Mitt. Münch. Ent.Ges. ofthisfieldtechnique,theadditionaluseofpitfallswasavoided.Pearson&Cassola(1992)Statethat(using theabove mentioned field technique)even unexperienced personswereable tocollect78-93% ofthe total species numbers within the first 50 culmulative hours of collecting at three Neotropical rainforest sites (Pearson &Cassola1992:Tab.2). Moreover, thecicindelidfaunaofthestudyareaconsistspredominantly ofarboreal, semi-terrestrial, and semiaquaticspecies. Suchnon-terrestrial speciesareunlikley tobecaught in pitfalls. However, a permanently installed Malaise trap in the understory of undisturbed TMP was regularyly checked for the presence of tiger beetles. The nomenclature used in that of Wiesner (1992). Results General aspects Species' ecological distributions and absolute numbers of observed specimens are shown in Pig. 5 and Tab. 1. During the study seven tiger beetle species were found. Pive ofthem were regulary observed and are regarded as common at the study site, but two {Ctenostoma maciilicoriie Chevrolat, 1856, Cicindelidia cyaniventris [Chevrolat, 1834]) wereonlytaken asSingleindividuals. InthecaseofC. maculicorne this can be easily explained by its arborealbehavior, while the reason for the scarcity ofCicindelidia cyaniventris is unclear.Thisspecimenwascollectedinthefirstdaysofthestudy.Becausethehabitatwherethisindividual was taken is quite common in the area and the locality was visited almost daily, the species' seasonal activity most probably had already passsed at the time of study. This may also be true for Megacephala fidiginosaBates, 1874, ofwhichonlyoneadultwascollectedatthebeginningofthestudy.However,larvae werefoundfrequentlyduringthewholestudy.Anotherspecies,whichwasreportedbySUMLIN(1994)from this area {Iresia pndchra Bates, 1881), could not be found. Approximately 280 man-hours of searching along forest pathes yielded more than 180 specimens of terrestrial and semi-terrestrial species (i.e. Odontocheila nicaraguensis Bates, 1874, O. iodopleura Bates, 1872, PseiidoxycheUa tarsalis Bates, 1869; Tab. 1). By contrast, only four individuals of O. nicaraguensis and five individuals ofeach of O. iodopleura and ofP. tarsalis were found during approximately 120 man-hours of searching on the undisturbed forest floor (see below). Species accounts Ctenostoma maculicorne Chevrolat, 1856. A Single specimen was found in a young secondary TMP at 600ma.s.l. in a sunny spot about 0.5 m above the ground on the leaf of an large terrestrial bromeliad {Bromelia sp.) (Pig. 1). Iresia pulchra Bates, 1881. This arboreal species (which could notbe found) was recorded for the study areabySumlin(1994).Thelocality (EstacionBiologicaCacao, 1000-1400m)lieswithinPRP. Themicrohab- itat of the species is unknown. Megacephalafuliginosa Bates,1874. At nightduring lightrain onAugust5, a Single adultspecimenwas found on a loamy trail in AP, at the border ofan abandoned pasture to a patch ofdense secondary TMP. Pragmentsofa second specimen were takena few days later from a Latrodectus-neiundera pieceofwood in a meadow. Larvaeburrows occurred commonly ondirtroads and trails through AP from500 to 600m a.s.l. Larvae were frequently observed at night feeding on small crickets. Tab. 1. Total abundances of regulary observed tiger beetles. AP, abandoned pastures; TMP, Tropical Meist Forest; RPWP, riparian Premontane Wet Forest; PRP, Premontane Rain Forest; LMRP, Lower Montane Rain Forest. Habitat type AP TMF RPWF FRF LMRP Megacephalafuliginosa {\arva\ hurrows) >50 - - - - Odontocheila nicaraguensis - >50 50 Oxycheila polita - - Odontocheila iodopleura - - Pseudoxycheila tarsalis 90 abandoned tropical moist/ premontane Iowermontane pastures prem.wetforest rainforest rainforest (AP) (TMF/RPWF) (PRF) (LMRF) 500-600m 500-700m 700-1400m 1400- 1500m Pseudoxycheila tarsalis Iresiapulchra Odontocheilaiodopleura Oxycheilapolita Cicindelidiacyaniventris Ctenostomamaculicorne Odontocheilanicaraguensis Megacephala fuliginosa Fig. 5. Ecological and altitudinal distribution of tiger beetles in eastern Guanacaste National Park, Costa Rica. Locality record of Iresia pulchra according to Sumlin (1994). Shaded background shows the corresponding altitudinal profile of the study area, roughly ranging from Maritza Biological Station