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A new stygobiont melitid amphipod from the Nullarbor Plain

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Title:
A new stygobiont melitid amphipod from the Nullarbor Plain
Series Title:
Subterranean Ecology
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Bradbury, J.H.
Eberhard, Stefan
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Subterranean Ecology, Scientific Environmental Services
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Biology ( local )
Cave Ecology ( local )
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Australia

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A new genus and species of melitid amphipod, Nurina poulteri, from the Nullarbar Plain, Western Australia, is described. The new taxon, from two caves in the Roe Plan region, is compared with melitids from elsewhere in Australia, and possible origins relevant to the recent geological history of the region are discussed. -- Authors
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Description
A new genus and
species of melitid amphipod, Nurina poulteri, from the
Nullarbar Plain, Western Australia, is described. The new
taxon, from two caves in the Roe Plan region, is compared with
melitids from elsewhere in Australia, and possible origins
relevant to the recent geological history of the region are
discussed. --
Authors



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RecordsoftheWestern Australian Museum20:39-50 (2000).Anewstygobiont melitid amphipod from the Nullarbor PlainJ.H.Bradbury1andS. Eberhard21Department of Environmental Biology, University of Adelaide, South Australia, 5005, Australia2Caveworks, Witchcliffe, Western Australia,6286,Australia email: john.bradbury@adelaide.edu.au Abstract -Anewgenusandspeciesofmelitid amphipod,Nurinapoulteri,from the Nullarbor Plain, Western Australia, is described. The new taxon, from two cavesinthe Roe Plain region, is comparedwithmelitids from elsewhereinAustralia, and possible origins relevant to the recent geological history of the region are discussed.INTRODUCTIONStygobiontamphipodsarebeingrecordedinincreasingnumbersfromwidespreadregions of Australia. Thenumberof described troglobite or troglophile species isnownear 50 (BradburyandWilliams, 1997a, b). The actualnumberofknownspecies is, however,muchgreater asmanyareintheprocess of description orheldincollectionspendingtaxonomictreatment.Themajorityis associatedwithgroundwatersincarbonate rockswhichhavebeenkarstified. The Nullarbor Plain,approximately200,000km2 ,locatedincentralsouthernAustraliaaround30-32latitudebetweenlongitudes 124and132E, is a region of Tertiary limestones, which arose from the seaintheMiddleMiocene(15MYA). After final emergence from the sea the Nullarbor limestonesunderwentkarstification, including thedevelopmentof caves which intersect the regionalgroundwatertable,althoughfewoftheseundergroundlakesappeartocontainaquaticmacroinvertebrates. Richards (1971) recordednoaquaticfaunafromacomprehensivesurveyofmanycaves,suggestingthatloweffectiveprecipitation, general absence ofpermanentsurface streams,andphreatic origin of the caveswithnoevidenceofmarineinundation,precludedcolonisation eitherbymarine or freshwater species. This is probably largely true, exceptinone region,theRoe Plains,anerodedarea of coastal lowlandinthe centralNullarborextending a distance of almost 300kmfromTwilight Cove (-32'5, 126E) to Wilson Bluff'5, 129E)andupto 40kmwide. This area of uplifted seabedislowlying,comparedwithmostoftheNullarbor,notexceeding amaximumaltitude of30m abovesealevelatitsnorthernmostmargin,andadjacent theSouthernOceaninthe Great Australian Bight alongthesouthernedge.AlthoughRichards(1971)foundnoevidence ofmarineinvasioninNullarbor caves, there are indications of sea-levels ashighas30m above the present level.AmongRoe Plains caves, therefore, marine intrusive species,orrelict marine species might wellbeexpected, as hasbeenfound in other regions of similar geological history,suchasNorthWest Cape (HumphreysandAdams, 1991; Knott, 1983; BarnardandWilliams, 1995; BradburyandWilliams, 1996, 1997b), the Ashburton RiverandlowerFortescueRiverareasinnorthernWestern Australia (Bradbury, unpublished),andinthe Flinders Ranges of South Australia (BarnardandWilliams, 1995). Knott(1983,1985) reportedona 1982 collection from waters ofNurinaCave (one of the Roe Plains caves).Henotedanumberofamphipodsthoughttobeof the gel1usMelitaLeach. These specimens have not, however, been formally described. Several generaandspecies attributed to the Melitidae havealreadybeenrecordedfromotherregionsofAustraliathathavebeensubjecttomarineinundation(Bradbury, 1999); all are stygobionts. One ofus(S.E.)accessedNurinaCave (#N46) as well as theunnamedadjacent cave designated cave N1327,inDecember 1998,andwasable to collectamphipodspecimens frombothsites. Three species of threeamphipodfamilies were representedinthe collections. Themostabundant,andthedominantspecies, which is described here,andthe only taxon taken fromNurinaCave, is almost certainly that collectedin1982andreportedbyKnott (1983); theothertwotaxawillbetreatedelsewhere,inconjunction with related collections.METHODS OF DISSECTION AND DESCRIPTIONMethods of dissection, descriptionandnotation follow those of BradburyandWilliams(1996,1997b).ThenotationM,withanappendednumber,indicates the position of an object as a fraction ofthedistancefromthebasetotheapexofan

