A remarkably rich prosobranch fauna endemic to the French Pyrenees

15 Pages·2001·1.2 MB·English

by  Boeters, Hans D

BASTERIA, 65:1-15, 2001
Aremarkably rich prosobranch faunaendemicto theFrench Pyrenees
Hans+D. Boeters
Karneidstrasse 8,D81545Miinchen,Germany
& AlainBertrand
Laboratoire Souterrain,F09200Moulis,France
This article describes a remarkably rich fauna offreshwater prosobranchs endemic tothe
French Pyrenees, which comprises three new (sub)species, viz.Moitessieria nezi spec. nov.,
Palaospeumbessoni rebenacqensissubspec. nov. and(?)P.nanum spec. nov., andAlzoniellajunqua
Boeters, 2000. These four endemic species can be found sympatric with two species of
Bythinellawhich havealarger distributioninthePyrenees.
Key words: Gastropoda, Prosobranchia, Moitessieriidae, Moitessieria, Palaospeum,
Hydrobiidae,Alzoniella,Bythinella,France,Pyrenees,taxonomy,biogeography.
I.SPECIATIONAND ITSTOPOGRAPHICAL AND GEOLOGICALASPECTS
1.Topographical and geological aspects
In the Pyrenees-Atlantiques, the Gave d'Ossau rises in the area ofthe Pic du Midi
d'Ossau, flows past Gabas, Laruns and Arudy, and finally into the Gave d'Oleron at
Oleronabout5km southwestofPau.At Arudy, the Gave d'Ossaubuttsagainst amora-
nicwall(Delfaud etal., 1980:figs 7-13) depositedonalayeroftheEarly Cretaceousperi-
od (cretace inferieur) whichis overlaidin the southby alayer of the LaterCretaceous
period (cretace superieur) (Delfaud, 1980:fig. 0-8).Where itbutts against the moranic
wallabout390 m above sea level, the Gave d'Ossau loops westwards from itsoriginal
south-northdirection.To the southofthis wall, thesmall river Nez has cut itsbed into
theLaterCretaceouslayerand flowsinasouth-northdirectiontowards Pau,joining the
Gave de Pau at opposite Pau. Themain source of theNez isL'OeilduNez, a
largekarstic spring 315 mabove sealevel only 4km distantfrom theloop ofthe Gave
d'Ossau at Arudy. L'Oeil du Nez is used forthe water supply of Pau. L'Oeil du Nez is
about75mlowerthantheloop oftheGave d'OssauatArudy. Thelarge karstic spring is
supplied by water trickling away fromthe Gave and making its way through the karst
(Bauer etal., 1992).
L'OeilduNez is themainsource ofthe Nez,butitisassociatedwith anumberofsmal-
ler springs. An examination of three ofthese smaller springs has revealed that karstic
watersoftheValleeduNez are inhabitedbythefollowing six prosobranchs, thefirstfour
ofwhichare characteristicofthis valley andcanberegarded asendemic:Moitessierianezi
2 BASTERIA, Vol. 65,No. 1-3, 2001
spec, nov.;Palaospeum bessoni rebenacqensis subspec. nov.; (?) Palaospeum nanumspec, nov.;
Alzoniellajunqua Boeters,2000;Bythinella servainiana (Paladilhe, 1870);Bythinella cf. utri-
culus(Paladilhe, 1874).
Thefour representatives ofMoitessieria, Palaospeum andAlzoniellaare stygobionts. The
numberof six taxaofthe Moitessieriidaeand Hydrobiidae isremarkablein viewofthe
fact thatthewaters of thebest-knownkarstic spring in France, the Source duLez north
of Montpellier, are not inhabited by more than seven species ofthese two families:
MoitessieriarolandianaBourguignat, 1863;Paladilhiapleurotoma Bourguignat, 1865;P. conica
Paladilhe, 1867; Arganiella exilis (Paladilhe, 1867); Bythiospeum bourguignati (Paladilhe,
1866); Belgrandia gibba (Draparnaud, 1805); Bythinella eutrepha (Paladilhe, 1867).
2. Speciation
Gorthner& Meier-Brook(1985) stressed thefollowing three factors asbeing essential
forspeciation resulting inendemisminfreshwater molluscsinLake Ochrid: (1) a great
age(Lake Ochridis datedasLatePliocene); (2) lowtemporaryfluctuationofabioticfac-
tors; (3) thepresenceofvariousecological niches.
