The paper describes the external structures of the late larval stages of two Palearctic myrmecophilous staphylinids: Amidobiatalpa and Oxypodahaemorrhoa associated with the Formicarufa species group. This is the first-ever description of the larva of Amidobia, and the only complete, detailed account of the morphology of this developmental stage in the genus Oxypoda currently available. For the first time in these two genera, 13 and 10 larval diagnostic features, respectively, are proposed. Morphological differences have been established between known and the newly described larvae of five species (genera) of myrmecophilous and one non-myrmecophilous Aleocharinae, belonging to three tribes. Amidobiatalpa and O.haemorrhoa are probably typical, tiny predators, like most other Aleocharinae, including non-myrmecophilous ones. Being very small and highly mobile, they are ignored by worker ants. Not surprisingly, no particular larval morphological modifications were found to enable them to survive among ants. Such features have, however, evolved in the larvae of larger aleocharines, that is, those that are perceived by ants and are wholly integrated with their hosts in the ant nest (e.g. Lomechusa). This comparative analysis of the functional morphology of the larvae of known myrmecophilous Aleocharinae is a springboard to further such studies of these interesting insects.
Keywords: Coleoptera; Aleocharines; Red wood ants; developmental stages; ecological preferences; external structure; larva; late larval instars; morphology; myrmecophile; rove beetles; symbionts.