On Specimens of Phreatoasellus kawamurai (Tattersall) (Crustacea: Malacostraca: Isopoda: Asellidae) Collected from a Lava Tube in Matsue in Shimane Prefecture, Japan

On Specimens of Phreatoasellus kawamurai (Tattersall) (Crustacea: Malacostraca:

Isopoda: Asellidae) Collected from a Lava Tube in Matsue in Shimane Prefecture, Japan

著者 Nunomura Noboru

著者別表示 布村 昇

journal or

publication title

Japan sea research

volume 49

page range 67‑76

year 2018‑03‑26

URL http://doi.org/10.24517/00050912

Creative Commons : 表示 ‑ 非営利 ‑ 改変禁止

日本海域研究，第49号，67‑76ページ,2018 JAPANSEARESEARCH,vol.49,p.67‑762018

OnSpecimensofP"花α""Se""s〃"α""""(TatterSall)(CruStacea:

Malacostraca:Isopoda:Asellidae)CollectedfromaLavaTubein MatSueinShimanePrefecture,Japan

NobomNUNOMURAI*

Received22September2017 Accepted28November2017

Abstract

Pﾙﾉ℃arOqSe""sknwα〃zｲノ(Tattersall)(Cmstacea:Malacostraca:Isopoda:Asellidae)Was redescribedbasedonspecimenscollectedfiomalavatubecalled..YOkid6,''inShimanePrefecmre・Asa resultofmyexamination,thesespecimensgenerallyagreedwiththeoriginaldescription,butseveral difYerenceswerefbund・Keydifferencesincluded:aconcavedposteriormarginofpleotelson;anot remarkablyshortpereopod4;thenumberofsetaeofexopodinrelationtopleopod3;numeroussetaeon themiddlelobeofmaxilla;andanotsoshortexopodinrelationtouropodwhichareconsideredtobea geographicva面ation.Collectingnewspecimenswouldbedifficultfbrtheconservationofrarespecies suchasL"cjOgo6/"sαﾉb"s(Regan),duetothedangerofgroundcollapse.Itherefbreredescribedthis speciesbasedonacollectionfiomthelavambeG･YOkid6,''inShimanePrefecture.

KeyWords:Asellidae,Isopoda,Phre"o"e""sルaMm"7"ﾉW,redescription,taxonomy

Anunderground‑waterasellidgenusPMeαmqse""

umotoischaracteristicinlaIgesize,blindoralmost MatsumotoischaracteristicinlaIgesize,blindoralmost blind,pigment‑lesswhitebodyihavingplumose5(not4)

setaeonmesialenditeonmaxillulaandsoon.

Hitherto,tenspeciesofthegenusP〃花α/OqSe""s havebeendescribedasvalid:kqwα〃"rqj(Thttersall, 1921),加加"(Chappuis,1955),qb'josﾙﾉew"(Ueno, 1927),"goe"恥(Matsumoto,1960),yosﾙﾉ"oe"s"

(Matsumoto,1960),"iei(Matsumoto,1978),加加α/oj (Matsumoto,1978),"e"oj(Matsumoto,1978),qwqe"sjp Nunomura,2014havebeenrecorded廿omvariousparts ofJapanandP〃肥α/o"e""s〃α""s(HenryandMagniez, 1991)fomKorea.

Recentlyblhadachancetoexamineaspecimen collectedfiDmalavatubecalled"YOkid6''(Fig.1),

whichhadbeencollectedbyMILHidenoriYOshigou.

Howeveritwas,regrettablyonlyafemalespecimen, therefbre,someadditionalspecimensincludingboth sexeswerenecessaryfbridentifying.Fo血nately)some additionalspecimenscollectedbyDI:lchitaroNiibeof ShimaneUniversitywereplacedatmydisposal,through thecourtesyofhim,withtheintroductionofMrb KazunariKadowaki.Asaresultofmystudyithese specimensagreewiththeoriginaldescriptionof PﾙﾉｾWOqSe""s"wα〃"r"(Thttersall),butsome

differenceswerefbund.

