Cryptic speciation in the fungus-growing ants Cyphomyrmex longiscapus Weber and Cyphomyrmex muelleri Schultz and Solomon, new species (Formicidae, Attini)

Nesting in abundance on stream embankments in the wet forests of Panama, the fungus-growing ant Cyphomyrmex longiscapus sensu lato has become a model organism for the study of behavior, ecology, mating frequency, cultivar specificity, pathogenesis, and social parasitism in the attine agricultural symbiosis. Allozyme markers, morphology, and other evidence indicate that C longiscapus s.l. is in fact a complex of two species, one of which is new to science and described here as Cyphomyrmex muelleri Schultz and Solomon, new species. Although both species occur sympatrically in the same microhabitats and are ecologically, behaviorally, and morphologically quite similar, they consistently cultivate two distantly related fungal symbionts. Thus, each of the two sibling ant species is specialized on a distinct cultivar species, contradicting the conclusions of a previous study. Information is provided for reliably separating the two ant species; morphometrics, ecology, behavior, biogeography, and natural history are summarized. Possible evolutionary mechanisms underlying cryptic speciation in C longiscapus s.l. are discussed.