Identification and Some Morphological Characters of Clethrionomys rufocanus and Eothenomys regulus from USSR, Northeast China, and Korea in Comparison with C. rufocanus from Finland-香川大学学術情報リポジトリ

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IdentificationandSomeMorphologicalCharactersof

(’/(イ///●/り刷りノ左It、ヾJ・/(/;ノ川ノ=バこ111(1どり///し〃りノ叩ヾハ.ヤー/////J

fromUSSR,NortheastChina,andKorea

inComparisonwith C.ク頑canusfromFinland

YukibumiKANEKO β/()ん甘ん、(7/⊥‘7/−(明7J明・.J−17(、J/坤・〃■∫(山(・(汀正明,〃‘ぜ1:け‘7し7JJ/J、り叫l・. 花々α桝αね〟間ノ(砂α乃 (AcceptedSeptember25,1989) AbstYaCi.Museumspecimensof210redLbackedvolesfromUSSR,nOrtheastChina (Manchuria),and Korea were compared with 70 specimens of Clethriono叩 ndbcanusfromFinland.Condylobasallength(CBL)correlatedpositivelywithages determined by developmental stages of molar roots in the samples from Finland

throughouttheyear.AllskullsmeasuringCBL=26mmormorehadrootsinthe SamplescollectedfromFinlandinthefirsthalfoftheyear.IntheAsiaticspecimens CO11ectedinthefirsthalfofayearandfrom4lONlatitudeandnorth(northernvoles), allskullswith26mmCBLormorelackedalveolarcapsules,indicatingthedevelop− mentofroots.Onthe!Otherhand,inmuseumspecimenscollectedinthefirsthalfof theyearandfrom410Nlatitudeandsouth(southernvoles),allskulls,eVeninskulls with26mmCBLormore,hadstronglybulgedalveolarcapsules,indicatingrootless molars.TheocclusalpatternsofM3changewithincreaseinCBLwerethesame betweenC.ndbcanusfromFinland品dnorthernvoles:Simplexformwascommon inlargerindividuals,Whereasthecomplexformwasrare.Ontheotherhand,the COmplexformwasabundantinallCBLclassesinsouthernvoles.Northernvoles WereSlightlynarrowerininterorbitalwidthandslightlyshorterintaillengththan SOuthernones.IidentifiedthenorthernvoleasC ndbcanus,andthesouthernvole as Eotheno叩 御Ius.Isuggest that the true geographicaldemarcationline

betweenthetwo specieslies on thewestern andsouthernboundary ofthe Kaima

Plateau,NorthKorea.

Key wo7ds:ClethriononvLS ndbcanus;Eotheno叩 Y℃guhLS;Identification;Distri−

bution;EasternAsia.

Introduction

Withtheexceptionof ClethYionoクク砂S ndilus,the classification of red− backedvoles(ClethrionoククりSandEothenonws)fromnortheastChina(Manchur− ia)andKoreahasbeenveryconfused.Thered−backedvoleofKoreawasfirst describedby Thomas(1907)under the name of Cmseoクク砂S regulus.Allen& Andrews(1913)andSowerby(1923)identifiedthevolefromKoreaandnorth− eastChinaas CγαSeOmyS rqgulus.In1926,Hintonrevisedtheclassificationof

red−backedvolesfromeasternAsiaandrecognizedonlyonespeciesofvolein

this region,namely EuotoブタひS(=Clethriononv)S)n4fbcanus.Since that time, manytaxonomistshavefollowedhisclassificationatthespecieslevel(Howell,

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1−.Ⅳ(川ヒ、片〔) 130 1929;Goodwin,1933;Kuroda,1934,1938,1939,1940;Allen,1940;Tokuda, 1941;Ellerman,1941;Mori,1942;Ellerman&Morrison−Scott,1951;Ognev, 1950;Jones&Johnson,1956,1965;Shou,1962;Won,1961,1965;Gromov et al.,1963;Zimmermann,1964;Gromov & Polyakov,1977;Aimi,1980; Gromov&Baranova,1981). Corbet(1978),however,prOpOSedanewclassificationofOrientalvolesof thisreglOn.HeallocatedthevolefromKoreaandtheProvincesofShansiand

Hopei,China,tO Eothenoプ呵′S,but also recognized C.n4bcanusin northeast ChinaandKorea.Honackiet al.(1982)followedtheclassificationofCorbet (1978)as did Nadachowski(1984).However,the descrimination of C. n4bcanus and E.r曙ulus remains unsettled,because Corbet(1978)only pro−

Videdsomesimplekeysforthesegroupsandacrudedistributionmap.

Inthepresentpaper,Icomparecranialandmolarcharactersofred−backed VOlesfromUSSR,nOrtheastChina,andKoreawiththoseofC.radbcanusfrom Finland.Bythesecomparisons and examination ofagevariation,Ipresent morepracticalcriteria foridentifying ClethrionoクワりS ndbcanusinthisregion

SeparatingitfromEothenonws rqgulus.

