Revised distribution and habitat associations for the protected slug Geomalacus maculosus (Gastropoda, Arionidae) in Ireland

2013·1.9 MB·English

by  Donnell, Rory Mc

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Revised distribution and habitat associations
for the protected slug Geomalacus maculosus
(Gastropoda, Arionidae) in Ireland
Rory Mc Donnell1,2, Kim O’Meara1, Brian Nelson3, Ferdia Marnell3 & Michael Gormally1
1AppliedEcologyUnit,CentreforEnvironmentalScience,SchoolofNaturalSciences,NationalUniversityofIreland,Galway,Ireland
2Currentaddressofcorrespondingauthor:DepartmentofEntomology,UniversityofCalifornia,Riverside,CA92521-001,U.S.A.;[email protected]
3NationalParks&WildlifeService,DepartmentofArts,Heritage&theGaeltacht,7ElyPlace,Dublin,Ireland.
Introduction
ThearionidslugGeomalacusmaculosusisrestrictedglobally 33
toIrelandandnorthernIberiaandthespeciesisprotected TheKerryslug,Geomalacusmaculosuswasfirstdiscoveredin
underbothEuropeanandIrishlegislation.SurveysinCos Co.Kerry,Irelandin1842anddescribedasanewspeciesin
Cork,KerryandGalwayinIrelandduring2009and2010 1843(Allman,1843).Today,itsglobaldistributionisnorth-
recordedthespeciesfromatotalof43hectads(10kmgrid ernIberiaandIreland(Platts&Speight,1988;Kerney,1999)
squares)andfromarangeofhabitatsincludingdeciduous anditisprotectedunderAppendixIIoftheBernConven-
forest,blanketbogandheath.WealsofoundG.maculosusin tionandinAnnexIIandAnnexIV(a)oftheEUHabitatsDi-
coniferplantationsandclearfellsitesinsevenhectadsinCos rective92/43/EC.UnderIrishlegislation,theslughasfurther
Cork,KerryandGalway,andonwetgrasslandinCo.Kerry. protectionundertheWildlifeAct1976underStatutoryIn-
Thespeciesrequirementfornearbystandingorflowing strumentNo.112of1990andsevenSpecialAreasofConser-
waterwasnotsupportedbyoursamplingaswecollectedit vation(SACs)havebeendesignatedforitsconservation
fromareaswheretherewerenoobviouswaterbodies. (NPWS,2010).
Nevertheless,theabovedatacomprisearangeof4300km2in Historically,withinIrelandG.maculosushasbeenconsid-
thethreecountiesandincludethreehectads(V55,V64and eredtoberestrictedtotheDevonianOldRedSandstone
V72)wherethelastrecordsarepre-1970.Inaddition,G.mac- strataofWestCorkandKerrywhereitoccursinthreegen-
ulosuswasfoundinsixhectads(Q91,V48,V82,V93,V94 eralhabitattypes.Thesearedeciduouswoodland(usually
andV97)wheretherearenopreviousrecordsofthespecies. Quercusdominated);blanketbogorunimprovedolig-
otrophicopenmoor;andlakeshores(Platts&Speight,1988;
Keywords:Gastropoda,Arionidae,Geomalacus,Kerryslug,ecology, NPWS,2010).Withinthesehabitats,thespeciestendsonly
distribution,Ireland. tobepresentifthereisoutcroppingofDevonianOldRed
Sandstone,humidconditionsandlichen,liverwortand/or
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mossesinwhichthespeciessheltersandfeeds(Platts& sitecontainedbackgroundinformationontheecologyofG.
Speight,1988).However,G.maculosushasalsorecentlybeen maculosus,diagnosticinformationonhowtocorrectlyiden-
collectedonbothgraniteoutcropsonblanketbogandfrom tifythespecies,informationonitsdistributionandhowto
aconiferplantationinLettercraffroe,Co.Galway(Kearney, contacttheprojectteam.Anecologicalinformationleafleton
2010).ThroughoutitsIrishrange,specimensthatoccurin G.maculosuswasalsodistributedtorelevantstakeholders
woodlandstendtobebrownwithyellowspotswhereasin (includingNationalParksandWildlifeServiceRangersin
moreopensituationsspecimenstendtobegrey/blackwith CosCorkandKerry;KillarneyNationalParkEducation
whitespots(Fig.1)(Platts&Speight,1988;Taylor,1906). Centre,Co.KerryandIrishmalacologists)andwasmade
SinceitsdiscoveryinIreland,G.maculosushasbeen availablefordownloadfromtheprojectwebsiteandalsothe
recordedfrom52hectads(10kmgridsquares–seeFig.2) websiteoftheConchologicalSocietyofGreatBritainand
butinsevenofthese,thespecieshasnotbeencollectedsince Ireland.Finally,popularpressarticleswerepublishedinna-
1970.Thisprovidedtheincentiveforthecurrentstudy tionalandlocalnewspaperswhichadvertisedandprovided
whereall52hectadswereresurveyed.Inaddition,apparent informationonthesurvey.
