Contr. Tert. Quatern. Geol. 37(1-2) 3-21 6 pis. Leiden, July 2000
Revision of Pliocene Glycymerididae
from the North Sea Basin
Peter W. Moerdijk
Middelburg, the Netherlands
and
Freddy A.D. van Nieulande
Nieuw- en Sint Joosland, the Netherlands
Moerdijk, Peter W. & Freddy A.D. van Nieulande. Revision of Pliocene Glycymerididae (Mollusca, Bivalvia) from the North Sea
Basin. — Contr. Tert. Quatern. Geol., 37(1-2): 3-21,6 pis. Leiden, July 2000.
The systematic status of Pliocene glycymeridid bivalves from the North Sea Basin is discussed. Chevronia n. subgen., Glycymeris
(Chevronia) obovata ringelei n. subspec., G. (Glycymeris) radiolyrata forma pseudodeshayesi n. forma, and G. (G.) radiolyrata
forma exaggerata n. forma, are proposed as new. Lectotypes are designated for G. (Ch.) obovata obovata (Lamarck, 1819) and G.
(Ch.) variabilis (J. de C. Sowerby, 1824).
Key words — Bivalvia, Glycymerididae, Pliocene, North Sea Basin, systematics, new taxa.
P.W. Moerdijk, Kingstraat 14, NL-4336LG Middelburg, the Netherlands [e-mail: pw.moerdijk@zeeland.nl]; F.A.D. van Nieulande,
Scheldepoortstraat 56, NL-4339 BN Nieuw- en Sint Joosland, the Netherlands.
Contents cene (Redonian) of France have been studied for com-
parison.
Introduction & van Nieulande concluded that, p. 3 Moerdijk (1995) 3 from external details of the ligament Systematic descriptions p. apart ornament, within 9 area are the Glycymerididae. In the Acknowledgements p. important
References 9 a new subgenus, Chevronia, is introduced p. present paper, for those shells that show combined features of ligament
and external ornament. Other fossil species from west-
Introduction ern, central and southern European localities have been
studied; a few are here referred to the new subgenus.
data material des- In the literature on Neogene molluscs from the North Stratigraphic concerning Belgian
cribed in the are according to De Meuter Sea Basin, there is little agreement over the systematic present paper
of Pliocene & status Glycymerididae. Moerdijk & van Laga (1976). The from the Lower Nieulande(1995) have recently noted that most previous very common glycymeridids
Pliocene of have turned authors had lumped Glycymeris variabilis and G. radi- (Kattendijk Formation) Belgium
In the results of of out to be related to the Miocene G. obovata baldii Glib- olyrata. present paper, a study repre- 1965 and here described sentatives of Glycymeris from the North Sea Basin Plio- ert & van de Poel, are as a new
subspecies, G. obovata ringelei. are cene, originating from temporary excavations in Bel- Lectotypes desig- obovata obovata and G. gium (see Marquet, 1995 for details), borehole material nated for G. variabilis. from the Netherlands, dredged and beach fossil material as reworked from especially Pliocene strata in the province of Zeeland (the Netherlands), as well as from SYSTEMATIC DESCRIPTIONS the Pliocene Coralline and Red crags (England). Speci- mens from the Miocene (Helvetian, Redonian) and Plio- Abbreviations — To denote the repositories of 4
illustrated and/or referred in the the specimens to text Favre (1918, pi. 34, fig. 230a-c). This valve has a label
following abbreviations are used: in Lamarck's handwriting associated.
Derivatio — nominis In allusion to chevrons on the
BMNH The Natural London History Museum, (De- ligament area.
partment of Palaeontology) (formerly British Diagnosis — Glycymeridids with subcircular, subequi-
Museum ofNatural History); lateral shells, external ornament almost obsolete to fine,
RGM Nationaal Natuurhistorisch Museum (De- and when present consisting mainly of radial elements,
of Cainozoic Mol- with partment Palaeontology, occasionally distinct, distant, radial grooves; liga-
lusca), Leiden (the Netherlands; formerly ment area with well-developed, regular chevron-shaped
Rijksmuseum van Geologie en Mineralogie); ligamental grooves.
NITG Nationaal Instituut voor Toegepaste Geo- Other species — The following (sub)species (see
wetenschappen-TNO, Utrecht, the Nether- Mayer-Eymar, 1868; Baldi, 1962; Maestrati & Lozouet,
have studied lands; 1996) we may be attributed to the new sub- KZGW Zeeuwsch Koninklijk Genootschap der genus:
Wetenschappen, Middelburg, the Nether-
lands. G. (Ch.) fichteli (Deshayes, 1852)
G. (Ch.) latiradiatalatiradiata(Sandberger in Giimbel, 1861)
G. (Ch.) l. obovatoides Baldi, 1962 Order Arcoida Stoliczka, 1871 G. (Ch.) l. subfichteli Baldi, 1962 Superfamily Limopsacea Dall, 1895
G. (Ch.) obovata baldii Glibert & van de Poel, 1965 Family Glycymerididae Newton, 1922 G. (Ch.)poustagnacensis Maestrati & Lozouet, Subfamily Glycymeridinae Newton, 1922 1996
G. (Ch.) saucatsensis (Mayer-Eymar, 1868) (non
Remarks — Moerdijk & van Nieulande (1995) noted Cossmann & Peyrot, 1914) that two of in groups glycymeridids were represented G. (Ch.) subterebratularis(d'Orbigny, 1852) the Pliocene North Sea Basin material, which could be G. (Ch.) turonica (Mayer-Eymar, 1868)
distinguished by using the following characters:
We have not (yet) seen any Recent species.