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40appendage;Slargespine;s,smallspine.Abbreviationsusedinthe figures are as follows: A, antenna;Abd,abdomen; ace, accessory; C, coxa; d, dorsal; dact, dactylus;E,epimeron; fl, flake; flag, flagellum; g, gill; G, gnathopod;Hd,head;i,-inner;juv,juvenile;L,left; lac, lacinia mobilis;LL,lowerlip;MD,mandible;med,medial;mol,molar; MP, maxilliped; MX, maxilla;0,outer;0,oostegite;opp,opposite;p,palp;P,pereopod;PC,prebuccalcomplex; pI, plate; Pp, pleopod; R, right;sp,spine;sq,squareview;sr,setaeremoved(sometimesmarkedbysockets); st, sternal gill; T, telson;V,uropod;VL,upperlip;VR,urosome; 1, 2, 3..7, first, second,third..seventh article, segment, somiteorepimeron (as appropriate).Mandibularpalpsetae are describedusingthenotationofKaraman(1969)andBarnardandBarnard (1983). SYSTEMATICS FamilyMelitidaeBousfield,1973Nurinagen.novoTypeSpeciesNurina poulterisp.novoDiagnosisPleonite six dorsolaterally naked, pleonite 5withrobust dorsolateral seta; rostrum obsolescent; lateral cephalic lobes strongly projecting, large, plate like,withdistinctventralnotchformedbythebluntextension of the anteroventral margin. Eyes absent.Firstantennalongerthanthesecond,ratioofpedunculararticles 1:1.3:0.5. Accessory flagellum four articulate, the fourth article tiny. Second antenna long, flagellummuchshorterthanpeduncle, calceoli absent.Vpperlip asymmetrical, ovateandapically piliose. Mandible:palpthree articulate, article one short, naked; third articlewithCDE setae; accessory blades numerous, with interrakerplumosesetaeandbrushybasal setae onto the molar. Lower lip: bearingbroadinnerlobes. Maxillae:moderatelysetosemedially,ovato-triangular,faciallysetose(pubescent),withmedialandapical plumose setae; outer platewithnine denticulaterobustsetae,palpsasymmetric the leftwiththin apicalandsubapical setae, the rightwithapicalbroadspines fused to the article as well as apicalandsubapical setae. Innerplateof second maxillawithoutplumosemedialsetae,butsomenakedpaired medial setae extendingtotheapex,somefacial. Bothplatesofsecondmaxillawithnakedapicalandsubapical setae ofmediumtomoderatelengthandbothwithfewmarginalsetules (pubescence). Maxilliped:innerplate long, extending toMO.7of outer plate,withamedialsubmarginaldisto-facialrowofplumosesetae extending more facial apically, blunt,nakedJ.H.Bradbury,S.Eberhardtooth likerobustsetae sub terminallyandanapical row ofplumosesetae; outer plate large,withlong, curved, robust apical plumose setae continuous with a distalrowof submarginal to apical, short to longnakedtooth setae,andmedial to sub marginal to facialpairedrowsoflongnakedsetae;medialmargin straight,withoutmarginal robust setae, the distomedial corner quadrate;palparticle two short, article three elongate,withnolateral setae; article three moderately to densely setose medially,witharowoflongsetaeatthebaseofthedactyldistolaterallyandfacially; apexproducedslightly,bearingmarginalsetules,dactylunguiform,multispinous,withoutfacial setules (not pubescent), bearing a longnakednailwithbasal setae. Coxae:onetofournormal,longerthanbroad,lackingposteriorrobustsetae;coxaeonetothreesubquadrate,notapicallyexpanded;coxafourmoderately excavate posteriorly; coxa five shorterthanfour; female coxa six anterior lobe ventrallyextended,coxasevensmall,unlobedanteriorly. Gnathopods: diverse, gnathopod onemuchsmallerthangnathopodtwo,dactylofgnathopodonewithout recumbentinnertooth spine,bothdactylswithdistinctnail. Firstgnathopodsmall,meruslacking hyaline lobe,withoutrastellate seta, carpus longerthanpropodus,notlobate,palmofpropodustransverse, short, deeply notchedinmales, distal row of long robust setaeborneonpalmarsubmargin eachwithasmallsubapicaltrigger;gnathopodtwoenlarged,1.5-2.xgnathopodone,carpusshort, triangularandlobate, dactyl enlargedandovate,palmstrongly oblique, setose, defining corner absent,butindicatedbylimit of robust setae; dactyl shorter than extent of robust setae. Pereopods: threeandfour shorterthanpereopods five to seven, posterior setaeonarticle six of pereopods threeandfour evenly spaced, weak; pereopods five to seven moderately long, six longest, the others subequalinlength, thebasis(article2)moderatelyexpanded,ovatorectangular, posteriorly extendedandslightly lobate; dactyls of pereopods lacking accessory spinules otherthantheusualsingle posteriorandanterior setules. Coxaetwoto six each bearing a single flask shapedgill,that of coxa sixsubequalinsize to the gill of coxa five. Without sternalgills.Oostegites: presentoncoxaetwoto five ofmaturefemales; narrow, marginally poorly setose. Epimera: posteroventralcornerofepimeraonetothreeacuminate,butwithoutspineorseta, posterior margins straight to slightly convex,withmoderatenumbersof setae; epimeratwoandthreewithfacial robust setae near the ventral margin. Pleopods: peduncleswithfew setae,ramiextending equally, basomedial setae of innerramibifid; retinaculaetwoperpleopod,plustwoaccessory retinaculae. Vropods: apico-Iateral corner of peduncles of uropods oneandtwowithoneandtworobust setae; lateral-andmedialdorsalmarginsofpeduncleof firsturopodspinose, of

