Table Of ContentElytra,Tokyo,36(1):213-225,May30,2008
OccurrenceofShikokuRepresentativesofBlindTrechines
(Coleoptera, Trechinae)Originatedin
Eastern Kyushu,SouthwestJapan
Shun-Ichi UENo
DepartmentofZoology,NationalMuseumofNatureandScience,
3-23-1 Hyakunin-cho,Shinjuku,Tokyo,169-0073Japan
and
Takao NAIT0
3-4-13Ikeda,Neyagawa-shi,Osaka,572-0039Japan
Abstract Two new blind species of the trechine genus Rakalttrech1ls are
describedfromthewesterncoastalareasof theIslandofShikoku,SouthwestJapan,
under thenamesRakantrechus(Paratrechiama)obscurusS.UtNoetNAIT0andR.
(Pffosotrechlama) c川'nsufar1s' S.UEN0etNAIT0. Theformerbelongstothenomura1
groupof thesubgenusParatrechiama and thelatterbearsaverycloserelationship to
thetypespeciesofthesubgenusPi1osotrechiama,bothendemictolimestonecavesand
mineaditsintheeasterncoastalareasoftheIslandof Kyushusofarasknownupto
thepresent. Thesearethefirstindisputableevidencesof theclosefaunal relationship
betweenthetwoislandsdisclosedinblindtrechinesontheShikokusideoftheBungo
Channel.
It is well known that the fauna and flora of the Island of Shikoku bear a close
relationshiptothoseofcentralKyushu. Thisistruenotonlyforepigeananimalsand
plants,but also for endogeanandhypogeanspeciesincludingflightlessblindtrechine
beetles. Thebest exampleofsucha relationship in theTrechinae is found in the
Rakantrechuscomplex, which isrepresentedby threegenera inthewesternpart of
Shikoku, i.e., Rakantrechus, YamautidiusandChaetotrechiama (cf. UtNo, 1982a-c,
etc.),andbytwogeneraincentral Kyushu, i.e.,RakantrechusandA11otrechiama (cf.
UENo, 1958, l960,1970,etc.). ThegenusRakantrechusinparticular isrepresentedby
thesubgeneraRakantrechus(s.str) and1[zushltesintheformerandbythesubgenera
ParatrechiamaandPi1osotrechiamainthelatter. However,nosubgenushasbeenknown
uptonowtohaveitsrepresentativesonbothsidesoftheBungoChannel thatseparates
Shikoku from Kyushu. The other twosubgenera Uozumitrechus and Izushites are
somewhat different both taxonomicallyandzoogeographically, anddonot show any
214 Shun-Ichi UtNoand Takao NAIT0
Fig.1. Mapshowing the localities of blind trechinebeetleson both sides of the Bungo Channel,
Southwest Japan; black triangles: Paratrechiama; black circles: Pi1osotrechiama. - 1,
Odorokami (RakantrechusobscurusS.UtNoetNAIT0);2, Karyu-doCave(R 1totrturainomura1
S. U色NO);3, Tsuruoka-koAdit (R nomuraiJoidinarum S. UtN0); 4, 0nagara-do Cave (R.
ttomuraihumerosusS.UtNo);5, Kozono-no-anaCave(」R elegansS.UtNo); 6,Tokura-no-ana
Cave(」R mirabilisS.U直NO);7, Kamagi (R.peninsu/arsi S.UtN0etNAIT0).
direct relationshipbetweenShikokuandKyushu.
In theautumnof2007,thesecondauthorofthepresentpapercameacrossablind
trechinebeetleonalowhillnearthewesterncoastofShikoku. Mostunexpectedly, it
didnotappeartobelongtoanygeneraorsubgeneratheretoforeknown fromtheisland,
but lookedsimilar tocertainspeciesofthesubgenusParatrechiamaofcentral Kyushu.