Materials and Methods

A totalof280specimens was examined:70specimens of C.n4fbcanus collectedfromKilpisjarvi(69003′N,20049′E),FinlandfromFebruarytoSeptem− ber,1983,byA.Kaikusalo;and210specimensofClethrionon砂SandEotheno− nりSfromUSSR,nOrtheastChina,andKoreahousedinthefollowinginstitu− tions:BritishMuseum(NaturalHistory)(BM),UK;MuseumofComparative Zoology,Harvard University(MCZ),American Museum of NaturalHistory (AMNH),UnitedStatesNationalMuseumofNaturalHistory(USNM),and FieldMuseumofNaturalHistory(FMNH),USA;andYamashinaInstitutefor Ornithology(YIO),Chiba,Japan・

Thelocality anditsreferencenumberinFig・9,1atitude,longitude,date collected,muSeum,and registration number of allspecimens examined are listedinthe Appendix.Latitude andlongitude ofthelocalities were deter− mined from the gazetteersinJohn&Johnson(1965),Zhuang(1983)and Su (1984).Someofthesespecimenswerepreviouslydescribedandidentifiedby Thomas(1907),Allen&Andrews(1913),Sowerby(1923),Hinton(1926),Howell (1929),Goodwin(1933),Kuroda(1934,1939),Allen(1940),Jones&Johnson(1956, 1965),Corbet(1978),andAimi(1980). Taillength(TL)wasrecordedfromtheskinlabeL Condylobasallength (CBL)andinterorbitalwidth(IOW)weremeasuredonundamagedskullstothe nearest O.1mm with a dialcaliperby the author.The CBLis the distance betweentheoccipitalcondyleandtheanteriorpartofpremaxillae・TheIOW

istheleastdistanceofthefrontalbonesbetweenorbits.

ThedisappearanceoftheM2alveolarcapsulewasrecordedfortheskulls

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Koshkina,1955).Three stages were recognized:a StrOng arChed alveolar CapSule;anintermediate stage,in which the capsuleis slightly swollen;a Cap?uleflattenedandreducedtoastraightline・ SkullsofC.クゆcanusfromFinlandwereagedaccordingtothedevelop− mentalstagesoftheirmolarrootsfollowingthecriteriaofAbe(1976).Eight ageclassesweredetermined:Ⅰ+II,ⅠII+IV,Ⅴ,lessthan33%ofrootratio(VI), from33to60%ofrootratio(VII),and61%ormoreofrootratio(VIII). PatternsofcrownwearofM墨weredrawnforC.ク頑canusfromFinland by the stereo microscope(SMZ−10)produced by Nippon Kogaku with an accessory apparatus at15Ⅹmagnification.For museum specimens,figures Were drawnfrom close−up Pictures ofthe molar rows(1.75Ⅹmagnification) usingthestereomicroscopeat6.6Ⅹmagnificationafterthepicturesweretaken inthemuseumwithanaccessoryclose−uplensattachedtoanOlympuscamera. DentalpatternsofM旦wereclassifiedintofourtypes(Abe,1982):type4+5is

COmplexformwiththreereentrantanglesonthebuccalside;type6hasthree

Salientanglesonthebuccalside,aShortposteriorloop,andaconfluentdental isthmusbetweentriangles;type9hasthreesalientangles,inwhichtheinternal

posterior enamellamella arestraightto convex;type7+8has three salient

angles on the buccalside with slightly concaveinternalposteriorlamella

exceptfortype9.Furthermore,thefourthoutersalientanglewascheckedon

theleft side of M3.

Results

l.1hriation qfClethrionomysrufocanusjhm j巧nland

InthelargesampleofC ndbcanusfromFinland,CBLcorrelatespositive− 1ywithsixageclassesdefinedonrootdevelopment(r=0.790,U=67,P<0. 001)andmaybeusedasanapproximateindicatorofage(Fig.1).Twoskulls havinganintermediatestageofthealveolarcapsule,OrWithoutthecapsule, arefoundamong15specimens(13%)inthe22−24mmCBLrange(Fig.1).Ten

Of18specimen岳(56%)with25mmCBLlackacapsule・Allskull占measuring

CBL=26mmormoreexhibitrootdevelopmentandthealveolarcapsulehas disappeared(ⅤⅠ,ⅤⅠIandVIIIageclasses).

ThedisappearanceofthealveolarcapsuleinrelationtoCBLwascompar−

edamongthesamplescollectedindifferentmonths(Fig.2).In C.glanolus,

thedevelopmentofmolarrootsisknowntoberetardedintheautumn−born

cohort compared with spring−Or Summer−born cohorts(Lowe,1971;Zejda,

1971).AmongspecimenscollectedinFebruary,March,andMay,thecapsule disappearedin animals as smallas CBL=24mm;Whereas,amOng those

takeninJulyandSeptember,thecapsulewasabsentonlyinindividualswith26

mmCBLormore(Fig.2).SpecimenscollectedinthelatermonthswithCBL

lessthan26mmpossessanalveolarcapsule,Whichsuggestsaretardationof

molar formation.In the followlng COmparison of capsule development,

museumspecimensweredividedintotwo periodsaccordingto thecollecting

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132 l二ん7机丸) ・‥I・Itトヰー ● ●● ■hl●l●− ● ⅦⅠ Ⅶ VI V III&Ⅳ Ⅰ&Ⅰ ム ● ● A 。。○く辟。80 ● 0 00 08 22 23 24 25 26 27 28 29mm CBL

Fig・1・Relationship between condylobasallength(CBL),age Classes(I−VIII)and

development ofalveolarcapsulein C.ndbcanus from Finland.SymboIs:CapSule present=Open Circle;CapSule absent=Closed circle;andintermediate stage= OPentriangle.