In 1991Boeters& Miillerdiscussedwhetherthesefactors couldalsoexplain theorigin
ofthe rich subterraneanprosobranch faunaofthe Rhonebasin ifthis basinis roughly
understoodasalake-likesubterraneanarea.Theycametotheconclusionthatfactors(1)
and(2) donot apply tothe Rhonebasinandthatthe subterraneanprosobranchs ofthe
Rhonebasin mighthaveinvaded thevalley fromthe neighbouringkarst.
As regardsthe subterraneanprosobranchs ofthe Nez,thefollowing canbe concluded.
Factor (1). In view of the fact thatthe waters ofthe Nez originate fromkarst of the
Cretaceousperiod in aregion which hasnotbeen covered by marinewaters any more
(Delfaud, 1980), it canbe assumedthatthis aquatic habitatexists fora very long time
already.
Factor(2). Evenundertheassumption thatthe areaofthe loopoftheGave d'Ossauat
Arudywascoveredbyice during periods ofglaciation,itcannot beexcludedthatthekar-
stic labyrinth ofthe Nez was not constantly, entirely frozenandremainedatleastpartly
inhabitableforfreshwaterorganisms. Referenceis madeto Bythiospeum spec, living ata
temperatureof4.5°C (in May) at thecave Angerloch (Upper Bavaria) supplied atleast
during thecoldseason by meltedsnow (Boeters, 1984: 144).
Factor (3). For Lake Ochrid Gorthner & Meier-Brook (1985) describedecological
niches fortwo species ofGyraulus. G. lychnidicus lives, forexample, onrocky limestone
bottomsofthe littoralzoneata depth ofnotmore than1 m,whereas G. trapezoides lives
onsoftbottomscoveredby Charabedsat a depth of6 to 15 m.
As regards subterraneanprosobranchs, we are not yet in a position to characterize
theirecological nichesadequately. In such a situationit seems logical to referto obser-
vations published forsubterraneananimalsotherthanmolluscs.Bou (1968: 469) exam-
inedthe subterraneanfaunaof water bodies and reported differencesbetweenpopula-
tions ofsprings emergingfrom thewater bodiesand ofartificialpipe wellsbored into
thesewater bodies:
"Si nousconsiderons les stations les plus riches ... nous remarquons que les especes
sont inegalement reparties. Les genresSalentinella, Microcharon,Stenasellus, etBathynella
sont abondantsdanslanappedes puits tubesalors queNiphargusgineti etAsellusalbigen-
sis se rencontrent essentiellement dans les sources, sur la peripheric des nappes."
Notenboom (1986: 81) foundHaploginglymus andPseudoniphargus species together in
somehyporheichabitats inthelowercourse of ariverbutadded: "Intheriver system of
Boeters&Bertrand:Afreshwaterprosobranchfauna inS. France 3
Fig. 1.Mapofsouthwestern France(top), with anenlargeddetail.
4 BASTERIA, Vol. 65,No. 1-3, 2001
the Rio Deva (Picos de Europa) which was investigated at several localities,
Haploginglymus shows a preference for the uppercourses, whilePseudoniphargus prefers
the lower courses."These observations show at leastindirectly that even subterranean
waters mayofferdifferentnichesforspeciation.
II. MOITESSIERIIDAEAND HYDROBIIDAE IN THEVALLÉEDU NEZ
As faras theVallee duNez hasbeenexamined,the valley is inhabitedbythreerepre-
sentativesof the Moitessieriidaeandthree speciesofHydrobiidae:Moitessieria nezispec,
nov.,Palaospeum bessoni rebenacqensis subspec. nov., (?) Palaospeum nanum spec, nov.,
ABlzoniellajunqyua Boetetrs,20h00,Bythineilla snervainiana (ePaladilhe,l1870l),anad cf.
utriculus(Paladilhe, 1874). Detailsofthesespecies are givenbelow.
Abbreviations used for collections: BOE, colln H.D. Boeters, München; MNHN,
Museum national d'Histoire naturelle, Paris; RMNH, Nationaal Natuurhistorisch
Museum(formerly Rijksmuseum van Natuurlijke Historie), Leiden.
