A Remarkable New Species of the Genus Platycerus (Coleoptera, Lucanidae) from Japan

2007·6.7 MB·English

by  Imura, Y

Elytra,Tokyo,35(2):491-496,November3,2007
ARemarkableNewSpeciesoftheGenusPlatycerus
(Coleoptera, Lucanidae) fromJapan
Yuki IMURA
Shinohara-cho1249-8, Kohoku-ku, Yokohama,222-0026Japan
Abstract AnewspeciesofthegenusPlatyceruswithpeculiarlyshapedgenital
organisdescribedfromthemountainousregionofJapanunderthenameP.sue.
It was jn the1980sthat twonewspeciesof thelucanidgenusPlatyceruswere
consecutivelyfound fromJapan,andtotalnumberofthespeciesincludedinthesame
genus swelled up to four, namely, P delicatulus LEWIS, 1883, P acutico11is Y.
KUROSAWA, 1969, P kawadai FUJITAet ICHIKAWA, 1982 andP.Sugitai OKUDAet
FUJITA,1987. Sincethen,thegenushasbeenwidelyandvigorouslysearchedbymany
coleopteristsattractedbythiscutelucanids. Asaresult,notafewfindingshavebeen
broughttolightontheirdistribution,geographicalvariation,habitatandrightdownto
theecologyinthelast twentyyears. Nevertheless,nodiscoveryhasbeenmadeat the
specjesleve1untilwell intothe2000s,andsuchhypothesisastheJapanesePlatycerus
containsfourspecieshasbecomewhateverybodybelieves.
However,astudyondetailedstructureofthemalegenitalorganrecentlymadeby
myselfrevealedthatP.sugitai isnotamonotypica1speciesbutshouldbeclassifiedinto
at least threedifferentcategories, that is,P.sugitaiendemictoShikokuandtwonew
speciesfromKyushuandtheKiiPeninsulaofHonshu, respectively(IMuRA,2007;see
theother pages of this volume). And besides, another remarkablespecies having
remained undiscovered isnow introducedintoscience.
InthecourseofcollectingfreshPlatycerusspecimensforexaminationofinflated
endopha11usandDNAanalysis,Irecentlyhadanopportunitytocomeacrossastrange
speciesinthemountainousregionofacertaindistrictofJapan. Viewedfromcharacter-
isticallypointedhindanglesofthepronotum,thebeetledoubtlessbelon9stothe9rouP
of P acutico11isbut isstrikingly different fromall theknownspeciesin thepeculiar
modificationofthegenitalorganinboththesexes. Inthepresentpaper,Iamgoingto
describeit under thenameofP.sueasaremarkablenewspecies.
I thank Dr. Shun-Ichi U直NO of the National Museum of Nature and Science,
Tokyo, forreviewingthemanuscriptof thispaper.
492 Yuki IMURA
Platycerussue IMuRA,sp
n ov.
[Japanesename:Takane-ruri-kuwagata]
(Figs.1-3)
Male. Length (includingmandibles):10.2-12.1 (arithmeticmean:10.76)mm.
Bodyabovefineblueandhardlybearinggreenish tinge;mandibles,palpi,antennae,
knees,protibiaeandproximalpartsoftarsialmostblack;distalpartsoftarsiandclaws
dark brown; meso- andmetatibiaeand femoraexcept for thedistalends yellowish
brown;venterblack, thoughlateralsidesofabdominalsternitesVIIusuallybrownish.
Headalmostasintheothermembersofthegenus;itsdorsalsurfacenotsocoarsely
scattered withsmall punctureswhicharenot con uent withoneanother;mandibles
(Fig.1-c) verysmallandshort,notconcaveaboveinbasalportions,not formjnga
longitudinalridgealonginnermargins,withtheoutermarginsroundlyarcuatethrough_
outandnotsubangulateat theapicalthirdasisoftenobservedinalliedspecies;apical
portions rather acutely tapering towards the tips which aresharply pointed; inner
marginsofretinaculairregularlyserrated,with threetofiveteethoneachside.
Pronotumtransverse, 1.47-1.58 (arithmeticmean: 1.52) timesaswideas long,
widest at or alittlebehindthemiddle; lateralsidesroundlyarcuateandirregularly
serratedinapicalportions, faintlyangulateat thewidestpart, thenratheracutelyand
straightlyconvergent towardshindangleswhichareprotrudent laterallywiththetips
rathersharplypointed; front anglesremarkablyprotrudinganteriadandtriangularly
pointed; disc moderately co nvex above, rather remarkably depressed along lateral
marginsnear front angles, with thediscscatteredwithpunctureswhicharealittle
smaller insizethan thoseonhead.
