Untangling the ant claws: the army ant Labidus mars is a Neivamyrmex (Formicidae: Dorylinae)

Authors: DUVAL, MEGAN - University Of Utah; PROBST, RODOLFO - University Of Utah; Branstetter, Michael; LONGINO, JOHN - University Of Utah

Submitted to: Insect Systematics and Diversity
Publication Type: Abstract Only
Publication Acceptance Date: 2/17/2025
Publication Date: 6/3/2025
Citation: Duval, M.E., Probst, R.S., Branstetter, M.G., Longino, J.T. 2025. Untangling the ant claws: the army ant Labidus mars is a Neivamyrmex (Formicidae: Dorylinae). Insect Systematics and Diversity. https://doi.org/10.1093/isd/ixaf016.
DOI: https://doi.org/10.1093/isd/ixaf016

Interpretive Summary: Army ants are a prominent group of insect predatory ants that occur in tropical and subtropical regions. In North and South America the taxonomy of species is challenging and there are often few morphological differences that define species and genera, particularly in the genera Neivamyrmex and Labidus. Using molecular data, a group of researchers from the University of Utah and ARS tested the taxonomic placement of male and worker specimens of the species Labidus mars and found that the worker belongs within the related genus Neivamyrmex rather than Labidus while the male was correctly place. Based on these results, the classification of Labidus mars and several related species names associated with the male caste was revised. These results improve knowledge of army ant taxonomy in the tropics which will aid future biodiversity and ecological research in the region. The study also demonstrates how molecular data can be used to check and fix the identity of insect taxa when morphological information is lacking.

Technical Abstract: The Eciton genus group are the New World army ants (Hymenoptera: Formicidae), important keystone predators in tropical and subtropical environments. Generic boundaries in the group have been considered solid and stable for nearly 100 years. One of its members, the genus Labidus, is wide-ranging and ecologically important, with a broad dietary niche and often high local abundance. The genus Neivamyrmex, although less conspicuous than the generalist and often surface-raiding Labidus, is the most diverse and wide-ranging New World army ant genus. Within these genera, species are currently recognized based on the morphology of workers and males. The absence of a tooth on the tarsal claws is thought to separate workers of Neivamyrmex from workers of the other New World army ant genera. Within Labidus, L. mars is unusual for being completely eyeless and subterranean, and morphologically similar to some Neivamyrmex species, leading us to question its generic placement. Here, we used ultraconserved element (UCE) data to show that Labidus mars is a Neivamyrmex, with all concatenated phylogenies (inferred using multiple partitioning schemes: unpartitioned, by locus, and Sliding Window Site Characteristics) and a species tree analysis recovering the same topology placing L. mars within Neivamyrmex. Based on these results, and review of key specimens, the following taxonomic changes are made: Neivamyrmex mars Forel 1912 new combination; Labidus nero (Santschi, 1930) (rev. stat.) is revived from synonymy under L. mars; L. denticulatus (Borgmeier, 1955) (new stat.) is raised to species.