Moitessierianezi spec. nov.(fig. 34)
Material. — France, Pyrenees-Atlantiques, springbelow the farms Hiqueres and Junqua, 1.35 km
WSW.ofthe center ofRebdnacq[UTMYN18];Boeters leg. 20.ix.2000(MNHN holotypeexBOE 1483,
shell;BOE 1483/2,shells) and 3/4.vi.l998 (BOE 1446/1,shell).
Shell. — Shell cylindro-conical. Spire with 6.25 convexwhorls, separated by a deep
suture. Thefirst threewhorlsofaboutthesame size; thefollowing ones, upto theaper-
ture,gradually increasing insize. Rows ofpits form aspiralsculpture (21 rows abovethe
edge oftheaperture). Thelastwhorlascends veryslightly ontheshellwall. Theapertu-
rallipis veryslightlythickened,indicatingthatshellgrowth hasbeencompleted. Thelip
makes merely point contact with the shell wall and does not close the umbilicus.
Apertureovoid andslightly oblique. Viewedfromtheside, the edge ofthe apertureis
curved like a question mark. Height and width ofshell 2.35 and 0.8 mm, heightand
widthofaperture0.6and0.5 mm (holotype).
Anatomy. —Unknown.
Differentiating features. —Moitessieria nezispec. nov. occurs closeto Moitessierialesche-
rae Boeters, 1981, in the west,andMoitessieriasimoniana (Saint-Simon, 1848) in the east.
TheshellofM.lescheraediffersby apartially scalaroidlastwhorlandclosely arrangedspi-
ral ridges. (Closely arranged spiralridges are alsoshownby two samples ofMoitessieria
spec, from the Pyrenees-Atlantiques, both collectedby Bertrand, atTardetsin deposits
ofthe SaisonandatAlcay). As regardsM. simoniana,Bodon& Giusti(1991) havepublis-
hed a biometricanalysis of six shells ofthis species from deposits ofthe Garonne at
Toulouseandfoundtheratios3.3-3.6for'totalheight:width ofsecond tolastwhorl'and
1.4-1.5for'height oflastwhorhwidthofsecondtolastwhorl'. Fortheholotype ofM. nezi
spec. nov.theseratiosare 3.3 and 1.5.The dataforM. nezispec. nov. showthatthe size
ofthe whorls scarcely increases before the fourthwhorl. Further, according to photo-
graphs offour ofthe shellsexaminedby Bodon&Giusti (1991: 3, fig. 1A-D), the height
ofthe shellinM. simonianais only 1.55-1.85mmandneverreaches2.35mm. Thesefin-
Boeters&Bertrand:Afreshwaterprosobranchfauna inS.France 5
dings agree with a shellheight of 1.65 mm ofanother specimen from deposits ofthe
GaronneatToulousewhichmightbea syntype ofM.simoniana(Boeters, 1988:pi. 1 fig.
1; SMF307268,excollnCharpentier, Lausanne).
Habitat. — Known from only a single spring, where it occurs sympatrically with
Palaospeum bessonirebenacqensis subspec. nov.,(?) P.nanumspec.nov.andAlzoniellajunqua
Boeters,2000.
Distribution. — France, Pyrenees-Atlantiques, subterraneanwaters feeding the Nez
whichflowsintothe Gave de Pau atJurangon.
Derivationominis. —Theepithet neziis derivedfromtheriver Nez. Itshouldbemen-
tionedthattheCarteTopographique 1546ET(1:25,000) designates theriver in question
"Nez" whereas Baueretal.(1992) speak of"Neez".
Palaospeum bessoni(Bernasconi, 1999)
Paladilhia bessoni Bernasconi,1999:385.
In the following, this species is described as inhabiting the French Pyrenees-
Atlantiques with two subspecies. Theirknown areas of distributionare about 43 km
apart. The nominate subspecies lives in karstic waters of the massiv ofthe Pic des
Vautours. These waters feed the Saison which flows into the Gave de Oleron at
Sauveterre-de-Bearn.Thenewsubspecies P.b. rebenacqensis subspec. nov. inhabitskarstic
waters inthe ValleeduNez.
Palaospeum bessonibessoni (Bernasconi, 1999) (fig. 29)
Shell(afterBernasconi, 1999:387). —Shell conical, with6.5 weakly convex, regularly
increasing whorls, suture deep, apex small and obtuse. Umbilical opening narrow.
Aperture oblong, border continuously slightly broadened, outer edge curved. Shell
smooth,lastwhorlsometimeswithmoreorlessblurredspiral lines(about 40to50lines
permm longitudinally). Judgingfromaparatypethe numberofwhorlscanbe asfewas
5.75; cf. belowunderB. b. rebenacqensis subspec. nov.