gaps(e.g.hectadsV97,V94,V93andV82)andeasternlimits Membersofthepublicsubmittingrecordswererequired
(e.g.hectadsW37,W36andW35)oftherangeofthespecies toincludeaphotographofthespecimenasthisenabledthe
werealsosearched.Finally,wesurveyedtheareain projectteamtoconfirmtheidentificationofthespecies.In
Oughterard,Co.Galwaywheretheslugwasrecentlyfound addition,iftherecordwasfromahectadwherethespecies
(Kearney,2010)inanattempttodeterminetheextentofits hadnotbeenpreviouslycollected,wevisitedthenewlocal-
occurrencethere. ityinanattempttoconfirmitspresence.SupplementaryIn-
formation1showsamapofnumberedIrishhectads.
Materials and methods Presenceandabsencedatelocalitydatageneratedduring
34 oursurveysarepresentedinSupplementaryInformation2
DiurnalactivityisrelativelycommonforG.maculosusdur- andSupplementaryInformation3.
ingwetweather(Platts&Speight,1988;Taylor,1906)andas
aresulthandsearchingwascarriedoutduringsuchcondi- Results and discussion
tionstomaximizethelikelihoodoffindingspecimens.At
eachsite,outcropsortreetrunkswerescannedorsearched Duringthesurvey,G.maculosuswasrecordedfromatotalof
forapproximately45minutes.Searchingforthespeciesin 43hectadsinIrelandandfromarangeofhabitatsincluding
woodlandsinvolvedcheckingunder‘carpets’ofepiphytic deciduousforest,blanketbogandheath(Fig.2).Specimens
bryophytesandlichensgrowingontreetrunkswhileon werealsoobservedinhabitatspreviouslyconsideredun-
blanketbogsandheaths,specimenswereoftenfoundby suitableforthespeciesincludingcommercialconiferplanta-
searchingbetweenthevegetationandthebaseofsandstone tions,clearfellsitesandwetgrassland(Supplementary
outcrops.Insomeinstances,recordswerealsogenerated Information2).Thesedatacomprisearangeof4300km2and
duringseparatepopulationdynamicsinvestigationsfrom includethreehectads(V55,V64andV72)wherethelast
trapsspecificallydesignedtocollectG.maculosus(McDon- recordsarepre-1970andsixhectadswheretherearenopre-
nell&Gormally,2011a,2011b;O’Meara,2011).Assoonasa viousrecordsofthespecies(Fig.2).Thesenewhectadsin-
specimenwaslocatedinahectad,itspresencetherewas cludereportedgapsintherange(V82,V93,V94andV97)
confirmedandthesquarewasnotrevisited.Ifthespecies highlightedintherecentKerrySlugThreatResponsePlan
wasnotfound,thenaminimumoftwositeswerechecked (NPWS,2010)andhectadV48.
foreachhectad. OfparticularinterestaretherecordsofG.maculosusin
Publicparticipationinthesurveywasencouragedbyes- hectadsM03(Co.Galway)andQ91(Co.Kerry)wherethe
tablishingaprojectwebsite(www.kerryslug.com).Theweb- specieswascollectedincommercialconiferplantations(pri-
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wehavealsocollectedthespeciesfromthetrunksof
conifersinaquantitativestudyatGlanteenassigForest(hec-
tadQ51)inCo.Kerry(Barrett,2011)andfromconiferplan-
tationsinhectadsV46,V47,V69,V77andV94.Wetherefore
concludethatconiferplantationsareasuitablehabitatfor
thespeciesinIreland.
