A New Isolated Trechus (Coleoptera, Trechinae) from the Micang Shan Mountains in Northeastern Sichuan, Southwest China

6 Pages·1999·6.8 MB·English

by  Ueno, S-I

Elyt1・a,Tot?,o,27(2):611-616,November13,1999
ANewIsolatedTrechus(Coleoptera,Trechinae) fromthe
MicangShanMountainsinNortheasternSichuan,
SouthwestChina
Shun-lobiUENo
DepartmentofZoology,NationalScienceMuseum(Nat.Hist),
3-23-1Hyakunin-cho,Shinjuku,Tokyo,169-0073Japan
Abstract A new speciesofthetrcchinegenusTli・colitisisdescribed from the
MicangShanMountainsonthebordersofnortheasternSichuanandsouthernShaanxi,
SouthwestChina,underthenameofT1i・colitis(s.str) lt11ula1. It isasmallspecies「eCO9-
njzedatfirstsightontheabsenceofthepreapica1poreoneachelytronandthepeculiar
conformationofitsmalegenitalia.
Inthepastdecade,manyspeciesof thetrechinegenusTrechushavebeende-
scribe mostlyby DEuvE, fromChina. They areabundantly found on the Tibetan
plateauanditscontinuations,or inthenorthernterritories,andaregraduallyreplaced
bythemembersofthegenusEpaphio,psisinthesouthernpartofthecountry.Anepit-
omeofthisis foundinSichuan;Trechusspeciescommonlyoccurinthenorthernand
northwesternareasoftheprovince,orintheeasternperipheriesoftheTibetanPlateau
(cf.DEUvE,1988,1989, l992,1995,1997;DEUVE&QUEINNEC,1993),buta「eonly
sporadicallymetwithonothermountains(cf.DEuvE,1992,1995;UENo,1998),Which
arefrequentlyoccupiedbythemembersof
ap 1opsls.
OnlytwospeciesoftrechinebeetleshavehithertobeenrecordedfromtheDaba
ShanMountainsandtheircontinuations,stretchingfromnorthwesttosoutheastonthe
bordersofSichuanandShaanxi andextendingintowesternHubei. 0neof themis
Epaphiopsis(Epaphiama)lame11ataS.UENoetYu(1997,p25,figs. l-3)described
fromShennongjiaat theeasternend of the DabaShans, and the other is Para-
gonotrechuslatico11isS.UENoetYu(1997,pp 29,33,figs4-6)recorded fromthe
LiangJiawanYakouontheDabaShans.NoTrechushasbeenmetwithinspiteof「e-
peatedinvestigationsmadebymanyentomologists,abovealtonShennongjia.
Onhisrecent triptotheMicangShanMountains, thenorthwesterncontinuation
oftheDabaShans,Yuki IMuRAcollectedtwodifferentspeciesofhumico1oustrechine
beetles.0neofthemisknownfromonlyafemalespecimenbutispossiblyreferableto
Epaphiopsislame11ata,whereastheotherisanindubitablenewspeciesofthegrand
genusTrechusandisuniqueinitsmorphologicalpeculiarities.Iamgoingtodescribe
this interestingnewspecies inthepresentpaper, under thenameofTrechus(S.St「.)
1'mu1-a1.TheabbreviationsusedhereinarethesameasthoseexplainedinpreviousPa-
612 Shun-IchiUENo
persofmine.
Beforegoinginto further details, I wish toexpressmyheartfelt thankstoDr.
Yuki IMuRA forhiseffort toobtaintrechinebeetles formeonthemountainsnever in-
vestigatedbeforebyentomologists,andalsotomyfrien(i,Mr.FANTing,whomade
everyefforttohelpDr.IMURA'sinvestigationinthefield.
Trechus(s.str)inMralS.UEN0,sp nov
(Figs.1-3)
Length:2.60-2.95mm(fromapicalmarginofclypeustoapicesofelytra).
Asmall isolatedspeciesofshortbroad faciesreadilyrecognizedontheabsence
ofpreapica1poreonelytra.Alsocharacterizedbythepolishedbodysurfacealmost
completelydevoidofmicrosculpture,small ateyes,tumidgenae,presenceofcontin-
uousbasaltransversesulcusonpronotum,stronglyconvexelytrawithonly feeblebut
coarselypunctatestriaeonthedisc,andpeculiarconformationofmalegenitalia.