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Anewstygobiontamphipodsecond naked; firsturopodwithbasofacial robust seta; rami ofuropodonesubequal, the lateralramusofuropodtwoshorter than the medial;ramiofbothuropodswithtworobust seta rows; thirduropodstronglyextended,peduncleofmoderatelength,outerramuslarge of one article only,innerramusshortandscale-like; lateralandmedial setae ofouterramusdense;pedunclewithapical, medialanddistalrobustsetae. Urosome: ventrodistal robust seta onurosomiteoneat baseofuropodone absent. Telson:shorterthanbroad,cleft95')'0,laterallyconvex,medially sinuous,bearinglong, medial, lateralandsub-apical robust setae,withoneortwoapicalorsub-apicalpenicillatesetaeandpairedlateralpenicillate setules.RelationshipsThefamilyMelitidaeischaracterised(BarnardandBarnard, 1983) by: the lower lips usually bearinginnerlobesweakto fleshy; maxillae fully tonotsetose medially; the firstgnathopodandalso the female secondgnathopod"melitid" in form;witha distinct palm; the male secondgnathopodenlarged,thepalmwithoutrobustsetaeorscatteredrobustsetae; thethirduropodisparviramous;the telson cleft;coxalgillsevenabsent;thefirstantennaaccessoryflagellumisoftwoormorearticles;peraeopods3--4areordinary,5-7basisvariablyenlarged,thedactylssimple;pleonitesandurosomitesonly occasionally dentate; the oostegitesnarrow.Nurinabears these characteristics.Nurinais similar toMelitainthatthepeduncleof thethirduropodisnotelongate,innerlobesarepresentonthelowerlip, the telson tapers distally,uropodthreeextendsbeyonduropodonein thewholespecimen,anteriorcoxae are significantly longerthanposterior coxae, the maxillaeareweakly setose medially, thesecondgnathopodnotbilaterallydiverse,norchelate,andthemandibularpalpthree articulate.However,Nurinadiffers fromMelitain that: the eyesarelost; the secondpedunculararticle of the firstantennais relatively longer, the third shorter; theprimaryflagellum of the firstantennais relativelymuchshorter -2xvs 5x the length of the peduncle;theaccessory flagellum is of four articles,ratherthan2+; the third article of themandibularpalpbearsCaswell as DandE setae; the inner lobes of thelowerliparebroad,butthinandpoorlydevelopedratherthanwelldevelopedandfleshy; theinnerplate ofthefirstmaxillipedistriangularratherthan'falcatotriangular' being straightnotcurved,andtheouterplatebearsnine robust denticulate setae asopposedto 7+; the dactyl of the maxillipedalpalpisbarely curved,notunguiform.Nurinadiffers fromPsammogammarusKaramaninthatthethirduropodisdistinctlyparviramousandtheanteriorcoxaearedistinctlylongerthanposteriorcoxae; fromGalapsiellllsJ.L.BarnardandAnchialellaJ.L.Barnard inthatthepeduncleofthe41thirduropodisnotelongate, the secondgnathopodstrongandthecarpusnotelongate;fromPsammoniphargusinthatthelowerlip bearsumerlobesandthemandibularpalpisnotreducedto a single article; fromNainaloaKaramanandBarnardandRotomelitaJ.L.Barnardinthatthe telson isnotrectangular,buttaperingandwithoutexcavateapices; fromMelitoidesGurjanovainthatthethirduropodexceedsthelengthofthefirstintheundissectedspecimen; fromVictoriopisaKaramanandBarnardandEriopisaStebbing inthatanterior coxaearesignificantlylongerthanposteriorandthatthethirduropodiswithouta second articleontheouterramus;fromMaleriopaBarnardandKaramanandParaniphargusTattersallinthatmaxillaebearmedialsetae; fromDulichiellaStoutinthatthemalesecondgnathopodsarenotasymmetrical,thebodyissmooth,withouttransdorsalserrations,andtheinnerplate of the first maxillabearsmanysetaeandisnotsickle like;fromTeganoKaramanandBarnardinthatthemandibularpalpisnotreducedtotwoarticles.SpeciesCompositionNurinacontainsonlyN.pOlllterisp.novoEtymologyNamedforthetypelocation,NurinaCave,Western Australia. Thegenderis feminine.Nurina poulterisp.novoFigures1-5TypeLocalityUndergroundwater,NurinaCave, Roe Plains,WesternAustralia, Australia, 127'E, 32'5.MaterialExaminedHolotype0,'a'9mm(WAM C 24436),NurinaCaveN46, Roe Plains,WesternAustralia,Australia, 127'E, 32'S,31December 1998,S.Eberhard.Allotype<.(,'b'7.5mm(WAMC 24437),samedataas holotype.Paratypes10,8.9mm(WAMC 24438)and15otherspecimens,samedataas holotype.Other MaterialAustralia:WesternAustralia:2<.(,cave N1327, Roe Plains, 127'E, 31S, 10 April, 1997, N. PoulterandD. Hall (WAMBES4648,BES4651); 8<.(,samedataexcept31December 1998,S.Eberhard (WAM).

