A new species of the genus Ligia (Crustacea: Isopoda: Ligoodae) from steep streams of Chichijima and Anijima Islands of the Ogasawara Islands

A new species of the genus Ligia (Crustacea:

Isopoda: Ligoodae) from steep streams of Chichijima and Anijima Islands of the Ogasawara Islands

journal or

publication title

Bulletin of the Toyama Science Museum

number 34

page range 73‑79

year 2011‑03‑15

URL http://repo.tsm.toyama.toyama.jp/?action=repos itory̲uri&item̲id=940

富山市科学博物館研究報告第34号，pP73‑79；（2011）

ANewSpeciesofthegenuSL噌加（CruStacea：IS0poda：Ligiidae）

fromsteepstreamS0fChichijimaandAnijimaISlandS0ftheOgawaraISlandS＊

NoboruNunomura')，HirokoHoriguchi2)，TetsuroSasaki3) MantaroHironaka2）andTakahikoHariyama2）

ToyamaScienceMuseuml)，LaboratoryofBiology，HamamatsuUniversitySchoolofMedicine2》‐

3）

InstituteofBoninology

Nishinakano‑machi，Toyama‑shi，939‑8084,Japan')，

1‑20‑1,Handayama，Higashi‑ku，Hamamatsu‑shi，ShizuokaPref，431−3192，Japan2)， Miyanohamamamichi,Chichijima,Ogasawaralslands,Tokyo，00‑2101,Japan3）

小笠原諸島父島･兄島の渓流から発見されたフナムシ属（甲殻亜門：等脚目：フナムシ科）の1新種

布村昇')，堀口弘子2)，佐々木哲朗31，

弘中満太郎2)，針山孝彦2）

富山市科学博物館')，浜松医科大学生物学教室2)，小笠原自然文化研究所3》

〒939‑8084富山市西中野町1‑8‑311)，〒431‑3192浜松市東区半田山1‑20‑12)，

〒lOO‑2101東京都小笠原村父島字宮之浜道3）

小笠原諸島父島と兄島の渓流から発見されたフナムシを新種Ljg/αro〃e""CO/αとして 記載した。本種は純粋な淡水域に生息する種としては本属で初めての記録と思われる。

本種は同じく父島の海岸に生息する〃gjaya脚α"jsﾙ〃Nunomuraともっとも類似する が、尾肢が長いこと、顎脚髪縫合線が完全に見られること、第1小顎の基節内葉先端 に歯に鋸状のものが含まれることなどにより区別される。

Keywords：Isopoda，Ligiidae，newspecles，〃g/αro〃e""CO/α，steepstreams Ogasawaralslands，Japan

Hitherto，thiIty‑threespeclesofthete汀estrialisopodgenusL壇jaFa6"c〃sl798areknownintheworld

nalfnss，2003)．Amon2themtwosDecies.〃宮jα加"j"e"sjsNunomural979and〃pjavα"?α"な〃/NImnm,,ra1990

(Schmalfnss,2003).Amongthemtwospecies,〃gjα加"j"e"sjsNunomura，l979andL壇jαﾉ"α"jsﾙ〃Nunomura，l990 havebeenrecorded廿omtheOgasawaralslands（Nunomura，1979,1983；1990,1991,Tsuge，2008）But,anyspecle真 hasnotrecorded廿omsteepstreamRecently，membersoftheLaboratolyofBiology，HamamatsuUniversitySchoOI ofMedicine，collectedsomespeclmensofanunidentifiedspecies〃gja廿omasteepstreamofChichijimalsland， Ogasawaralslands（Fig｣‑2)，andsubmittedthosespeclmenstothesenlorauthorfbridentificationLater，additionai speclmensinbettercondition，collected師mChichijimaandAnijimaislands，weremadeavailablebvT・Sasakifbr smdyJnthispaper,anewspecies,L堰jaro"で""CO/α,isdescribedandillustrated､Thenewspeciesisthe価rstrepre sentatlveofthegenusinhabitinginsmallstreamsonsteepslopes．

＊ContributionsfTomtheToyamaScienceMuseum，No.40号

Nllnomura，N・an〔lcla

ThetypematerialisdepositedintheNationalMuseumofNatureandScie､Ce,Tokyo（NSMT),ToyamaScience Museum,Toyama（TOYA）KitakyushuMuseumofNaturalHistoryandHumanHistory，Kitakyushu（KMNH）and OsakaMuseumofNamralHistory,Osaka（OMNH).Sizeofspeclmensisindicatedbythebodylength（BL）measured homthemidpointoftheanterlormarginoftheheadtothemidpointoftheposterlormarginofthepleotelson．

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Fig.2AspectsofsamplingSites，

