soldierless Apicotermitinae: insights into a poorly known and ecologically dominant tropical taxon

Termites are among the most important animals in tropical ecosystems where they often make up over 10 % of the total animal biomass and enhance ecosystem productivity. While termites in general have been the focus of a reasonable amount of work, this effort is not equally distributed among taxonomic groups. The soil-feeding Apicotermitinae, in particular, have received less attention than other taxonomic groups. In terms of species diversity and abundance, the Apicotermitinae dominate African and Neotropical rainforests, where they generally feed on soil organic fractions. Whereas basal Apicotermitinae possess soldiers, this caste is missing in a large cluster of species, collectively called the Anoplotermes-group, which possibly constitutes a monophyletic lineage. These soldierless Apicotermitinae evolved alternative defensive strategies, such as defensive body rupture through autothysis or dehiscence. As species identification in termites is commonly based on characters of soldiers, the Anoplotermes-group has long been neglected by taxonomists, but alternative diagnostic characters, derived from the worker gut topology and enteric valve structures, are now routinely used. Although species identification based solely on worker characters is feasible and new molecular techniques greatly facilitate taxonomic studies, the biology of soldierless Apicotermitinae remains poorly known. The main objective of this paper is to increase the awareness and understanding of this dominant soil arthropod through a comprehensive review of their lifestyle and ecological importance.