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42J.H. Bradbury, S. Eberhard Figure 1Nurina poulterimale 8.9 mm: whole; holotype, male 'a': rightgnathopod1andpalm,leftgnathopod2,rightpereopod3.---------

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AnewstygobiontamphipodDiagnosisAs forthegenus.Descriptionofholotype(male'a')Body(Figure1):Length9mm.Urosomewithfew,scatteredweaksetules,urosomitefivewithonedistolateralrobustseta.Head:rostrumobsolescent, eyes absent.Firstantenna(Figure1):Length 0.6 xbody,1.4 xsecondantenna;flagellum longerthanpeduncle,oftwentyarticles,theultimatearticle tiny;pedunclearticleone0.7 xthesecondwhichis longest,thethirdshortest,ratioof articles1:1.3: 0.5, articleonewithfew setae,bearinga ventrodistalgroupofsimpleandpenicillate setaeandonerobustseta;sparseshortandlongsetaepresentonarticlestwoandthree;calceoliandaesthetascsabsent;accessoryflagellumfourarticulate,theultimatearticle tiny,extendingtoMO.3of the fifth article oftheprimaryflagellum;primaryflagellumsparselysetulate, articles3-4short.Secondantenna(Figure1):lengthOAxbody,pedunclemuchlongerthanflagellum,articlesfourandfiveequallylong,sparselysetulate,otherarticleswithfewsetae,lengthratioofarticles1:3.3:3.1;flagellumshort,eightarticulate,moderatelysetose, lacking calceoli.Upperlip:asymmetrical,offset to the right, ovate, apically piliose.Lowerlip(Figure2):bilobed,theinnerlobesbroad,weak,extendingtoMO.7oftheouterlobes;outerlobeswithstrongdenticulatedistalsetae,medialanddistomedialpilia.Left mandible(Figure2):palpthreearticulate, ratio of articles 1:3.5:3,thefirst articleshortandnaked,thesecondlinear,longerthanarticleonewithfewmedialandnolateralsetae; article threesublinear, lacking AorB setae,withle,3D,4Esetae; incisorbearingfive teeth, laciniamobilisfour, accessory setalrowofeightrakersandfourinterrakers;molarwithdistalplumosesetaandperipheralposteriorpubescence.Right mandible(Figure2):palpsimilar, articletwobearingfewsetae, article threewithle,3D, 4Esetae,mandiblewithfiveteeth,laciniamobilisbifidandstronglydenticulate.Firstmaxilla(Figure2):leftandrightsidesasymmetrical;innerplateovatotriangularbearingeightleftandsevenrightplumosedistomedialandapical setae coveredinshortsetules(pubescence);outerplatebearingninedenticulateterminalrobustsetaeonbothsides, faciallysetulate(pubescent); leftpalp,second articlewithasubapicalrowofeightslendersetaeandsix apicalslendertostrongnakedsetae;rightpalparticletwowithasubapicalrowofsevennakedandonedistallyplumosesetae,twomediodistalnakedsetaeandthreebroadtoothspines fused totheapex.Second maxilla(Figure2):apicolateralmarginofbothplatessetulate(pubescent),terminatinginlongnaked,curvedsetae in apicalandsubapical rows;medialsetaeofinnerplatenotplumosealthoughsometerminallyrastellate.Maxilliped(Figure2):pedunclebearingfew setae;43innerplatesubrectangular,faciallyanddistolaterallysetulate(pubescent); theouterplatebearingamedialsubmarginalrowoffourteennakedtoothsetaecontinuouswithamedialsubapicalrowof four tooth setae, all increasing inlengthdistallyformingasubmedialpallisaderowof teeth,distomedialto apicofacialpairedrowsofnakedsetae,anapicolateral to apicalrowoffour longplumosesetae, apicofaciallyandapicolaterallypubescent;theinnerplatewithamedio-to apicofacialrowofelevenplumosesetae,sevenapicolateralplumosesetaeandthreesubapicalstrongnakedtoothspines;medialmarginstraight,naked,theapicomedialcornersubquadrate;palparticlethreewithamedialto distolateralrowof long setae,andarowoflongsetae basal tothedactyl,theapexmarginallysetulatewithagroupofslendersetae facialatthehingeof the dactyl, thedactylitselfbearingthreeaccessoryposteriorsetulesandtwosetulesbasaltothenail.First gnathopod(Figure1):small;coxalplatesubrectangular,apicallyroundedwithanapicomarginalrowofeightlong,slendersetaeandfiveanteroventralshortslendersetae;merusposteriorlybulbousandsetatewitha