HatsImeura‑gawaRiveI。，Chichijima，0雷 L壇jα rl･ " 〃Nunomura，sp.､．

(takenbySasaki）

ANewSpeciesoftheGenusLjgia

TaxonomV

L増加 〃E"" 〃Nunomura，Sp.n．

INewJaPaneSename：NagaI･e‑hmamuShil

（Figsl‑6）

M1花"α／exα "ed：Holotype：male（BL15．5mm)，NSMT‑Cr21253，upperstreamofHatsuneuraRiver，240m 加mrivermouth,Chichijimalsland,Ogasawaralslands,27。04535N，142.13.20」'E,45minaltimde，l7June2010‑

coⅡT､SasakiAllotype：female（BL18．4mm)，NSMT‑Cr21254,samedataasholotypeParatypes：lmale（BL8．6 mm),NSMT‑Cr21255，andlfETnale（BLl50mm)，NSMT‑Crsamedataasholotype;lmale（BLl32mm)，and2 fbmales（BL73−uOmm）OMNHAr‑8372,samedataasholotype；lmale（BLl5」m、),TOYACr‐23271andlfe‐

male（BLl45mm）TOYACr‑23272，samedataasholotype；lc7（paratype，BL62mm)，TOYACr‑23273and2早 早（BL9.7〜13.8,Ⅱ､）TOYACr‑23291‑23292，samelocalityasholotype，23June2007,collTakahikoHarivamal Male，KMNHIvR500，496)，lfemale（KMNHIvR500，497）

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Fig.3L増加 〃ell" ﾉaNunomura，sI〕.n．

Dorsalviewofholotype（takenbySasaki）

Fig.4AIivestateofL噂iα '"e"" 肱 Nunomura，sp.n．inAnijima．

(takenbVSasaki)．

Non‑type：lJ4早早，upperstreamofTakinoura‑gawa,Amiima27oO7'012,N，142.12518'E，l60minaltimde，ll June2010,co1TetsuroSasaki；6早早，downstreamofariverofAniiima27｡061424N，142。12518'，l50minal‐

timde，coll・TetsuroSasaki．

D c叩"o〃Bodyoval（Figs3,4，5A)，22timesaslongaswide（excludingantennaeanduropods).Colorgener‐

allypalegray，mottledwithirregulardarkernlarkingsondorsalsurface、Evesrenifblm，eachwithabout750onnnatidia，

Distancebetweeneyesrelativelynarrow，0.5timesofeyelength、Surfaceofdorsalsurfaceofbodyalmostsmoothwith sca枕eredmanymlnutegranules、Pleotelsonwith2pairsofrelativelyshallowconcavities；medialareaofposterlormal･‐ ginofpleotelsononlyslightlyandroundlyprotnlded、

Antennule（Fig6A）small，flrstsegmentrectangular，secondsegmentrectanguler；teIminalsegmentsmaⅡand semlcerculAntenna（Fig6B),reachingthemiddlepartofseventhpereonalsomlte,composedof5peduncularand25 Hagellarsegments、

Rightmandible（Fig6C）withincisorprocess3‑toothed;laciniamobilis4‑toothed；8，enicilsbehindlaciniamobilis3 molarprocesswideLehmandible（Fig6D）withincisorprocess3‑toothedラlaciniamobilis2‑toothedう6penicilsbehind laciniamobilis；molarprocesswide・Maxillula（Fig.6E）with3penicilsondistalmarginofinnerendite；outerendite withlOteethうinnergroupof6teethslenderandsawlike，outergroupof4setaestouterandsmallerinnerteeth，Max‐

illa（Fig6F）bilobed；innerlobewithroundapicalmargln；outerlobewithnumeroushairMaxilliped（Fig6G）with enditebearinglOplumosesetaeondistalmargln；palp5‑segmented；segments2‑4withshortsetaedenselyonlnner marglnandl−3setaeatdistalpartonoutermarglnぅtenninalsegmentsmall，withshortsetaearoundmargm・

Pereopodl（Fig6H）withbasisrelativelystout,with3‑7setaeoneachmarginうischiumO,7timesaslongasbasia

Nllnomura，N、tln(lelal

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Fig.5Z噌jα 〃ell"co〃Nunomura,sp.､．