Bodyshortandbroad,withtransverseheadandprothorax,stronglyconvexovate
elytra, and short appendages; surfacepolished; microsculpturepractically absent,
thoughvestigesoffinetransverselinesarevisiblethroughintegumentontheanterior
partofheadandlargepartofelytra;innerwingsabsent.Colourbrowntolightbrown,
moreor less infuscated in forebody;clypeus, labrum,palpi,several apical anten-
nomeres,epipleura,apicalsternites,andlegsyellowishbrown,moreor lesspalerthan
theotherpartsofbody.
Headtransverse,only three-fourthsaslongaswide; dorsumdepressed, though
both thesupraorbital areasand fronsaremoderatelyconvexdueto deeply carved
frontal furrows,whichareveryobtuselysubangulate,moderatelydivergent in front
andwidelysobehindtowardsdeepneckconstriction;supraorbital poresclosely lo-
cate lyingonlinesdivergentposteriorly,theanteriorpairbeingfoveolate;eyessmall
and at,thoughindividuallyvariableinsizeandconvexity;genaetumid,two-thirdsto
oneandone-ninthaslongaseyesandsometimesslightlymoreconvexthaneyes,com-
pletelyglabrous; neckverywide,with theanterior constrictiondeeplyandsharply
markedatthesides; labrumtransverse,withtheapicalmargindeeplyemarginateand
sometimesslightlybisinuateat thebottom;mandiblesshortandstout,bidentate,with
sharplyhookedapicalportions;mental toothbroadandporrect,distinctlybifidat the
tip;submentumsexsetose,withtheinnermostpairsmallerthantheothers;palpishort
andstout,penultimatesegmentswidelydilatedtowardsapices,aboutaslongasapical
segment inlabialpalpus,obviouslylongerthantheapicalinmaxillarypalpus,apical
segmentselongatedsubconica1; antennaeshort andstout though subfiliform rather
thansubmoniliform, reachingbasal fifthofelytraor extendingslightlybeyond that
level,segment2aboutaslongassegment3andaboutfive-sixthsaslongasscape,seg-
ments 4-10subequa1inlengthtooneanother,eachlessthantwiceaslongaswideand
slightlyshorter thansegment2or3,terminalsegment thelongest,slightly longerbut
narrowerthanscape.
NewIsolatedTl・icoitusfromtheMicangShanMountains 613
Fjg.1. T1j,coitus(s.str)imu,-a!S.UtNo,spnov.,3, fromtheJiaojiaHeValleybelowDabaontheMi-
cangShanMountains.
Pronotumtransverse,wider thanhea widestataboutthree-fifthsfrombaseora
littlebeforethat level,andmoregraduallynarrowedtowardsbasethantowardsapex;
pw/HW1.36-1.48(MI41),PW/PL137-1.53(MI44),PW/PA t43-1.55(M I48),
Pw/PB1.27-1.39(MI.33);sidesmoderatelybordered,narrowlynearfrontanglesand
ratherwidelyat thereflexedpostangularparts,ratherstronglyarcuateinfront,lessso
behindmiddle,andhardlyorveryslightlysinuatejustbeforehindangles,whichare
obtuseandmoreorlessworn-outatthecomers;apexmoreorlessnarrowerthanbase,
614 Shun-IchiUENo
PB/PA1.07-1.18(M1.12),eitherstraightorveryslightlyarcuate,with frontangles
rounded and not advanced; baseslightly produced at the median part and nearly
straight,brie?ybutdistinctlyemarginateoneachsideabovebasalpeduncleofelytra,
andbrie?y arcuateanteriadat eachhindangle; dorsumwell convex and smooth,
steeplydeclivousposteriadandattheantero-latera1parts;medianlinedistinct,particu-
larlynearapical transverseimpression,whichisdistinct,linearandcontinuous;basal
transversesulcussharplycarved;nopostangularcarinae;basalareanarrowandtrans-
verselyconvex.