WhyG.maculosusisrestrictedtothesouthwest(Cos
CorkandKerry)andwest(Co.Galway)ofIrelandisanim-
portantquestiontoaddressintermsoftheconservationof
thespecies.AccordingtoRodriquezetal.(1993)thespecies
hasapreferencethroughoutitsIrishandIberianrangefor
anAtlanticclimatewheremeanannualrainfallisabove
1000mmandmeanannualtemperatureliesbetween8°C
and12°C.TheentireIrishwestcoastfallsintothismeteoro-
logicalcategory(www.meteireann.ie)whichhelpsexplain
itspresenceinCosCork,KerryandGalwaybutitdoesnot
accountforitsabsenceinotherareasofthewestwheresuit-
Fig.1.Woodland(le4)andopen(right)formsofGeomalacusmaculosus. ablegeology,climateandhabitatsexist.Thiswouldsuggest
thatsomeotherfactorsareinvolvedindeterminingtheIrish
distributionofG.maculosus.Onepossibilitythatneedstobe
marilycomprisedofPiceasitchensisandPinuscontorta).The consideredisthatthespeciesnativerangeinIrelandisthe
specieswasfirstreportedinM03byKearney(2010)andwe southwestandthatitwasinadvertentlyintroducedtoCo. 35
recordeditconsistentlythereonconifersandongraniteout- Galway(e.g.duringforestryoperations)buttotestthis
cropsonblanketbogfromJanuary2010toFebruary2011. hypothesisdetailedinformationregardingitsrangein
UntiltherecentdiscoveryofthespeciesinCo.Galway, Connemaraandageneticcomparisonofpopulationsfrom
G.maculosuswasthoughttobefoundinIrelandsolelyin bothareaswouldbenecessary.
areaswheretheunderlyinggeologywassandstone.Itspres- Duringsurveys,juvenileslugswereregularlyencoun-
enceongranite,therefore,raisesquestionsaboutitsre- teredduringthedayforagingonthenorthsideoftrunks,
portedhabitatandgeologicalspecificityinIreland.Tohelp butonoutcropsonblanketbogsandheaths,adultswere
addressthisissueitisusefultoexaminethegeologicalasso- moreregularlyobservedandjuvenileswereseldomencoun-
ciationsofthespeciesinnorthwestIberiawhereG.maculo- tered.Platts&Speight(1988)statedthatG.maculosusis
sushasbeenrecordedongranites,slates,quartzite,schists, rarelyobservedmorethanafewmetresfromstandingor
gneissandserpentine(Castillejoetal.,1994)soitspresence flowingwaterbutthismicrohabitatassociationwasnotsup-
ongraniteinCo.Galwaythenmaybeconsideredrelatively portedbyoursamplingaswecollectedthespeciesfrom
unsurprising.Nevertheless,thisassociationhasobviousim- areaswheretherewerenoobviouswaterbodies,particularly
plicationsforfuturenationalsurveysandtheconservation inwoodlands.Occasionally,wefoundthewoodlandform
ofthespeciesinIreland. (brownandyellow)inmoreopensituations(e.g.blanket
ThepresenceofG.maculosusinhectadQ91isalsoofnote bog)andtheopenform(blackandwhite)inwoodedareas.
asthisareawasoutsideofthepreviouslyknownrangeof Arangeofsitesinotherhectadswerealsovisitedduring
thespeciesinCo.Kerry.Interestingly,thisrecordisalso wet,overcastconditionsbutnospecimensofG.maculosus
fromaconiferplantationsimilartothehabitatwhereG. werelocated(SupplementaryInformation3).Theseinclude
maculosuswasfoundinCo.Galway(Kearney,2010).Infact, hectadsW35,W36andW37whichareadjacenttothecur-
R. Mc Donnell et al.–GeomalacusmaculosusinIreland
B77-2012-29:Basteria-2010 14/09/2013 12:48 Page 36
pronouncementregardingthecurrentconservationstatusof
thespecies.However,itisimportanttobearinmindthat
thereweresuitablegeologyandhabitatswithinthesehec-
tadsandconsequently,theyshouldbeapriorityforfuture
surveyefforts.Also,giventhatthespeciescansurvivein
commercialconiferplantations,wealsosuggestthatfuture
nationalsurveysforG.maculosustargetthishabitatthrough-
outthecountry.
Acknowledgements
ThisresearchwasfundedbytheNationalParks&Wildlife
Service,DepartmentofArts,Heritage&theGaeltacht.We
aregratefultoEstherAsprey,MartinCawley,SaraCurtis,
ClareHeardman,RoryHodd,GeraldineHolyoak,Helen
Riney,EugeneRoss,JennySeawright,ThomasSheehan,Car-
olineSullivanandDavidTulopforsubmissionofrecords.
