In the recently published field guide on the odonata of REGUA, A Guide to the Dragonflies and Damselflies of the Serra dos Orgaos, the scientific name of the Blue-wedged Dancer is given as Argia claussenii. Rosser Garrison pointed out that this in fact is A. croceipennis, therefore we have amended our odonata list. We are indebted to Rosser for sharing drawings and scans of both species with us that support his view.
The appendages of these two species are quite similar and there are also considerable similarities in colour pattern. However, under the microscope the difference in the shape of the cerci (placement of ventral tooth) can be clearly seen.
In the field there are luckily also a few differences that help identify the species. Argia claussenii has clear wings, whereas those of A. croceipennis are amber colored, and A. claussenii has an occipital bar, whereas A. croceipennis does not. These characteristics are very much in line with the species occurring in fast flowing and rocky streams in the foothills of REGUA. Below are examples of both species, kindly made available by Rosser.
Tom’s excellent guide is available in the UK from Alan Martin. Please send a cheque for £30.50 which includes postage and packing, made out to the ‘Brazilian Atlantic Rainforest Trust’ with your name and address to Alan Martin, Alureds Oast, Northiam, East Sussex, TN31 6JJ.
Orders from other countries should be sent directly to Tom Kompier at firstname.lastname@example.org. Copies will also be available from the REGUA stand at the British Birdfair on 21st – 23rd August at Rutland.