A，habitus，dorsalview；B，penes，ventralviewうC，endopodofpleopodl；Dexopodo菅 thesame；E，lehmalepleopod，ventralview2ラF，rightendopodofpleopod2，ventral vlewぅG，exopodofthesame，ventralview；H，endopodrightplexopodofexopod3‑

ventralviewラIexopodofthesame；J，endopodofleflpleopod4，ventralview；

K，exopodofthesame；L，endopodofpleopod5，ventralview；M，exopodofthesameo ventralviewラN，lefturopod，dorsalview；O，posterlormarginofpleotelson，dorsalview (A‑E,H‑O,Holotypemale;F‑G,paratypefemale)．

with5setaeonmnermarglnandlsetaatouterdistalangle；merus0．8timesaslongasischium，with2‑3setaeon 1nnermargln；carpusL2timeslongerthanmerus，with2setaeonlnnermargm；propodusslightlylongerthancarpu＆

with9‑lOsetaeonlnnermargmandll‑l2shortsetaeonoutermarginラdactyluswithoutanyprotuberance、

Pereopod2（Fig61)withbasis26timesaslongaswide;ischiumO､7timesaslongasbasis,with3setaeonouter marglnラmenlsslightlyshorterthanischium,with2groupsof5−6setaeonlnnerdistalpartandouterdistalangle)今 calpus1．3timesas］ongasmerus，bearing4setaeonlnnermargin，slightlybecomingthickerinbasalpart；propodus O,8timesaslongascarpus，with6‑7setaeonoutermarg1n、

Pereopod3（F喝6J）withbasis31timesasIongaswide,with5setaeonlnnermarglnandlOshortsetaeon outermargin；ischiumhalflengthofbasis，with7−8setaeonlnnermarglnand4setaeincludingalongeroneonouter margln；merusl,ltimeslongerthanischium，with4setaeonlnnermarginand3setaeincludingalongeroneonoutel・

marglnondistalpartofoutermarg1,；carpus1．2timeslongerthanmerus，withlsetaonmnermarglnand5−6setae onoutermargln；propodusO､9timesaslonEascarpus，with5−6setaeonlnnermarglnandaboutlOsetaeonouter

margm．

ANewSpeciesoftheGenus〃9m

B1 A,C−G H−I

Fig.6L増jα 〃e"" 〃Nunomura，sp.､．

A，rightantennule，dorsalviewラB，rightantenna，dorsalview；C，rightmandible，ventral view；D，lehmandible，ventralview；E，lefimaxillula，ventralviewラF，lefimaxilla，ven‑

tralview；G，leftMaxilliped，ventralview；H，leftpereopodl，廿ontalviewぅ1−N，right pereopods2‑7inmale，廿ontalview（All；Holotypemale)．

Nunomura．N，an〔leial

Pereopod4（Fig6K)withbasis24timesaslongaswide,with2setaeonlnnermarginand2setaeonoutermar‐

gin；ischiumO､6timesaslongasbasis，withl2setaeonlnnermarglnandlsetaonoutermargm；merussligh[ly shorterthanischium，with8setaeonlnnermarginand5setaeonouterdistalangleラcamusO､9timesaslongmerus・

with6setaeonlnnermarg1nand2−3setaeonouterdistalangle；propodus1．2timeslongerthancarpus，with9‑10 setaeonlnnermarginand8setaeonoutermarg1n，

Pereopod5（Fig6L）withbasis25timesaslongaswide,with4‑7shortsetaeoneachmargin;ischiumO,7times aslongasbasis，with5−6setaeonlnnermarginandlsetaonoutermargln；merusslightlyshorterthanischium，with 3setaeondistalmargmラcamus1．6timeslongerthanmerus，with6−7setaeon1nnermarginand2setaeonouterdis‐

talangleラpropodus1．2timeslongerthancaIpus，with6setaeon1nnermarglnand4‑5shortsetaeonoutermargln、 Pereopod6（Fig6M）withbasis2．5timesaslongaswide,with6‑7setaeonoutermargin；ischiumO7timesaslong asbasis，withstrongsetaatouterdistalangle；memsO､8timesaslongasischium，with2‑3setaeon1nnermargln andouterdistalangle；carpus1．6timeslongerthanmerus，with8‑lOsetaeon1nnermarginand4−5setaeonouterdis‐ talangle；propodus1．2timeslongerthancal･pus，withll‑l2setaeonlnnermarginandaboutadozenshortsetaeon

outermargln・

Pereopod7（Fig6N）withbasis35timesaslongaswide,with2setaeondistalpartofinnermarginandlseta onoutermargin；ischiumalmostaslongasbasis，with3setaeonlnnermarglnandl−2setaeonouterdistalangle；

merus0.7timesaslongasischium，with6setaeonlnnermarginand4setaeonouterdistalangle；carpus1.7times longerthanmerus，with8−lOsetaeonlnnermarginandll‑l2setaeonoutermargln；propodus1．3timeslongerthan carpus，with5setaeonlnnermarginandll−l4setaeonoutermargln・