- external ornament; Remarks — Other glycymeridid shells with well-
- of ornament ligament area. developed ligament grooves have been referred to the
genera MelaxinaeaIredale, 1930 and Tucetona Iredale,
but less 1931. Useful, important, characters are: However, both of these show, in contrast with
Chevronia, a pronounced external ornament.
- shell form, i.e. outline and convexity; Glycymeris (s. lat.) cor (Lamarck, 1805), which has
- shell thickness; also been described as G. violascens (Lamarck, 1819),
- dimensions; G. nummaria(Linne, 1758) and G. insubrica (Brocchi,
- form of ligament area; 1814), also has ligament grooves, but these are irregu-
- form and of adductor often position muscle scars; lar, intercalating under the beaks and start their
- of characters juvenile shells. development in varying stages of growth. In juveniles,
the ligament area is always smooth. In addition, juvenile
With the of respect to importance characters of external shells show a marked concentric ornament. The subgen-
shell with eric ornament, we agree earlier authors, e.g. Nicol classification of this species and its close relatives,
(1956); however, features of the ligament have only will have to be revised.
been considered rarely important. In our experience,
these uniform however, are very within a species and
quite constant in phylogenetic development. Combining Glycymeris (Chevronia) obovata ringelei n. subsp. external and ornament ligament area ornament leads to PI. 1, Fig. 2
a good basis for (sub)generic divisions ofglycymeridids.
1878-81 Pectunculus — glycymeris L., var. transversa
Genus da 166 Glycymeris Costa, 1778 Nyst, p. (partim, non Wood), pi. 17, fig. 8b?,
Subgenus Chevronia n. subgen. e, g.
71950 Glycymeris (Gl.) pilosa (Linne, 1767) — Heering,
33, pi. 8, figs 9, 10. — p. Type species Arca obovata Lamarck, 1819. Accord- 1957 1758 Glycymeris glycymeris Linne sp. forme ing to Janssen (1979), Glycymeris obovata obovata (see
variabilis Sowerby, 1824 — Glibert, p. 16 PI. 1, Fig. 1) has often been misinterpreted, and is in (partim). need nomenclatural of stability. We here designate as 1962 Glycymeris variabilis deshayesi (Mayer, 1868) — of iectotype G. o. obovata the specimen illustrated in van Regteren Altena et al., p. 14, pi. 5, fig. 18a. 5
reminiscent of G. latiradiata. 1965 Glycymeris (s.s.) glycymeris variabilis (Sowerby, grooves, in this respect
— de 83 with rather 1824) Glibert& van Poel, p. (partim). Hinge well developed long teeth, continuing Ringele 1974 Glycymeris glycymeris kattendijkensis under ligament area (13 anterior, 12 posterior). Liga-
(MS name). ment area near equilateral, rather high, with incised
1979 Glycymeris glycymeris pilosatumida (Bucquoy, muscle chevrons (9 anterior, 8 posterior). Adductor
& Dollfus, 1891) — Geys & Dautzenberg the scars large, broad and callous, almost touching Marquet, pi. 14, fig. 4. hinge plate; pallial line parallel to the ventral shell mar-
gin, clear. Inner margin with well-developed crenula-
Diagnosis — Glycymeridid with a thick and inflated, tions.
with external — considered subcircular, orthogyrate, equilateral shell, Remarks The present taxon has been by
consisting of fine radial threads and of- related G. 1758 ornament very many authors to be to pilosa Linnd, distant radial with ten some grooves, well-developed and/or G. glycymeris Linne, 1758. Both these species with hinge teeth, an equilateral ligament area distinct, have well-developed external ornament and smooth, chevrons adductor muscle of rather coarse and scars and are thus to inequilateral ligament areas, assignable
about and in contact with related G. obo- equal height width, hinge Glycymeris s. str., and are not closely to
plate. vata ringelei, which differs from G. o. baldii from the
— Fifth (Bel- Locus typicus harbour dock, Antwerp Antwerp Member (Berchem Formation, Miocene) by its inflated gium). smaller, thicker, relatively higher and more
— base Plio- Stratum typicum Kattendijk Formation, shell with a better developed hinge with relatively
cene. longer hinge teeth.
— who Derivatio nominis Named after A. was The differs in from its Ringelé, new subspecies some respects
the first to recognise it as a distinct taxon. Oligocene and Miocene relatives (see Dollfus &
— is RGM 394 099 bivalved Glibert de Types Holotype (a speci- Dautzenberg, 1909); we follow & van Poel harbour 12 men) from Antwerp (5th dock, April 1971), (1965) in their treatment of Oligocene and Miocene
base Nieulande and rank it sub- Kattendijk Formation (ex van Colin); representatives of G. obovata as a new bivalved Nieulande are four specimens (van be paratypes species. Glycymeris o. ringelei may distinguished from and and four Colin, no. 108) the type locality level, from G. variabilis in that it is more equilateral and or-
Nieulande no. from accentuated radial bivalved specimens (van Colin, 110) thogyrate, has a less ornament, a
Kallo (Ttunnel construction pit). better developed hinge and its anterior adductor muscle
— tunnel construction Other material Kallo (Beveren scar is somewhat less slender and (almost) touches the
bivalved 1 pit, Kattendijk Formation), 5 specimens, hinge plate. Most specimens of G. variabilis are decid-
valve Nieulande inflated than those (van Colin, nos 106, 107); Antwerp edly less of G. o. ringelei.
