Description of the female of Platycheirus altomontis Merlin & Nielsen in Nielsen, 2004 (Diptera, Syrphidae) with notes on the occurrence and hilltopping behaviour of rare French montane and Alpine Syrphidae

A focused search in very high (2500–3200 m asl) Alpine mountain tops France resulted the discovery of rare Alpine-endemic syrphid Platycheirus altomontis Merlin & Nielsen Nielsen, 2004, including its hitherto unknown female. description female is given and further complemented with behavioural observations this species special reference to hilltopping. Additional records are provided for new French fauna from montane habitat focus on altitude (>2750 m) hilltopping behaviour. The Rohdendorfia alpina Sack 1938 was observed large numbers at scree slopes above 2750 males were found sitting hilltops up 3200 m. Hilltopping behaviour Syrphidae over whole altitudinal range visited, multiple engaged even 3000 appears be more common some genera (e.g. Parasyrphus Pipizella ) than others may linked specific phenotypes species. latter Cheilosia melanura (Becker, 1894) which much smaller lower altitudes.