Fig・2・Monthlyvariationoffrequencydistributions ofcondylobasa11ength(CBL) With development of alveolar capsuleinC.rt4bcanus from Finland.One square indicates one specimen.SymboIs:CapSule present=Open reCtangle;CapSule absent=Smallclosedrhombuswithinasquare;andintermediate stage=Ⅹ−1etter withinasquare.

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Tablel・FrequenciesofdentalpatternsofM30nbothsidesinClethriononv7S

ndbcanusfromFinland.

Left side

Type6 Type4+5 Type7+8

T p y e 9

Rightside Type6 Type4+5 Type7+8 Type9 Total 0 6 5 0 1 1 0 3 7 9 9 2 3 0 0 3 1 4 1 1 6 9 5 0 0 3 2 7

Table2.Frequencies of dentalpatterns of theleft M3in Clethrio

ndbcanusfromFinlandobservedinsevenCBLclasses.

CBLclasses(mm) Type6 Type4+5 Type7+8 y T p e 9 22.0−22,9 23.0−23.9 24.0−24.9 25.0−25.9 26.0−26.9 27.0−27.9 28.0−28.9 Total 0 0 0 2 6 2 0 0 1 O 1 8 0 2 7 1 9 1 1 3 0 0 0 6 6 2 0 4 1 1 6 8 8 4 1 1 9 1 2 1 6 (JulytoDecember).

Thecorrespondence ofthe occlusalpatterns betweentheleft andright

M旦s was tested(Tablel).The G−teSt With Williams adjustment(Sokal&

Rohlf,1973)indicatedthatbilateralpatternswerestronglyassociated(Gd5= 56.3616,U=9,P<0.005).0nly theleft side pattern was examinedin the

followlngStudy.

ThedentalpatternofM旦ChangeswithincreaseinCBL(Table2).Type 6wasthemostfrequentintheCBLclassesunder24mm.(Thesimplexform (type7+8)variedgreatlyfrom17tolOO%in23−27mmCBLclasses.Another Simplex form(type9)occurred at O−33%1evelin23−27mm CBL classes.

Thecomplexform(type4+5)wasobservedatll−25%1evelin25−27mmCBL

Classes.Thus,the two simplex forms(type7+8and tiTpe9)were foundin largenumbers(75−100%)in24mmCBLclassormore.

AfourthoutersalientangleofthegrindingsurfaceinM3wasobservedin

Onlyoneskullamongthe70specimensof C.ndbcanusfromFinland.

TheIOWandTLofC.n4bcanusfromFinlandvariedseasonally(Fig.3):

IOWorTLareslightlynarrowerorshorterinFebruai・ythan’inothermonths

and are slightly wider orlongerinJune thanin other months.TheIOW

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134 ト 〟(川亡・ノh

陀B5一箪r

MAR l t.−

 ̄−1−

m

鮭虹止且臥軋⋮TL

●:ニー≡

P 1虹

Fig.3.Monthly variation of frequency distributions ofinterorbitalwidth(IOW) andtaillength(TL)inrelationtodevelop・

ment of alveolar capsulein C.n4bcanus

from Finland.,One rectangle shows one SPeCimen.SymboIs:CapSule present= open rectangle;CapSule absent=Closed rectangle;andintermediatestage=Ⅹ− 1etterwithinarectangle. 」UL SE ●∴11J・右/∴・ノト:′−、/・しt、/ルノノバ・・・イ/‥ん/ノ).り′一/−.\ヾ人′、,..一〃//‥/ヾ/〔Ⅵ/ノ=..′ノ.・./八.り1.′

PlotsofCBLandtheoccurrenceofthealveolarcapsulewerearranged

fromnorthtosouthanddividedintotwoperiods(fromJanuarytoJune,and fromJulytoDecember)forthemuseumspecimensexamined(Fig.4).Inthe

firsthalfoftheyear,thealveolarcapsuleis absentin allskullsmeasuring

CBL=26mm or more(andin some skulls only24and25mm)from410N

latitude and north;Whereas,from4lONlatitude and south,the capsuleis uniformlypresenteveninskullswith26mmCBLormore.Alternatively,in

thesamplesofthesecondhalfoftheyear,thecapsuleisabsentintwoskulls

(locality9)measuringCBL=25−26mmfrom4lONlatitudeandnorth,andthe CapSuleispresenteveninskullswith26mmCBLormorefrom410Nlatitude and south ThefrequencyofM旦dentalpatterns(Fig.5)indicatesthatsimplexforms

(type7+8and type9)(Fig.6)are most common(91/109=83.5%),and the complexform(type4+5)(6/109=5.5%)andthefourthoutersalientangle(4/