Closerexaminationprovedthathisfirst impressionwasindisputablycorrect,andthat
the trechinebeetlewas closely related toR nomura1S. UtNo (1960, p 37) of the
NewBlindTrechinesfromWesternShikoku 215
nomura1groupofParatrechiama,whosememberswereknownonly fromcavesand
minesintheSaiki-TsukumiareaofeasternKyushu.
Onlysixweeksafter thisastonishingdiscovery,hemademoreunexpectedfinding
on theSada-misaki, the longest and slenderest peninsula in Japan protruding west-
southwestwards from the northwestern corner of Shikoku towards the Saganoseki
Peninsulaofeastern Kyushu. It was recognisedon thespot that the trechinebeetle
discoveredon theSada-misakiwasasecondspeciesof thesubgenusPi1osotrechiama,
whosetypespecies,R. (Pit.)mlrabilisS.UENo(1958,p 201,figs.1-2)hasbeenknown
only fromapair ofspecimens of the typeseries,andsincethesmall limestonehill
embracingthetypecavewasexcavatedbyalimefactorysometimeinthe1960's, no
more topotypica1specimensof thisinterestingspecieshavebeenobtainablesince then.
Hisdiscoveryofasecondspeciesofthesubgenuswasthereforeveryimportantnotonly
zoogeographicallybutalso fromthetaxonomicalviewpoint.
Thediscoveriesofthesetwospeciesarealsosignificantbecausetheyareincredibly
closetotheir counterpartsoccurringineasternKyushu,suggestingthattheirspeciation
musthavetakenplacein rather arecentperiod,mostprobablysometimein thelast
GlacialEpochaftertheseparationofShikoku fromKyushuwascompleted. Inviewof
all theseimportance,wearegoingtodescribethetwonewspeciesin thepresent paper
under the names Rakantrechus (Paratrechiama) obscurus and R. (Pi1osotrechiama)
penlnsularis. Theabbreviationsemployedherein are thesameas thoseexplained in
previouspapersofthefirst author's.
Rakantrechus (Paratrechiama)obscurusS.UtNoet NAIT0,sp nov
(Figs 2-4)
Length:4.80-5.60mm(fromapicalmarginofclypeustoapicesofelytra).
CloselysimilarinexternalmorphologytoR.(P.)nomurairiomuraiS.UtNo(1960,
p 37,figs.1-2;1985,p 77,pi t4, fig 28) fromKaryu-doCaveinSaiki-shiofeastern
Kyushu, andagreeswithit inmanyrespects,butslightlylarger onanaverageand
recognisedatfirstsightbythedarkcolorationofthebody. Evidentlydifferent fromit
intheshortbroadaedeaguswithlargeteeth-patchesinsidetheinnersacandwithshort
broadstylesbearingonlytwoshortsetaeateachapex.
Colourdarkbrown,particularlydarkerintheforebody,basalhalvesofelytra,and
femora,shiny, faintlyiridescent in thebasal foveaofelytra; palpi, apical halvesof
antennae, andabdominal ventritesmoreor less lighter thandorsum. Apterousand
anophthalmjc.Microsculpturefinethoughdistinctlyimpressedonhead,mostlyCOnSSit-
jng of transversemeshes; largely perceptibleon pronotum and consisting of fine
transverselines; largelyevanescentonelytrathoughpartiallyobservableasfinet「ans-
verse lines.
Headsubquadrate,aboutaslongaswide,widestataboutbasalthird,andnea「ly
parallel_sjded;genaeeitherstraightor veryslightlyarcuate,completelyglab「ouS;neck
broad,neck constrictiondistinct thoughusuallyveryshallow; frontal furrowsdeeply
216 Shun-Ichi U直NOandTakao NAIT0
impressedexcept forposteriorparts,moderatelyarcuate,andnotangulateatmiddle;
fronsandsupraorbitalareasmoderatelyconvex, thelatterbearingtwopairofsupra-
orbitalsetaeonlinesconvergentposteriad;apicalmarginoflabrumnearlystraightat
middle;mandiblesfairlylong,gentlyincurvedattheacuteapices;mentaltoothporrect,
truncatedat thetip;palpislender;antennaelongandslender,reachingapicaltwo-fifths
ofelytra, pedicel theshortest andantennomere3 thelongest, terminalantennomere
about aslongasantennomere8.