Asthisspeciesmaydwellonlyinthelimitedcaves, collectingofnewspecimensisverydifYicult,especiallyi collectioninthislavambemaybedifficultfbr conservationofrarespeciessuchasL"ciOgobi"sα必蛎

I N o t o M a r i n e L a b o r a t o l y , D i v i s i o n o f M a r i n e E n v i r o n m e n t a l S t u d i e s , I n s t i t u t e o f N a t u r e a n d E n v i r o n m e n t a l T E c h n o l o g y , K a n a z a w a

Universityi4‑lMu,Ogi,Noto‑cho,927‑0553Japan

･AuthorfbrcoITespondence

Yakid

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Fig.1Mapshowingthesurveyarea

〃

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Regan,anddangerousgroundcollapse・Therefbre, almostalltheappendagesofmainlymalespecimens

collectedfiomthislavatubewillbedescribed.

AsellotaLatreille,1802 AsenidaeRafinesque,1815

P"だα〃"se""s加叩α"z""(Tattersall,1921) (Figs.2‑5)

CQ"j伽油eα肋wα腕""Thttersall,1921, pp､417‑419,figs・ll‑18;‑,Ueno,M.1927,360‑361.

"4se""s(P〃だαjo"e"s)kqwα加"y･qj(Thttersall, 1921);Matsumoto,1962,pp.166‑168,figs・l‑21;‑, Matsumoto,1963,59‑63,figs.113‑122.

P〃花"o e""s伽wα碗"""(Tattersall,1921):

Nunomura,2013,pp.54‑57,figs・19‑20.

M"e伽/ex"""ed:13(7.6mminbodylength) and3早早(4.5‑8.Omminbodylength).YOkid6,alava mbe,Daikonshimalsland,volcanicislandinthemiddle ofNakaumi,Matsue‑shi,Shimane‑ken,28,Nov.2004, coll.IchitaroNiibe;13(10.6mminbodylength),same localityjl8,Nov.2004,coll.IchitaroNiibe;333(7.2

‑9.0mminbodylength)andl？(approximately9mmin lengt:posteriorpartbroken),10,Dec.2004,coll.Ichitaro Niibe;1？(12.4mminlength),samelocalityう11,Apr、 2005,coll.HidenoriYoshigou.Thesespecimenswillbe

depositedatTbyamaScienceMuseum(TOYA Cr‑2375323762).

DGsc叩加〃q/"'"/eji℃〃〃"伽.Body(Fig.2A) slenderofunifbnnwidth,about4.5‑4.8timesaslongas wideexcludingbothantennaeanduropod・Colorwhite inalcohol.Surfacesmooth.Cephalon(Fig.2E)almost 0.6timesaslongaswide,withoutanyprQjections.Eyes verysmall,eacheyewith2‑3onnnatidea・Pereonal somitessubequalinlengthandalmostunifbrminwidth.

Pleotelson(Fig.2F)1.8timesaslongaswide,posterior marginwithapairofshallowconcavitiesandsmall p呵ectionofmedialarea.

Antennule(Fig.2B),reachingthemiddleareaof cephalon,composedof3peduncularsegmentsandl5‑16 flagellarsegments,manyofthemwithl‑2aesthetascs.

Antenna(Figs.2CandD),reachingalmosttheposterior endofseventhpereonalsomite,with5peduncular segmentsand44‑71Hagellarsegmentsinmale.Lefi mandible(Fig.3A):parsincisiva5‑toothed;lacinia mobilis2‑toothed;11‑12serratedsetae;palp three‑segmented;segment2aslongassegmentl,with 6‑20setaeondistalhalfitenninalsegmentwith8‑20 shortsetaeoninnermargin・Rightmandible(Fig.3B):

parsincisiva5‑toothed;11‑15serratedsetae;palpasleft one.Maxillula(Fig.3C):mesiallobewith5plumose segments,twoofthemshorterthantheothers;lateral lobewithl2teethatthetip,fiveofthemserrateand shorterthree.Maxilla(Fig.3D):mesiallobewithl8 serratedsetaeand24‑30setae;middlelobewith24‑30 andlaterallobewith30‑33setae.Maxilliped(Fig.3E): enditewith6couplinghookonlateralmargin;palp five‑segmented,secondsegmentbiggest,withl5‑16 setaeoninnermarginand3setaeonmaIgin;third segmentsquarewithsetaeoninnermalginandmore thanl5setaeoninnermargin;fburthsegmentslender;

with2setae,fifthsegmentwithmorethan21‑23setae aroundthemargin;epipoditewideandalmosttriangular, withl5‑17setaearoundmargin.

