Early detection of an invasive harvestman in an oceanic island? Remarkable findings of Parabalta reedii (Opiliones, Gonyleptidae) in the Juan Fernández Archipelago, Chile

Abstract

The Juan Fernández islands (Chile) are a volcanic archipelago, 670 km away from the continent. Arachnids still remain understudied in those islands. We report the first two records of Parabalta reedii (Butler, 1874) (Opiliones, Gonyleptidae) from the Robinson Crusoe Island. One specimen was collected near San Juan Bautista town (in 2011), while a population was documented in 2020, in secondary forests also around town. Since other arachnological expeditions did not report the presence of this species, it is suggested that these findings might correspond to an incipient introduction, possibly associated with imported goods from the continent. Otherwise, it would be hard to explain why such a conspicuous harvestman has not been noticed before. An accurate assessment of the native or introduced nature of these populations will require further mainland and island surveys, as well as molecular studies. We aim to call the attention to a possible new invasive species in the Juan Fernández archipelago. Oceanic islands have a strong conservation value because of their high levels of endemicity and vulnerability to biological invasions. This finding could be considered as a warning call for other potential arthropod introductions.