ThanksalsotoPaulWhelan(biology.ie)forhostingthe
KerrySlugwebsiteandtoDavidBourke,ConnorDolan,
ClareHeardman,PaddyGraham,SarahO’Loughlin-Irwin,
MichaelSullivan,DeclanO’DonnellandJohnHynesforas-
36 sistancewithfieldwork.WearegratefultoDavidBourke
andBrendanCanningforassistancewithproducingthedis-
tributionmapandtoIngaReichforuseofphotographs.
References
Fig.2.DistributionmapofGeomalacusmaculosusinIreland.Solid Allman,G.J.,1843.Onanewgenusofterrestrialgastropod.–
circlesrepresenthistoricalrecordsconfirmedduring2009-2011,hollow Athenaeum829:851.
circlesarehistoricalrecordsunconfirmedduring2009-2011,solid Barrett,D.,2011.Assessmentoftheimpactofconiferforestryonslug
squaresrepresentnewrecordsduring2009-2011andX'sarehectads communitieswithparticularreferencetoGeomalacusmaculosus.–
wherenospecimenswerecollectingduringoursurveys. B.Sc.thesis,NationalUniversityofIreland,Galway,Ireland.
Castillejo,J.,Garrido,C.&Iglesias,J.,1994.TheslugsofthegenusGeo-
malacusAllman,1843,fromtheIberianpeninsula(Gastropoda:Pul-
renteasternrangelimitofthespeciesinIrelandandV36 monata:Arionidae).–Basteria58:15-26.
wherethespecieshasbeenreportedlycollected(Kerney, Kearney,J.,2010.Kerryslug(GeomalacusmaculosusAllman1843)
1999)buthasnotbeenverified(NPWS,2010).While,G.mac- recordedatLettercraffroe,Co.Galway.–IrishNaturalists’Journal
ulosuswasnotfoundinthirteenhectadswherethereare 31:68-69.
previousrecordsfortheslug,itwascollectedinsixnewhec- Kerney,M.P.,1999.AtlasofthelandandfreshwatermolluscsofBritain
tadsduringthissurvey.Withoutfurtherresourceswhich andIreland:1-264.Colchester.
wouldpermitmoreextensivesearchingofthethirteenhec- McDonnell,R.J.&Gormally,M.J.,2011a.Distributionandpopulation
tads,itwould,atthisstage,beunwisetomakeadefinitive dynamicsoftheKerrySlug,Geomalacusmaculosus(Arionidae).Irish
Basteria77(1-3)
B77-2012-29:Basteria-2010 14/09/2013 12:48 Page 37
WildlifeManuals,No.54.NationalParksandWildlifeService,De- Galway,Ireland.
partmentofArts,HeritageandtheGaeltacht,Dublin,Ireland:1-93. Platts,E.A.&Speight,M.C.D.,1988.Thetaxonomyanddistributionof
Dublin. theKerryslug,GeomalacusmaculosusAllman,1843(Mollusca:Ari-
McDonnell,R.J.&Gormally,M.J.,2011b.Identificationofalivetrap- onidae)withadiscussionofitsstatusasathreatenedspecies.–
pingmethodfortheprotectedEuropeanslug,Geomalacusmaculosus IrishNaturalists’Journal22:417-30.
Allman1843(Arionidae).–JournalofConchology40:483-485. Rodriguez,T.,Ondina,P.,Outeiro,A.&Castillejo,J.,1993.Slugsof
NPWS,2010.ThreatResponsePlan-KerrySlugGeomalacusmaculosus. Portugal.III:RevisionofthegenusGeomalacusAllman,1843(Gas-
1-59,Dublin. tropoda:Pulmonata:Arionidae).–TheVeliger36:145-159.
O’Meara,K.,2011.LaboratoryandfieldinvestigationoftheKerrySlug Taylor,J.W.,1906.MonographoftheLandandFreshwaterMolluscaof
(Geomalacusmaculosus)–B.Sc.thesis,NationalUniversityofIreland, theBritishIsles2:1-410.Leeds.
37
R. Mc Donnell et al.–GeomalacusmaculosusinIreland
B77-2012-29:Basteria-2010 14/09/2013 12:48 Page 38