(connection 5th harbour dock to Amerika dock), 14
valves, 2 bivalved specimens (RGM 494 115); Kallo Glycymeris (Chevronia) variabilis (Beveren tunnel construction pit, base Oorderen Mem- (J. de C. Sowerby, 1824) ber, Lillo Formation), 4 bivalved specimens, 5 valves Pis 2, 3; PI. 4, Figs 1,2 (van Nieulande Colin, nos 112, 113); Kallo (tunnel
works, base Oorderen Member), 9 bivalved specimens *1824 Pectunculus variabilis J. de C. Sowerby, p. Ill, (van Nieulande Colin, no. 109); Antwerp (Kaai 27, pi. 471 (lower and central figures). ?Luchtbal Member), 1 valve (van Nieulande Colin, no. 1845 Pectunculus variabilis— Nyst, p. 249, pi. 20, fig. 90, leg. A. Haandrikman); Ellewoutsdijk/Baarland la, b. (Western Scheldt, dredged, derived Pliocene), 47 valves 1851 Pectunculus glycymeris L. — Wood, p. 66, pi. 9, (Moerdijk Colin); Borsele (de Kaloot, province of Zee- fig- lg- 2 valves land, beach material, derived Pliocene), (van 1851 Pectunculus glycymeris L. var. subobliquus Wood,
Nieulande Sutton i. Colin, no. 102); (Suffolk, England, p. 66, pi. 9, fig. lh,
Pectunculus L. var. transversa S. Coralline Crag, ex P. Cambridge Colln/L. van der Slik), 1878-81 glycymeris,
RGM 394 Wood — Nyst, 166 (partim), pi. 17, fig. 8a, c, f. 1 worn valve (cf. Glycymeris o. ringelei, p.
1879 Pectunculus glycymeris — Wood, p. 43, pi. 6, fig. 116). 5a. Description (holotype) — Height, width and semi-
1879 Pectunculus glycymeris var. nummarius — Wood, of valve 58.2 and 18.5 diameter right are 54.2, mm, 6, 5b. p. 43, pi. fig. respectively; of left valve 54.2, 58.3 and 18.7 mm, re- 1937 Glycymeris glycymeris variabilis (J. Sow.) — van spectively. Thick and firm, inflated, almost orthogyrate, Regteren Altena, p. 55, pi. 3, fig. 50. near-equilateral, broadly oval, posterior side slightly 1950 Glycymeris glycymeris variabilis (Sowerby, 1824) longer, transition from margins into ventral mar- upper — Heering, p. 30 (partim), pi. 8, figs 1-6. gin somewhat shorter rounded; umbones protruding. 1957 Glycymeris glycymeris Linne sp. 1758 forme
Shell surface almost with somewhat — smooth, very fine, variabilis Sowerby, 1824 Glibert, p. 16
irregular, radial threads; with a few distant radial (partim). 6
1962 Glycymeris variabilis — van Regteren glycymeris ornamented with incised ligament grooves in a regular Altena et al., 55 ), 4, 50. p. (partim pl. fig. roof-shaped pattern, anteriorly with 8, posteriorly with 7 1965 Glycymeris (s.s.) glycymeris variabilis (Sowerby, grooves. Hinge not especially well developed, hinge 1824)— Gilbert& van de Poel, 83. p. teeth relatively short, 8 in number anteriorly as well as 1974 Glycymeris glycymeris variabilis (Sowerby, 1824) posteriorly. Below either end of hinge plate, callus of
— Ringele (MS), p. 96 (partim), pi. 4, fig. 5a, b. adductor muscle scars missing, as is inner shell layer 1979 Glycymeris glycymeris variabilis (Sowerby, 1824) which would have preserved the pallial line. Inner shell — Geys & Marquet, pi. 15, fig. 1. margin crenulate, 35 crenulations visible. 1995 Glycymeris (Glycymeris) variabilis (J. de C.
Material studied — area harbour dock — Antwerp (6th Sowerby, 1824) Moerdijk & van Nieulande, pi. construction 4, fig. 1. pit, Oorderen Member), 14 valves (RGM
393 819, leg./don. M. van den Bosch); connection 5th
harbour dock Amerika Original diagnosis — 'Obliquely suborbicular, rather to dock, ?Luchtbal Member, 2
striated specimens 394 3 valves Nieulande convex, finely longitudinally, becoming smooth (RGM 118), (van
or sulcated by teeth of the and lines Colin, no. Ill); Stuyvenberg, 1 bivalved specimen, 6 wear; hinge upon valves sluice the area of the ligament, numerous; beaks short nearly, (NITG Colin); Kallo (sea construction pit,
close' de Oorderen 3 valves (J. C. Sowerby, 1824, p. 111). Member), (Vervoenen Colin, no. F
Revised diagnosis — Moderately large, inequilateral, 251 B); Kallo (Waesland tunnel construction pit, Oor-
deren level with obliquely oval glycymeridid with a rather flat shell, a Member, Angulus benedeni), 1 valve
near-smooth Nieulande external ornament with very fine, irregular (van Colin, no. 17); Kallo (Beveren tunnel
radial construction Oorderen level threads, quite short hinge teeth, a ligament area pit, Member, with A. bene-
with 1 distinct chevrons and with the slender adductor deni), valve (Moerdijk & van Nieulande, 1995, pi. 4,
muscle RGM 393 scars at some distance from the hinge plate. fig. 1; 826); Mill-St. Hubert, borehole mate-
— series 24 Types The original type consists of three rial, Pliocene, valves (very inequilateral and thick-
here specimens; we designate lectotype the specimen in shelled form, van Nieulande Colin, no. 137); Reek
J. de C. of Sowerby's pi. 471 (bottom figure) (BMNH (province Noord-Brabant), auger drill 41 (45F/48),
PI. since it 43188a) (see 2, Fig. 1), most clearly repre- 18.00-31.80 mbs, Pliocene, c. 290 valves (juv., 1 frag-
sents the well-known, quite flat and inequilateral form. ment ofan adult specimen, with very coarse radial lirae,
The right valve illustrated in the centre of this plate is NITG Colin, MOL 683); Nijmegen (province of Gel-
eroded and rather inflated heavily worn, and more derland), 'Midden-Plioceen', 85 valves, 21 fragments than the equilateral lectotype. However, it may be re- (NITG Colin, MOL 686); Borsele-Baarland, dredged, ferred to the present species as well, and is designated reworked from Pliocene strata, 28 valves (Moerdijk paralectotype (BMNH 43188b) (see PI. 2, Fig. 2). The Colin); Baarland, 5 valves (very inequilateral and in specimen pi. 471, top figure, may be assigned to G. thick-shelled form, Moerdijk Colin); Veere-Domburg,
forma forma radiolyrata pseudodeshayesi n. (see below; washed ashore, reworked from Pliocenestrata, 23 valves PI. 5, Fig. 3). (Moerdijk Colin); Borsele-de Kaloot, 7 valves (Moer-
Locus — Suffolk data typicus (no additional locality dijk Colin); Walton-on-the-Naze (England, Red Crag, available). RGM 394 119, ex F.J. Janssen Colin), 11 valves.
