planularia kintradwellensis. The facies represent shallow water deposits and clasts forming the boulder beds transported during syn-depositionary development of the Helmsdale Fault into contemporaneous, deeper water shales and fine grained calcareous sandstones.
This section has provided the largest number of specimens for study and is nominated as the type section. The ammonite biostratigraphy has been defined by Buckman (1932) and Linsley (1972), with the upper part of the Boulder Bed sequence more reliably dated by palynological studies of Riley (1980) and Barron (1989). Planularia kintradwellensis has its first appearance and acme in the cymodoce Zone and final appearance in the mutabilis Zone. Fig. 2. Fig. A. Holotype, to be deposited in the Natural History Museum, London; length: 313pm; locality: Kintradwell Boulder Beds, Helmsdale; Fig. 8 Waterston (1950Waterston ( ,1951, Lee (1925), Lee & Pringle (1932) and Zeigler (1962aZeigler ( , 1962b. Waterston (1951) also studied the foraminifera, but only published a list of forms retrieved. The present study concentrated 45 samples across this sequence. As a facies it is equivalent in age to the deposits of the Helmsdale/Brora Outlier and represents somewhat deeper water deposition, related to further depositional distance from shore. This is reflected in the predominance of radiolaria and agglutinated foraminifera. Calcareous forms are subordinate, but Planularia kintradwellensis occurs amongst them and is limited to the topmost part of the baylei Zone and the cymodoce Zone.
3) Flodigarry, Staffin Bay, NE Skye (Grid Ref. NG46867149, Fig. 1 Point 4). The ammonite biostratigraphically is well established follow-ingSykes (1975)and Sykes&Callomon(1979) for thecallovian to Oxfordian and Wright (1973Wright ( ,1990 and Turner (1966Turner ( ,1970 for the Kimmeridgian. The sections at Flodigarry are tectonically disturbed, but it is still possible by careful correlation of the limestone marker beds to match up sections. The Callovian to the Lower Kimmeridgian is part of the author's research on the foraminifera1 and radiolarian distribution in Scotland (Fig. 1, points 1-4) and there is some overlap with the previous work of- Young (1987) who studied the Lower Kimmeridgian at Staffin Bay. The author's sections were arranged to test the first appearance of the typical Kimmeridgian microfaunas. Planularia kintradwellensis was recovered from the baylei and lower most cymodoce Zones, with no occurrences in the Oxfordian or Callovian sequences (Gregory in prep.).

4)
Blackhead, Dorset (Grid Ref. Fig. 1 Point 7). This section has been nominated elsewhere as the type sub-Boreal Lower Kimmeridgian (see Ziegler 1962b). Ammonite biostrahgraphy is well established from the work of Arkell (1933Arkell ( , 1947 and Cox & Gallois (1981) and the sequence is typified by shales and clays, with siltstone and limestone marker bands. Micropalaeontological research of the Callovian-Portlandian of this particular area has been intense from the initial work of Blake (1875) and Neaverson (1921) which merely listed foraminifera through to the more substantial research of Lloyd (1958Lloyd ( , 1959Lloyd ( , 1962, Barnard (1951Barnard ( , 1952, Gordon(1965Gordon( ,1966, Shipp (1989)andYoung(1987.Planularia kintradwellensis was recovered by both Lloyd (1958) and Young (1987) as Planularia curticostata and Saracenaria sp. 2 respectively. The specimens were collected from the lower parts of the mutabilis Zone.

CONCLUSIONS
Planularia kintradwellensis is a benthonic foraminiferid which appears to be stratigraphically confined to the baylei-mutabilis Zones of the Lower Kimmeridgian of the Boreal and sub-Boreal deposits in the United Kingdom. Facies dependent distribution, often quoted as a limitation in benthonic foraminifera1 biostratigraphy, is not a major limiting factor in the distribution of this taxon. P. kintradzuellensis occurs across several facies types, bat its colonizing potential is somewhat limited when oxygen depleted conditions prevailed. Migration rate and dispersion lag accounts for the slight discrepancies in the first and last appearances of the foraminiferid in the various basins. Until more information from offshore sectors is made available migration routes cannot be predicted with any confidence.