distalrowof long,strongsetae;carpussubtriangular,shortaboutO.5xpropodus,notlobate,bearingpost-transverserowsofstrongrastellateandafewelongatesimpleslendersetae;propodustrapezoidal,apicallyexpanded,longerthanwidewithfewanterior,posteriorandfacial setal rows,sevenclusters ofelongatefacialsetaeatthedactylbase;palmarcornersubquadrate,thepalmshort,marginallyfinelydenticulate,stronglynotched,withasubpalmarrowofsevenstrongsetaebetweenthecornerandnotch,thepalmarangletransverseto slightly oblique;thedactyl short,withthreemedialsetaeandalongslendersetabasaltothenail,reachingalmosttothepalmarcorner.Second gnathopod(Figure1):muchlargerthenthefirst;coxalplatesubrectangular,broadlyroundedapicallywithfourshortanteroventralandsevenlongerapical setae;meruspostdistallyextended,subquadrate;carpussubtriangular,moderatelylobate,bearingtransverseposteriorrowsoflongsetae;propodusmuchenlarged,three times the firstgnathopod,ovate,longerthanwide1.5xwithseventransversedorsal(anterior)rowsandsixventral(posterior)rowsof setae;palmstronglyoblique,roundedwithouta clearlydefinedpalmarcorner,thepalmdelineatedbyamarginalrowofrobusttriggersetaeandlongslendersimplesetae; the dactylshortof thepalmarcornerbearingarowof smallhookedsetaesubmarginaltotheproximaledge,asmallrecumbentinnertoothspineandsingle setabasalto the nail.Pereopods(Figures1,3):pereopodsthreeandfourequalin length,longerthanthegnathopods;coxathreesubrectangular,apicallyrounded,broaderthanlong,withonly a

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44J.H.Bradbury,S. EberhardFemale'b'RMXlpalpLMP inner plateLLLMP outer plateLMDFigure2Nurina poulteriholotype, male'a':mouthparts(all illustrations exceptwhereindicated);allotype, female'b':apexofright first maxilla palp.

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AnewstygobiontamphipodRP6Figure3Nllrilla pOlllteriholotype,male'a';pereopods4-7.45

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46fewmarginalsetaeventrally;coxafourovatorectangular,moderatelyexcavate posteriorly,withsmallmarginalventral setae; coxae fiveandsix bilobed; coxa fivewitha singleslendersetaventralontheanteriorlobeandsmallventralandpostventral setules; coxa sixwithtwoverysmallposteriorsetules; coxasevenlackingananteriorlobe,bearingonesmall posterior setule.Pereopodsthreeandfoursecondarticlebearinglong, straight, distallycurvedposteriorsetae, articles threeandfourwithfewshorttomediumlength setae, articles fiveandsixwithmixedslenderandrobustsetae.Pereopodsfivetoseven;basismoderatelyexpanded,withsmallposteroventrallobes,shorttomediumlengthanteriorrobustsetaeandshort,weakposteriorsetae;merustopropoduswellarmedwithlongrobustandslendersetae,extremelylongposteriorlyonthecarpusof each, dactylswithoutaccessory setae exceptthenormalsingleposteriorandouterpenicillate setules.Gills(Figure5):coxaetwoto sixbearingflaskshapedgills,decreasingin size posteriorly,althoughgill sixnotsignificantlysmallerthangill five.Pleopods(Figure4):peduncleseachbearingtworetinaculaeandtwoaccessory retinaculae distomedially,andfewshortsetae,someplumose; ramisubequalinlength, basal articles eachwithseveral setae,themedialsetaeofmedialramidiamondheaded,all rami of fourteen articles, except themedialthirdbeing of twelve articles.Epimera(Figure 4):epimeraonewithoneanteriorandonemidsubmarginalrobustseta,thepostventralcorneracuminatebutnotspinous,theposteriormarginslightly convex, almost straight,withsix small setules;epimerontwowithtwoanteroventralsubmarginalrobustsetae,thepostventralcorneracuminate,notspinous, theposteriormarginslightlysinuouswithfivesmallsetae;epimeronthreewiththreeanteroventralfacialrobustsetae,thepostventralcorneracuminatebutnotspinous,theposteriormarginslightlysinuouswithsix