Stratum — Red additional strati- Remarks — A borehole typicum Crag (no at Reek has yielded numerous
graphic details available). valves with juvenile a remarkably coarse radial orna-
Description (lectotypej — Height, width and semi- from sediments of Pliocene ment, age. In reworked diameter are 61.9, 64.9 and 17.6 respectively; right material from the mm, dregded Western Scheldt a very in- valve, the side obliquely oval, inequilateral, posterior equilateral, oblique and thick-shelled forma of G. vari-
and drawn out and known. longer ventro-posteriorly, anteriorly abilis is From borehole Mill-St. Hubert, numer- ventrally regularly rounded, dorso-posteriorly straight ous similar specimens are available, but their adductor
(slightly damaged anteriorly above midline), umbo not scars are markedly broader and almost touch the hinge prominent, shell rather very faintly opisthogyrate, flat plate, as in G. obovataringelei. and shelled. thick External ornament con- Some moderately specimens of G. variabilis are more inflated,
of fine, radial because of often with sisting very irregular threads, a somewhat coarser radial ornament than in visible wear only near ventral lines ir- The border; growth typical examples. anterior adductor muscle scar is regular, distinct, particularly As a result of slender well. posteriorly. less as However, these shells are inequilat- wear, umbonal is four concentric eral and in region decorticated; oblique as typical G. variabilis, with a nar-
growth zones are visible in this crossed region, by about row hinge and short teeth, with similar characters of the 40 also radial sulcae because of run- prominent wear, ligament area and with the anterior adductor muscle
to about ning shell midline. scar at some distance from the hinge plate. In this re- Below the is beak a broadly triangular ligament differ from obovata area, spect, they G. ringelei, and seem to
inequilateral, anterior somewhat form slightly part longer, represent an early of G. variabilis, possibly of and almost reaching the inside border ofthe hinge plate; stratigraphical significance. 7
G. and G. distinct Material of this inflated form of G. variabilis exam- sider G. obovata, turonica variabilis
ined is from the following localities: Sudbourn Hall taxa.
(Coralline Crag), 5 valves (NITG Colin, MOL 694);
Gedgrave (Coralline Crag), 1 valve (RGM 394 117); Genus and da Costa, 1778 Kallo (sea sluice construction pit, base Oorderen Mem- subgenus Glycymeris ber, probably reworked from older strata), 2 valves
Type — Arca glycymeris Linne, 1758, by mono- (Vervoenen Colin, no. F 251 B); Bergen op Zoom species (borehole Vreederust, 49B/173, 81.30-95.70 mbs), 1 typy.
— subequilateral, with small valve (Heering, 1950, pi. 8, figs 13, 14, 20, NITG Colin, Diagnosis 'Subcircular, teeth relatively short, transverse, becoming MOL 678); Western Scheldt (province of Zeeland, umbones; surface smooth costate' obsolescent medially; or (Newell dredged, reworked from Pliocene strata; Terneuzen in Moore, 1969, N267). (Put van Terneuzen, ZZ8 (Schot), 1 valve and 1 dam- p.
Revised diagnosis — Subcircular, subequilateral; teeth aged valve (KZGW Colin, no. 3082 GM 98-03); Elle- relatively short, transverse, effacing medially; external woutsdijk, 1 valve (KZGW Colin, no. 648b, leg. C. well ornament fine to coarse, consisting of radial as as Brakman); Baarland, 5 valves (Moerdijk Colin); concentric elements, all Recent species with a hairy Schaar van de Spijkerplaat, 1 valve. periostracum, and a (near-)smooth ligament area.
