Bhutanese snails, the smallest one: Truncatellina bhutanensis spec. nov. (Gastropoda, Pulmonata, Vertiginidae)

2013·1.1 MB·English

by  Gittenberger, Edmund

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Bhutanese snails, the smallest one: Truncatellina bhutanensis
spec. nov. (Gastropoda, Pulmonata, Vertiginidae)
Edmund Gittenberger
NaturalisBiodiversityCenter,P.O.Box9517,NL2300RALeiden,TheNetherlands;[email protected][correspondingauthor]
Pema Leda
NationalBiodiversityCentre,Serbithang,Bhutan
SherubSherub
UgyenWangchuckInstituteforConservationandEnvironment,Bumthang,Bhutan
country(Nordsieck,1974).Dataonlocalmolluscanfaunas 29
Truncatellinabhutanensisspec.nov.isdescribedfromwestern haveneverbeenpublished.Withthisarticleaseriesofpa-
Bhutan,whereitwasfoundtobecommonincalcareous persisstarted,aimingateventuallyageneraloverviewof
areasataltitudesbetween2100and2650m. theBhutanesemolluscanfauna.Thevarioustaxawillbe
dealtwithinapragmatic,notataxonomicallydetermined
Keywords:Gastropoda,Pulmonata,Orthurethra,Vertiginidae, sequence.TworecentlypublishedarticlesonTruncatellina,
taxonomy,Bhutan. viz.Hausdorf&Wronski(2011)andPokryszkoetal.(2009),
providedaneasybaseforthepresentpaper.
Introduction Material and methods
Hardlyanythingisknownaboutthemolluscanfaunaof Sincethereisnocollectionanywherewithmollusksfrom
Bhutan.NearlyallallegedlyBhutaneserecordsofmolluscs Bhutan,allthestudymaterialshouldbecollectedfirst.Col-
thatcouldbefoundturnedouttobeincorrectbymodern lectingwasstartedinamodestwayin2012andcontinued
standards.ThisisbecausethefrontiersbetweenBhutanand fortendaysin2013.Inthisinitialphaseprioritywasgiven
neighbouringcountrieshavenotalwaysbeenstableinthe toareaswithcalcareoussoilsorlimestonerocks,sincethere
past.SeverallocalitiesthatarenowsituatedinSikkim, thehighestdiversitywasexpected.Inadditiontocollecting
India,forexample,arereportedfromwesternBhutan,both atsight,bottomsamplesweretakentobesortedoutinthe
inoldcollectionsandintheoldliterature.Infact,asfaras lab.Wedidnottrytostandardizeourmethods.Arepresen-
knownnow,onlyasinglemolluscanspecies,viz.Phaedusa tativevarietyofhabitatsatdifferentaltitudeshasnotyet
(P.)bhutanensis(Clausiliidae),waseverdescribedfromthe beeninvestigated.Asaconsequence,conclusionsabouteco-
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logicalaspectscannotbebasedonourmaterial. 2100malt.;27°20’N 89°34’E;E.Gittenberger&PemaLedaleg.,
Thefollowingabbreviationsareused:H=height;NBCS= 6.iv.2013(NBCS1001/3).
