Riding on ants: A new report of this interesting behavior in Attacobius spiders (Araneae: Corinnidae)

Abstract

Ants are among the most ecologically dominant animals in several terrestrial ecosystems. Some myrmecophile species use ants to transport themselves, a behavior known as phoresy or phoresis. Although phoresis is commonly reported in arachnids such as pseudoscorpions or acari, it is very unusual among spiders. Phoresis on ants has only been reported in one genus of spiders, the sac-spider Attacobius Mello-Leita˜o, 1925 and for only two Brazilian species. In this report, we describe this amazing behavior in Attacobius nigripes (Mello-Leita˜o, 1942) for the first time in association with a new host, the leaf-cutting ant Acromyrmex lobicornis Emery, 1888. This record extends the geographic distribution of this spider species to the southwest of Argentina, from the Chacointo the Monte Desert region. We briefly describe the riding behavior of spiders and discuss the myrmecophile association between this species and A. lobicornis. More studies are needed to understand the evolutionary context of this association.