A New Upper Hypogean Species of the Subgenus Yuadorgus (Coleoptera, Trechinae) from Southwestern Shikoku, Southwest Japan

5 Pages·2002·5 MB·English

by  Ueno, S-I

Elyt,-a,「okyo,30(2):285-289,November22,2002
ANewUpperHypogeanSpeciesoftheSubgenusYuadorgus
(Coleoptera,Trechinae) fromSouthwestern
Shikoku,SouthwestJapan
Shun-lobiUENo
DepartmentofZoology,NationalScienceMuseum(Nat.Hist),
3-23-1Hyakunin-cho,Shinjuku,Tokyo,169-0073Japan
and
YoshiyukiITO
1407-2Nunoshida,KochiCity,Kochi,781-5101Japan
Abstract Anewspeciesofthetrechinesubgenusyuado,gusisdescribed from
thesouthwesternpartoftheIslandofShikoku,SouthwestJapan,underthenameofRyu-
gadous(Yuado,gus)kasahara1. Thisisthefirstupperhypogeanspeciesof thesubgenus
andmarksthesouthwesternlimitoftherangeofgenericdistribution.
Inthepresentpaper,wearegoingtodescribeanewupperhypogeanspeciesof
trechine beetle from southwestern Shikoku,SouthwestJapan, indedication to the
memoryofSumaoKAsAHARA(1935-2001).KAsAHARAwasagoodfriendofoursand
alwayshelped thesecondauthorof thepresent paper indetermining thescientific
namesofnewlyfoundspecies.HewasdeeplyinterestedinthecarabidfaunaoftheIs-
landofShikoku,anddescribedsomenewpterostichineandharpalinespeciesfromthe
ShikokuMountainsincollaborationwithITO.Webothmisshimsorely.
What istakenup tohismemory isanewspeciesofYuadorgusofthetrechine
genusRyugadousdiscoveredbythesecondauthoronahilllyingontheleftsideofthe
Shimanto-gawaRiver,wherenoeyelesstrechinebeetleshavepreviouslybeenknown.
Thisisnotonlythefirstupperhypogeanspeciesofthegenusbutaspeciesoccurringat
thesouthwesternperipheryofthegenericdistribution.Asisusual foramemberofthe
genusRyugadous, external peculiarityof thenewspecies is not particularly pro-
nounced,but itsspecificstatusisclearlyexhibitedbythecharacteristicconfiguration
ofitsmalegenitalia.
Theabbreviationsemployedinthepresentpaperarethesameasthoseexplained
inapreviouspaperofthefirstauthor's(cf.UENo,1979,pp 2-3).
286 Shun-IchiUENoandYoshiyukiITO
Ryugadous(Yuadorgus) kasaharalS.UENoetY.ITO,sp nov.
(Figs.1-3)
Length:3.80-4.35mm(fromapicalmarginofclypeustoapicesofelytra).
Externally similar toR e1ongatulusS.UENo (1979,pp 4, 7, figs 6-8) from
Ganigoe-no-kanaudoatOkuodo,butthepronotumisnarroweratthebaseonanaver-
agewiththesideslessdeeplysinuatebeforethebase,andtheelytraaremoreregularly
roundedatthesidesinapicaltwo-thirds,moreevenlyconvexonthedisc,andusually
lesssalientatthehumeralangles.Definitelydifferent fromRe1ongatulusinthecon-
figurationofmalegenitaliaaswillbedescribedlater.
Colour moreor lessevidentlydarker than inR e1ongatulus,legsandventerof
hindbodyparticularlydarker,sometimeswithdarkreddishbrowntibiae.Headas in
R e1ongatulus, though thelabrum is less deeply emarginateat theapex, which is
nearlystraightinmedianthird;antennaealittlelonger,reachingapicalthirdtothree-
sevenths(usuallytwo-fifths)ofelytrain(5,apicalthree-seventhsofelytrain Prono-
.
tumusuallymorecontractedat thebasethaninRe1ongatulus,widestataboutthree-
fourths frombase;PW/HW135-1.45(MI39),PW/PL0.99-1.06(M1.02),PW/PA
1.34-1.43 (M I38),PW/PB139-1.49(M I44),PB/PA 0.91-1.00 (M0.96);sides
morenarrowlybordere beforethewidestpartinparticular, thaninRe1ongatulus,
similarlyarcuatein frontbutusually lessdeeplysinuateataboutbasal fifthoralittle
behindthatlevel,andtheneithersubpara11e1orveryslightlyconvergenttowardshind
angles,whicharemoreor lesssharpandprotrudeposteriorly; frontanglesobtuse
thoughmoreorlessproducedforwards.
