New records of rare pierids (Lepidoptera: Pieridae) in Slovenia

. The authors present new and unpublished information on the distribution of three pierid species in Slovenia, i.e. Gonepteryx cleopatra (Linnaeus, 1767), Colias erate (Esper, 1805), and Colias myrmidone (Esper, 1781). The first two species are very recent additions to the Slovene butterfly fauna and their status in view of the new records is discussed. Colias erate could be considered a resident species in Slovenia as it was found in two consecutive years on two sites along the Drava channels below Formin and Zlatoli č je hydroelectric power plants. Colias myrmidone has suffered strong decline throughout the western limit of its distribution in central Europe and should be considered near extinct in Slovenia. The last records of this species in Slovenia are documented.


Introduction
Slovenia lies at the junction of four zoogeographical regions, all characterised by specific and rich butterfly fauna.The Mediterranean region extends into the coastal area of Slovenia and the Vipava valley, while the alluvial planes of the Drava and Mura Rivers, including the neighbouring hills, could be regarded as part of the Pannonian region.The largest part of Slovenia, however, is covered by the Alpine region with its transition zones to colline belt and the Continental region.Nevertheless, typical butterfly representatives of the first two regions are hard to pick, and the prefix sub-Mediterranean (-Pannonian) characterises the habitats and faunas of both regions more precisely.
One of the candidates as a representative of the Mediterranean butterfly fauna is certainly Gonepteryx cleopatra (Linnaeus, 1767), for the first time recorded in Slovenia in July 1988 (Carnelutti 1989).A specimen was caught and examined in the Dragonja valley near Sečovlje.
The species had been earlier listed by Carara (1928) for the fauna of Trieste region, but even the author doubted the validity of the record.The second specimen was found on July 27th 1996 at an unusually high altitude (900 m) on Mt.Velika Plešivica in the vicinity of Croatian border SW of Ilirska Bistrica about 40 km inland (Verovnik 1997).These two records were most probably strayed animals from the nearby populations in Croatian Istria, where the species is resident as far north as the Mirna valley (Carnelutti 1989).The three new records from the coastal region could present a slight expansion of the species along the Adriatic coast.
The second pierid Colias erate (Esper, 1805) could be under the present distribution considered an Eastern European faunal element in Slovenia, and is currently the species which has expanded its range in Europe to the greatest extent.The species' range was limited to an area eastward from the Crimea until the 1960s.After this it gradually expanded westwards, but was limited to the Transcarpathian plains until end of the 1980s (Hesellbarth et al. 1995).
Further westward expansion has been documented by the first records from Hungary in 1988 (Hreblay & Gyulai 1990), Slovakia in 1989 (Horka 1991), Croatia in 1989(Kranjčev 1991), and Austria in 1990 (Hellmann 1991).The first record for Slovenia came with a short delay in 1993, when a single male was collected at Hraščica near Gančani in the plains north of the Mura River (Gomboc 1996).Despite further efforts by Slovenian entomologists, no further specimens were recorded until 2003, when the first author found a specimen at the Drava River channel near Formin.
The Danube clouded yellow Colias myrmidone (Esper, 1781) had a different fortune in Slovenia compared with the two previously mentioned species.It seems to be losing grounds in Europe and is retreating eastwards.Regional extinction has been reported from Germany, Austria, Hungary (Van Swaay &Warren 1998) andCzech Republic (Beneš &Konvička 2002).
The species should be considered near extinct in Slovenia as it has not been recorded for more than a decade.Most of the sites where species survived until the mid-1980s were reexamined and many potential sites in NE Slovenia have been surveyed without success.Documentation of the last records is presented in this paper.

Gonepteryx cleopatra
The species was found at three sites in the coastal region of Slovenia: -30.

Colias erate
The species was found at two sites along the channels of the Drava River below the hydroelectric powerplants Formin and Zlatoličje.At both sites the habitat was xerothermic grassland on SW facing channel slopes, partially overgrown with bushes in the otherwise rural countryside.The lower parts of the slopes were occasionally mown and this is where most of the specimens were observed.
6.9.2003 -single slightly worn male 26.5.2004-freshly emerged male 30.6.2004 -single slightly worn male 5.7.2004 -single worn male 10.9.2004 -three males 19.9.2004 -single worn male 30.9.2004 -nine males and a copula, most of the males and the female were fresh.

Colias myrmidone
The records from 1982 onwards are included in the list.The presence of the species based on earlier records has already been summarized by Hafner (1909), Jež (1983), andCarnelutti (1992b).