small setae.Pleon(Figure4):pleonitesoneto threeandurosomiteonebearingfewweakdorsalanddorsolateralsetae; urosomitetwowitha single postlateralrobustseta,urosomitethreenaked.Uropods(Figure 4).Firsturopod:longest;pedunclelength 1.3xthelengthof theinnerramus,bearingarobustseta basofacially, a dorsolateralrowof threerobustsetaeandtwoapicodorsalrobustsetae,andadorsomedialrowoftworobust setaeandone apicomedialrobustseta;ramisubequalinlength,theinnerramusbeingslightly longer, theouterramusbearingtwolateralandtwomedialrobustsetae, theinnerramuswithonelateralandthreemedialrobust setae,andeachwithfive apicalrobustsetae.Seconduropod:smallerthanthe first, 0.6x the length; thepedunclelengthequaltotheinnerramus, slightlylongerthantheouter(l.lx),pedunclebearingsingleapicolateralandapicomedialrobustsetae;outerramuswithtwoJ.H.Bradbury,S.Eberharddorsolateralandonedorsomedialrobustsetaeandfive apicalrobustsetae, theinnerramuswithtwodorsolateral,twodorsomedialandfiveapicalrobustsetae.Thirduropod:stronglyextended,length0.8xuropodone;peduncleshort, lessthanO.5xthelengthof theouterramus,withfive apicolateralrobustsetaeandoneapicomedialrobustsetabasal to theinnerramus;innerramussmall, scale like,OAxpedunclelength,bearinga singledistalrobustseta;outerramuselongate,onearticulate, linear,subrectangularwithawidthtolengthratio of 0.2,bearingfive lateralandfivemedialtransverseranksofmixedlongrobustsetaeandverylongslendersimple setae,anapical cluster of sixshortrobustsetaeandtwelve very longslendersimplesetae.Telson(Figure 4):lengthlessthanwidth,shorterthanurosomite three (0.75x), cleft 95%oflength, lobessubtriangular, lateralmarginalmoststraight, medially concave,narrowingdistally to amiddistalpeakbearingthreesmallapicalacuminations,lateralandmedialrobustsetae dorsallyatMO.8,andtwosubapicalrobustsetaemedialto the apex,pairedpenicillate setulessublateralatMO.85anda singlesubapical penicillate setule as well asoneortwomarginalnakedsetae,otherwisewithoutdorsofacial setation.Descriptionofallotype(female'h')Similar to the holotype, except inthefollowing:Body:Length7.5mm.Mandibles:palpsthreearticulate, ratio of articlelengthsR 20:54:45, L 20:58:45, setae of article threeofbothle,20,4E.Maxillae:innerplate of first maxillabearingL 8,R8plumosemedialandapicomedialsetae;palpsasymmetric, leftpalpsecondarticleterminatinginlongstrongsetae, similar totheholotype,therightpalpterminatinginstrongsetaeandbroadfusedtoothspines, differing from theholotypeinnumberof denticulations (Figure2).Firstgnathopod(Figure5):firstgnathopodsmall,smallerthangnathopodtwo, similar to themaleholotypeexceptthatthepalmlacks a notch.Secondgnathopod(Figure 5):muchlargerthangnathopodone;propoduslarge, ovatorectangular;palmwithouta clearlydefinedcorner,indicatedbytheextentofrobusttriggerbearingsetae; dactyl slightlyshorterthanthepalm,bearingtwofacial setules a smallrecumbentinnertoothspineatthebaseof thenailandarowofsubmarginalhookedsetae; coxae (Figure 5)twotofive each bearing, inadditionto a flaskshapedgill,narrow,moderatelysetose oostegite, theanteriorlobe of coxa sixextendedventrallyintoanelongatecurvedplate.Uropods. First uropod:pedunclebearingarobustventrofacial seta, adorsolateralrowof threerobustsetaeandtwoapicolateral setae,andamedialrowoftwodorsolateralrobustsetaeandoneapicomedialrobustseta;outerramusbearingtwodorsolateral,twodorsomedialandfive apicalrobustsetae;innerramusonedorsolateral,

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AnewstygobiontamphipodnUropod21Uropod 347Figure 4NlirinapOlilteriholotype,male'a'abdomen,thirdpleopod,uropods1-3,telson.

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48 }.H. Bradbury, S. Eberhardg gRC?,,\Figure 5Nurilla poulteriallotype, female 'b':gnathopods1-2, coxae3-7indicatingcoxal gillsandoostegites.