Pronotumsubcordate,evidentlywider thanhead,aboutaslongasoralittlelonger
than wide, widest at about three-fourths from base, and contracted posteriorly;
PW/HW 1.34-1.43 (M 1.39), PW/PL 0.93-0.98 (M 0.95), PW/PA 1.35-1.48
(M I42),PW/PB149-1.64(MI56);sidesratherwidelyre?exedinfront,theborders
becomingnarrowerposteriad towardsante-basalsinuation1ocatedbetweenbasalsixth
andfifth,moderatelyarcuateinfront,nearlystraightatmiddle,andeithersubpara11e1
orveryslightlyconvergenttowardshindangles,withshallowante-basalsinuation;apex
about aswideasora littlewider than base, nearlystraight or veryslightlyarcuate,
PA/PB 1.01-1.15 (M1.10),with f1-ontanglesobtuse,narrowly rounded,andhardly
producedforwards;baseslightlybutwidelyemarginate;hindanglesusuallysharpand
oftendenticulateat thetips,protrudentposteriadorpostero-laterad,withpostangular
setae widely removed forwards; dorsumconvex,especially in anterior half, with fine
medianlinenarrowlydeepenedinbasalarea;apicaltransverseimpressionshallow,basal
one narrow but distinct, arcuate, interrupted at middle, and laterally reaching the
bottomofbasalfoveae,whicharefairlylarge,deep,andshallowlyextendinganteriad;
postangular carinae vestigial; basal areanarrow andmore or lessuneven. Lateral
expansionofpropleuranarrowly visiblefromabovebehindmiddle.
Elytraoblong-ovate, muchwider than pronotum, evidently longer than wide,
widestataboutmiddle,andalmostequallynarrowedtowardsapicesandbases,though
apicalpartsareamplerthanthebasal;EW/PW172-1.83(MI75),EL/PL2.61-2.74
(M 2.67), EL/EW 156-1.65 (M I60);shoulders feebly arcuate, with prehumera1
bordersobliqueandnearlystraight;sidesfeeblyarcuatefrombehindshoulderstobefore
apices,whichareconjointlyandratherwidelyrounded,moderatelyborderedexceptfor
prehumera1parts which are finely bordered; dorsum convex, steeply declivous in
marginalareas,transverselydepressedinbasalareas, formingafoveadelimitedoneach
sidebyobtusebasalcarinaformedbyproximalportionof interval5;striaesuperfjcjaI,
indistinctlycrenulate,clearlyimpressednearsuturebutobliteratedat thesjde,strja8
distinctly impressed inapical half;scutellarstrioleshort but distinct; apjca1strjole
distinct,moderatelycurved,freeattheanteriorendthoughdirectedtothesjteofstrja
5; intervals atexceptfortwoparasutura1ones;apicalcarinanotprominent;strja3wjth
twoSetiferousdorsalporesaf t/7-1/6and2/5-4/9frombase,respectively;stria5also
With twoSetiferousdorsalporesat about1/4and3/5-2/3 frombase, respectively;
P「eaPiCa1Porelocatedattheapicalanastomosisofstriae2and3,andmoredistantfrom
apexthanfromsuture;marginalumbilicateseriestypicalofParatrechiama.
Vent「alsurfacesmooth;analventriteprovidedwithapairofmarginalsetaejn
,
NewBlindTrechinesfromWesternShikoku 217
Fjg 2. Rakantrechus(Paratrechiama)obscurusS.UtNoetNAIT0,sp nov., from Odo「okami in
,
Tsushima-cho.
