Elyt,a,Tokyo,36(1):227-228,May30,2008 Symbiotic Host ofTriartiger reductus NoMURA (Coleoptera,Staphylinidae, Pselaphinae,Clavigeritae) in the Islandof Tsushima, Japan Takashi KoMATsUI) andMunetoshi MARUYAMA2) 1) DepartmentofBiology,FacultyofScience,ShinshuUniversity,Asahi3-1-1, Matsumoto,Nagano,390-8621Japan 2)TheKyushuUniversityMuseum,Hakozaki6-10-1,Fukuoka,812-8581Japan TheclavigerinebeetleTriartiger redtlctiisNoMURA, 1997(Fig. 1)wasrecorded from the Islandsof Tsushima, westernJapan, and only a few specimens have hitherto been collected (NoMURA,1997).Thoughitwaspresumedtobeamyrmecophileasmostspeciesofthesupertribe Clavigeritae, no information on antassociation of thisspecieswasavailable. Recently, T. K. visitedTsushimafor investigationofmyrmecophi1ousinsectsandfoundnumerousspecimensof this rarespecies. Thebeetleswerecollectedfromthe nestsofCrematogasterosakensis FOREL, 1900 (Myrmicinae). Sixteen colonies of C. osakensls were investigated, seven of thembeing parasitizedbyT reductus. DuringhisfourdaysofinvestigationinTsushima,T. K.investigated atotalof17speciesofants(totally91colonies),butbeetleswerefoundonlyinthenestsofC osakensls. Therefore,C osakenslsismostprobablythehostantof T reductus. Normallythreeor Fig.1. Aliving 「ria・lt1ge・l ・,ec11lctl1s,dorsalview 228 Takashi KoMATsUand Munetoshi MARUYAMA Fig.2. TriartlgerreductusinanestCrematogasterosakensis fourbeetleswerefoundpercolony,thoughsometimesmorethantenbeetleswerefoundinasingle antcolony(Fig 2).WhenT. K.inspectedanunderstonecolony,thebeetleswalkedslowlyinthe trailofantsandescapedintotheholecontinuingunderground.Theantsshowedclearinterestin thebeetlesandtappedtheirbackswiththeirantennaeforashort time.Behaviour thatantcarries thebeetlewithitsmandibleshasnotbeenobservedinthesymbioticassociationofCosakenslsand T reductus, thoughthisbehaviouriscommonlyobservedinassociationsbetweenbeetlesof the genus Diartiger SHARP, 1883, a close relative of Triartiger, and ants of the genus Laslus FABRICIUS,1804 (Formicinae) (MARUYAMA,pers.obs) Triartiger reductusNoMURA,1997 Speclmerlsex:1amined 27exs.,Sasunaotsu,Kamiagata-machi,Tsushima-shi,Nagasaki,Japan, 27-IV-2008, T. KoMATsUleg;5exs.,samedatabut, 29-IV-2008. In thecollectionsof the KyushuUniversityMuseumandtheNationalMuseumofNatureandScience,Tokyo. Symbiotichost.Crematogasterosakensis. Reference NoMURA, S., 1997. A revision of the clavigerinegenus T1・iartiger KuBoTA (Coleoptera, Staphylinidae Pselaphinae) fromTaiwanandJapan.Elytra,Tokyo、25:435-444.