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

Abstract

Ants are a ubiquitous, diverse, and ecologically dominant group and use different types of substrates for nesting. Ant nests offer protection and food in a temperature- and humidity-stable environment. Such an environment attracts numerous organisms that live in association with these social insects. The occurrence and interactions of some myrmecophilous groups have been widely studied, such as those of coleopterans and lepidopterans. Other groups have been neglected in this regard, such as gastropods. This study presents a series of observations of the interactions between gastropods and the Neotropical ponerine ant Neoponera verenae. A total of 56 individuals belonging to four families, seven genera, and eight species of terrestrial gastropods were found in ant nests established in three types of substrates (dry cocoa pod, soil, and decaying wood trunk). The most frequent gastropod family was Achatinidae (n = 41), followed by Scolodontidae (n = 13), Helicinidae (n = 1), and Vitrinidae (n = 1). The most frequent genera were Allopeas and Leptinaria (both from Achatinidae), which together accounted for 57.1% of the observed specimens. Young and adult individuals of Leptinaria sp.1 were found in ant nests. Neither aggressive nor predatory behaviors were recorded in interactions between ants and gastropods. Gastropods mainly made use of the shelter provided by ant nests, their favorable and stable microclimatic conditions, and the abundant food resources stored in waste chambers. Our study includes unpublished records of ant nest commensals and presents hypotheses on the close interactions between gastropods and ants.