— studies of Discussion When we had just started our
Remarks — The subgenus is redefined here to distin- Pliocene glycymeridids from the North Sea Basin, we guish it from Chevronia (see above). assumed G. variabilis to be the direct descendant of
what we now refer to as G. obovata ringelei. Shells of
G. (Ch.) turonica (PI. 4, Fig. 3) from the Miocene and Glycymeris (G.) radiolyrata Pliocene (Redonian) of the Nantes area (France), how-
& van Nieulande, 1995 much with G. variabilis. Moerdijk ever, also have affinity Gly- Pis 5, 6 cymeris turonica is a common species from the Miocene
(Helvetian) in the Tours area (France). Generally, but
— described G. erroneously, this species is lumped with G. bimaculata Discussion When we first radiolyrata, a
few valves of form related to but deshayesi or with G. texta (Dujardin, 1837). The a obviously it, larger
to 90 mm) and more inflated were before us. Now Helvetian form is quite small, with an almost equilat- (up
radial external that we have seen additional material, the following eral, inflated shell, a very fine, mainly
the features of this form be added: a relatively thicker ornament and many distinct chevrons on ligament may
of the area shell, with a better developed hinge, the adductor mus- area. Specimens from the Redonian Nantes
these cle rests on an internal buttress. The majority of are as a rule larger and clearly inequilateral; were scar valves further into two discussed by Lauriat-Rage (1981) and referred to as may be subdivided categories, viz. form with fine and ‘Glycymeris (Glycymeris) glycymeris (Linne, 1758) a principally equilateral regular with et variabilis shell ornament, and an inequilateral form very sous-especes pilosa (Linne, 1758) (Sow- ends the contin- coarse and ornament. Both of erby, 1824)'. The Redonian shells have many characters irregular
uum are clearly distinct, but some are inter- in common with G. variabilis, especially with the more specimens them be related. will inflated forms: clearly opisthogyrate, inflated, inequilat- mediate, suggesting to Below, we
refer to these forms as forma pseudodeshayesi n. forma, eral and oblique shell, a moderately developed hinge in view of their having similar shell inflation and and position of the adductor muscle scars. Juvenile strong
fine reticulate ornament as G. bimaculata deshayesi specimens of G. turonica and G. variabilis are very (Helvetian) of Touraine similar; the external ornament in the former is similar (Mayer-Eymar, 1868) [Miocene
latter. and Redonian ofwestern and as to that ofthe more finely ornamented shells of the (Mio-Pliocene) France], external forma n. since characters of In addition, G. turonica and G. variabilis have the con- exaggerata forma,
are in comparison to the typical centric colour bands in common. The number of liga- ornament exaggerated
form. ment chevrons in G. turonica is as a rule much higher.
PI. Forma differs from However, in a lot from St-Julien-de-Concelles (see 4, pseudodeshayesi (PI. 5, Figs 1-3) the form in attaining larger dimensions, in being Fig. 3), the number of ligament chevrons is lower, as in typical and in illus- more in a better developed hinge some specimens of G. variabilis. The specimen inflated, having the of the adductor muscle close to the trated in Lauriat-Rage (1981, PI. 4, fig. 1), from Le Pi- position scars,
also has fewer chevrons than hinge plate. It be distinguished from forma exag- geon Blanc, ligament may from collected at Sceaux gerata (see below), as well as the typical form, by specimens e.g. d'Anjou. Judging reticulate shell it that G. the finer and more ornament. from shell features, seems plausible turonica regular, Forma (PI. 6, Figs 1 -3) also differs from and G. variabilis are related. exaggerata
G. vari- the form in being more inflated, in a At present, we are unable to decide whether typical having
better and in the adductor mus- abilis is directly related either to G. obovata ringelei or developed hinge having
cle close the It is to G. turonica. For the time being, it seems best to con- scars to hinge plate. distinguished 8
from both forma pseudodeshayesi and the typical form 1950, pi. 7, figs 15, 16, 19, 20, NITG Colin, MOL 690)
in having reticulate shell ornament. and 3 very coarse, fragments (NITG Colin, MOL 688); Bergen op
From boreholes at Ouwerkerk and Bergen op Zoom Zoom (borehole Waterleiding 3, 49E/30, 87.60-94.50
have f (the Netherlands), we only seen pseudodeshay- mbs), 1 valve (Heering, 1950, pi. 8, figs 11, 12, NITG
esi, based on excellently preserved material. The level MOL Colin, 689); Bergen op Zoom (waterleiding Ber-
which yielded the specimens at Ouwerkerk is an gen op Zoom 3, 87-94 (?mbs), 1 valve, RGM 4326; St. of the Luchtbal Member equivalent (Middle Pliocene). Jansteen (borehole 55A/24, borehole A), 8.60-9.40 From the from same borehole, samples some metres mbs), 1 fragment (NITG Colin, MOL 691); Kallo above the level and ornamented with this inflated finely (Beveren tunnel construction pit, base Oorderen Mem- form have the form. No of f. yielded typical specimens ber, 3 valves, van Nieulande Colin, nos 93, 93a, 114); have been found in their exaggerata original Antwerp (Boudewijnsluis excavation, base Oorderen stratigraphical context in of the outcrops/ex- any Member, 1 valve (Marquet Colin); Kallo (sea sluice studied. inter- cavations This complicates a satisfactory construction pit, ?base Oorderen Member, 8 valves,
pretation of the material. The only articulated specimen Vervoenen F 717 Nieulande Colin, no. Aa; 1 valve, van
originates most probably from the upper part of the Colin, no. 101; Kallo (Beveren tunnel construction pit,
Kattendijk Formation, from sediment fill. These Oorderen level with judging Member, Atrina(' ?), 1 valve, van
distribution patterns indicate that these formae may be Nieulande Colin, no. 94; Antwerp (construction pit 5th of stratigraphical value. The bulk of the material from harbour dock, level unknown, from sediment dump), 1
Belgian outcrops, as far as could be determined, origi- valve (RGM 2657); Antwerp (Oorderen polder, Plio- nates from the base of the Oorderen Member (Lillo cene, level unknown), 2 valves (RGM 56908); Antwerp Formation), where the typical form of G. radiolyrata (Ford plant north of Noordkasteel, level unknown, from also occurs. Specimens showing features intermediate sediment dump), 1 valve (RGM 394 097); Antwerp between f. pseudodeshayesi, f. and the typi- exaggerata (5th harbour dock, level unknown, from sediment cal form do occur in our material, albeit rarely. Typical dump), 6 valves (RGM 100 394, 100 396-397, 100 401); features of f. pseudodeshayesi in particular would sug- Antwerp (level unknown), 1 valve and 1 specimen gest that G. radiolyrata evolved from G. bimaculata s. (RGM 56 896, 494 098). Dredged, reworked from Plio- lat. Previously illustrated material that may be-attributed cene strata is material from Baarland (1 valve, Moer- to f. pseudodeshayesi includes: dijk Colin), Ellewoutsdijk/Baarland (4 valves, van
Nieulande Colin, no. 103; Vervoenen Colin, no. F 717.