Differentiating features. —See subB. b. rebenacqensis subspec. nov.
Palaospeum bessonirebenacqensis subspec. nov. (figs 3-4, 30)
Palaospeumbessoni(Bernasconi, 1999);Boeters,1999: 193,194,fig. 3,195,figs5-6.
Material. —France,Pyrenees-Atlantiques; (i)spring below the farms Hiqueresand Junqua,1.35km
WSW.ofthecenterofRebenacq[UTMYN18];Boetersleg., 3./4.vi.l998(RMNH59396/holotype,shell,
59397/1, shell; BOE 1446/7[not 2], shells,and BOE 1446/6,animals) and 20.ix.2000 (BOE 1483/12,
shells, and BOE 1483/13,animals);(ii)springinthe right embankment between the roadwayand the
Ruisseaux-de-Nez immediatelysouth ofthe bridge at I.acoucure, WSW.ofRebenacq [UTMYN18];
Boetersleg., l.vi.1998 (BOE 1445/1 [not6], shell).
6 BASTERIA, Vol. 65,No. 1-3, 2001
Figs 2-4.Palaospeumspec.,France,Pyrénées-Atlantiques,Rébénacq,belowthefarms HiqueresandJunqua.
2,(?)P. nanumspec. nov.;3-4,P.bessonirebenacqensissubspec. nov. 3,twoviewsofajuvenileshell,the left one
with areconstructed dotted frontalviewofthe sameshellwith merely4.0 whorls,for comparisonwith the
shell offig. 2with also4.0whorls;4,plan-view ofanadult shell witharrowsmarkingthediameter ofthefirst
1 1/2whorls.Scale bar 1mm.
Shell. —Shell elongated conical, with5.0-5.75 whorls, separated by a clearly indented
suture. Whorlsmoderately convex, narrow shouldered,withatmostavery weak spiral
structure.Last whorlforming halfofthe totalheightofthe shell.Aperture slightly obli-
que,ovate,withasharp edge. Thecolumellarborder ofthe apertureis strongly broade-
ned,ittouchesthelastwhorlforonly ashort distanceand formsabroadfunnelwiththe
shellwallin the umbilicalregion. Viewed fromthe side, thepalatal border of the aper-
tureis very slightly curved.
Height 3.0-4.5mm; width1.5-2.15mm(n =10).
Operculum very paleyellow, nucleusnot setoff.
PAnatomy. —aEyes notldetaected.Asmdallmantleitenltaclheispresenitasain pleu-
rotoma Bourguignat, 1865. This observation supplements the description given by
Boeters (1999). Grainsofblack pigment foundonly atthebaseofthe mantlecavityand
in malesin the areabetween the intestineand theprostate. Gillwith 16-17leaflets (n =
2).Afterleavingthe stomach,the intestinesurroundsthestilesac atacleardistanceand
forms a Z-shaped loop, followed by a V-shaped bend. The penis is slim, withoutany
appendices. In females the gonopericardial duct is absent. One ofthe two receptacula
foundin femalesjoins the oviduct nearthe genital opening, the otherseems to have a
comparatively long pedunculus sinceitssac canbe seen through the shelljustbelowthe
suture as flanked by the intestineandthe mostproximal gland ofanagglomeration of
three glands accompanying theoviduct.
Differentiatingfeatures. —The diameterofthefirst 1 1/2whorlsof shells ofP.b. besso-
niis the same or slightly smaller thanthat ofP.b. rebenacqensis subspec. nov., despite the
fact thattheshellsofP.b. bessoniareabout25% higher,as is shownin the following table
(measurements in mm). As regards the determinationofthe diameterofthe first 1 1/2
whorls,referenceis madetofig. 4.
Boeters&Bertrand:Afreshwaterprosobranchfauna inS. France 7
BB.. bb.. bbeessssoonnii BB.. bb.. rreebbeennaaccqqeennssiiss ssuubbssppeecc.. nnoovv..