Discussion
Regional or national faunas are highly dynamic and new species appear or go regionally extinct in short periods of time.In the last century, human impact has overrun the slow climatic changes that tailored the distribution of potentially mobile animal groups in the past.The presence of Gonepteryx cleopatra in Slovenia has been anticipated for quite some time, as it is a common species along the Adriatic coast (Jakšič 1988) and locally present also in the warmest parts of the southern Alps in Italy (Sala 1996) and occasionally in Switzerland (SBN 1994).The three new records in the coastal region do not confirm a permanent residency of the species in Slovenia, but the increasing frequency of observations indicates that it might soon be resident here.All the observed specimens were males, which are much easer to identify than females, whose presence would be a stronger indicator of their residency.To monitor the expansion of this species into Slovenia, a special attention should be given to the inspection of Gonepteryx females in the coastal part of Slovenia and in the Vipava valley.

Butterflies in
The presence of a viable population of Colias erate in Slovenia is undisputed, and the observation of a copula and a large number of males at different occasions gives us good hopes that the species will survive in this region.Colias erate is a well-known migratory butterfly, and rivers serve as natural corridors for its expansion.Thus the presence of its colonies near the Drava River in Slovenia is not unexpected.Such colonies at the edge of their distribution are very vulnerable to climatic fluctuations (e. g. very cold winters) and human impact (collecting included).Therefore further monitoring of the known colonies and similar habitats in the neighbourhood will be necessary to determine the establishment of the species in Slovenia.
The males of Colias erate could be identified on the wing due to intensive pale yellow coloration contrasting the broad black border similar to that in Colias croceus (Furcroy, 1785).Both species share the same habitat with the much more common Colias croceus.They have a similar fast patrolling flight low over the ground with abrupt and short stops.The larval food plant Medicago sativa L. has not been found at the sites along the channel, but they are most certainly present in the neighbouring rural countryside.Since the adult and larval habitat is entirely anthropogenic no specific conservation effort is needed.
The present existence of Colias myrmidone in Slovenia is highly questionable, given the fact that the systematic search in the last eleven years has yielded no results.Its existence in Slovenia cannot be entirely ruled out, as it is best exemplified in its rediscovery in the vicinity of Kranj in 1993 after a gap of almost 60 years.According to the material present in the collections of the Natural History Museum of Slovenia, the species was last collected on the nearby Soriško polje in 1935 and Medvode in 1937 (Čelik et al. 2004).Whether the collected specimen was a strayed migratory specimen or one of the last members of for a long time overlooked population remains disputable.Due to the lack of migrations at its NW area border in Germany (Kudrna & Mayer 1990), where the species probably became extinct in the 1990s (Settele et al. 2000), one should be inclined towards the second option.
At the beginning of the 20th century, the species was locally abundant in the hills west of Ljubljana and in the western part of Dolenjska region (Šentjernej, Novo mesto) (Hafner 1909).
Its presence in NE Slovenia was first mentioned by Hoffmann & Klos (1914) for the surroundings of Maribor.In 1989, the second author found the species in the Slovenian part of Carinthia and it turned out that this was the last of the three recordings in this part of Slovenia.These finds were exciting though not entirely unexpected.The species was locally present also in the Austrian part of Carinthia in the Drava River valley as far west as Villach (Thurner 1948).Recently, the species went extinct in most parts of Austria with few populations left in the north-eastern part of the country (Höttinger & Pennerstorfer 1999).In order to enhance our possibilities for refinding (and conserving) Colias myrmidone in Slovenia much more information on habitat preferences and ecology of closest extant populations should be gathered.

Zahvala
We are grateful to Chris Van Swaay for comments and corrections of the manuscript, and Maja Zagmajster for producing the map.Tone Lesar, Bojan Porenta, Ali Šalamun, and Marko Stropnik are thanked for permission to publish their records.
Europe have much benefited from human traditional farming in the past, and maintenance of these semi-natural grasslands and their management constitute an essential part of butterfly conservation.On the other hand, intensive farming and urbanisation have caused large-scale extinction of several butterfly species, especially in Western Europe(Maes & Van Dyck 2000).The investigation of changes in the distribution and composition of butterfly fauna in Slovenia is hampered by scarcity of older faunistic publications and lack of intensive survey that would give comparable results for the entire country.Only in the last decade has a deliberate action been taking aim at the production of a national distribution atlas of butterflies in Slovenia.Despite a shortage of past distribution information, some positive changes have been observed in Slovenian butterfly fauna.Some of the previously rare and local species(Carnelutti 1992a) have become much more widespread.Among these, Polyommatus amandus (Schneider, 1792), Brenthis ino (Rottemburg, 1775), and Heteropterus morpheus (Pallas, 1771) are the most prominent examples.The three species studied are new changes to the butterfly fauna of Slovenia.