Pereopodl(Fig.4A):basisabouttwiceaslongas wide,with5‑6setaeoninnermaIginand2‑4setaeat innerdistalangleand2setaeonoutermaIginwide;

ischiumtwo‑thirdsaslongasbasis,withasetaoninner marginand2setaeonoutermargin;merustrapezoid,

旬 巳

／二三

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、

I

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Fig.2P/71eaioase"uskawamuﾉa/(Iattersall,1921)

A:Dorsalviewofwholebodyinmale,B:Antennuleofmale,C:Antenn offemale,E:Cephalonofthesame,F:Pleotelsonofthesame,G:Uro D=1.Omm,B,G=0.3mm,F=0．5mm.

aofmale,D:Antenna pod.Scalebars:A,C,

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Fig.3Phﾉeaioase"uskawamura/(Iattersall,1921)

A:Leftmandible,B:Rightmandible,C:Maxilluia,D:Maxilla．E;Maxilliped,F:PIeopodlin male,G:Pleopod2inmale,H:Pleopod2infemale,I:Pleopod3,J:Pleopod4,K:PIeopod 5.Scalebars:A,B,E,F=0.2mm,C,D=0．1mm、H‑J=0.5mm(A‑G,l‑Kmale,H:C,D

=0.1mm、H‑J=0.5mm(A‑G,l‑K:male,7.6mminbodylengthH:femalel2.4mminbody length).

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Fig.4P/71eaioase"Lﾉsﾉ(awamL"ai(1attersall,1921) A‑G:Pereopodsl‑7inmale・Scalebars:A‑G=0.5mm

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Fig.5DorsaIviewoffemaleofPhﾉeaioase"uskawamuﾉa/( Iattersall,1921)

A:Dorsalview,B:LateraIview(bodylengthl2.4mm;phototakenbyMr.HidenoriYOshigou)

with7setaeoninnermarginand2setaeatouterdistal angle;carpustriangular5with6setaeoninnermargin;

propodusabout3timesaslongaswide,withl5‑17 setaeoninnermarginand3setaeatouterdistalangle;

dactylusaslongaspropodus,withlO‑11setaeoninner margin,withagroupof7‑8spine‑likesetaeondistal outermargin.

Pereopod2(Fig.4B):basis3timesaslongaswide, with3setaeoninnermarginand8‑10setaeonouter margin;ischiumthree‑fburthsaslongasbasis,with4‑8 setaeoninnermarginand5‑6setaeonoutermargin;

merus55%aslongasbasis,with4‑5setaeoninner marginand4setaeincludingalongoneatouterdistal margin;calpusl.9timesaslongaswide,withlOshort setaeoninnermarginandl‑3setaeonoutermargin;

propodusO､8timesaslongascarpus,with3‑5setaeon innermarginandl‑2setaeonoutermargin;dactylus one‑thirdaslongaspropodus,with4‑5spine‑likesetae

onlnnermargln.

Pereopod3(Fig.4C):basis2.4timesaslongas wide,with2‑6setaeonbothmargins;ischiumtwo‑thirds aslongasbasis,with3‑4setaeoninnermargin,6‑7 setaeonoutermargin;merusshort,0．6timesaslongas ischium,with6‑7setaeoninnermarginand4‑6setae includingalongoneonouterdistalarea;calpus2.S timesaslongasmerus,with8‑10setaeoninnermargin and2setaeondistalmalginandabout4‑5shortsetaeat outerdistalangle;propodusO.7timesaslongascarpus, with7‑8setaeoninnermarginand5‑6setaeonouter margin;dactylustwo‑thirdsaspropodus,with2 spine‑likesetaeoninnermarginandagroupof5‑6setae.

Pereopod4(Fig.4D)95%aslongaspereopod3:

basis2.4timesaslongaswide,with3‑6setaeoninner marginandl‑10setaeonoutermargin;ischium three‑fburthsaslongasbasis,with3‑7setaeoninner marginand4‑6setaeonoutermargin;merusO．8timesas

longasischium,with5‑6setaeoninnermarginand4‑6 setaeaincludingalongoneatouterdistalangle;carpus 1.8timesaslongasmerus,withlO‑13setaeoninner marginand5setaeondistalmargin;propodusO.9times aslongascarpus,with8‑9setaeoninnermarginand 6‑lOsetaeonoutermargin;dactylusone‑thirdlongas propodus,with3‑4spine‑likesetaeoninnermarginand 5‑6setaeondistalpartofoutermargin.