LLooccuussttyyppiiccuuss ((BBiiddaalluunniiaa)) LLooccuuss ttyyppiiccuuss ((ffaarrmmJJuunnqquuaa))
SShheellllhheeiigghhtt 33..1100--44..4477--55..5544((nn ==3377)) 22..9955--33..4466--33..6600((nn ==88))
WWhhoorrllss 55..7755((nn== 11)) '')) 55..0000--55..7755((nn ==33))
DDiiaamm..ffiirrsstt IIVV22wwhhoorrllss 00..6600((nn ==ll)) '')) 00..6600--00..6622--00..7700((nn == 1100))
UUtthhuurrbbiieettttaa LLaaccoouuccuurr
SShheellllhheeiigghhtt 33..7700--44..3377--55..3355((nn ==2266)) CCoouulldd nnoottbbeeeexxaammiinneeddbbeeccaauussee
DDiiaamm..ffiirrsstt l1lV/22wwhhoorrllss 00..5577((nn ==11)) 22)) ooffppaarrttiiaallddaammaaggee
1)Paratype(BOE 1468exBernasconi):Heightofshell 4.5mm,diameteroffirstl'/2whorls 0.60mm
2) Bernasconi,1999:389,fig. 9.
Ashellheight ofonly 2.15mm, insteadofatleast2.95 mm, distinguishes (?) P.nanum
spec. nov. from P.b. rebenacquensis subspec. nov.
Witha height ofupto 5.54 mmP.b. bessoniisthe largest representative ofsubterrane-
anprosobranchs known fromwestern Europe. Itis not surprisingthat ithas beendes-
cribedfroma caveand akarstic spring andnot from theinterstitialofgravel deposits.
Whilecomparatively large prosobranchs havealso occasionally been discoveredingra-
vellayers,theirshellheighthasneverexceededabout4mm(Nicolas, 1891:20,Avenionia
fabrei Nicolas, 1891;Boeters, 1973:65,Paladilhia pleurotoma Bourguignat, 1865).It canbe
assumedthatthe continuousshifting ofgravel deposits doesnot suitprosobranchs with
large shells.Only sedimentationzones, characterizedby comparatively smallerparticles
and a correspondingly smallerporesize, are relatively stable.Therefore, only akarstic
environmentpermits thedevelopment ofshellsofsuchasize asare characteristicofboth
subspecies ofP.bessoni. Itfollowsthatpopulations ofthetwo subspecies cannothavecon-
tactwitheachotheracross gravelbeds ofrivers; onthecontrary, thesegravel bedsarea
separating factor. In thiscontext it should notbe overlookedthatabasis forthis inter-
pretationcanbe seeninBoiling's observation(1966: 82,83)that thevariationinshellsize
ofsubterraneanrepresentatives of another genus, viz.Bythiospeum, is related to their
habitat: " ... formenbestimmendist vor allem die RaumgroBe des Karstsystems bzw.
KorngroBe desKieses, Enge, Weite,TiefeundStromungsgeschwindigkeit derunterirdi-
schen Wasserlaufe" (p. 82). "Die relativ groBte Einheitlichkeit der Pragung des
GehausecharaktersfindetsichbeimFormenkreisderaciculaHeld.Ob es sich nunumdie
Zwerge derBayerischen Schotterebene,desRheingrabens oderdesUntermainshandelt
oderumFormendes [Karsts] desNeckars, desTauber-,Kocher-oderJagst-Gebietes mit
ihren wesentlich groBeren,ja Riesenstticken, immer habenwir [etc.]" (p. 83). Ifthe
...
particle sizeofgravel, ormoreexactly itsinterspaces, istobeunderstoodas asize deter-
mining factor, thelogical conclusionis thatitwillleadto localseparation ofpopulations
andof speciation.
Habitat. —Karstic watersof theValleedu Nez.
Distribution.—France, Pyrenees-Atlantiques, Vallee duNezatRebenacq.
Remarks.—According to Boeters (1999: 196) P.bessoni mightbe a polytypic species.
The populations atAlcay and Uthurbiettaare 6 kmapart, whereas the population at
Rebenacq occursabout43km distantfrom thesetwo sites.
8 BASTERIA, Vol. 65,No. 1-3, 2001
Figs 5-16.Bythinella spec. 5-14,B. servainiana (Paladilhe,1870),France,Pyrénées-Atlantiques (5-7,between
St.Jean-de-LuzandHendaye atfarmHaicabia (BOE 357)(5=24 and 7 =25); 8-10, Rébénacq,150mE. of
Mairie (BOE 1487);11-12, Buzy atArudy (BOE 1485); 13-14, Louvie-Soubiron atLaruns (BOE 1482);15,
Bythinellareyniesii (Dupuy, 1851),France,Hautes-Pyrénées, Bagnères-de-Bigorre,Pare desThermes (BOE
195). 16,B. darrieuxii (Folin&Bérillon, 1877),France,Pyrénées-Atlantiques, Arnéguy(BOE 1491, Falkner
ded.).Scale bars1mm.