NationalBiodiversityCentre,Serbithang;S=station;W= DistrictParo.—S164:14kmSEofParo,N-sideriver,near
width.Whenthereareover25specimensinasample,these monasteryTachugangLhakhang;2150malt.,amongrocks,nearsmall
arereferredtoas‘many’. rockface;27°20’N 89°30’E;E.Gittenberger&PemaLedaleg.,6.iv.2013
(NBCS1002/many).S167:S-slopeEoflimestonequarryNWofDobji
Systematic part Dzong;2300malt.;27°17’N 89°31’E;E.Gittenberger&PemaLedaleg.,
7.iv.2013(NBCS1003/holotype,1004/6).S168:rockyS-slope9kmSSW
VertiginidaeFitzinger,1833 ofChuzom;2450malt.;27°14’N 89°30’E;E.Gittenberger&PemaLeda
TruncatellininaeSteenberg,1925 leg.,7.iv.2013(NBCS1005/12).S169:rockyS-slope12kmSSWofChu-
zom;2650malt.;27°13’N 89°29’E;E.Gittenberger&PemaLedaleg.,
Theclassificationoftheconchologicallyhomogeneous 7.iv.2013(NBCS1006/many).S170:10kmSWChuzom;2500malt.;
genusTruncatellinaR.T.Lowe,1852,nexttoVertigoO.F. 27°14’N 89°30’E;E.Gittenberger&PemaLedaleg.,7.iv.2013
Müller,1773,inthefamilyVertiginidae,albeitinaseparate (NBCS1007/20).S171:smallgullywithhighrockfaceatN-side;2150m
subfamily,wasatleastpartlybasedonthefactthattheseare alt.; 27°18’N 89°33’E;E.Gittenberger&PemaLedaleg.,7.iv.2013
allminutesnails.Longbeforetheareaofcladisticsstarted, (NBCS1008/15).S178:SofParo(=Rinpung)Dzong,E-sideriver;2250m
Steenberg(1925)publishedhisadmirablydetailedanatomi- alt.;27°25’N 89°25’E; E.Gittenberger&PemaLedaleg.,11.iv.2013
caldescriptionsandillustrationsofthesetaxa,andintro- (NBCS1009/20).S177:8kmSWParonearDzongdrakha;2530malt.;
ducedthesubfamilyTruncatellininaeforthecombined 27°23’N 89°24’E;E.Gittenberger&PemaLedaleg.,11.iv.2013
TruncatellinaandColumellaWesterlund,1878.Thesegenera (NBCS1010/36[noparatypes;seebelow]).
arecharacterizedbyamongothersagenitaltractwithoutan
30 externallyvisibleprostateandagut-furrowcrossingtheal- Description.–Shell(Fig.1)fragile,lightbrown,rather
bumenglandinsteadofrunningparallelwithit,aradula glossy,almostcylindricalwithadomedapicalpart;teleo-
withatricuspidcentralandbicuspidlateralteeth,anda conchwithrelativelycoarsegrowthlines,oneorafewof
mandiblewithmanysmallplatesthatareseparatedbynar- whichmaybethickenedasribletsneartheaperture;with5-
rowridges.Theseandothercharacterstateshavenotyet 5¾convexwhorls,whichareseparatedbyadeeplyincised
beenvaluedinacladisticalanalysis.Inapreliminary,molec- suture;umbilicusverynarrow.Aperturesquarish,some-
ularphylogenyreconstruction,Armbrusteretal.(2005)con- whathigherthanbroad,withanarrowlyreflected,slightly
firmedthecloserelationshipsbetweenTruncatellinaand thickenedaperturallip.Insidetheaperturethereisonlya
Columella,butatthesametimeshowedthatVertigoismuch prominentto,rarely,obsolete,palataldenticle,whichisvisi-
moredistantlyrelated.Itisbeyondthescopeofthisarticle bleinfrontalview,andsometimesaninconspicuouscol-
todiscussthishereinmoredetail. umellardenticle,whichisonlydiscernibleinveryoblique
view.Thepalatalisisthinlycoveredwithmoreorlessangu-
TruncatellinaR.T.Lowe,1852. larmicro-protuberances(Fig.2).Measurements,H1.4-1.85
Typespecies,bymonotypy:T.linearis(R.T.Lowe,1852). mm,W0.75-0.85mm.
Differentiation.–Hausdorf&Wronski(2011)listedall
Truncatellinabhutanensisspec.nov.(Figs1,2) Truncatellinaspecieswithapalatalisthatisvisibleinfrontal
view,asinT.bhutanensis.Thelatterspeciesdiffersfromall
Material(paratypes,unlessstatedotherwise).– DistrictThim- thosespeciesbyacombinationofcharacterstates,viz.its
phu.—S160:cross-roadtoquarrynearBjimina(13kmSWofThim- smallsize,theabsenceofribletsandtheabsenceofapari-
phu);2300malt.;27°24’N 89°34’E;E.Gittenbergeretal.leg.,16.vi.2012 etalis.Truncatellinacallicratis(Scacchi,1833)mayrecallT.