Penes（Fig5B）pairedeachpenisabout80timesaslongaswide,apicalparttaperlngtowardthetip,withmuch

hairondistalDart・

Pleopodlwithendopod（Fig5C）pentagonal,withsetaemuchhair;exopod（Fig5D）rounded,with3‑4setae P1eopod2（Fig5E）withendopodstraightanditsapicalareaslightlyrounded；exopodround,with4setaearound

themargln･

Pleopod3withendopod（Fig5H）pentagonalうexopod（Fig51）semicircular,with24‑25setaeonmargln Pleopod4withendopod（Fig5J）rectangular;exopod（Fig.5K）roundlytriangular,bearingl9‑27setae・ PIeopod5withendopod（Fig5L)；exopod（Fig5M）roundlytriangularbearinglO‑23setaeonmargln

Uropod（Fig5M）q8timesaslongasbodylengthDistalhalfofpeduncleblackincolor,Peduncleoframiin length；endopodof1．6timeslongerthanpeduncle．

Fセ脚α/e､Generallysimilartomaleexceptfbrpleopod2：Endopodoffemalerectangular（Fig5F)．

HabitatThepresentnewspeciesdwellsinsteepmountamtorrentofupperareaofsmaⅡ廿eshwaterstreams（Fi9 5，6)．

Re脚伽Thepresentnewspeciesismostcloselyalliedto〃gjaya碗α"jsh",ashoredwellerofChichijimalslan｡， Ogasawaralslands（Nunomura，1990),inhavingsimilarbodycolor‑palegray,mottledwithirregulardarkermarkings ondorsalsurface，swollenapicalpartofstylusonmalepleopod2，andabsenceofmaIenrstpereopod・ButL ro〃e""CO/αissepal･ated廿omL・yamanishiibythefbllowingfeatures：maxillipedalpalpofiscompletedsegmented、 whereaslncompleteinLVa版α"jsh"うantennaofL，torrenticolaislongerandreaches7thpereonalsomlteandnageⅡum composed25segmentsLro〃e""CO/α，whereasthelatterreachesmedialpartofumodalbasisandcomposedof32 HagellarsegmentL．yα"2α"jsﾙ〃；teetharepresentontheouterenditeofmaxillulastronglyserratedinL．yα〃α"jsﾙ"・ ratiooframitobasisofuropodis1.9〜2.4mL，／o〃e""CO/α，whereas0.7〜1.5inL.yα脚α"/sﾙ",．presenceof5stronger saw‑like5teethonthemaxillulaareinL．ro〃e""CO/α，whereasonly3teethinL．yα" "isﾙ"・

L／C〃e""CO/αisalsoalliedtoanotherOgasawara‑species,L6o""e"（Nunomura，1979）inhavingswollenapl‐

calpartofstylusonmalepleopod2andabsenceofmale耐stpereopod，however，thefbrmerlsseparated侭omthe latterbythefbllowingfeamres：longerandreaching7thpereonalsomlteandhaving25HagellarsegmentinL ro〃e""CO/α，whereasatmostreaching5thpereonalonly22HagellarsegmentsZ,．加"加e"sjs；ratiooframitobasisof uropod1.9〜2.4inL・ro〃e""CO/α，whereas1.6〜l7inL加"加e"s/s,．deeperconcavityofposterlorendofpleotelsonin

ANewSpeciesoftheGenusL壇"

LIC〃e""CCIα,itsdepthtopleotelsonwidthis5％,whereas,3.5％inL加""7e" teethonouterenditeofmaxiⅡula islOtorrenticola，whereas6inLbo"加e"sjs，andeachtoothofthenewspecies2､OtimesaslongasthatofL 加""7e"s/s；onlylrowofsmalldenticlesonapicalpartofendopodofmalesecondpleopodinLro〃e""CO/α，whereas 6‑7rowsofdenticlesinL・加"加e"s/s；ratiooflengthtowidthofpenesinthenewspeciesis1.7timesaslongas thatofL・加""7e"s/s；numberofpenicilsofbothmandiblesofL．／o"で""CO/α11−12，whereas6inL・加"脚e"s噸

E""'0/o邸ﾉ.Thespecincepithetisana町ective,acombinationoftheLatintorrentis（＝roarlngstream）andⅧcola (＝dwellers)．Thisspeciesdwellsabsolutely廿omtheroarlngstreamofChichijima,Ogasawaralslands

Acknowledgements

WewouldliketoexpressourslnceregratitudetoMsShokoUmehara（InstituteofBoninology）fbrherhelpin coⅡectingthesematerials,toM胆MasaakiTakiguchi，Dr､HideakiMori，MmHideyukiChiba（JapanWildlifeResearc雲 Center)，Mr､RiichiroTatsuta（MinistrvoftheEnvironment）fbrtheirofferingusefUlinfbmlationisabouttheAnijima

lsland．

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