Elytraelongate,muchwiderthanpronotumandabouthalfaslongagainaswide,
widest at aboutmiddle, andmoregradually narrowed towards basesthan towards
apices, with ample rounded apical halves; EW/PW 1.65-1.75 (M 1.70), EL/PL
2.49-2.74(M2.61),EL/EWl47-1.54(MI52);sidesmoderatelyroundedinapical
two-thirds,withapicesratherwidelyandalmostconjointlyrounded;humeralangles
usually lesssalient thaninR e1ongatulus;dorsummorestronglyconvex,withadeep
round depression inbasal area; striationas inR e1ongatulus,withdistinctscutellar
striole,striae1-4deepenedinbasaldepression,stria5alsodeeply impressedat the
basalportion;stria3withasinglesetiferousdorsalporeaf t/7-1/5frombase,stria5
withtwosetiferousdorsalporesatabout3/10and5/8frombase, respectively.Legsas
inRe1ongatulus.
Malegenitalorganverysmallandlightlysclerotized,generallysimilartothatof
Re1ongatulus,butmarkedlydifferentinthelongerandnarrowerapical lobeofaede-
agusandshort,somewhatpara11e1ogrammaticcopulatorypiece.Aedeagusalittleless
thantwo-seventhsas longaselytra,gentlyarcuateandlightlycompresse with the
dorsal marginsemicircularly rounded in profile in proximal two-thirds; basal part
fairly large,hardlybentventradattheleve1ofparameralarticulation,withlargebasal
orificewhose sidesare only shallowly emarginate; sagittal ailerondistinct though
small;vieweddorsally,apical lobenearlyparallel-sidedandnarrowlyroundedatthe
New r前do,gtlsfromtheUpperHypogeanZone 287
Fjg. 1. Ryugadous(Yulado,gus)kasaha,-a1S.UENoetY.ITO,sp nov., fromFudo-yamainsouthwest-
,
ernShikoku.
tjp;viewedlaterally,apicallobelongandnarrow,feeblycurvedventraci,graduallyand
slightlydilatedtowardsapex,whichisrounded;ventralmarginshallowlybutwidely
emarginateinprofile.Innersaccoveredwithhardlysclerotizedscalesnearapicalori-
ficeandarmedwithacopulatorypieceabouttwo-seventhsaslongasaedeagus;copu-
latorypiecesomewhatpara11e1ogrammaticwithbisinuateventro-apica1andmoreir-
288 Shun-IchiUENoandYoshiyukiITO
3
/ /
/、一一ー/
l
0.3mm
Figs. 2-3. MalegenitaliaofRyugadous(Yuado,gus)kasaha,alS.UENoetY.ITO,sp nov., fromFudo-
yamainsouthwesternShikoku;leftlateralview(2),andapicalpartofaedeagus,dorso-apica1view
(3).
regularly sinuatedorso-proxima1margins, narrow area along ventral margin more
heavilysclerotizedthantheotherpart,particularlyinrod-likeproximalportion.Styles
slender withnarrowapicalparts, leftstyleonlyslightly longer than theright,each
bearingthreeapicalsetae,whicharesometimessupplementedwithashorterminute
fourthsetaononestyle(cf.Fig2).
Typeseries. Holotype: (3,allotype: , paratypes: 7 6 (incl 2 tenera1
,
),20-IX-1993,Y. IT01eg.AlldepositedinthecollectionoftheDepartmentofZo-
ology,NationalScienceMuseum(Nat.Hist),Tokyo.
