Zeldzame libellen in Nederland in 1997

Edelaar, P., 2000. Rare dragonfly species in The Netherlands in 1997. Brachytron 4(1): 3-12. The submitted Dutch records of a selected number of rare dragonfly species are reviewed annually. Acceptability is judged independently by each of six committee members, based on the documentation available (e.g. descriptions, drawings and pictures). In this report the records of 1997 are presented. Of each accepted record the province, nearby city or village, date(s), number, sex and observer are given. In addition, not (yet) accepted records and records received without documentation are listed. More general comments for every species are stated: Calopteryx virgo is locally recovering. The species, however, shows a very stable distribution in general; Sympecma fusca displays a spectacular increase, especially in the southern part of the country (below the River Rhine); Sympecma paedisca was generally believed to be extinct recently. However, a healthy population was (re)discovered; Coenagrion hastulatum remains rare and threatened, new sightings seem to be previously unknown populations and not new colonisations; Cercion lindenii is increasing, especially in the southern part of the country. However, numbers are often very low, which on the other hand could be due to difficulties in observing the species on large open water bodies; Aeshna affinis seems to be present in low numbers every year now, whereas it used to be extremely rare; Aeshna subarctica is now known to be not uncommon but only so in the north-eastern part of the province of Drenthe; Aeshna viridis was found on rare occasions outside its usual range. However, the present status of this species is too common for continued inclusion on the list of rare dragonflies; Anax parthenope was observed for a few days at one locality, constituting only the second record up to 1997; Gomphus vulgatissimus still shows signs of recent recovery after being highly restricted to a few locations up to a couple of years ago; Cordulegaster boltonii is still an extremely rare species. One individual was observed at a location potentially suitable for a new population; Orthetrum brunneum is also recorded outside the province of Limburg, in the province of Gelderland, again in a man-made pioneer habitat (a chalk quarry); Orthetrum coerelescens is spreading in the south. The species perhaps benefits of improved water quality and increased availability of man-made habitat; Crocothemis erythraea is found at a number of sites yearly now, although successful reproduction has not been confirmed until 1997. In addition, some vagrants are also reported; Sympetrum depressiusculum was found at a number of localities in the south. However, no populations seem to be present in The Netherlands. All individuals are thought to originate from nearby Belgian populations; Sympetrum fonscolombii is still present and reproducing after the large influx in 1996. However, compared with 1996 the numbers are reduced; Sympetrum pedemontanum was found to reproduce near a large Belgian population. Furthermore, there are indications of reproduction elsewhere. The species seems to increase since its first observation in 1982; Leucorrhinia pectoralis is limited to a number of well-developed lowland marshes, but can also be found near well-vegetated fens: it is unclear whether these individuals are stragglers or members of small populations.