218 Shun-Ichi U直NOandTakao NAIT0
4
/
\ /
///一一//
l
0.5mm
Figs 3-4. Malegenitalia ofRakantrech1ls (Paratrechiama)obscurusS. U1aNo et NAIT0,sp nov.,
fromOdorokamiinTsushima-cho;leftlateralview(3),andapicalpartofaedeagus,dorso-apica1
view (4).
with twopair of them in早. Legs fairly longandslender;protibiaegently dilated
towardsapices,longitudinallygroovedontheexternalface,andglabrousontheanterior
face;mesotibiaabouttwo-fifthsaslongaselytra,metatibiaaboutahalfaslongaselytra,
andveryslightlyoutcurvedattheapicalpart;tarsithin,mesotarsusabout two-thirdsas
longasmesotibia,metatarsusabout three-fourthsaslongasmetatibia;tarsomere1a
littleshorterthantarsomeres2-4combinedinmesotarsus,alittlelongerthantarsomeres
2-4combinedinmetatarsus.
Malegenitalorgansmallandratherlightlysclerotised,similartothatofRnomurai
inbasicconformation, butmarkedlydifferent in theshapeof aedeaga1apical lobe,
developmentofteeth-patchesinsidetheinnersac,andapicalsetaeofstyles. Aedeagus
nearlyone-fourthaslongaselytra,shortandbroad,aboutashighaswide,withdorsal
marginalmostsemicircularlyroundedinprofile;vieweddorsally,aedeagusbroadtothe
baseofapical lobe,emarginateontheleftsideatthelevelofapicalorifice,andthen
abruptly narrowed to obtuse extremity; viewed laterally, apical part tapered and
decurved from behindmiddle, abruptlynarrowed from thebase of apical lobe, and
narrowlyroundedattheterminalportion;basalpartsmall,notsharplybentatthelevel
ofparamera1articulation,anddeeplyemarginateat thesidesofbasalorifice;sagittal
aileronhyaline,ofmoderatesize;ventralmarginnearlystraight atmiddleinprofile.
Innersacdevoidofdifferentiatedcopulatorypiece,but largelycoveredwithscalesof
various degreeofsclerotisation, which formelongate teeth-patches on the left side,
smaller dorsal one above larger ventral one. Styles relativelybroad, leftstylemuch
New Blind Trechinesfrom Western Shikoku 219
longer than theright,eachbearingtwoshortsetaeattheapex.
Typeseries. Holotype: ,allotype: ,paratypes:6 早,21-X-2007, T. NAIT01eg.
DepositedinthecollectionoftheDepartmentofZoology,NationalMuseumofNature
andScience,Tokyo.
Type locality. Odorokami, 40m inaltitude, of Tsushima-cho [now included in
Uwajima-shi] at thewestern part of EhimePrefecture, westernShikoku, Southwest
Japan.
Notes. Though almost identical withR r1omurai in external characteristics, this
newspeciesisfullydescribedsincetheoriginaldescriptionofR nomura1wasmadehalf
acenturyago,whenourknowledgeoftheJapaneseTrechinaewasstill insufficient. The
dark coloration of itsbody isquiteexceptionalamongthe blind trechinesofJapan, in
spiteofthe fact thatsimilarlydark-colouredblindspeciesareoften found in thecaves
ofSouthwest China and Indo-china.
Thepresent newspecieswasfoundnear thesourceofanarrowbranchstreamof
theHowara-gawaRiverat thesoutheastern foot of Amamori-yama(303minheight),
about5kmnorthbyeast fromthebaseoftheYuraPeninsula. Thislocalityisabout56
kmdistant totheeastbynorthinabeelinebeyondtheBungoChannelfromKaryu-do
Cave, the typelocalityof Rakantrechus (Paratrechlama)nomurainomurai, andabout
60.5kmdistant to theeast inabeelinebeyondtheBungoChannel fromthesiteof
Kozono-no-anaCave,thelosttypelocalityofR. (P.)elegansS.UENo(1960,p 43,fig.
