Abstract:
The nomadic, swarm-raiding army ant Labidus praedator (Smith, 1858) is an important
arthropod predator in the Neotropics with a strong ecological impact on invertebrate
communities. However, despite its high abundance and ubiquity over a large distribution
range, it received relatively little scientific attention. Moreover, the taxonomic status is
confusing because some morphological descriptions point towards the co-occurrence of
several distinct taxa which are lumped together as L. praedator in most classical keys. Yet,
clarifying genetic studies are lacking. Here, we show strong genetic differentiation within an
L. praedator population in Mexico. Both microsatellite genotype patterns and phylogenetic
analyses (concatenated nuclear and mtDNA sequences, including the coxI genetic barcoding
region), reveal the occurrence of two strongly isolated lineages. Colonies from the very
same location, clearly identified as the same species (L. praedator) according to classical
morphological keys, exhibit an extremely high average sequence divergence (9.7–12.8 %),
which was well in the range of divergence among GenBank sequences from other Labidus
species. Thus, our data very likely show genetic differentiation at species level or cryptic
speciation within L. praedator, which should be recognized when investigating biodiversity
and ecological importance of army ants (or other arthropods) in the Neotropics.