109=3.5%)are uncommon among northern voles.In contrast,the simplex

formisuncommonamongsouthernvoles(23/97=23.7%),thecomplexformis themostdominant(69/97=71・1%)・andthefourthangle(Fig・6)ocurred

frequently(59/97=60.8%).However,geOgraphicalclinalvariationlS nOt

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N 12 34 「 5 6 R 4g 87 m 9 ≡ LU ⊂】 =) 10 ト [ く m 12 13 1‘ 4d- 」_] [[ 3334 3弓 [ 20 24 28 20 2ム 28mm CBL CBL −A− −B− Fig・4・Latitudinalvariationoffrequecydistributionsofcondylobasallength(CBL)

withdevelopment ofalveolar capsuleln Samples ofred−backed voles from USSR, northeast China,and Korea.The numbers(1−34)show thelocalities which are explainedinthe Appendix.Theleft column(A)contains samples collected from JanuarytoJuneandtherightcolumn(B)samplescollectedfromJulytoDecember. FurtherexplanationisgiveninFig.3.

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】 ̄、八一〃し丸) 136

15』叫

2 」」コ_ −..

35L止

叫 ん L_血_…□ ロー7 JUL 賦 t rr ̄「!….−.18 l!rr ‥….−一19

止L__..□20

しrTr=...一口21 三三 t rTr..…[コ24 トrl=ト__⊂コ25 ■ = [!.…トー26

址‖._]28

=「=巨.□29 8I!.「「...■_

95踊]

JUN JUL

10 し≡,rr叫_ □ 30

‖」山

一25L』

岨{[31

=「「‥_..□32 !「「1_.上]33 ■ rr こ ‥....⊂コ34 ,..□

13」L□.._.−

1‘L』__.⊂コ

151r ̄「!.…⊂コ 16ロ_」コー.…□ 豊野Ld lu虔﹂巾S壬寸 の山d>ト の◆ト山d>ト 爪◆寸山d>卜 り山d>ト む−ひ⊂d l⊂巾旧市S占ヾ の山d>ト の.ト山d>ト 山◆寸山d>ト ∽山d>卜 Fig.5.Frequencydistributionsofdentalpatterns(type6,type4+5,type7+8,and type9)andtheoccurrenceofthefourthoutersmallsalientangleintheupperleftside

M3insamples ofred−backedvolesfrom USSR,nOrtheastChina,andKorea.The nt品bers(1−34)showthelocalitieswhichareexplainedintheAppendix.

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.」 β (、

Fig.6.Common dentalpattern of M3.

A,the simplex form of northern vole

(AMNH34038collected fromlocalityll,

COndylobasallength=25.4mm with roots);B,the complex form of southern

VOle(USNM199665collectedfromlocality

14,COndylobasallength=25.3mmwithout roots);C,the complex form with the fourthoutersma11salientangle(arrow)of

southern vole(USNM 294646 collected

fromlocality20,COndylobasallength=25. 2mm without roots).Thelocality num− bersareshownintheAppendix.

繁治責闇U

l■■

ThefrequencyoftheM3dentalpatternsinrelationtoCBLisshownforthe

samplesfromlocalitiesl,5,7and9(Table3),and27and30(Table4).Other samplesaretoosma11innumbertotabulate.Inlocalitiesl,5,7and9,the simplexforms(type7+8andtype9)occurprincipallyinanimalswithlarge CBL,thecomplexform(type4十5)isinfrequent,andtype6wasobservedin animalswithasmallCBLexceptforlocality5,Wheresmall−Sizedindividuals are absent.In contrast,mOSt Skulls fromlocalities27and30possess the complexformatalmostallCBLsizes,andthesimplexformsareuncommon. Inthemuseumspecimens,theIOWrangedfrom3.2to4.1mmforspecimens collectednorthof4lONlatitude;Whereasthewidthvariedfrom3.9to4.7mm forspecimensfromsouthof410Nlatitude(Fig.7).TLrangedfrom20to49 mminnorthernvoles,andfrom30to54mminsouthernones(Fig.8).Thus,

northernvolesareslightlynarrowerininterorbitalwidth andshorterintail

than southernindividuals. 3.7bo乃0ク鶴首c c(フ乃CJ〟ざわ乃

Therewasasharpcontrastinmolarrootoccurrencebetweennorthern?nd

southernvolesamongthespecimenscollectedinthefirsthalfofayear(Fig.4)・ Thenorthernvolehasrootedmolars,WhichbegintodevelopfromCBL=24to 25mm.Furthermore,amOngnOrthernvoles,thesimplexformofthedental patternisthemorecommon,thecomplexformisuncommon,thefourthouter salientangle occurredin a smallnumber(Fig.5),andtype6withconfluent dentalisthmusappearedinthesmalトsizedCBL(Table3).Thesecharacteris− ticsarethesameasdescribedforC.ndbcanusfromFinland(Fig.1andTable 2).Consequently,Iidentifythevolescollectedfrom410NandnorthasCleth− ル・頼りり・.\Ⅵ/こぃ/′′〃\.