in the northwest to the summit of Cerro Cacao in the southeast. Squares indicate the proofed distributions, broken lines potential distributions. Questionmarks indicate uncertain distribution limits. Oxycheila polita Bates, 1872. The species was regulary observed in two small, 5-10 meters wide, rapid flowingriverswithinRPWFand PRFbetween600and800ma.s.l (Fig.2).Individuaiswerefoundforaging on largerocks (witha thinmossand algaeCover)and logs withinthe riverbed andonbroad-leafed plants borderingitsbanks.Whendisturbed,beetlesfrequentlyenteredthewateronthedownstreamsideofrocks or logs (water temperature around 22°C). Highest density was 5 specimens/100m river. Copulation was observed several times during the whole study time. At one occasion, the semiaquatic lizard Norops oxylophus, which is a typical inhabitant of riparian habitats at Maritza, was observed hunting O. polita. Pseudoxycheila tarsalis Bates, 1869. This species was commonly found within PRF on a loamy, broad foresttrailonCerroCacaobetween 1100and 1200ma.s.l. Maximumdensity was8specimens/100m trail. Thelowermostsightingatthe study sitewas at900 ma.s.l., where five individuals wereobserved onbare ground at a free fall in dense undishjrbed primary forest on a steep loamy slope. Additional Single m specimens were takennear abuilding on a loamy path across a large, grassy Clearing at 1100 (Estacion m Biologica Cacao) and on a narrow trail across an small open area in Iower montane rain forest at 1500 nearthesummitofCerroCacao(Fig.4).Alllocalitieshadonlyasparsecoverofleaflitterwithsmallpatches ofbare ground. When disturbed, most individuals tried to escape by running into leaf litter, small twigs or low Vegetation. Most of the specimen observed were active in small sunny spots, while shaded areas or a search during overcasted sky yielded only a few animals. Copulation was observed inone instanton August 27, 1993. Odontocheila nicaraguensis Bates, 1874. O. nicaraguensis was common on trails through primary and secondary TMP and RPWF at 500-700 m a.s.l. The specieswas regulary found in shade orsemi-shadebut seemed to prefer sunny spots. The most frequently observed habitat, which yielded maximum densities ofupto15specimens/100mtrail,wereforesttrailswithsomeherbaceousVegetation,spotsofbareground, and sparse leaflitter (Fig. 1). Beside that, single specimens were found in undisturbed, dense forest. One of these specimen was the only tiger beetle captured in the Malaise trap (dense understory of primary TMF). Three other individuals were observed one on bare ground at a treefall, the other on a steep 91 embankmentnear a small river, and the third at a nestofleaf-cuttingants. As a rule, O. nicaraguensis was most common in such places, which had a constant supply ofground humidity. It did not occur on well drainedand comparativelydry forested ridgesand in thestony floodplainsofsmall rivers. Densitieswere highest during sunny weather, but even during light rain a few animals were frequently observed. The species was found foraging on the ground as well as in low herbaceous Vegetation, but when disturbed allanimalsflewintolowVegetation.Theescapedistancewasabout2mandtheescapeflightsranged from m 1 to5 m. The perchheights afterlanding wasbetween0.3 and 1.5 above the ground. Copulations were observed frequently throughout the study period. Odontocheila iodopleura Bates, 1872. On the steep north-western slopes of Cerro Cacao in PRF at 700- 1300 m, O. iodopleura ecologically replaces O. nicaraguensis. It was common along narrow trails through primary forests (Fig. 3). The prefered microhabitatsofO. iodopleura are identicallywith those ofO. nicara- guenesis (seeabove), with theexception that the firstspecies apparently avoids the centersoflargersunny areas (e.g. small Clearings) and was more often observerd among totally shaded situations. On a steep loamy slope five additional individuals were observed on bare ground at a fallen free within dense undisturbed forest. Maximum densities was 20 specimens/100 m trail. Copulation was observed several times only on August 26. The escape distance was as low as 0.5-1 m and the short escape flights ranged from 0.3 to 1.5 m. Cicindelidia cyaniventris (Chevrolat, 1834). A single specimen was collected on August 6 