1824 Pectunculus variabilis J. de C. Sowerby, pi. 471, From the Red Crag is 1 valve (J. de C. Sowerby,
top figure. 1824, pi. 471, top figure, BMNH 43188c) (see PI. 5, 1950 la Glycymeris spec, Heering, p. 34, pi. 7, figs 15, Fig. 3 here). 16, 19, 20.
1950 Glycymeris (Gl.) pilosa (Linne) var. tumida
B.D.D. — Heering, p. 34, pi. 8, figs 11, 12. Material of f. examined for the exaggerata present paper
includes: Specimens illustrated by Wood (1851, pi. 9, fig. Id), under the name Pectunculus glycymeris L. (pi. 9, fig. ' Antwerp? (original label stating, Pectunculus pilosus Id), and Wood (1879, pi. 6, fig. 4a) as P. pilosus var. uit het in het Scaldisien Diestien, gevonden; gere- insubricus Brocchi, could also belong here. manieerd (gevuld met Diestien, ged. met Ditrupa)’ (=
‘Pectunculus pilosus from the Diestian, found in the recorded in the literature Specimens previously that may Scaldisian; reworked (filled with Diestian, part with be referred to f. exaggerata include: Ditrupa’), 1 bivalved specimen (NITG Colin); Kallo
(Vrasenedok excavation, base Oorderen Member, 1957 Linne Glycymeris glycymeris sp. 1758, forme tu- probably reworked from older strata), 1 valve (Marquet mida B.D.D., 1891 — Glibert, pi. 1, fig. 4. Colin); Kallo (Beveren tunnel construction base 1992 Glycymeris cf. bimaculata (Poli, 1795) — Moer- pit, & Nieulande Oorderen reworked from older dijk van in Moerdijk et al., p. 18 Member, probably
bottom valve (partim), pi. 4, right-hand figure. strata), 1 (van Nieulande Colin, no. 93b); Verre-
broek (Liefkenshoektunnel construction pit, Oorderen Material of f. pseudodeshayesi examined for the present Member, level with Atrinar(?), probably reworked from is follows: paper as older strata), 1 valve (van Nieulande Colin, no. 100, leg.
G. Garding); Kallo (sea sluice construction pit, ?base
Ouwerkerk (borehole 42H19-4(A40), 114.50-115.75 Oorderen Member, probably reworked from older mbs, Luchtbal 3 1 394 3 valves Member, valves, fragment (RGM strata), (Vervoenen Colin, no. F 717 A, A2);
Zoom 121, leg. Deltadienst); Bergen op (Vreederust, dredged, reworked from Pliocene strata are specimens borehole 49B/173, 81.30-95.70 mbs), 1 valve (Heering, from Ellewoutsdijk, 1 valve (Moerdijk Colin); Baar- 9
de stratigraphique et land, 1 valve (Moerdijk Colin); Ellewoutsdijk/ Baar- Atlantique France); signification
washed paleobiogeographique. — Mem. Mus. natn Hist, nat., n.s. land, 1 valve (van Nieulande Colin, no, 105b); (C: Sci. Terre), 45: 3-173, 18 pis. ashore, reworked from Pliocene strata: Nieuwesluis, 1 Maestrati, Ph. & P. Lozouet, 1996. Les Glycymerididae valve (Simons Colin). (Mollusca, Bivalvia) de l'Oligocene Superieur (Chattien)
du Bassin de l'Adour, France. — Ann. Paleont. (Vert.-
Additional data — As far as the stratigraphical distri- Invert.), 82(1): 3-25. bution of the typical form is concerned, it should be Marquet, R., 1995. Pliocene gastropod faunas from Kallo noted that it has also been found in the Ouwerkerk (Oost-Vlaanderen, Belgium). Part 1. Introduction and of at level which is borehole Zeeland), a — (province Archaeogastropoda. Contr. Tert. Quatern. Geol., 32(1- the well in the equivalent to Luchtbal Member, as as 3): 53-85, 6 pis.