The voles collected from410N and south are allocated to Eothenon砂S regulus.This species has the same palatalshelfin the skullasin Cleth−

Yionoqsbutlacksrootsevenin oldage,andthemolarreentrantfolds are

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138 1 ̄、〃(7〃(、毎

Table3.Frequencies ofdentalpatterns oftheleft M3inred−backed voles from USSR and northeastChina foundin CBLclasses.

CBLclasses(mm) Type6 Type4+5 Type7+8 V− T p e 9

Locality1 23.0−23.9 24.0岬24.9 25.0−25.9 Total 1 5 6 2 1 Locality5 24.0叫24.9 25.0−25.9 26.0−26.9 Total 8 2 1 1 1 Loca王ity7 22.0−22.9 23.0−23.9 24.0−24.9 25.On25.9 26.0−26.9 Total 5 1 1 3 1 1 1 Locality9 20.0−20.9 21.0−21.9 22.0■22.9 23.0−23.9 24.0−24.9 25.0−25.9 26.0叫26.9 Total 0 0 0 0 1 1 0 2 2 0 2 3 4 2 1 4 1 tionoftraitsformsthegenericdiagnosticofEothenoクワ砂S(Hinton,1926;Eller− man,1940;Corbet,1978).BecausetheholotypeofCYtlSeOプ呵ノSrqulusThomas, 1907(BM6.12.6.89)isfromlocality30(Figs.4,5,7,and8,andTable4),the SOuthernvolecanberecognizedasE.rqulus.Eotheno〝りLS Yqulus averages

Slightly widerinIOW andlongerin TL than C.ndbcanus from the USSR, northeast China,and North Korea;however,IOW and TL show slight se良一 SOnalvariationin C.ndbcanusfromFinland(Fig.3),andtherangesofIOW andTLoverlapbetweenthetwospecies(Figs.7and8).ThedistributionofC. radbcanusandEク聯Iusisshownbythelocalitiesexaminedinthisstudy(Fig. 9). Discussioll FewstudieshavebeenmadeonthedevelopmentofmolarrootsoronM3 0CClusalpatternchange with CBL growthinthenominatesubspecies of C.

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山口⊃トl↑く﹂ 3.2 4.0 4月 32 48 ‘8爪m IOW IOW −A− −B一 Fig・7・Latitudinalvariationoffreque?Cydistributionsofinterorbitalwidth(IOW)

withdevelopmentofalveolarcapsulelnSamplesofredLbackedvolesfromUSSR,

northeastChina,andKorea.FurtherexplanationisgiveninFigs・3and4・

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1二 八’(丁招来) 140 山D⊃ト︻↑<﹂ 15 35 55 15 35 55mm TL TL −A− −B−

Fig.8.Latitudinalvariation of frequency distributions of tai11ength(TL)with developmentofalveolarcapsuleinsamplesofred−backedvolesfromUSSR,nOrtheast

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Table4.Frequencies of dentalpatterns oftheleft M3in red−backed voles

fromKorea foundinCBLclasses.

CBLclasses(mm)

Type6 Type4+5 Type7+8

y T p e 9

Locality27 21.0−21.9 22.0−22.9 23.0−23.9 24.0−24.9 25.0【25.9 26.0−26.9 Total 1 0 3 4 3 3 4 1 0 0 0 2 0 2 4 2 1 3 6 3 5 0 2 Locality30 21.0−21.9 22.0−22.9 23.0−23.9 24.0【24.9 25.0−25.9 26.0−26.9 Total e 13222yp13 T 3 * 1 3 3 2 3 3 5 1

*Theholotypeof CYaSeOnV}S喝ulus Thomas,1907(BM6.12.6.89)isclassifiedinthis

CategOry. thecementspacesofmolarsareclosingatapicalportionsofroots,thegrowth StageOfwhichcorrespondswithmyfindingthatskullswith24−25mmCBL exhibittheinitialstageofroot−Closing(agegroupIII&IV)(Fig.1).Further− more,hei11ustratedmolarswithrootsforspecimenswithCBL=26.1mmor more・Thus,hisfragmentarydescriptiondoesnotcontradictmyresults. Miller(1912)andCrowcroft&Godfrey(1959)studiedtheoccurrenceofa COmplexM旦in C・n4bcanusfromScandinavia,buttheydidnotpresentage

Variation and theirlocalities examined.In theisland population of C

nihcanus onHokkaido,Japan,Abe(1982)demonstratedthatthetype6was dominantinyounganimalsandthendecreased,thatthecomplexformoccurred lessthanlO%tillagegroupV,andthatthesimplexforms(type7十8andtype 9)increasedinnumberwithage.Thus,hisfindingsaccordwithmystudyof C・n4bcanusfromFinland.Dentalpatternsmayvarygeographically,because theproportionofthecomplexformis6.2%(1/16)inScandinavia(Miller,1912), 14・5%(10/69)inFinland(Table2),9%inHokkaido(Abe,1982),andO−9.1%in localitiesl,5,7,and9,nOrtheastChina(Table3).