on a trail througha5-10 m fall secondary growth ofpresumedlyTMF at650 ma.s.l. Thelocality was totally shaded and offered small spots ofhumid,bare, loamy soil amonglargeareascoveredbyleaflitter. Thisspecimen made no attempt to escape by flight. Ecological distribution and species assemblages The distributional data suggest the presence of four distinct tiger beetle species assemblages in the five major habitats along the transect (Fig. 5, Tab. 1). These are associated with (1) abandoned pastures, (2) Tropical Moist Forests/Riparian Premontane Wet Forests, (3) Premontane Rain Forest, and (4) Lower Montane Rain Forest. Fach ofthe four majorhabitats had a unique species assemblage. Within AP and LMRF only a single adultspecimenofeachspecieseachwasfound (MegacephalafuliginosaandPseudoxi/chcila tarsalisrespective- ly). Althoughrecorded onlyonceinLMRF, P. tarsalis ispresumed tohavea widerdistributionhere. There are suitable habitats to some extant and this life zone is well inside the species' ecological distribution in CostaRica (Palmer 1976, 1983).Themeagerresultsofmyresearchwerecertainlycausedbytheconstantly overcasted to rainy weather during all Visits in the cloud forest. TMF/RPWFandPRFareeachiiihabitedbyassemblagesoffoursympatricspecies (Tab. 2). Icombined Tab. 2. Parameters ofniche segregation in forest tiger beetles assemblages of two major habitats in the eastern partoftheGuanacasteNationalPark,CostaRica.Totallength(withoutlabrum)roundedtonearesthalfmm;body size ofIresia pulchra according to Sumlin (1994). Species TMF and RPWFon thebasisofthe commonoccurrenceofOdontocheila riicaraguensis inbothzonesand its nearly complete absence in other zones (see below). However, the species was most common at more humid Sites (e.g. riparian forestoredaphichumid places) and did notoccuron the dryestridges ofTMF. FurthermoreCienostoma niaculicorneand Ciciiuielidiacx/aniventrisarepresumed tohaveawiderdistribution both in TMF and RPWF. ThedistributionoftwospeciesoverlappedslightyatthetransitionofTMF/RPWFandPRF:inonecase, aspecimenofO. iodopileiirnwastakeninsideasecondaryRPWFneartoPRFamongseveralO. uicaraguensis. Vice versa, a Single individual of O. JÜcaraguenesis was observed among several O. iodopleiira in PRF near to RPWF. In the major habitats where more than one species occurred, sympatric tiger beetles differed well in their ecological parameters (Tab. 2): TMF/RPWF is inhabited by Odontocheila uicaraguensis and Oxi/cheila polita, which are both comparably common. Two other species were found only as Single individuals (Ctenostoma maculicorne, Cicindelidia cyaniventris). The habitat use of these four species is obvious: one arboreal (C. tuacidicorne), onesemiaquatic (O. polita), and two forest floor species; thelatterbeingdifferent inbodysizeandpresumablyalsoinmicrohabitatuseandactivityseasons:C. cyaniventrisbeingthesmaller, exclusively terrestrialspecieswithaprobableadultactivityonlyduringthebeginningoftherainy season. PRF is inhabited by Pseudoxycheila tarsalis, Oxycheila polita, Iresia pulchra, and Odontocheila iodopleura. Under consideration ofa wide occurrence of/. pulchra within PRF, the species assemblage again consists ofone arboreal (I. pulchra), one semiaquatic (O. polita), and two terrestrial species; the latter two differing in bodysizes and microhabitats: P. tarsalis being a large, exclusively terrestrial species prefering sunny places; O. iodopleurabeingasmallspecies, inhabitinglowVegetationandpreferingmoreshadedsituations. Discussion General aspects, ecological distribution, and species assemblages Available Information on habitat preferences of some of the species agree well with literature data (e.g., Ctenostoma maculicorne: Naviaux 1998 for the genus; Oxycheila polita: Cummins 1992; Pseuoxycheila tarsalis: Palmer 1976, 1983, Cassola 1997; Cicindelidia cyaniventris: Murray 1979 for Mexican populahons). ThepresentstudyreflectsonlyatemporarilylimitedaspectofthetigerbeetleassemblageoftheMaritza area,namelythemidrainyseason.Thoughmidrainyseasonispresumedtobeagoodtimeforaninventory of tiger beetles in the tropics (Pearson & Derr 1986), the observations of just one adult individual of Megacephalafuliginosaand Cicindelidia cyaniventriseach atthebeginningofthestudy timesuggests thatthe