5; 2006, p 30). All thespecimensof thetypeserieswerefoundout fromaheapof
weatheredshaleaccumulatedonashalebed. Mostof themoccurredin ratherashallow
partof theheap, inparticular fromamongtangledgrassroots.
It isdifficult todeterminebywhatmeanstheancestorofR. obscurusreached the
westerncoastoftheIslandofShikokuandsuccessfullycolonizedthere. Itmusthave
originatedsomewhereincentral Kyushu,sinceitscon-subgenersflourishnowinonly
thatareaandnowhereelse. Todisperseeastwardsfromeastern Kyushu,however, the
ancestralbeetlemust havecrossedtheBungoChannel,or astrongtidalcurrent,even
thoughthewidthofthechannel is30kmorsoinabeeline. Therefore, immigrationby
meansofsweepstakesdispersaldoesnotseemplausiblefor flightlessblindbeetleslike
trechines. Ontheotherhand,directdispersalthroughlandbridgesmaynotbepossible,
sincewehavetogoback to themiddlePleistocene, four hundredor fivehundred
thousand years ago, for findinganappropriateland connectionbetween theSaiki-
TsukumiareaofeasternKyushuandtheTsushimaareaofwesternShikoku. Thislapse
oftimeistoolargetokeepthetrechinebeetleunchanged,whichwasalreadyadaptedto
thelifeunderthegroundandwascloselysimilarinfaciesandotherexternalpeculiarities
tohighlyadaptedcavernico1ouscongenersendemictoeasternKyushu. Theirspeciation
musthavetakenplaceratherrecently,mostprobablyinthelatePleistocene. Otherwise,
theyhavebecomedifferentiatedintospeciesmorewidelydifferent fromeachother.
AnotherpossibilityoftheeastwarddispersaloftheancestorofR.obscurusistaking
thesamerouteasthatofR. (Pi1osotrechiama)peninsularis,that is,fromtheSaganoseki
PeninsulaofeasternKyushutoSada-misakiPeninsulaofwesternShikoku, thenspread
220 Shun-Ichi U直NOandTakao NAIT0
southwardsalongthewesterncoastofShikoku,andthroughthebaseoftheKomobuchi
Peninsula to the Amamori-yamaHills. This is, however, a longway, and further
painstakinginvestigationsareneeded forobtainingevidencesof itstrack.
Rakantrechus (Pi1osotrechiama)peninsularisS.UtNoet NAIT0,sp nov
(Figs 5-7)
Length:4.50-5.20mm(fromapicalmarginofclypeustoapicesofelytra).
CloselysimilartoR. (Pi1osotrechiama)mirabilisS.UtNo,butmuchlarger,witha
littlesmallerheadandalittlemoreelongateelytra. Evidentlydifferent fromthetype
speciesinconfigurationofaedeagus,whichiscompressed,higheratmiddle,with larger
basalpart,muchlarger teeth-patchinsideinnersac,anddifferentlyshapedcopulatory
piece.
Colour somewhat darker thaninR mirabilis, reddishbrown,shiny; palpi, anten-
nae,venter of hindbody, andlegsyellowishbrown,obviously lighter thandorsum.
Bodyelongate,sparselycoveredwithfairlylonghairsonpronotum,pubescentonelytra;
apterousandanophthalmic. Microsculptureclearlyimpressedandmostlyconsistingof
widemeshesonhead, formedbyfinetransverselinesonpronotumandelytra,though
partiallydegeneratedon the formerandmostlyevanescent on thelatter.
Headrelativelysmallthoughsimilar inshapetothatofRmirabilis,aboutaswide
aslong,andwidestataboutbasalthird;dorsumdepressedandglabrous;frontalfurrows
distinctlyimpressed,gentlyarcuate,andnotangulateatmiddle; fronsandsupraorbital
areas gently convex, the former seemingly ridged, the latter bearing two pair of
supraorbital setae on lines convergent posteriad; genae feebly and evenly convex,
sparselycoveredwithfairlylonghairs; labrumtransverse,shallowlyemarginateatthe
apex;mandiblesfairlystout,brieflyincurvedattheacuteapices;mentumwithaporrect
toothinapicalemargination,whichissimpleatthetip;palpislender;antennaelongand
slender, reachingapical fourthofelytrain ,apicalthree-eighthsofelytrain早,pedicel
theshortest, a littlemore thanahalf aslongaseachof antennomeres3-7, which is
nearly four timesas longaswide, antennomeres8-10graduallydecreasinginlength
towardsapex,terminalantennomereaboutaslongasantennomere8.
