Facultative commensalism of gastropods (Mollusca: Gastropoda) in Neoponera verenae Forel, 1922 (Formicidae: Ponerinae) nests

Abstract

Ants are a ubiquitous, diverse, and ecologically dominant group that uses different types of substrates for nesting. These nests provide protection and food in a temperature- and humidity-stable environment, which attracts numerous organisms that live in association with these social insects. The interactions between ants and some myrmecophilous groups, such as coleopterans and lepidopterans, have been widely studied, while other groups, such as gastropods, have received less attention. In this study, we present observations of the interactions between the Neotropical ponerine ant Neoponera verenae and terrestrial gastropods. We found 56 individuals belonging to four families, seven genera, and eight species of terrestrial gastropods in ant nests established in three types of substrates (dry cocoa pod, soil, and decaying wood trunk) in the Atlantic Forest Biome. The most frequent genera were Allopeas and Leptinaria (Achatinidae), which accounted for 57.1% of the observed specimens. The gastropods mainly used the shelter provided by ant nests, their favourable and stable microclimatic conditions, and the abundant food resources stored in waste chambers. Young and adult individuals of Leptinaria sp. were found in ant nests, but no aggressive or predatory behaviours were recorded in interactions between ants and gastropods. Our study includes unpublished records of ant nest commensals and presents hypotheses on the close interactions between gastropods and ants.