activityperiodofthesetwospecieshadalreadypassed.Itisknownthatspeciescompositionofassemblages and habitats of tiger beetles change markedly with the dry and the rainy season in the tropics (Pearson & Derr 1986, Pearson 1988). Fahr (unpublished manuscript) found that in a climatically semihumid area in West Africa relative abundance and habitat use of cicindelids changed considerably even during the rainy season. One of the most remarkable facts of the present study is the complete lack of diurnal, non forest- dwellingspecies inthestudy area. Suchspeciesarecommon membersoftigerbeetleassemblagesinother parts ofthe Neotropics (e.g., Pearson etal. 1993, Pearson & Huber 1995, Rodriguezetal. 1998) as well as intheOldWorldtropics.Theexplanationmaybeeasy: althoughheavilydeforestedatpresent(withmany savanna-likeareasintheGuanacasteNational Park)thewholenonswampareaofnorthwesternCostaRica is presumed to have been completely forested in the past (Hartshorn 1983, Janzen 1986). Consequently, speciesrestrictedtoopen,terrestrialhabitatsareunlikelytooccurinthestudyarea.Throughoutthetropics the occurrence ofdiurnal terrestrial (non-riparian) tigerbeetles ofopen habitats seems tobe linked to the occurrence of naturally open habitats like grasslands or thom forests. Pearson (1980) found Odontocheila uicaraguensis and O. iodopleura occurring together in a Caribbean lowland rainforestinCostaRica,aswellasanequivalentspeciespairofsimilardivergentsizesthroughout several lowland rainforest sites in Costa Rica, Panama, Ecuador and Bolivia. By contrast, O. uicaraguensis and O. iodopleura are well differentiated at Maritza with respect to their ecological distribution. The only exception is a small transitional zone at the foot of Cerro Cacao. This Situation is perhaps caused by the transitional characterofclimate at the study area. There is a well defined dry seasonof4-5 months at the lowerpacific foothills (where O. nicaraguenis occurs)whichisprobably not suitable for O. iodopleura. Vice versa those areas at the mid-elevation slopes of Cerro Cacao, which receive sufficient humidity for O. iodopleura, are presumedly too cold for O. uicaraguensis. 93 Tigerbeetles are known to have several strategies to minimize competitionamong sympatric species. Mostcommonly,temporalorspatialseparationsoccur(Willis1967,Rumpp1977,Knisley1984,Ganeshaiah & Belavadi 1986, Schultz & Hadley 1987, Schultz 1989). Pearson & Mury (1979) and Pearson (1980) found thatamongco-occurringspeciesdivergentmandiblesizesoccurs,whichforceeachspeciestoforage on a different part of a prey spectrum. In the case of the Maritza beetles spatial Separation seems to minimize competiton within adult species' assemblages during the study time at mid-rainy season. However, temporal separations are likely to occur as well. Are tiger beetles really appropriate indicator taxa for tropical forests? Pearson and collaborators suggested the use of tiger beetles as indicator taxa for biodiversity and monitoring studies in tropical environments (Pearson 1992, Pearson & Cassola 1992, Pearson & Huber 1995, Rodriguezet al. 1998). Two ofthe major arguements for this are (1) that tigerbeetles canbe readily surveyed,evenbyinexperiencedpersons,and (2)thatonlowertaxonomiclevelspecializationonanarrow habitatmakesthemsensitivetohabitatchanges. InastudyonVenezuelanspecies' assemblagesRodriguez et al. (1998) found that primary, semi-disturbed, and disturbed forest each had a characteristic species assemblages, dependingonthedegreeofdisturbance. In thepresentstudythehabitatsaresimilartothose investigated by Rodriguez et al. (1998). In general, my own results support the findings of the study in Venezuela: the only heavily disturbed major habitat at Maritza (AP) had a completely different faunal structure (only a Single nocturnal species) than the other, more or less primary habitats. However, none of the places at Maritza where larger number of terrestrial tiger beetles occurred, are really primary. All microhabitatswhichyielded morethanSinglespecimens-evenwithinlargeareasofundisturbedprimary forest-areassociated with man-made trails. Completely natural microhabitats (e.g.,bareground atfallen trees, bare areas at nests of leaf cutting ants) are rather restricted and were inhabited by only a very few