Boeters&Bertrand:Afreshwaterprosobranchfauna inS. France
9
(?)Palaospeum nanumspec. nov.(figs 2, 31)
Material. — France, Pyrenees-Atlantiques, springbelow the farms HiqueresandJunqua, 1.35 km
WSW.ofthe center of [UTMYN18];Boetersleg., 20.ix.2000(RMNH82617,holotype,shell;
BOE 1483/1,shell).
Shell. —Shellelongated conical, withonly 4.0moderately convex whorls, separated by
aclearly incisedsuture.Thelastwhorlaccounts forabout63% ofthetotalheight ofthe
shell.Thecontour ofthe apertureratherresemblesabluntedright-angled triangle,with
thebluntedacute angles connectedbyits columellarborder.Theborderofthe aperture
is slightly broadened,more clearly its columellarsection which touches the shell wall
over a short distance and forms a narrow funnelwith the shellwall ofthe umbilical
region. Viewedfrom the side, the palatal borderof the apertureis only very slightly Z-
shaped. Height, 2.15mm;width, 1.08mm (n = 1).
Operculum unknown.
Anatomy. —Unknown.
Differentiating features.—Theshellheight in (?) P. nanum spec. nov. isabout2/3 that
ofP.b.rebenacqensis subspec. nov.; shells oftheformerspecies have merely4.0 insteadof
5.0-5.75whorls.
Habitatanddistribution.—Foundin asingle spring sympatricallywithMoitessierianezi
spec, nov.,Palaospeum b.rebenacqensis subspec. nov. andAlzoniellajunqua Boeters, 2000.
Remarks. —Since anatomicaldataarenot yetavailable,the question ofwhetherthis
species reallybelongs toPalaospeum is stillopen.
Derivationominis.—Theepithet nanumisbasedonthe Latinnanusforgnome.
Alzoniellajunqua Boeters, 2000(figs 32-33)
Alzoniella(Alzoniella)junquaBoeters, 2000: 155,figs4-5,20-21,27.
Thisspecies is eyeless. Ithasbeenfoundintwo differentsprings oftheValleeduNez.
Inone spring sympatrically with Moitessierianezi spec, nov., Palaospeum b. rebenacqensis
subspec. nov. and (?) Palaospeum nanum spec, nov.; in the other one together with
Bythinella servainiana.
Bythinella servainiana(Paladilhe, 1870) (figs 5-14,22-25)
Paludinella servainiana Paladilhe, 1870: 205 [39]. Type localities: "Des environs deSaint-Jean-de-Luz
(Basses-Pyrenees) ... aussi dansledepartementde1'H/rault,dansunefontaine pres deGignac."
Paludinella companyoi Paladilhe 1870: 204 [38]. Type localities: "Bourassol [= Burrassol], pres de
Toulouse (Haute-Garonne)[partim], etSalces (Pyrenees-Orientales) [locustypicusrestr.; cf.Bernasconi,
2000: 100]."
Material. —France. Landes: Mont-de-Marsan,springin leftbankofMidouze, about 150mW.offor-
merrailwaybridge[UTMYP06], Boetersleg., 27.V.98 (BOE 1440).