Elytraratherrobust foramemberofthegenus,1.68-1.77(arithmeticmean:1.70)
timesaslongaswide,widestobviouslybehindthemiddle,withthelateralsidesnearly
straight and slightly divergent posteriad in apical halves and roundly arcuate near
apices;shouldersdistinctandsubangulate,withaverysmallhumeraltoothoneachside;
surfaceratheruniformlyscatteredwithsmallpunctureswhichareoftenarrangedin
longitudinalrows;intervalsratherroughlyrugose-striatenearthesuturalpartinmedian
portions.
MalegenitalorganasshowninFigs 3a-f;apicalmarginofbasalpieceonventral
sidenottriangularlypointedbutsubtrapezoidallyprotrudedapicad;paramerewiththe
lateralsidenotstronglyin atedinbasalportion,itsinnermarginonventralsidefaintly
emarginatethroughout,andinner-apicalangleeffacedinbothventralandlateralviews;
viewed dorsally, inner margin of each paramere widely and roundly emarginate
throughout,withtheinner-basalangleobliquelyprotrudent;aedeaguswiththeproximal
Partasin theothermembersofthegenus;distalpartwineglass-likeinshape,deeply
re-entrantapicadat themiddletoformalargeU-shapedsclerotizedplatein ventral
view; itssurfacerathercoarselyand transverselywrinkled thoughnoobliquekeel is
developed, with theperipheralportionnear thebordersbetweenendopha11us rather
coarselyscatteredwithsmallgranules;endopha11uswhenfullyinflatedlarge,robustand
RemarkableNewPlatycertisfromJapan 493
b b
l 2
a
Figs.1-2. Platycerussuesp nov;1, (holotype);2, (paratype). - a,Habitusindorsalview
b,dittoinventralview;c,mandiblesindorsalview
nearly rectangularly inflexed at themiddle; itsbasal portionstrongly inflated,stoutly
producedventrad,withapairofsmallprotrusionsatthetip;medianportioncylindrical,
nearlyparallel-sided indorsal view, withapairof larger membranousprojectionson
both sidesof flagellum; flagellum indicated by longitudinallyset linear scleritecom-
pletelyattached to themembranouswall of endopha11us, thoughvestigial in thearea
between the paired projections in mid-endopha11us; apical portion of endopha11us
cylindrical andstout, noaccessory inflationbeingdeveloped, with the tiphemispheri-
ca11y rounded.
Female. Length(includingmandibles):9.8-21.1mm. Bodyabovebrassywith
agreenishtingeonheadandpronotum;antennaealmostblack,mandibles,palpi,knees,
protibiaeand tarsi reddish black to reddishbrown;meso- and metatibiae and femora
except for the distal ends dark yellowish brown; venter black, with a remarkable
greenish tingeonmetasterna;abdominalsternitesdark reddishbrown.
494 Yuki IMURA
Headsmaller thaninmale,withthedorsalsurfacemuchmorecoarselyscattered
with larger punctureswhich are confluent with one another in anterior and lateral
portions;mandibles(Fig 2-c)smallandshort,withthebasicstructurealmostasinthe
othermembersofthesamegenus.
Pronotumtransverse,1.41timesaswideaslong, widest nearlyat themiddle, and
moreacutelynarrowedtowardsapexthan towardsbase; frontanglesmuchshorterand
lessstronglyprotrudedanteriad than inmale, hindanglesasinmale; lateralmargins
irregularly anddistinctly serrated; discscatteredwith larger puncturesthan inmale,
which areconfluent withoneanotherin lateralportions.
Elytramuch robuster than inmale, 1.50timesaslongaswide, widest obviously
behindthemiddle,withthesideseitherstraightorveryslightlyemarginateforashort
behind shoulders, moderately arcuate from behind themiddle to apical tips;
way
shouldersdistinct andsubangulate, withasmall humeral tooth oneachside;surface
ratheruniformlyscatteredwithsmallpunctureswhichareoftenarranged in longitudi-
nalrows;intervalsonlyfaintlyrugose-striatenear thesuturalpart inmedianportions.