Skulls and dentalcharacters of C.n4bcanus from northeast China and

Koreahavenotbeenstudiedindetail.Hinton(1926)examinedspecimensfrom

LakeBaikal,Irkutsk,USSR,andKorea,butdidnotexaminespecimensfrom northeastChina・Hestudied four specimens with roots fromIrkutsk,three

SpeCimenswithrootsfromPotaidonandPochong,NorthKorea,and12speci− mens without roots from South Korea.Based on these examinations,he allocated the voles from northeast Chinaand Korea to Euotonqys(=Cleth− rionoク叩S)ク頑canusク聯Ius,becauseheconsideredtherootdevelopmenttobe

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142 1−.〃‘J〃t・Å・り

11ざ 12ざ 12ざ 13〔F 13ごE

Fig・9.Localities of C.n4bcanus(a closed circle)andE.rqulus(an open circle) identifiedinthepresentstudy.Thenumbers(1−34)indicatethelocalitieswhichare

explainedintheAppendix.

retardedinparallelamongthenortheastChinaandKoreanvole(C.n4bcanus regulus),theChinesevole(C.n4bcanus shanseius)andtheJapanesevole(C・ r84bcanus smithii).However,myStudyshowsthat,aSfoundin C.n4bcanus

from Finland,Skulls with26mm CBL or more have rootsin allmuseum

specimens collected at or north of4lON andin the first half of a year・ Consequently,thedevelopmentofrootsdoesnotabatein C.プ頑canus from eastern Asia as stated by Hinton(1926);Only the samples collectedin the

secondhalfoftheyearfromFinlandandeasternAsiashowretardationofroot

development(Figs.2and4).Ontheotherhand,VOleslivingsouthof410Nlack roots,eVenin those with26mm CBL or more.With regard to rooted or rootlessmolars,aSharpcontrastexistsnorthandsouthof41DN.Thepresent findings,therefore,CannOtSuppOrttheclassificationofHinton(1926).

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Howell(1926)(theYaluRiver,NorthKorea),Kuroda(1934)(SouthKorea), Jo′neS&Johnson(1965)(theYaluRiver andSouthKorea),Won(1961,1965) (South Korea)and Aimi(1980)(South Korea),tOO,did not pay attention to

molarrootconditionintheclassificationofvoles.Iexaminedalltheirspeci− mens(exceptWon,1961,1965),andfoundrootlessmolars amorigthesespeci− mens(Fig.4).Tokuda(1941)examinedred−backedvolesfromnortheastChina

and Northland South Korea,but did not distinguish skulls with orwithout

roots.Thus,hisdataonthedentalpatternfrequencyisnotcomparablewith

thepresentstudy.

Corbet(1978)distinguished C.n4bcanus andE.Y<gulusinthisregionby

the character of rooted or rootless molars,Which accords with the present

taxonomicconclusion.However,hiskeyisnotalwayscompleteforpractical

identificationbecausehedidnotanalysethesizerangeofskullsthathaveroots

andthosethatdonot.AlthoughNadachowski(1984)distinguishedtwospecies from NorthKoreafollowingCorbet(1978),hedidnotspecify theskullsizes Withandwithoutroots.Fromthisstudy,thesetwovolescanbeidentifiedby

theabsenceorpresence ofrootsatleastin26mmCBLormore,Whenvoles

werecollectedduringJanuarytoJune.Furthermore,theinterorbitalwidthis

also a key character to discriminate the two speciesin this reglOn:Whenit exceeds4Amm,itisE Hinton(1926)mentionedthattheM旦OfyoungEvotoプクV)S ndbcanusク聯Ius (=EothenoブタひS rqgulus)tendstobemorecomplex.However,hisobservation

isnotsupportedbecausethecomplexform(type4+5)wasfoundinallCBL

Classes(Table4).Thefourthoutersalientangleisacommoncharacter(Figs. 5and6)asdescribedinHinton(1926)andNadachowski(1984).

Jones&Johnson(1965)distinguished C.rtち舟canus Yqulus(=E.regulus) from C.γゆcanus a7Seわevi(=C.ndbcanus)from North Korea by a wider

interorbitalwidth,longertaillengthandothers,thoughtheymisidentifiedone SpeCimen(AMNH34011)of C.nttilus as C.n4舟canus a7uわevi.Theformer

two characterswereconfirmedinthisstudy.

Someauthorsnotedhabitatforred−backedvolescollectedinthisregion. However,becauseidentificationissometimesuncertain,Irefertothedescrip− tion of the voles thatIexaminedin this study.Allen&Andrews(1913)

reportedthatthehabitatisthinlyorheavilyforestedintheTumenRivervalley

(localitylO)and the edge of primevalforestsin Nonsatong(localityll). Sowerby(1923)collecteda1argenumberofred−backedvolesinforestedareas (ImienMpO,locality7)andintheopenvalleyofthelowerSungari(locality9); thesespecimensareidentifiednowasC.ndbcanus. Thomas(1907)describedthehabitatoftheholotypeof CγαSeOnサSプ守宮ulus

as“mossytalusovergrownwithbushes”and“fromburrowinbarleyfieldon

dryhillside”fromthefieldnoteofM.P.Anderson.Hisoriginalfieldnotes further mentioned:“The vole653etc.(now registered as BM6.12.6.98)is

COmmOninthisneighborhood.Itchieflyaffectstherocksbutisalsofoundin

grassyembankments,Whereitburrows near the surface.Ihave sometimes

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144 1’.ん〃汀如

“AtMingyong(=locality30)isoneoftheKing’sreservedforests,Itconsists Ofscattered pines of fair size,and oh some of the higher slopes,firs.The

mountains are rocky and unfertile and the soil seems to retain moisture

poorly”.Ontheskinlabels,thehabitatisdescribedasfollows:“Mossystones amongbushes;Burrowinstone−Wa11edembankment;Byrockamongbushes and grass;Stone,Wallon grassy flat;Under decayinglog on hillside”・

Therefore,these habitat descriptions suggest that E.rqgulus prefers princi− pa11yrockyareas,Whereas C.クゆcanuslivesmainlyinwoodedareas.