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Anewstygobiontamphipodtwodorsomedialandfive apicalrobustsetaeThirdlIropod:verysimilartothemaleholotype;innerramusbearingasecondsmallapicalseta;outerramusofonearticle,bearingfivetranslateralclustersofrobustandslendersetaebothlaterallyandmedially,andsixrobustandsix verylongslenderapicalsetae.Descriptionofmale8.9mmSimilar totheholotype,exceptin the following:First antenna:primaryflagellumoftwentyfourarticles (apex lost),thefirst elongate,2xarticle two,theaccessoryflagellumof four articles,extendingtoMO.7of article four oftheprimaryflagellum.FirstgnatllOpod:withadeeppalmarnotch.SecondgnatllOpod:verymuchlargerthanthe first,propodusenlarged3.5xthefirst.Uropods. FirstlIropod:pedunclewithfourdorsolateral,twoapicolateral,twodorsomedialandoneapicomedialrobustsetae;innerramusbearingonedorsolateral,threedorsomedialandfiveapicalrobustsetae;outerramusbearingtwodorsolateral,threedorsomedial,andfiveapicalrobustsetae.Seconduropod:pedunclebearingonlya singleapicolateralrobustseta;innerramuswiththreedorsolateral,twodorsomedialandfiveapicalrobustsetae;outerramuswithonedorsolateral,threedorsomedialandfiveapicalrobustsetae.Thirduropod:pedunclebearingsmallbasalandlateral facial setae,twoapicolateralandtwoapicomedialrobustsetae;innerramussmall, scale like,bearingtwoapicalrobustsetae;outerramusonearticulate,withsixtransversemedialandlateralclustersofrobustandverylongslendersetae,theapexwithfiverobustandtwelveverylongslendersetae.Telson:therightlobebearinganadditional,fifth,lateralrobustseta,theleft lobewithoutthisaddition.DistributionNurinaCaveN46andcaveN1327, Roe PlainsWesternAustralia.EtymologyNamedforMrNormPoulterwhowasinvolvedinthecollection ofspecimensfrombothNurinaCaveandcaveN1327,andwithoutwhoseparticipationthisnewspecieswouldnothavebeendescribed.DiscussionThreecavesareknownontheRoePlains,althoughonlytwoof these -NurinaCave(N46)andcaveN1327 intersect the regional water-table.NurinaCaveis locatedapproximately14kmsouthoftheHamptonScarp,olderodedsea-cliffsmarkingthenorthernextentoftheRoe Plains,andapproximately30kmnorthof thepresentcoastline.Theelevationoftheentranceis24.8 m+/ -1.5m49abovemeansea-level(WiglevandHill, 1967).Severalwaterqualitvmeasurementshavebeenmadeinthecave:thesalinityandchemicalcompositionof thewaterisessentiallythesameasseawater,exceptthatit isenrichedwithcalcium (GilliesonandSpate, 1992; Jamesetal.,1991; Lowry, 1970).Entranceto the cave is viaopenverticalpassages.N. pOlllteriisabundantinthepoolimmediatelybelowtheentranceand,althoughpresentelsewherein the extensive cavesystem,is far lessabundant(Eberhard, 1999).CaveN1327 liesapproximately6kmnorth-westofNurinaCave.Groundwaterpoolsarerelativelyshallowlessthan2m -includingsomewitha siltysubstrate.Thephysicochemistryofthewaterisunknown.Theentranceto thiscaveISquiterestrictedandthepotentialforexternalfoodsupplythusreduced.In thiscaveN.pOlllteri(aswellasotheraquaticinvertebrates)iscloselyassociatedwithintrusivetreeroots(malleeEucalyptusspp.)whichpenetrateto adepthofapproximately25 mtoreachthewater-table(Eberhard,1999).Theserootsappearcropped,similartorootmatsatYanchepCaves,WesternAustraliawhichareheavilygrazedbyadiversecommunityofaquaticinvertebratesOasinskaetaI.,1996).TheNullarborregionwasinundatedbytheseafollowingsubsidenceduringtheearlyCretaceous,thefirstlimestonesformingabout45MY AintheMiddleEocene(Lowry,1970),withatleasttwoperiodsofrecessionduringtheOligoceneandEarlyMiocene,followedbyupliftduringtheMiddleMioceneabout15MYA(LowryandJennings,1974).Smcethattime,theNullarborPlainhasnotbeensubject tomarinetransgressionuntiltheLatePliocene-EarlyPlei"tocenewhensea-levelreachedabout30 m dboveitspresentlevelThistransgressionerodedthe RoePlains,andtheHamptonRangescarpto till'northIStheoldseacliffofLatePlioceneage.ThehistoryofmarinetransgressionsandrecessIOnssuggeststhatNurina pOlllteriis aspeciesderivedfromthestrandingofamarineprogenitorfollowingoneoftheseepisodes.OtherelementsoftheNullarborcavefauna,however,suggesta relictterrestrial/freshwateroriginpostdatingtheLatePlioceneearlyPleistoceneemergenceoftheRoePlainseitherbyundergrounddispersalfromtheplateauorbyvicariantextinctionofsurfacedwellingancestors(Gray,1973 a, b).Nevertheless,NurinabearsmanysimilaritiestomarineMelitaandisconsideredto be ofmarineratherthanfreshwaterorigin.Similarmarine-derivedtaxahavebeendescribedfromNorthWestCape,WesternAustraliaandtheFlindersRanges,SouthAustralia(HumphreysandAdams,1991;Knott,1993;BarnardandWilliams, 1995;BradburyandWilliams,1997a, b).