basal Oorderen Member during excavation ofthe Verre- Mayer-Eymar, C., 1868. Catalogue systematique et descriptif broekdok, which levels have yielded well-preserved des fossiles de terrains tertiaires qui se trouve au Musee
follows: federal de Zurich, 3. Mollusques; Famille des Arcides, material. Data are as Kallo (Verrebroekdok, Zurich, 124 base Oorderen Member, - 17.10-17.50 m, 1 valve pp. Meuter, F.J. de & P.G. Laga, 1976. Lithostratigraphy and (Moerdijk Colin); Ouwerkerk (borehole 42H-19- biostratigraphy based on benthonic Foraminifera of the 4(A40), 106-107 mbs, Luchtbal Member, 3 valves, 2 Neogene deposits of Northern Belgium. — Bull. Soc. fragments (RGM 394 120, leg. Deltadienst). beige Geol., 85(4): 133-152, 1 pi. 1995. Moerdijk, P.W. & F.A.D. van Nieulande, Glycymeris
(Glycymeris) radiolyrata nov. sp. (Bivalvia, Glycy-
ACKNOWLEDGEMENTS merididae) from the Pliocene of the North Sea Basin. —
Contr. Tert. Quatern. Geol., 32(1-3): 3-17, 4 pis.
We wish to thank the following people for assistance in Moerdijk, P.W., R. Pouwer, R. Rijken & F.A.D. van 1992. Fossiele Zeeuwse stranden various G. H. A. P. Nieulande, schelpen van ways: Garding, Gunst, Janse, Jeffery
— Geol. Zeeuwsch Gen. enstromen, deel 1. Werkgr. Kon. (BMNH), W. Krull, A. Krull-Kalkman, R. Marquet, T. Wetensch., Publ. 2:1-38, 10 pis. Meijer (NITG-TNO), R. Pouwer (NITG-TNO), R. Newell, N.D., 1969. Family Glycymerididae. In: Moore, R.C. and Rijken, G. Simons, M. Vervoenen, J. van der Voort (ed.). Treatise on Invertebrate Paleontology, Part N(2), F. Wesselingh (NNM-Naturalis). Mollusca 6: N267-N269. Geol. Soc. Am., Boulder/Univ.
Kansas Press, Lawrence.
Nicol, D., 1956. Distribution of living glycymeridids with a
REFERENCES — 70: 48-53. new species from Bermuda. Nautilus,
Nyst, P.H., 1845. Description des coquilles et polypiers
str. des fossiles des terrains tertiaires de la Bruxelles Baldi, T., 1962. Glycymeris s. europaischen Oligozans Belgique.
und Miozans. — Ann. hist.-nat. Musei nat. Hung., (Nyst), 675 + ii pp., 48 pis.
Mineral. Palaeont., 54: 85-153, 11 pis. Nyst, P.H., 1878-1881. Conchyliologie des terrains tertiaires
Dollfus, G. & Ph. Dautzenberg, 1909. Conchyliologie du de la Belgique, 1: Terrain pliocene. — Ann. Mus. r. Hist,
— 28 Miocene moyen du Bassin de la Loire, 1. Pelecypodes. nat. Belg., 3:1-263 (1878); pis (1881).
1937. tot de kennis der Mem. Soc. geol. Fr. (Paleont.), 27(5): 1-500, 46 pis. Regteren Altena, C.O. van, Bijdrage sub-fossiele die de Favre, J., 1918. Catalogue illustre de la Collection Lamarck, fossiele, en recente mollusken, op
Conchiferes dimyaires fossiles, Premiere partie. Geneve Nederlandsestranden aanspoelen, en hunner verspreiding, 184 12 (Georg & Cie), 117 pis. Amsterdam (Universiteit van Amsterdam), pp.,
Geys, J.F. & R. Marquet, 1979. Veldatlas voor de cenozoische pis. Bloklander & L.P. fossielen van Belgie, 1. Neogeen. Rotterdam (Backhuys), Regteren Altena,C.O. van, A. Pouderoyen, de Nederlandse stranden 125 pp., 45 pis. 1962. De fossiele schelpen van
— 26: 5-16. Glibert, M., 1957. Pelecypodes du Diestien, du Scaldisien et en zeegaten. Tweede serie, 1. Basteria,
— de evolutie du Merxemien de la Belgique, premiere note. Bull. Ringele, A., 1974. Bijdrage tot de systematiek, en uit Inst. r. Sci. nat. Belg., 33(9): 1-40, 1 pi. de paleoecologie van Bivalvia Neogene afzettingen van Univ. Glibert, M. & L. van de Poet, 1965. Les Bivalvia fossiles du Noord-Belgie, Deel 1. Systematiek. Leuven (Kath.
CenozoTque etranger des collections de l'Institut Royal des Leuven), 136 pp. (unpubl. PhD).
Sciences Naturelles de Belgique, 1: Palaeotaxodontida et Sowerby, J. de C., 1823-1829. The Mineral Conchology of
Eutaxodontida. — M6m. Inst. r. Sci. nat. Belg., (2)77: 1- Great Britain, or coloured figures and descriptions of those
112. remains of testaceous animals or shells which have been
Heering, J., 1950. Pelecypoda (and Scaphopoda) of the preserved at various times and depths in the earth, 5.
408-503. Pliocene and older-Plistocene [s/'c] deposits of the London (Arding/Richard Taylor), 160 pp., pis
Netherlands.— Meded. Geol. Sticht., (C)4(l)9: 1-225, 17 Wood, S.V., 1851-1860. A monograph of the Crag Mollusca,
pis. or, description of shells from the Middle and Upper
Janssen, R., 1979. Revision der Bivalvia des Oberoligozans Tertiairies ofthe east of England, 2. Bivalves. — Monogr.