individuals. Additionally, in the case of OdontocJieila nicaraguensis, there were no differences in relative abundance on trails through primary forest compared to trails through secondary growth. It thus seems that the overall high densities of tiger beetles in the whole area is primarily caused by human activities. TheSituationattheVenezueleansitesofRoomcuEZetal. (1998)mightnotbeverydifferent: transectswere established along forest trails, too. Theseresultsquestionthesuitabilityofterrestrialtigerbeetlesasindicatortaxaforthebiodiversityand habitatqualityoftropicalforeststosomedegree.Itisofcourseverylikelythatthe"trail-fauna"ofotherwise undisturbedforestsrepresentsthe"naturalfauna"withrespecttotheirspeciescomposition,butabundanc- es seem to be artifical. From a methodical point of view, the presence of only restricted and small populations in a completely natural tropical forest (without trails) does not seem to be appropriate for a efficient inventory use. However, further studies should be done on distribution and densities of tiger beetles of completely primary versus slightly disturbed tropical forests. Acknowledgements Ithankthe"ServiciodeParquesNacionalesofCostaRica"forresearchandcoUectionpermitsandespeciallyRoger Blanco for his invaluable help during my fieldwork at Maritza. I am grateful to Jürgen Wiesner, Wolfgang Lorenz, and Roger Naviaux fortheircareful determinationofsome ofthe species and for providingimportant literature. Many thanks also to Dietrich SCHALLERforimproving the language. References Cassola, F. 1997: Studies on tiger beetles. XC. Revision of the Neotropical genus Pseuäoxycheila GufiRiN, 1839 (Coleoptera, Cicindelidae). - Fragm. Entomol. 29, 1-121. Cummins, M. P. 1992: Amphibious behavior of a tropical, adult tiger beetle, Oyxcheila polita Bates (Coleoptera: Cicindelidae). - Coleopt. Bull. 46, 145-151. Fahr, unpublishedMS: DieSandlaufkäfer(Cicindelidae: Coleoptera)desComoe-Nationalparks, Elfenbeinküs- J. te: Faunistik, Zoogeographie und Ökologie. - 35 pp. Ganeshaiah, K. N. & V. V. Belavadi 1986: Habitat segregation in four species of adult tiger beetles. - Ecol. Entomol. 11, 147-157. 94 Hartshorn, G. S. 1983: Introduction (to Plants). In: Janzen, D. H., Costa Rican Natural History. - Chicago, University ofChicago Press, 118-157. HOLDRIDGE, L. R. 1967: Life Zone Ecology. Revised edition. -SanJose, Tropical Science Center. Janzen, D. H. 1986: Guanacaste National Park: Tropical ecological and cultural restoration. -SanJose, Editoral Universidad Estatal a Distancia. Knisley, C. B. 1984: Ecological distribution of tiger beetles (Coleoptera: Cicindelidae) in Colfax County, New Mexiko. -Southwest. Nat. 29, 93-104. Murray, R.R. 1979:TheCiciiuMn faunaofMexico: rängeextensions, additions,andecologicalnotes(Coleoptera: Cicindelidae). - Coleopt. Bull. 33, 49-56. Naviaux,R.1998:Ctenostoma(Coleoptera,Cicindelidae).Revisiondugenreetdescriptiondenoveautaxons.-Soc. Entomol. Fr., Mem. No. 2. Palmer, M. 1976: Natural history and behavior ofPseudoxychila tarsalis Bates. -Cicindela 8, 61-92. Palmer, M. 1983: Pseudoxychiln tarsalis (Abejön Tigre, Tiger beetle). - In: Janzen, D. H., Costa Rican Natural History. - Chicago, University of Chicago Press, 765-766. Pearson, D. 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D. 1989: Habitat preference and seasonal abundances of eight sympatric species of tiger beetles (Coleoptera, Cicindelidae) in Bastrop State Park, Texas. -Southwest. Nat. 34, 468-477. Schultz,T. D.&N.F. Hadley 1987: Microhabitatsegregationand physiological differencesinco-occurringtiger beetle species Cicindela oregona and C. tranquebarica. - Oecologia 73, 363-370. SuMLiN, W. D., III. 1994: Studies on Neotropical Cicindelidae V: A review of the genus Iresia (Coleoptera). - Cicindelidae: Bull. VVldw. Res. 3, 1-32. Tosi, J. A. 1969: Repüblica de Costa Rica. Mapa Ecolögico. -SanJose, Centro Cientifico Tropical. Wiesner, 1992: VerzeichnisderSandlaufkäferderWelt-ChecklistoftheTigerBeetlesoftheWorld.-Keltern, J. Verlag Erna Bauer. Willis, H. L. 1967: Bionomics and zoogeography of tiger beetles of saline habitats in the Central United States (Coleoptera, Cicindelidae). - Univ. Kans. Sei. Bull. 47, 145-313. Author's address: Michael Franzen Hauptstraße la D-85467Oberneuching,Germany 95