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50ACKNOWLEDGEMENTSThe authors wish tothankProfessor Bill Williams for helpfulcommentsuponthe manuscript,andAndySpateforhiscontributiontoourunderstandingofthegeomorphic history of the Nullarbor Plain.REFERENCESBarnard,J.L.andBarnard,CM.(1983).FreshwaterAmphipodaoftheWorld.1.EvolutionaryPatterns.II.Handbook and Bibliography.HayfieldAssociates,MountVernon, Virginia. Pp. 1-830. Barnard, J.L.andWilliams, W.D. (1995).ThetaxonomyofAmphipoda(Crustacea)fromAustralianfreshwaters.Part2.RecordsoftheAustralian Museum47(2):161-20l.Bousfield,E.L.(1973).Shallow water gammarideanAmphipodaofNewEngland.Cornell University Press, Ithaca,NewYork. Pp. 1-312. Bradbury, J.H. (1999).ThesystematicsanddistributionofAustralianfreshwateramphipods:a review.Pp533-540.InSchram,F.R.andJ.CarelvonVaupelKline, (eds).CrustaceansandtheBiodiversity Crisis. Proceedingsofthe Fourth International CrustaceanCongress,Amsterdam,TheNetherlands,July20-24,1998.Brill, Leiden. Bradbury, J.H.andWilliams, W.D. (1996).FreshwateramphipodsfromBarrow Island,WesternAustralia.RecordsoftheAustralian Museum48:33-74 Bradbury, J.H.andWilliams, W.D. (1997a).Amphipod(Crustacea)diversityinundergroundwatersofAustralia:anAladdin'sCave.MemoirsoftheMuseum ofVictoria56(2): 513-519.Bradbury,J.H.andWilliams,W.D.(1997b).TheamphipodstygofaunaofAustralia:descriptionofnewtaxa (Melitidae,Neoniphargidae,Paramelitidae),andasynopsisofknownspecies.RecordsoftheAustralian Museum49:249-34l. Eberhard,S.(1999).ThebiologicalimportanceofcavesN46,N327andN1327ontheNul/arborPlain.UnpublishedreporttotheSpeleologicalResearchGroup.ofWestern Australia,andDepartmentofConservationandLandManagement(Southeast Region). Gillieson, D.andSpate, A (1992).TheNul/arborkarst.In: Gilleson D., (ed.). Geology, climate,hydrologyandkarstformation:fieldsymposiuminAustralia,guidebook.SpecialPublicationNo.4:65-100.DepartmentofGeographyandOceanography,UniversityCollege,AustralianDefenceForceAcademy,Canberra.---------J.H.Bradbury,S.EberhardGray,M.R. (1973a).CavernicolousspidersfromtheNullarborPlainandsouth-westAustralia.JournaloftheAustralianEntomologicalSociety12: 207-22l.Gray,M.R. (1973b).SurveyofthespiderfaunaofAustraliancaves.Helictite11(3): 47-75.Humphreys,W.F.andAdams,M. (1991).Thesubterraneanaquatic fauna of theNorthWestCapepeninsula,Western Australia.RecordsoftheWestern Australian Museum15: 383-411.James,J.M.,Pilkington,G., Rogers,P.andSpate,A. (1991).TheNullarborcarbonateaquifer, Australia:theimpactofmanandsuggestionsforfuturemanagement.ProceedingsoftheInternationalConferenceonEnvrionmentalChangesinKarstAreas.I.G.U.-I.G.S.,Italy,15-27September,1991:QuadernidelDipartimentodiGeografian.13,1991-UniversitydiPadova:205-214Jasinska, E.J., Knott,B.andMcComb,AJ.(1996). Rootmatsingroundwater: a fauna-rich habitat.JournaloftheNorth AmericanBenthologicalSociety15 (4):508519.Karaman,G.5. (1969). XXII BeitragzurKenntnisderAmphipoden.ObereinigeFormendesGenusSarathrogammarus(Gammaridae)ausAfghanistan.Acta MuseiMacedoniciscientiarum NaturaliumSkopje 11(11): 195-208.Knott,B.(1983).AmphipodsfromNurinaCaveNullaborPlain.Australian Speleological Federation Newsletter101: 3-4.Knott,B.(1985).Australianaquaticcavernicolousamphipods.Paper presentedtothe 15th biennialconferenceAustralianSpeleologicalFederation,Hobart.pp.1-1l.Knott,B.(1993). StygofaunaofCapeRangepeninsula,WesternAustralia:Tethyanrelicts.RecordsoftheWesternAustralian Museum,SupplementNo.45:109127. Lowry,D.C(1970). GeologyoftheWesternAustralianpartoftheEucla Basin.WesternAustraliaGeologzcalSurvey Bulletin122:201pp. Lowry,D.CandJennings, J.N. (1974).TheNullarborkarst, Australia.Zeitschrift fiirGeomorphologie18(1):36-8l.Richards,A.M.(1971).AnecologicalstudyofthecavernicolousfaunaoftheNullarborPlainSouthernAustralia.JournalofZoology,London164: 1-60. Wigley, T.M.L.andHill,AL.(1967). ElevationsintheMaduraarea,WesternAustralia.Helictite,October1967:IQ-B.Manuscriptreceived12May1999;accepted5October1999.