Evolving under myrmecophily: a cladistic revision of the symphilic beetle tribe Sceptobiini (Coleoptera: Staphylinidae: Aleocharinae)

Abstract. A phylogenetic analysis is carried out using Falagriini as the sister taxon of the tribe Sceptobiini. The trees resulting from a series of matrix manipulations and analyses are highly congruent. Two clades are produced: Dinardilla includes two species, and Sceptobius includes three species. Symbiochara Fenyes and Apteronina Wasmann are synonymized with Sceptobius Sharp, and Apteronina wasmanni Mann is synonymized with Sceptobius dispar Sharp.
All sceptobiine species are obligate inquilines of either Liometopum apiculatum Mayr or L.occidentale Wheeler (Hymenoptera: Formicidae: Dolichoderinae). Preliminary behavioural observations indicate that the subdivision into two clades is reflected in the types of interactions with host ants. Dinardilla beetles actively interact with the host, while Sceptobius beetles are more peripheral within the nest. These ecological and behavioural differences are believed to be produced by an interaction between ecological specialization, chance historical events, and geographic isolation during the speciation of the host ants.