(NBCS1000/many).S166:16kmSSWofThimphu,3kmNofbridge; bhutanensistosomeextent,butnotsimultaneouslyinall
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ingaparietalis;Truncatellinahimalayana(Benson,1863),
whichcomesgeographicallyclose,istoothlessandprovided
withriblets.TruncatellinaasirensisHausdorf,2011,from
SaudiArabia,lookssomewhatsimilarbythelackofriblets,
butisevensmallerthanT.bhutanensisandprovidedwitha
parietalis.ThesamplefromS177isexcludedfromthetype
seriesbecausetheshellsareslightlydifferentbythetotal
lackofapalatalisandashellheightupto1.95mm.
Notes.–TheTruncatellinaspeciesoftheHimalayanarea
arepoorlyknown.Onlyfortheextremelysouthwesternpart
oftheHimalaya,inPakistan,exceptionallygooddataonno
lessthanfourspeciesareavailable(Pokryszkoetal.,2009).
FromBhutanasingleTruncatellinaspeciesisknownnow.At
alllocalities,exceptforS170,itwasfoundtogetherwith
Gastrocoptahuttoniana(Benson,1849),whichhasaslightly
larger,moreelongated,spindle-shapedshellwithseveral
aperturalteeth.TakingintoaccountthattheBhutanmollus-
caninventoryhasstartedjustnow,itwouldnotbesurpris-
ingifadditionaltaxawerediscovered.
Acknowledgements
31
WeareindebtedtoDr.PemaGyamtsho(thentheMinister,
MinistryofAgriculture&Forests),DashoSherubGyaltshen,
Secretary,MinistryofAgricultureandForests,MrNawang
Norbu,Director,UgyenWangchuckInstituteforConserva-
tionandEnvironment,MsDr.TashiYangzomeDorji,Pro-
gramDirector,andMsSangayDema,DeputyChief
BiodiversityCurator,NationalBiodiversityCentre,fortheir
valuableadministrativesupportandadvises.Wemostcor-
diallythankourguideandabledriverLekiDorji,whocon-
tributedalsotothecollecting.
Figs1,2.Truncatellinabhutanensisspec.nov.,holotype(NBCS1003);S- References
slopeEoflimestonequarryNWofDobjiDzong;2300malt.;27°17’N
89°31’E;E.Gittenberger&PemaLedaleg.7.iv.2013.1,shell,H=1.8 Armbruster,G.F.J.,Böhme,M.,Bernhard,D.&Schlegel,M.,2005.The
mm;2,detailofpalataldenticlewithmicro-protuberances. H3/H4histonegeneclusteroflandsnails(Gastropoda:Stylom-
matophora):TS/TVratio,GC3driveandsignalsinstylom-
matophoranphylogeny.–JournalofMolluscanStudies71: 339-348.
characterstates;shellsoftheformerspeciesareusually Hausdorf,B.&Wronski,T.,2011.FirstrecordsofTruncatellinaspecies
larger,especiallybroader,lessfragile,sculpturedwith fromArabia(Gastropoda:Vertiginidae).–JournalofConchology
riblets,andprovidedwiththreeaperturaldenticles,includ- 40:505-508.
E. Gittenberger,P. Leda & S. Sherub–Truncatellinabhutanensisspec.nov.
B76-2013-06:Basteria-2010 14/09/2013 12:46 Page 32
Nordsieck,H.,1974.ZurAnatomieundSystematikderClausilien,XIV. tigininae,Gastrocoptinae,Pupillinae(inpart).–AnnalesZoologici
Phaedusinae,II:Phaedusabhutanensisn.sp.undihreBeziehungen 59:423-458.
zubenachbartenArten.–ArchivfürMolluskenkunde104:41-49. Steenberg,C.M.,1925.Étudessurl’anatomieetlasystématiquedes
Pokryszko,B.M.,Auffenberg,K.,HlaváČ,J.Č.&Naggs,F.,2009.Pupil- maillots(fam.Pupillidaes.lat.).–VidenskabeligeMeddelelserfra
loideaofPakistan(Gastropoda:Pulmonata):Truncatellininae,Ver- DansknaturhistoriskForening80:i-viii,1-211,pls1-34,5pp.
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