Phylogeny, taxonomy and nest architecture of the fungus-growing ant genus, Sericomyrmex (Hymenoptera: Formicidae)

The fungus-growing ants (Myrmicinae: Attini) comprise a diverse and intriguing clade of obligate fungivores. All attine species grow fungus gardens inside their nests on organic substrates collected by foraging workers, effectively practicing agriculture in a way similar to humans. Sericomyrmex is a poorly known genus of fungus-growing ants that is closely related to the leaf-cutting genera Atta and Acromyrmex, the dominant herbivores in Neotropical ecosystems. Sericomyrmex includes 22 described species and subspecies and is distributed throughout most of South and Central America. This genus is known for its problematic taxonomy, including vague descriptions and absence of morphological characters that delimit species. I describe my current efforts to delimit Sericomyrmex species by integrating multiple sources of information. A molecular phylogeny based on one mitochondrial and two nuclear markers apparently recovers a lower number of species than currently recognized or, alternatively, may fail to recover the actual number of species due to a very recent rapid radiation and insufficient variation in the chosen markers. A similar lack of informative variation is found in morphological characters, which so far resolve only 5-8 operational "species." In an effort to increase the resolving power of molecular markers, I generated transcriptome data for three species of Sericomyrmex with the goal of finding genes evolving at rates appropriate for inferring species-level phylogeny. I am also exploring ecological and behavioral data as sources of information about Sericomyrmex species boundaries, particularly nest architecture, based on field work in Guyana, Peru, Brazil and Central America.