(Chattium, Kasseler Meeressand). — Geol. Abh. Hessen, Palaeontogr. Soc. Lond., 1-150, pis 1-12 (1851); 151-216,
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Lauriat-Rage, A., 1981. Les Bivalves du Redonien (Pliocene Wood, S.V., 1872-1874. Supplement to the monograph of the 10
Crag Mollusca, or, description of shells from the Middle
and Upper Tertiairies of the east ofEngland, 3. Univalves
and Bivalves. — Monogr. Palaeontogr. Soc. Lond., 31 +
99 pp., pis 1-7(1872); 99-231, pis 8-21 (1874).
Wood, S.V., 1879. Second supplement to the monograph of the Crag Mollusca, with descriptions of shells from the
Upper Tertiairies of the east of England. Monogr.
Palaeontogr. Soc. Lond., 1-58, 1 pi.
Manuscript received 30 June 1999, revised version accepted
30 May 2000.
PLATE 1
Fig. 1. Glycymeris (Chevronia) obovata obovata (Lamarck, 1819), interior of left valve, Dornberg, Ahnetal (Germany), Oligocene,
Chattian, Kasseler Meeressand (A. Janse Colln), x 2.25
2. - - Fig. Glycymeris (Chevronia) obovata ringelei n. subsp., RGM 394 099 (holotype), A exterior ofleft valve (x 1.5), B interiorof
right valve (x 1.5), C - interior ofleft valve (x 1.5); Antwerp, 5th harbour dock (province of Antwerp, Belgium), Pliocene,
base Kattendijk Formation, ex van Nieulande Colln. 11\1
PLATE 1 12
PLATE 2
Fig. 1. Glycymeris (Chevronia) variabilis (J. de C. Sowerby, 1824), BMNH 43188a(lectotype), right valve, A - exterior, B - interior
views, Suffolk (England), Pliocene, Red Crag (previously illustrated by J. de C. Sowerby, 1824, pl. 471, bottom figure), x
1.3.
Fig. 2. Glycymeris (Ch.) variabilis, BMNH 43188b (paralectotype), right valve, A - exterior, B - interior views, Woodbridge
(Suffolk, England), Pliocene, Red Crag (previously illustrated by J. de C. Sowerby, 1824, pl. 471, centra figure), x 1.4. somewhat 10 bar in Borsele-de Kaloot Fig. 3. Glycymeris (Ch.) variabilis, left valve of a juvenile specimen, eroded, x (scale mm).
(province ofZeeland), beach material, derived Pliocene(Moerdijk Colln). 13\2
PLATE 2 14
PLATE 3
Fig. 1. Glycymeris (Ch.) variabilis, right valve, A - exterior; B - interior views, Walton-on-the-Naze(England), Pliocene, Red Crag Nieulande (van Colln, leg. J. van der Voort), x 2.
Fig. 2. - Glycymeris (Ch.) variabilis, left valve of inequilateral and thick-shelled form, A interior, B - exterior views, Mill-St.
Hubert, the Netherlands), Pliocene, Langenboom (province of Noord-Brabant, van Nieulande Colln, no. 137), x 2.5. 15\3
PLATE 3 16
PLATE 4
left of inflated - - interior Fig. 1. Glycymeris (Ch.) variabilis, valve form, A exterior, B views, Kallo, sea sluice construction pit,
base Oorderen Member (probablyreworked from older strata), VervoenenColln, no. F.25B, x 1.25.
Fig. 2. Glycymeris (Ch.) variabilis, left valve of inflated form, A - interior, B - exterior views, SudbournHall (England), Coralline NITG MOL 1.4. Crag, Pliocene, Colln, 694, x
Fig. 3. Glycymeris (Ch.) turonica (Mayer-Eymar, 1868) s. lat., interior ofleft valve, St-Julien-de-Concelles (Nantes area, France),
Mio-Pliocene, Redonian, van Nieulande Colln, x 1.4. 17\4
PLATE 4 18
PLATE 5
- - interior borehole Fig. 1. Glycymeris (G.) radiolyrata f. pseudodeshayesi n. forma, left valve, A exterior, B views, 42H19-4(A40),
114.50-115.75 mbs, Pliocene, ‘Luchtbal Member’, leg. Deltadienst, RGM 394 121, x 5 (photographs by W. Krull,
Oostburg).
Fig. 2. Glycymeris (G.) radiolyrata f. pseudodeshayesi n. forma, right valve, Antwerp, Boudewijnsluis, base Oorderen Member,
Marquet Colln, x 1.6.
- Fig. 3. Glycymeris (G.) radiolyrata f. pseudodeshayesi n. forma, BMNH 43188c, right valve, A - exterior, B - interior views, x 1,C
detail of hinge plate, x 2, ?Suffolk (England), Red Crag (previously illustrated by J. de C. Sowerby, 1824, pl. 471, top
figure). 19\5
PLATE 5 20
PLATE 6
Fig. 1. Glycymeris (G.) radiolyrata f. exaggerata n. forma, A - interior, B - exterior views, x 1.15, C - detail of umbonal region,
Kallo, Beveren tunnel construction pit, base Oorderen Member (probably reworked from older strata), 10 April 1975, van
NieulandeColln, no. 93b.
Fig. 2. Glycymeris (G.) radiolyrata f. exaggerata n. forma, Kallo, sea sluice construction pit, ?base Oorderen Member (probably
reworked from older strata), Vervoenen Colln, no. F 717 A2, x 1.75.
3. f. left Vrasenedok Fig. Glycymeris (G.) radiolyrata exaggerata n. forma, valve, Kallo, excavation, base Oorderen Member reworked from older (probably strata), Marquet Colln, x 1. 21\6
PLATE 6