First record of Pantala flavescens (Anisoptera: Libellulidae) from the remote Amsterdam Island, southern Indian Ocean

摘要

Natural colonization of macroinvertebrates into the Sub-Antarctic area is generally accepted to be a rare event. In February 2017, two live adults of Pantala flavescens (Libellulidae) were recorded on the isolated Amsterdam Island (37 degrees 50 S, 77 degrees 30 E), southern Indian Ocean. This circumtropical species, common name the Globe Skimmer, can fly several thousand kilometers. This paper analyzes the weather conditions in this sector of the Indian Ocean in February 2017 to assess the probability of arrival of the dragonflies by air from their known migration route at lower latitudes between India and East Africa. The probability that this species could establish and form a permanent population on Amsterdam Island is discussed. Some favorable habitats are present but temperatures are probably too low to allow the dragonflies to complete their development. Odonata have never been observed on Sub-Antarctic islands and reports of natural arrival of insects into these islands mainly concern Lepidoptera. Here we also report observations of Vanessa cardui (Nymphalidae) which has established a permanent population on Amsterdam Island and has been observed on several occasions in the Crozet Archipelago.