Pereopod5(Fig.4E)alittlelongerthanthefbur precedingpairs:basistwiceaslongaswide,withalong setaatinnerdistalangle,2setaeoninnermarginand3‑4 shortsetaeonoutermargin;ischiumO.8timesaslongas basis,with4‑5setaeoninnermarginand3setaeonouter margin;merushalfLlengthofischium,with5‑7setaeon innermarginand21ongsetaeatouterdistalangle;

carpustwicelongerthanmerus,with6‑7setaeoninner marginand5‑7setaeatouterdistalangle;propodusO.9 timesaslongascarpus4‑5timesaslongaswide,with4 setaeoninnermarginandasetaonoutermargin;

dactylusone‑thirdaslongaspropodus,with2‑3 spine‑likesetaeoninnermargin.

Pereopod6(Fig.4F):basiselliptical,with8‑10 setaeoninnermarginand6‑7setaeonoutermargin;

ischiumalmostaslongerasbasis,with3‑6setaeoninner maIginand4‑8setaeonoutermargin;merusO.6timesas longasischium,with5‑6setaeoninnermarginand3 setaeatouterdistalangle;carpusabouttwicelongerthan merus,with8‑14setaeoninnermarginand6setaeon outermargin;propoduslongO.9.3timesaslongas carpus,with6‑10setaeoninnermargin,1．9timeslonger than7‑8shortsetaeonoutermalginandaspineondistal margin;dactylusone‑fburthaslongaspropodus,with2 spine‑likesetaeoninnermarginand5‑6setaeonouter

margln.

Pereopod7(Fig.4G):basiswith9‑12setaeoninner marginand6‑8setaeonoutermargin;ischiumalmostas longasbasis,with2‑4setaeoninnermalginand5‑6 setaeonoutermargin;merusO．7timesaslongas ischium,with6‑7setaeoninnermarginand7setaeat outerdistalangle;carpusl.8timesaslongasmerus, with5‑10setaeoninnermarginand4‑5setaeonouter distalangle;propodusalittlelongerthancarpus,with 7‑8setaeoninnermargin,3setaeonoutermarginand

4‑6setaeatouterdistalangles;dactylusO.8timesaslong aspropodus,withl‑2spine‑likesetaeoninnermargin andasetaonoutermargin.

Pleopodl(Fig.3E):sympodl.4timeslongerthan wide,innerborderwith4hook‑likepromberances;

exopodovoid,with29‑33setaearoundthemargin.

Pleopod2(Fig.3F):sympodrectangular,alittle longerthanwide;endopodrectangular,2.5timesaslong aswide,withlonghorn‑shapedbasalapophyse extendingtowardtheinnermarginofpeduncleanda smallpromberanceatthetip;exopod2‑segmented,basal segmentpentagonal,with3setae,terminalsegment elliptical,withl5‑19setaearoundthemargin.

Pleopod3(Fig.3H):endopodovate;exopod rectangularandlargerthanendopod,twiceaslongas wide,withatransversesumrelineand9‑14setaeon basalareaofoutermargin.

Pleopod4(Fig.31):ramielliptical,endopod elongated,exopodwithS‑shapedsumrelineand3setae onbasalpartofoutermargin.

Pleopod5(Fig.3J):bothramielongated,butshorter thanpleopod4.

Uropod(Fig.2G)longandoccupiedabout28‑33%

ofthewholebodyandtwiceaslongaspleotelson;

sympodoccupiesof60%ofwholeuropodlength,with 5‑6setaeoninnermarginand6setaeonoutermargin;

endopodthree‑fifthsaslongasbasis,with3setaeon bOthmarginsandatufiof5‑6setaeatthetip;exopodO.7 timesaslongasendopod,with2setaeoninnermargin,3 setaeonoutermarginandamfiof5‑6setaeatthetip.

Female:Body(Fig.5)4timesaslongaswide.

Antennawith72〜80flagellarsegments・Tbtallengthof pereopodabout98%aslongaspereopod3.Pleopodl semicircular.Pleopod21anceolate,withl6setaearound thetip・Uropodnotsolongasmale:occupiedabout22%

ofthewholebodyandaslongaspleotelson.Other feamresimilartomale.Otherfeamresareasmale.

Habitat:Specimenswerecollectedmainlyfifomthe shallowrockybottomwithmud,nearentrance,mainly shallowerthanlOcminwaterdepth.

Re"Ic"ks:Thespecimensexaminedinthissmdyare identifiedtobePh花αm e""s"nwa碗z""(Thttersall).