Elytraovate,usuallyalittlemorerotundatein than in ,obviouslywider than
pronotum,longerthanwide,widestatabout four-ninthsfrombases,andmoregradu-
allynarrowedtowardsbasesthantowardsapices;EW/PW143-1.53(MI48),EL/PL
2.76-3.05(M2.91),EL/EW132-1.42(M I36);shouldersroundedcontinuouslyto
prehumera1borders;sidesnarrowlyborderedthroughout,gentlyarcuateatmiddle,less
soin frontandbehind,andrathernarrowlyroundedatapiceswhichformasmallre_
entrant angle at suture, preapical emargination shallow but appreciable; dorsum
strongly convex, steeply declivousat the lateral andapicalparts;striaesuperficial
thoughrathercoarselypunctateonthedisc,evanescentattheside,stria1entire,dis-
tinctlyimpressedbeforemiddle,2alsodistinctthoughobsoletenearbase,3shallower
thaninnertwoandoftenfragmentary,4justperceptiblebeforethemiddle,5-7efface
8impressedbehindthemiddlesetofmarginalumbilicatepores;scutellarstrioleab_
sent;apicalstrictodistinctlyimpressedthoughshortandlightlycurve freeat thean_
teriorendbutapparentlydirectedtothesiteofstria5;intervalssmoothandcompletely
at,apicalcarinaobtuse;stria3withtwosetiferousdorsalporesaf t/7-1/6 and 3/7_
1/2frombase,respectively;preapicalporeabsent;marginalumbilicateporesregular.
Ventralsurfacesmooth;visiblesternites3-5eachwithapairofparamediansetae;
analsternitewithapairofmarginalsetaein ,withtwopairofthemin Legsshort
.
but fairlythin;protibiaestraight,moderatelydilatedtowardsapices,andexternally
grooved;tarsi fairlythin,tarsomere1aboutaslongastarsomeres2and3togetherjn
bothmeso- andmetatarsi; in , twoproximalprotarsomeresmoderatelydilatedand
ratherstoutlyproducedinwardsatapices.
Malegenitalorgansmallandrather lightlysclerotized.Aedeagusthree-tenthsas
longaselytra,fairlyslender,gentlycompressedandlightlyarcuate,graduallyandreg_
ularlytaperedfrombehindmiddletowardsapexinpro Ie,withfairlylargebasalpart
andlongspatulateapicallobe; dorsalmarginmoderatelyarcuateatmiddleinlateral
View;basalpart fairlylargebutlow,hardlybentventrad,distinctlytuberculateatthe
proximalend,andwithanextremelynarrowhyalinesagittalailerononthetubercle;
basalorificelarge,withthesideswidelybutnotdeeplyemarginate;viewedlaterally,
apical lobenarrowlyproducedandpointedattheextremity;vieweddorsally,apical
lobenearlyparallel-sidedandsymmetricalthoughsomewhat inclinedtotheleft,wjth
thetipwidelyandstronglyrounded;ventralmarginwidelyandshallowlyemarginate
inprofile.Innersacarmedwithaslendersubcylindrica1copulatorypiecealittleless
thanone-fourthaslongasaedeagus,lyingdiagonallyfromrightproximaltoleftapjca1
NewIsolatedT1i・echusfromtheMicangShanMountains 615
3
、 ノ
、、_ /
l l
0.2mm
Figs 2-3. MalegenitaliaofTrechus(s.str)imulaiS.UENo,spnov.,fromtheJiaoJiaHeValleybelow
DabaontheMicangShanMountains;leftlateralview(2),andapicalpartofaedeagus,dorso-apica1
view(3).
just insideapical orifice,with theblunt apexalmost protrudingoutside; no teeth-
patches.Stylesrelativelystraightwithverynarrowapicalparts, Ie量styleonlyalittle
longer thantherightandwith rudimentaryventralapophysis,eachbearingonlytwo
shortapicalsetae.
Typeseries. Holotype: ,allotype: ,paratypes:4 6 (incl tenera11
, ,
2 ),4-VI-1999,Y. IMURAleg.Alldepositedatpresent inthecollectionoftheDe-
partmentofZoology,NationalScienceMuseum(Nat.Hist),Tokyo.
Typelocality. MicangShanMountains,JiaojiaHeValleybelowDaba,1,350m
inaltitude,inNanjiangXianofnortheasternSichuan,SouthwestChina.
Notes. IhavebeenunabletofindanyTrechusspeciesdirectlyrelatedtothepres-
entnewtrechine.Itmaybeplacedinitsownsubgenusseeingthatitexhibitsacombi-
nationofmanypeculiarities,but Iprefertorefrain frommakingsuchaproposal,at
leastatthepresentmoment,sincetherearenumerouscongenersnotavailableformy
study.