Typelocality. Fudo-yama,550minaltitudeonthenorth-northeasternslope, in
Taisho-cho ofKochiPrefecture, on thePacificsideofthe IslandofShikoku,South-
westJapan.
Notes. Of thetwo, previously known congenersofYuadorgus isolated in the
southwesternpartofthesubgenericdistributionalarea(cf fig.1inUENo,1979,p 2),
R.pravusS.UENo(1979,pp 4,6,figs 4-5)occursinanabandonedaditofananti-
monymine,calledMiyanotani-no-kanaudo,whichisgeographicallynearertothehabi-
tat ofR kasahara1thanGanigoe-no-kanaudois,thelatterbeinginhabitedbytheother
species,R e1ongatulus. The former adit isabout 11kmdistant to theeast-northeast
fromFudo-yama,whereasthelatteraditsareabout17.5kmdistanttothenorth-north-
west fromthesamehill.UnlikeFudo-yamawhichliesontheleft(southern)sideofthe
Shimanto-gawa River, the two mines are located on the right (northern) side, and
Miyanotani-no-kanaudo ismuchnearer to (only18kmdistant from) the river than
Ganigoe-no-kanaudois(about7kmdistant fromtheriver). Inspiteofsuchageo-
graphicalsituation,R kasaharaiisdoubtlessclosertoRe1ongatulusthantoR.pravus
NewYuadorgtlsfromtheUpperHypogeanZone 289
inboththeexternalandgenitalicmorphology.Thisisparticularlyapparent inthecon-
fjgurationofthemalegenitalia,sincethoseofthelatterspeciesarequiteunique(cf
figs.4-5inUENo,1979,p 5).
Fudo-yamaisahill780minheightlyingabout6kmsouthoftheShimanto-gawa
River.ThetypespecimensofRkasahara1weredugout fromcolluviadepositedalon9
theheadwatersofastream owingdowntheeasternsideofthehillandemptyinginto
theShimanto-gawa.Thecollectingsiteisabout 150mbelowthenorthernridgeand
shadedbyasmallpatchofmainlyevergreenbroadleavedtrees.Thispatchofnatural
forestisnotlargeandsurroundedbyplantationsofJapanesecedar.Thetrechinebeetle
was foundat adepth of40-70cm, togetherwithanotherupperhypogeancarabid,
Pterostichus(Sphod1・?eronla)miyamaiKAsAHARAetY.ITO(1987,p.142, figS.1-5;
alsOY.ITO&KASAHARA,1988).
要 約
上野俊一・伊東善之:四国南西部の地下浅層から見つかったヒラタメクラチビゴミムシ亜属
のl新種. - 四国の南西部,四万十川本流の左岸(南側) に位置する不動山の地下浅層から,
イシカワメクラチビゴミムシ属ヒラタメクラチビゴミムシ亜属の1新種を記載し, これを昨年
のg月に亡くなった笠原須磨生氏に捧げて, カサハラメクラチビゴミムシRyugado1ls(「tladorgus)
kasaha,-ais.UtNoetY.ITOと命名した. この新種は, 同属の種としては初めて地下浅層から記録
されるものであり, しかもその生息地が属の分布域の南西端に位置することでひじょうに興味
深い.
References
ITO,Y.,&S.KAsAHARA,1988.OccurrenceofPte,'ostic1lusmtyama1insouthwesternShikoku.ColeOpte''-
1sts'News,nokyo,(83/84):8.(InJapanese)
KAsAHARA,S.,&Y.ITO,1987.AnewPte,ostich1ls(Coleoptera,Carabidae)f「omtheuppehypOgeanZone
ofcentralShikoku,SouthwestJapan.Ko,I、t lt,To(kyo,55:139-145.
UtNo,S.-I.,1975.ThecavetrechinesofthesubgenusYuado,gus(Coleoptera,Trechinae).Bull natn.Sci.
Mus.,Tokyo,(A),1:169-178.
_ 1g7g.Newyuadog1ls(Coleoptera,Trechinae)fromsouthwesternShikoku,Japan.Jspeleo1.Soc.
Japa'i,4: l-10.