Thoughtheoriginaldescriptionofthisspeciesdidnot

refertoeveryappendage.Afterthat,U6no(1927), Matsumoto(1961),Matsumoto(1962),Matsumoto (1963)referredandfiguredsomeappendages.Recentlyl Nunomura(2013)redescribedthisspeciesbasedonthe specimensfifomMatsuyama,Shikokuandpointedout severaldifferencesfifomthesepapers・Ifbundnotafew differencesamongtheabove‑mentioneddescriptions.

Amongthesedifferences,lengththeratioofbody lengthtobodywidth,relativelengthofuropod,number offlagellarsegmentsisconsideredtobechangeable accordingtheirage.Astothenumberofcouplinghooks onmalepleopodandnumberofcouplinghooksof maxilliped,thepossibilityoftheindividualvariationiS highel:Whereas,thefbllowingfeaturesareconsideredto begeographicallycharacteristicvariation,becausethe feamresarestablesinthepresentspecimens:(1) presenceofapairofconcavitiesontheposteriormargin ofpleotelson(entireinoriginaldescription),(2)not remarkablyshorterpereopods4(ratiooftotallengthof pereopod4topereopod3inoriginaldescription95 98%,but82%intheMatsumoto'sreport(1963),(3) morenumbersofsetaeexopodpleopod3(uptol4inthe presentspecimens,whereas9inoriginaldescriptionand Matsuyamaspecimens),(4)numeroussetaeonmiddle lappetofmaxilla(24‑30inthepresentspecimens, whereasl6inMatsuyamaspecimens,notreportedin originaldescription),(5)relativelylongerexopodof uropod(morethanO.70inthepresentspecimens, whereasaboutO.55inoriginaldescriptionandO．33in Matsuyamaspecimens)and(6)lessnumerousinner spine‑likesetaeondactylusofpereopodl(10‑llinthe presentspecimensandl2intheoriginaldescription, whereasl5‑16inMatsuyamaspecimens).

Asexplained‑above,thisspecieshasunremarkable butnotafewgeographicalvariations.Thesemaybe becausetheirinherentlackofdispersalabilityandlack ofdispersalabilityofisolation.

Acknowledgment:Iwouldliketoexpressmysincere gratimdetoDr・IchitaroNiibe,FacultyofLife, EnvironmentalScience,ShimaneUniversityjfbrhis kindnessinplacingtheimportantmaterialatmydisposal, toMr.HidenoriYoshigou,ChugaiT℃chnosCorporation,

inhiskindnessingivingchancetoexaminethefirst specimensandphotos,andtoMr.KazunariKadowakiof

ShimanePrefectureNamreObservationlnstructorfbrhis

kindnessinarrangetheintroductionofDr.Niibe's collectionfbrthepresentsmdy.

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島根県松江市大根島の熔岩洞から発見されたナガミズムシ P施肥α加伽e伽s加叩α卿"〃j(Tattersall)

（甲殻類，等脚目，ミズムシ科）の標本について

布村昇'＊

2017年9月22日受付 2017年ll月28日受理

要 旨

島根県松江市の大根島は島全体が火山で，主に玄武岩の溶岩からなるが，溶岩が流れる際に できた熔岩燧道である幽鬼洞から発見されたナガミズムシ属（甲殼亜門，軟甲綱，等脚目，ミ ズムシ科)の標本を調査したところ,助花"oqse"""wα腕"mi(Thttersall)と同定された。しかし，

原記載や従来報告された幾つかの報告との形態的相違が見つかった。そのうち，腹部節後端にl 対の浅いくぼみがあること，第4胸脚が第3胸脚に比して著しく小さくはないこと，尾肢が比較 的短いこと，第2小顎の基節内葉の剛毛数や第3腹肢外肢の剛毛数が多いこと，第1胸脚指節内縁 の鰊の数が少ないこと，尾肢外肢の長さが内肢に比して著しく短くないことなどは地理的変異 と考えられる。なお，顎脚の交尾鉤数やオス第1腹肢基節の交尾鉤数などは個体により変異があ るようである｡そのほかの変異は成長の変化に伴って変化する形質である可能性が高い｡なお，

この燧道はドウクツミミズハゼのなどの貴重種が生息しており，崩落の危険があるため入洞は 禁止されており，今後も多くの標本を採集することは困難であると思われるので主に分類形質

として必要となる可能性の高いオスのほとんどの付属肢の形態を記載しておく。

キーワード：ナガミズムシ，ミズムシ科，等脚目，再記載，分類

'金沢大学環日本海域環境研究センター研究領域部門海洋環境領域臨海実験施設

ム4‑1

*連絡著者

〒927‑0553石川県鳳珠郡能登町小木