BULLETIN DE L' INSTITUT ROYAL DES SCIENCES NATURELLES DE BELGIQUE ENTOMOLOGIE, 75: 29 1-303, 2005 BULLETIN VAN HET KONINKLIJK BELGISCH fNSTITUUT VOOR NATUURWETENSCHAPPEN ENTOMO LOGLE; -75,: ,29 1-303, 2005 Faunistics of the Dolichopodid fauna (Diptera: Dolichopodidae) of the Voeren region (Belgium) with new records for species for special faunistic interest by Marc POLLET, Wouter DEKONINCK & Patrick GROOTAERT Abstract the department of Entomology of the KBIN in the early 80'ies. During the 90 ' ies inventories were focused mainly The s ubregion of Voeren, an enclave of the Flemish province of on Flanders which resulted in a fair coverage of its Limburg in the Wallon province of Liege, was sampled for long-legged were recorded flies (Dolichopodidae, Diptera) for the first time in 2003. Fifteen sites surface. As a result, Dolichopodidae in both ancient forests, naturally afforested plots a nd pl antati ons were from about 40% of all UTM 5 km squares in Flanders investigated with Malaise traps, white pan traps and pitfall traps from (POLLET, 2000). However, sampling efforts appeared April until October. The total yield comprised 26.268 specimens of at strongly biased among provinces with Limburg the least least 62 species, with fo ur species accounting for 85 .6% of the speci­ mens. Besides 15 rare, 2 vulnerable and 2 insufficiently known species, sampled (33.3%) as compared to Oost-Vlaanderen Neurigona pal/ida was redi scovered which had previously been con­ (44.3%), Vlaams Brabant (45.5%), Antwerpen (53.1 %) sidered extinct in Flanders. Hercostomus vivax and Neurigona erich­ and West-Vlaanderen (58.2%). The subregion ofVoeren soni are recorded for th e first time i n Flanders, and Hercostomus argentifrons and Medetera unisetosa are recorded for the first time (see Fig. I) - as an enclave of the province Limburg in Belgium. Data on the distribution and ecology of 17 species of within the boundaries of the Wallon province of Liege special faunistic interest are given, including a ll new records for - had not been sampled at all at that point. Flanders since POLLET (2000). Factors explaining the estimated rari ty of these species are discussed. During 2003 a project [AMINAL/B&G/30/2002] was sta11ed by the Flemish Administration of Nature and Key words: Dolichopodidae, Voeren, Limburg, Belgium, faunistics, Enviro1m1ent to study the (re)colonization potentials of ecology, distribution, Red Data Book. invertebrate faunas during afforestation processes. Both ancient forests, spontaneous afforestations as well as plantations were included in the sampling program that Samenvatting was conducted in the Voeren subregion of the province Limburg. In the present contribution, faunistics are De deelregio Voeren a is enclave van de Vlaamse provincie Limburg in de Waalse province Luik werd in 2003 voor het eerst onderzocht op presented of the Dolichopodidae that were established slankpootvliegen (Doli chopodidae, Diptera). Van april tot oktober during this inventmy, whereas results on the impact of werden vijftien pl aatsen in zowel oude bossen, natuurlijk verboste the forest developmental stage on the dolichopodid fau­ habitats en aanplantingen bemonsterd met behulp van Malaisevall en, witte watervall en en bodemvall en. In totaal werden 26.268 exemplaren nas will be treated in a separate paper. verza meld, behorend tot tenminste 62 soorten. Vier soorten vertegen­ woordi gden 85.6% van de totale vangstopbrengst. Naast 15 zeldzame, 2 bedreigde en 2 onvoldoende gekende soorten, werd ook Neurigona Material and methods pal/ida - die tot hi er toe als uitgestorven voor Vlaanderen werd beschouwd - opni euw ontd ekt. !-lercostomus v ivax . en Neurigona erichsoni werden voor h et eerst in Vlaanderen vastgesteld , terwijl A total of 15 sites (site VOERO 1-15) were investigated !-lercostomus argentiji·ons en Medetera unisetosa als ni euwe soorten using one Malaise trap, 3 pitfall traps (9.5 em, depth 9 em) aan de nati onale soortenlijst kunnen worden toegevoegd. Gegevens over de verspreiding e n de ecologie van 17 faunistisch interessante and 3 white pan traps (rectangular - 17 x 10 em, depth so01ten werden in deze bijdrage opgenomen, inclusief ail e nieuwe 5 em) in 11 sites. In sites VOER06 and VOER13-15 on vangsten sinds POLLET (2000). Factoren die de vastgestelde zeldzaam­ the other hand, only 3 pitfall traps were installed. Pitfall heid van deze soorten be.in vloeden, worden besproken. and pan traps were placed in one row with internal Slcutclwoorden: Dolichopodidae, Voeren, Limburg, Belgium, fa unis­ distances of 3-5m. They were filled with 10% formaline tiek, ecologie, verspreiding, Rode lijst (or about 3.5% formaldehyde) solution and detergent, whereas 70% alcohol solution was used in the coll ecting jars of the Malaise traps. Traps were in operation between Introduction 2 April and 8 October 2003 and were emptied 1 2 times, usually at fortnightly intervals. Dolichopodid specimens Large-scale surveys on Diptera in general, and on were sorted out by the second author and subsequently Empidoidea