Thetypespecimensofthisinterestingnewspecieswerecollectedbysiftingdead
leavesinadeciduousbroadleaved forestonthele量sideoftheJiaojiaHeValleyatthe
southernsideofthemainridgeoftheMicangShanMountains,togetherwithasingle
femaleofEpaphiopsls(Epaphiama)cf. lame11ataS.UENoetYu.Itisdedicatedwith
pleasuretoDr.YukiIMURA,aneminentspecialistoftheCarabinae.
要 約
上野俊一:中国四川省米 山産チビゴミムシ属の孤立した1新種. - 過去10年ほどのあ
いだに, 多くのチビゴミムシ属の新種が中国から記載された. しかし, その大多数はチベット
高原やその周縁部の地域に分布するもので, ほかの山地からの記録はひじょうに少なく, とく
616 Shun-IchiUENo
に南方の地域では, ケムネチビゴミムシ属の種によって置き換えられる傾向が強くみられた.
この事情は, 四川省北東部と1峡西省南部とを境する大巴山脈やその延長上に位置する山地でも
同様で, これまでには, 湖北省側の神衣架から記載されたケムネチビゴミムシ属の1種と, 四
川盆地の周縁部に広く分布するハバビロチビゴミムシ辞の有翅の1種が知られているにすぎな
かった.
1999年の初夏に行われた井村有希博士らの現地調査で, 大巴山脈の北西方向への延長部に当
たる米 山脈から2種のチビゴミムシ類が発見された. そのひとつは, おそらく神衣架産の
Epaphiopsis(Epaphiama)lame11ataS.UENoetYuに同定されるものではないかと考えられるが,
他のひとつは明らかな新種で, しかもチビゴミムシ属Trechusのなかに孤立した地位を占める
ものと認められた. とくに上翅の亜端毛を欠くことや, 体表に微細印刻がなく, 前胸背板基部
の横溝が一続きの深い溝になっていること, 雄交尾器の形状が特異で, きわめて狭い矢状片を
そなえた矢状突出部が中央片の基部にあり, 交尾片が細長くて端孔のすぐ内側に斜めに位置す
ることなど, 独立の亜属が認められるのではないかと思われるほど特異な点が多い. しかし,
チビゴミムシ属は, きわめて多数の種を含むチビゴミムシ亜科では最大の属であり, 個々の種
の吟味も系統関係の解析もまだ不十分であるうえに, 今なお多くの新種が記載されっづけてぃ
るとぃう事情を考慮して, 差し当たりはこのチビゴミムシを, チビゴミムシ亜属のうちの孤立
した地位にある新種だと認めるにとどめ, これを採集者の井村博士に捧げて, T,iechus(s.str)
imut-aiS.UENoと命名記載した.
References
DEuvE,Th.,1988. NouveauxCarabidaeetTrechidaedoChine[Coleoptera]. Revuefr:Ent.,(N.S),10:
249-259.
- 1989. NouveauxTrechinaeduNepaletduSichuan(Coleoptera,Trechidae). Boll. Mus reg.
Scinat.,no,・inc,7:315-319.
- 1992. ContributionalaconnaissancedesTrechidaeasiatiques(Coleoptera). Bull.Soc.ent.Fr.,
97:171-l84.
- l995. Contributional'inventairedesTrechidaeTrechinaedeChineetdoThailande[Coleoptera].
Revuef◆rEnt.,(N.S),17:5-18.
- 1997. NouveauxTrechiniduTibetetdesregionslimitrophes[Coleoptera,Trechidae]. Ibid.,19:
139-154.
- &E.QuEINNEc,1993. NouveauxTrechusduQinghai,duSichuanetduGansu,Chine(Cole-
optera,Caraboidea:Trechidae). Opusc.zoo1.fhmin.,(104):1-9.
UENo,S.-I., l998. TheTrechinae (Coleoptera) fromMt.GonggaShananditsvicinities, Southwest
China,withnotesontheEpaphiopslsfromMt.cruelShan. Elyt1・a,To(kyo,26:263-287.
- &P. Yu, 1997. Twonewtrechinebeetles(Coleoptera,Trechinae)fromHubei,CentralChina.
Jspeteo1.Soc.Japan,22:24-36.