In comparison with the map of Corbet(1978),the distribution of C.

ndbcanus extendsfartherto thewestinnortheastChina andlessto southin

NorthKorea(Fig.9).Nadachowski(1984)reported C.ndbcanus from Sam−

jiyon(4lO29′N,128012′E),Hyesan(41014′N,128007′E)andPektu−San(42000′N,1280

03′E),andE.rqulus wascollectedfromSokvang−Sa(38035′N,127013′E)and Kumgang−San(38040′N,128008′E).Therefore,Isuggest that the southern

distributionallimitofC.ndbcanusisthewesternandsouthernboundaryofthe

KaimaPlateau,NorthKorea,ahigh1andthatKishida&Mori(1931)andJones &Johnson(1965)notedismostlycoveredwithconiferousforestsresemblingthe flora of northeast China.However,the northeast boundary of E.

needs to be clarified.Li(1983)collected C.ndbcanus from the Liaodong Peninsula,China,neartheYaluRiver,buthismethodofidentificationfor C.

n4bcanuswasnotgiven.

Acknowledgements

Igratefully acknowledge Mr.Asko Kaikusalo,Who provided me with

excellentspecimensfromFinland,andthecuratorswhoallowedmetoexamine

specimensin their care:Mr,Iain R.Bishop,British Museum(NaturalHis−

tory),Mrs.MariaE.Rutzmoser,MuseumofComparativeZoology,Harvard University,Dr.Guy G.Musser,American Museum of NaturalHistory,Dr・

MichaelD.Carleton,UnitedStatesNationalMuseumofNaturalHistory,Dr. BruceD.Patterson,FieldMuseumofNaturalHistory,andMr.K.Momose, Dr.R KakizawaandDr.N.Kuroda,YamashinaInstituteforOrnithology.I furtherthankDrs.M.D.CarletonandG.B.Corbetforcheckingandimprov− inganearlierdraftofthispaper,andMissDaphneM.Hillsforlocatingthe field notes of M.P.Anderson housedin the British Museum(Nat.Hist.).

This work was partly supported by a Short Term Visitor Grant from the

SmithsonianInstitution,the KarlP.Schmidt Fund ofthe Field Museum of NaturalHistory,andthefundof“0verseasScientificResearchGrantfor1982 (62041089)and1983(63043061)”deliveredbytheMinistryofScienceandCulture

OfJapan.

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1519−2806pp. Thomas,0.1907.TheDukeofBedford’szoologicalexplorationineasternAsia.II.Listofsma11 mammalsfromKorea andQuelpart.Proc.Zool.Soc.,London,1906:858−865. Tokuda,M.1941.ArevisedmonographoftheJapaneseandManchou−KoreanMuridae.Trans. Biogeogr.Soc.Japan,4:1−155. Won,P.0.1961.Avi−mammalianfaunaofKoreafromtheviewpointoftheForestryProtection. Inst.Agri.,Minist.Agri.andForestry,Korea:31r135. Won,P.0.1965.StudiesontheecologicalobservationofrodentiainManchuriaandKorea.Rep. Coll.EastCount.Pt.2,Nat.Sci.,Ⅰ:331−422&III:135−200. Zejda,J.1971.Differentialgrowthofthreecohortsofthebankvole,Clethriono〝砂SglaYeOlusSchreb. 1780.Zool.Listy,20:229−245. ZhuangJin−Nan(ed、).1983.GazetteerofChina.AnindextotheatlasofthePeople’sRepublicof China.AtlasPubl.Comp.,315pp. Zimmermann,K.1964.ZurS宜ugetier−FaunaChinas.ErgebnissederChinesische−DeutschenSam− melreisedurchNord−undNordostLChina1956,No.15.Mit.Zool.Mus.Berlin,40:87−140. Appendix 斗.−ゾ吊■∴・、、/::山/J∴/‥ノ Localitynumbersusedthisstudy(seeFig.9),locality,1atitudeandlongi− tude,mOnthandyearcollected,muSeum,andregistrationnumberofallspeci− mensexaminedarelistedbelowfromnorthtosouth.Localitynumbersl−13 areherereferredtoClethrionoクク砂Sγゆcanusandnumbers14−34toEothenonv)S j・.ゞJ//ノド. 1.Monoma River,Amurland,USSR;49015′N,136019′E;January1930, AMNH85424−29,85436−37,85448−50,85452,85454−55,85458. 2.Jaramtai,Inner Mongolia,China;49012′N,120O24′E,May1935,YIO873 −874. 3.Xia−hinggan−1iang,Heilung−kiang ProvリChina;apprOXimately48030′N, 127030’E;June1935,YIO875−881.