in particular, in Belgium were initiated b y identifi ed by the seni or author. Detailed information on 292 Marc POLLET, Wouter DEKONINCK & Patrick GROOTAERT I I Flanders Wallony Antwerpen Oost­ West­ Limburg VIaanderen VIaanderen Fig. I - Location of the subregion Voeren (prov. Limburg) in Belgium the sampling strategy and the recorded environmental and subsequent publications. In the countty list of variables is given in DEKONJNCK et al. (2005). each species, references are only given for post-1982 For all species, estimates of rarity and recent decline (the cut-off year for Negrobov's record gathering) and were retrieved from POLLET (2000). For species of special other records, not included in his catalog. Doubtful faunistic interest, three data sources were consulted to records are indicated by a question mark. Non-European present up-to-date information on their distribution and regions are separated from European records by a semi­ ecology: (i) the Fauna Europaea on-line database (http:// colon. www.faunaeur.org/) with respect to their distribution in New records for Flanders are given in the following Europe (POLLET, 2004); (ii) the documented Red List of format: PROVINCE: locality, toponym [= name of site Dolichopodidae of Flanders and associated databases or area], sampling date/period, no. males no. females, (POLLET, 2000) with Belgian distributional records from sampling method, collector. Records from Voeren are 1850-1997 (further indicated as "Distribution in Bel­ listed as follows: locality, toponym [ = name of forest] gium" ), and (iii) an unpublished database with identifi­ (sampling site code), sampling period, no. males, no. cation results of approx. 250.000 specimens collected in females, sampling method. Particular information that Belgium mainly between 1997 and 2004 (further indi­ applies to more than one record is mentioned at the end cated as " New records"). of these records, if appropriate, preceded by "all ". All Data on the distribution of the species in Europe were specimens of the Voeren sampling campaign were col­ retrieved from the Palaearctic catalog (NEGROBOY, 199 1) lected by the second author (Wouter Dekoninck) and all Afforestation: Case study "Voeren": Dolichopodidae 293 dolichopodid specimens listed are stored in the personal & GROOTAE RT, 1987), in contrast with the average 20 collections of the senior author (Marc Pollet) unlike species that were coll ected per site in the Voeren region, otherwise mentioned. ranging from 12 (site VOER10) to 29 (site VOER04). Most probably the observed low species diversity is also List of abbreviations related to the rather low pH of the soil (min. 4. 71 , max. 6.12) in the sampling sites, especiall y as compared to Countries: AT: Austria; BA: Bosnia and Herzegovina; BE: forests in the more western sandy loamy Houtland region. Belgium; BG: Bulgaria; BY: Belarus; CH: Switzerland; Four species represent together 22.178 or 85 .6% of CY: Cyprus; CZ: Czech Republic; DE: Gennany; DK: the collected specimens, including 2 ewytopic forest Denmark; EE: Estonia; ES: · ·Spain; FI: Finland; species (Sciapus platypterus: n = 4.107, 15.9%; Dolicho­ FR: France; GB: Great Britain; GR: Greece; GR-AEG: pus popularis: n = 3.886, 15 .0%), one eurytopic species North Aegean Islands (Greece); HR: Croatia; HU: with a preference fo r stmny, d1y habitats ( Cluysotus Hungary; IE: Ireland; IT: Italy; LU: Luxembomg; MK: gramineus: n = 3.989, 15.4%) and one ewytopic species the fonner Yugoslav Republic of Macedonia; NL: The with a strong affinity for humid forests (Dolichopus un­ Netherlands; NO: Norway; PL: Poland; PT-AZO : Azores gulatus: n = 10.196, 39.4%). The remaining 3.723 speci­ (Pmtugal); RO: Romania; RU-RUC: Central European mens belong to no less than 58 species. The proportion of Russia; RU-RUE: Eastern Emopean Russia; RU-RUN: the most abundant species per site varies between 36.4% Northern Emopean Russia; RU-RUS: Southern European (site VOER04, Clu ysotus gramineus) and 94.1% (site Russia; RU-RUW: Nmthwestern Emopean Russia; SE: VOER13, Dolichopus ungulatus). Sweden; SI: Slovenia; SK: Slovakia; UA: Ukraine; YU: Among the 62 species, 38 or 61.3% are considered at Yugoslavia (Serbia, Kosovo, Voivodina, Montenegro); low risk at present which implies that they have recently EPA: Eastern Palaearctic; NEA: Nearctic; NRE: Near East; (1981- 1997; see PoLLET, 2004) been recorded from at NAF: North Africa. See http://www.faunaeur.org for more least 10% of the sampled UTM 5 km squares in Flanders information about the delimitation of the above regions. and that they show a maximum decline since 1981 of 25%. Further, 15 rare, 2 vulnerable species and one Collecting methods: HC: collected by hand; MT: Malaise species that was supposedly extinct in Flanders have been trap; OBS: observation; PT: pitfall trap; SW: collected by coll ected, along with two species with an insufficiently sweepnet; W iT: window trap; WPT: white pitfall trap; known ecology. The survey also yielded two new species WW1:: white pan trap; YWT: yell ow pan trap.