France, Pyrenees-Atlantiques:Between St.Jean-de-Luzand Hendaye, about 200m S. ofthe sea and
N. ofNIOc, springonfarm Haicabia [UTMXP00],Boetersleg., 18.ix.70 (BOE 357);Ascain,springat
10 BASTERIA, Vol. 65,No. 1-3,2001
wash-house W. ofthe church [UTMXP10],Boeters leg., 27.ix.68 (BOE 192);Arneguy,well (ironpipe)
about300mNE.ofthechurchand totheright oftheroadleadingtoSt.Jean-Pied-de-Port[UTMXN37],
Boetersleg., 21.ix.70 (BOE 362); Arneguy.well(ironpipe) about 1.3km NE. ofthe church and tothe
rightoftheroad leadingtoSt.Jean-Pied-de-Port[UTMXN37],Boetersleg., 21.ix.70(BOE363);St.Jean-
Pied-de-Port,springonfarmMitchadoyabout 800m NW. ofthe railwaystation [UTMXN48],Boeters
leg., 16.ix.70(BOE351); tothe right ofthe road from St.Jean-Pied-de-Porttowards Caro,Fontaine-de-
Sante [UTMXN47], Boetersleg., 16.ix.70(BOE352);St.Jean-Pied-de-Port,springtothe right ofD301
about3.3kmSE. ofthe railway station[UTMXN47],Boetersleg., 16.ix.70(BOE353); Louvie-Soubiron
atLaruns,wash-house [UTMYN16],Boetersleg.,15.ix.00(BOE 1482);BuzyatArudy, overflowofwater
reservoir [UTMYN07], Boetersleg., 19.ix.00 (BOE 1485);Rebenacq,spring 150m E. ofMairie [UTM
YN18],Boetersleg., 20.ix.00 (BOE 1487).
Theonly taxaofBythinella with a type locality in Pyrenees-Atlantiques arePaludinella
darrieuxiiFolin&Berillon, 1877,andPaludinellaservainianaPaladilhe, 1870,fromthesur-
rounding ofSt.Jean-de-Luz attheFrench Atlanticcoast.Paladilhe,however, also descri-
bedhisspecies from Herault,from aspring at Gignac in the bankof the river Herault.
Hereit isassumedthatthe "fontainepres deGignac" is the FontainedeJourmacabout
2.5km southwestofGignac, sincethisspring isrepresented inPaladilhe'scollectionwith
asample ofBelgrandiella spec. Bernasconi(2000:25) treatsPaludinellaservainianaas syno-
nymofPaludinellaeurystoma Paladilhe,1870.This viewcan, however, hardlybe accepted
despitethefact thatoneofthetypelocalitiesofPaludinella servainiana,.i.e.thatinHérault,
isnot morethanabout5 km distantfrom thatofB. eurystoma. As regardsthesetwo taxa,
Bernasconi supplies no anatomical dataon samples from Heraultnor from Pyrenees-
Atlantiques, butonly onsamples fromAudeandAriege.
Anexaminationofasample fromthetypelocality ofPaludinella eurystoma ["la fontaine
de Girardä Saint-Jean-de-Fos (Hérault)" (BOE 114)] has revealedthatthe species from
the Vallée du Nez is different.It is also foundin the area ofthe only type locality of
Paludinellaservainianain Pyrenees-Atlantiques, viz. on the farm Haicabia between St.
Jean-de-Luz andHendaye. Shellsfromthe farmHaicabia correspond tothe syntypes of
Paludinellaservainiana Paladilhe, 1870, as photographed by Bernasconi (2000: 100).
Consequently, thatspecies willherebe designated Bythinella servainiana. Itis widespread
in Pyrénées-Atlantiques and Landes. Asyntype ofPaludinellacompanyoi Paladilhe, 1870,
photographed by Bernasconi(2000: 100),belongs to B. servainiana,which impliesthatit
isdistributedeastwardsupto Haute-Garonne.B. servainianacanalsobefoundintheval-
ley ofthe Gave d'Oleronwhichfeeds thekarstic springs ofthe ValleeduNez.
Shell.—Shellelongated conical with aflattenedapex and 4.0whorls. Thewhorlsare
quite convex andseparated by a deep suture. The apertureis slightly slanted ovate. Its
columellarborder touches the last whorl overa long distance and is faintly reflected
below the umbilical slit. Height, 2.53-2.85-3.12 mm; width, 1.40-1.49-1.56mm (n =3,
BOE 1487); and2.80-2.94-3.00mmand 1.48-1.53-1.60mm, resp. (n=4,BOE 357).
Anatomy. —Eyes present. Withtheexception ofitssnout,the headisweakly blackish
pigmented. Apart from thewhitemargin, the mantleisstrongly pigmented black. Male
copulatory organ:initsinactive state,thepenis is slightlylonger thanitsaccessory organ
(n = 2, BOE 537). Female sex tract: length ofthe tube-shaped bursa about2/3 ofits
pedunculus. A singlereceptaculum present,
Differentiating features. — The shell ofBythinella eurystoma (Paladilhe, 1870) differs
fromthatofB. servainianaby athickened umbilical, aperturalborder (figs 17-18),which
canbe seenonthe border ofthe apertureimmediately under the suture whenviewed