FemalegenitalorganasshowninFigs 3g-f;gonocoxiteratherstout,subovoidin
shape,with thelateralsidesgraduallydivergent towardsthebasein ventral view; its
inner-apical corner not angulatebut nearlystraight or faintly rounded, outer corner
effaced.
Typeseries. Holotype: ,mountainousregionofJapan,collectedbyY.IMURAin
2007, tobepreserved intheDepartmentofZoology, NationalMuseumof Natureand
Science,Tokyo. Paratypes:15 10 早,samedataasfor theholotype,preservedin
,
thecollectionof Y. IMURA (Yokohama).
Notes. Thepresentnewspeciesisreadilydiscriminatedfromalltheotherspecies
ofthegenusbypeculiarlyshapedmalegenitalorganasdescribedabove. Concerningthe
female genitalia, thenewspecies differs from thealliedspecies in characteristically
featuredgonocoxitewhichisrobusterandmuchlessacutelynarrowedtowardstheapex.
Also from theexternal appearance, thenewspeciesisdistinguishable fromtheallied
species in the following respects: 1) outermarginsofmalemandiblesusuallymore
roundlyarcuate throughout andoccasionallysubangulateasinmost individualsofP
acutico11isandP.sugltai;2) innermarginsofmalemandiblesnot forminglongitudinal
ridgeas inP acutico11isandP.sugitai; 3)pronota1discmorewidelydepressedalong
lateralmarginsnear frontangles;4)elytraalittlerobuster,with thedisclessfinelyand
alittlemoresparselyrugose-striatethaninP.sugltai,thoughrathersimilar insculptural
patterntoacertaingeographical raceofP acutico11is. Thesediagnosticpointsarealso
available for two speciesallied toP.sugltai described from Kyushuand the Kii
new
Peninsulaontheother pagesof thisvolume (IMuRA, 2007).
Fig.3. GenitalorganofPlatycerussuesp nov;a-f,malegenitaliawith fullyinflatedendophalius;g-
l, femalegenitalia. - a, Ventralview;b, rightsubventra1view;c, rightlateral view; d, right
subdorsalview;e, apicalview; f,rightsubdorsalview;g,1eftlatera1view;h,subapicalview,1,left
gonocoxiteinventral view.
RemarkableNewPlatycerusfromJapan 495
496 Yuki IMURA
The distribution of the new species is considered to be restricted to the high
altitudinalareaonacertainmountainrange,anditshabitatmightbeeasilydamagedif
manycollectorsmakearushfor there.SincethegenusPlatycerusisimmenselypopular
amongmaniacsinJapan,it ishighlyplausiblethatanannouncementofdetailed locality
causes a rush of collectors, and in its turn givesanadverseeffect to thehabitual
environment. ThisiswhyIrefrainfromrevealingtheexactlocalityinthepresentpaper.
Itsdetailswillbebroughttolightafterweknowmoreonthedistributionalrange,local
andindividualvariations,habitatandecologyofthenewspecies,sothatwecanmake
aprospectsfor theprotectionofthisvaluablelucanid.
Etymology. Thenameofthenewspecies,Sue [su:orsu],comesfromanickname
ofmywife,Masumi,ProfessorofInternationalUniversityofHealthandWelfare,who
isalwayssympatheticabout myentomologicalactivities.
要 約
井村有希:本邦から発見されたルリクワガタ属の顕著な1新種. - 本邦の山岳地帯から得ら
れたルリクヮガタ属の1種を新種と認め, タカネルリクワガタPlatycerussueという新名を与え
て記載した. 形態学的には, 前胸背板の後角が尖るコルリクワガタ群に属するが, 雌雄交尾器の
形態がおおきく異なるため, 既知種からの識別はきわめて容易である. 新種名の「ヌー」 は, 筆
者の妻の愛称にちなむ. 本種はこれまで, 某山塊の一角から得られているにすぎず, きわめて局
地的な分布を示すものと考えられる. ルリクワガタ属は愛好家からの人気がひじょうに高いグ
ループであるため, 20年ぶりに本邦から発見された顕著な新種であることや, 生息範囲が限定さ
れている可能性が高いことなどを考慮すると, 産地の公表は採集者の殺到と乱獲に伴う現地の環
境破壊を招き, ひいては社会問題にまで発展する可能性が高い. したがって, 本種の分布範囲や
生息環境, 生態などに関するより詳細な知見が得られ, その保全対策に対する目処が立つまで,
具体的な産地名の公表は差し控えておくことにしたい.
References
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