Pronotumcordate, obviouslywider thanhead,slightlywider than long, widest at
about three-fourths frombase,andcontracted at base; PW/HW 136-1.47 (M I 42),
PW/PL1.05-1.13(M1.09),PW/PAca.146-1.56(Mca.151),PW/PB145-1.64(M
1.56);sidesmoderately reflexed in front, narrowlysobehindmiddle, ratherstrongly
arcuate in apical three-sevenths, almost straight behind middle, briefly and deeply
sinuatebetweenbasaleighthandsixth,andthenmoreor lessdivergent towardshind
angles, which are sharp and protrudent postero-1aterad; postangular setae a little
removed forwards;apexnearlystraight,usuallysomewhat widerthanbase,sometimes
aswide as the latter, PA/PB ca. 097-1.08 (M ca. 1.03), with front angles nearly
roundedoff;baseeitherstraightorveryslightlyemarginateatmiddle,brieflybutdeeply
emarginateoneachsidejust insidehindangle;dorsummoderatelyconvexandsparsely
221
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222 Shun-lobi UENoandTakao NAIT0
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Figs 6-7. MalegenitaliaofRakantrec/uls(Pi1osotrechiama)peninsularisS.UtNoetNAITo,sp nov.,
from Kamagi on theSada-misaki Peninsula; left lateral view (6), andapical part of aedeagus,
dorso-apica1view (7).
extendanteriorly parallel to lateralborders; postangular carinaeobtuse; basal area
narrowandmoreor lessuneven. Lateralexpansionofpropleurahardlyvisiblefrom
above
Elytraoblong-oval,evidentlywider thanpronotum,muchlongerthanwide,widest
at aboutmiddle,andequallynarrowedtowardsbasesand towardsapices; EW/PW
1.55-1.67 (M I59),EL/PL2.89-3.05(M2.97),EL/EW167-1.77(M I71);shoul-
derswidelyrounded,prehumera1bordersobliqueandstraight;sidesnarrowlybordered
throughout,nearlystraightbehindshoulders,thenfeeblyarcuatetobeforeapices,which
are widely and conjointly rounded; dorsum rather flat thoughsteeply declivous in
narrowlateralparts,shallowlydepressedinbasalareasandformingasmalltransverse
fovea;striaedistinctandalmostentirethoughmoreorlessshalloweratthesidethanon
thedisc,irregularlycrenulate,stria8notparticularlydeepenedinapicalpart;scutellar
strictoshortandshallow;apicalstrioledeeplyimpressed,moderatelycurved,andalmost
joiningstria5oratleastdirectedtotheterminusofstria5;intervalsslightlyconvexnear
suture,eachbearingirregularrowsofpubescence;apicalcarinadistinct thoughobtuse;
stria3withtwosetiferousdorsalporesatabout2/15and1/3-2/5frombase, respec_
tively;stria5withasinglesetiferousdorsalporeatabout5/8frombase;preapjca1pore
locatedat theapicalanastomosisofstriae2and3,andmoredistant fromapexthan
fromsuture;marginalumbilicateseriesasinthetypespecies.
Ventral surfaceglabrous and smooth; each ventrite usually with two pair of
paramediansetae;analventriteprovidedwithapairofmarginalsetaein ,withtwo
pair of them in 早. Legslongandslender; protibiaegentlydilated towardsapices,
longitudinallygroovedontheexternalface,andglabrousontheanterior face;mesotjbja