4.Yalu St.,GreatKhingan Mts.,hnerMongolia,China;48030′N,122012′E; No寸ember1934,FMNH46034;July1935,FMNH44353;September1939, FMNH49906;October1939,USNM27055;FMNH49905. 5.NeltaRiver,Amurland,USSR;48019′N,135005′E;February1930,AMNH 85471,85474−76,85480,85483−84,85490,85492−94,85499,85503−05、 6.Hsialing,Kirin ProvリChina;45018′N,127018′E;June1938,MCZ41144; June1937,YIOlO86,1092;October1937,MCZ41145;September1939, FMNH49904.

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7.Imien−pO,Heilung−kiangProvリChina;45006′N,128DO6′E;September1914, USNM199643,FMNH43416;October1914,USNM199644−47,199649 −51,199653,FMNH43415;September1915,USNM201255,201258−66. 8.Kaolingtsu St.,Kirin Prov.,China;44048′N,128048′E;June1940,USNM

270556.

9.SungariRiver,60milesSWofKirin,China;43054′N,126030′E;June1913, USNM197β20−24;July1913,USNM197825−28,197831,35,FMNH

43413−14.

10.Tumen River,North Korea;apprOXimately42020’N,130040′E;October 1935,BM1938.8.臥16. 11.Nongsa−dong,North Korea;42002′N,128049′E;May1912,AMNH34023, 34029−30,34035,34038−40. 12.Potai−dong,North Korea;aPprOXimately41O43′N,128022′E;May1912, BM13.5.27.53−54,MCZ15292,USNM197976−77,AMNH34007,34009, 34015. 13.Pochong,NorthKorea;apprOXimately41031′N,128018′E;June1912,BM 13.5.27.56,AMNH34016−18. 14.YaluRiver,150milesuptheYaluRiver,NorthKorea;apPrOXimately400 25′N,124050’E;May1914,USNM199638−41,199642;June1914,199665. 15.Changjon,NorthKorea;38044′N,128011′E;June1929,YIO73.

16.1mile N of Oho−ri,South Korea;38020′N,128032′EiApri11954,USNM 298952−53;June1954,USNM298956.

17.Kumhwa,SouthKorea;38017′N,127028′E;June1952,USNM294648−49; November1906,BM7.6.3.61;July1952,USNM294650,298063;September 1952,USNM298064.

18.1mile W of Tangjonggok,South Korea;38Oll′N,12809′E;April1954,

USNM298954−55.

19.Taegwang−ni,SouthKorea;38011′N,127006′E;March1954,USNM298949. 20.Chip’0−ri,SouthKorea;38008′N,127019′E;June1952,USNM294644−47. 21.3milesSWofYanggu,SouthKorea;38006’N,128000′E;April1954,USNM

298950−51.

22.Chang Amトri,Idong Myon,South Korea;38003′N,127012′E;February

1974,BM75.806;November1973,BM75.802;December1973,BM75.803

−805.

23.Ori−dong,SouthKorea;38003′N,126058′E;September1952,USNM298067. 24.Ch’ongsong−ni,South Korea;38002′N,127′09′E;September1952,USNM

298065;October1952,USNM298066.

25.3miles SSE Sumil−ri,South Korea;38002′N,127030′E;September1954, USNM29905. 26.Samsimgok−ri,Shinbook Myon,PochonGun,KyonggiDo,SouthKorea; approximately37050′N,127010′E;November1973,BM75.817. 27.KwangnpngNationalForest,SouthKorea;BM37045′N,127011′E;Febru− ary1974,BM75.782−785;March1974,BM75.786−788,75.793−796; April1974,BM75.789−792;June1974,BM75.797−801. 28.NearPup’yong−ni,CentralNationalForest,SouthKorea;37044′N,127012′

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148 11〃(川‘一山

E;August1952,USNM298068;November1954,USNM300646.

29.Ilyung−ri,Changhon Myon,Yangju Gun,KyongyiDo,South Korea; approximately37040′N,127000′E;February1974,BM75.807;Apri11974, BM75.808−811,75.813−814;May1974,BM75.815,816.

30.Mun’gyong,110 miles SE of Seoul,South Korea;36044′N,128007′E; November1905,BM6.12.6.89(theholotypeofC7WeOクク砂S YqgulusThomas,

1907),6.12.6.98,100;December1905,BM6.12.6.90−97,6.1.6.101−106. 31.Near Ch’ongju,Chung Chong Prov.,South Korea;36038′N,127029′E;

December1906,BM7.6.3,53−60. 32.10mi1esNofTaegu,SouthKorea;35052′N,128035′E;December1905,BM 6.12.6.107;January1906,BM6.12.6.108,6.12.6.110. 33.Yonggwang,SouthKorea;35016′N,126031′E;May1930,YIO75−76. 34.30mi1esNofPusan,SouthKorea;35008′N,129bO4′E;August1952,USNM 298069.

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