De Zuidelijke heidelibel (Sympetrum meridionale) in België en Nederland Herkenning, verspreiding en status in Noordwest-Europa

De Knijf, G. & T. Termaat, 2009. Sympetrum meridionale in Belgium and The Netherlands. Identification, distribution and status in North-western Europe. Brachytron 13 (1/2): 4-18. Since 2000 sightings of Sympetrum meridionale have become frequent in Belgium and The Netherlands. First records came from Belgium, soon followed by observations in The Netherlands. S. meridionale is difficult to identify among other Sympetrum species, notable S. striolatum and S. vulgatum with which in often co-occurs. S. meridionale shows a lot of variation in coloration depending on age and sex. In general it can be distinguished by the paucity of black markings. Fully coloured imagines can be recognised by their rather pale coloration. It is advisable that several characters are checked for correct identification. In the 19th century, the species was only observed once in The Netherlands (Friesland). More records are available from Belgium, mostly from Selys, but its former status remains unclear. It is plausible that the species could reproduce then, but only sporadically and not over a longer time period. Records from the 20th century are very scarce. There is one observation in 1906 in a large peat bog area at 700 m altitude in Belgium and one in The Netherlands in 1994. Since 2000, 26 records are available from 15 localities in Belgium, nearly all from the northern part. S. meridionale could reproduce successfully at least on three localities: in 2000 in Harchies (Henegouwen), in 2003 in Kallo (port of Antwerp) and in 2006 and 2007 in Ekeren (north of Antwerp). Only two records are available from the Netherlands for the period 2000- 2005. Since e2006 the species has been observed at no less than 35 localities. At one locality (Voornes Duin, Zuid-Holland) it was able to reproduce from 2006 to 2008. This recent increase in records has also been noted in several other regions or countries in North-western Europe. For the French regions Picardie and Nord-Pas-de-Calais, no records from before 2000 are available. Since then, several records are known. S. meridionale could reproduce en mass at water reservoirs in the region Champagne-Ardennes. No populations are present in the Lorraine region, but the species has been noted at several localities, especially in the valley of the Moselle. The only record for Luxembourg is from 1993 and also originated from this river valley. The last records in the UK already date back from 1948, when the species was noted on the Channel Islands. This might reflect a lack of experience of English odonatologist with the species. In Germany, the species has always been limited to Baden-Württemberg and Bavaria. In more northern regions like North Rhine-Westphalia, the species was first observed in 2000. It has been observed since 2006 in most of the German federal states and reproduction has been recorded at several localities. We suppose that the recent increase of records of S. meridionale in Belgium and The Netherlands is primarily due to climate change, As so, it follows the recent increase of several other southern species, like Crocothemis erythraea, in Northern Europe. Specimens of S. meridionale have been observed in Belgium and The Netherlands at a broad spectrum of habitats, ranging from heathlands to forest edges, peat bogs, dune waters and garden ponds. All localities where reproduction could be observed can be characterised by the presence of relatively small, shallow and very thermophilic water bodies, which partly dry out in summer. Well developed emergent vegetation is present at the shore. Imagines of S. meridionale can be observed in Belgium and The Netherlands from mid June to early September. The species has only one generation per year in Belgium and the Netherlands.