-1 Cranefly (Diptera: Tipuloidea) fauna of a boreal mire system in relation to mire trophic status: implications for conservation and bioassessment Jukka Salmela 1, * and Jari Ilmonen 2 1 Department of Bio- and environmental sciences, University of Jyva ¨skyla ¨, P.O. Box 35, FIN-40014, Finland; 2 Finnish Environment Institute, P.O. Box 140, FIN-00251 Helsinki, Finland; *Author for correspondence (e-mail: jueesalm@cc.jyu.fi) Received 11 May 2004; accepted in revised form 20 October 2004 Key words: Bioassessment, Limoniidae, Peatlands, Pediciidae, Species diversity, Tipulidae Abstract Craneflies (Diptera Tipuloidea) are a typical but poorly known insect group in various moist environments, such as mires. The area of natural mires has strongly decreased in Finland, and there is an urgent need to study and describe the fauna of mires and to determine whether different mire categories support different assemblages of craneflies that might have indicator value. Craneflies were studied using Malaise traps in the Kauhaneva mire system in minerotrophic and ombrotrophic sites, the former subdivided into meso- and oligotrophic sites. A total of 29 cranefly species were recorded. Species richness was highest in mesotrophic sites while the number of species was equally low in oligo- and ombrotrophic sites. Phylidorea squalens, Erioptera flavata, Pedicia rivosa and Tricyphona immaculata were identified as indicators for mesotrophic sites, but no indicators were found for oligo- or ombrotrophic sites. No differences between the species composition of minerotrophic (meso- and oligotrophic combined) and ombrotrophic sites were detected, but when three classes of trophic status were compared, a statistical difference was found. Cranefly species richness in Kauhaneva was low compared to pristine spring habitats. Our results imply, that a focus towards conservation and restoration of mire types with high trophic status would benefit also the con- servation of cranefly diversity in the boreal ecoregion. Bioassesments and ecological surveys of craneflies should be designed to cover adequately all trophic status classes within a mire, and especially the mire types with highest trophic status. We also review the distribution and ecology of some potentially regionally threatened cranefly species. Introduction Craneflies (Diptera: Tipuloidea) are a group of nematoceran flies comprising four families (Limoniidae, Pediciidae, Tipulidae and Cylindro- tomidae) (Stary´ 1992). Craneflies usually dwell in variable aquatic and semiaquatic environments, such as sea shore meadows (Theowald 1982), mires (Krogerus 1960), brooks (Mendl 1973) and springs (Salmela 2001). The larvae of many species inhabit a very wide moisture gradient (Brinkmann 1991) and it is relatively difficult to define purely aquatic or terrestrial species. However, some tipuloids are terrestrial and their larvae live in e.g. fruiting bodies of fungi and decaying wood (Reusch and Oosterbroek 1997). Craneflies, especially families other than Tipulidae, are very poorly known in Finland and species new for regional fauna are commonly recorded (Salmela 2001). So far, the Finnish cranefly fauna has not been red-listed due Journal of Insect Conservation (2005) 9:85–94 DOI 10.1007/s10841-004-5275-7 Ó Springer 2005