Stranger in a known land: Bayesian analysis confirms the presence of an Australian leaf miner in the Chilean Atacama Desert

Several species of leaf-mining moths have become invasive in many parts of the world. Their success seems to be related, at least in part, to their small body size, short life cycles, high dispersal capabilities and relatively plastic host-plant associations. Here, we provide the first report of established populations of the elachistid moth, Elachista synethes, in South America (specifically the Azapa Valley, northern Chilean Atacama Desert). E. synethes is a widespread polyphagous species native to Australia, Tasmania and New Zealand. The immatures in the Azapa Valley were found associated with the South American native rescue grass, Bromus catharticus. Interestingly E. synethes is known to use B. catharticus as a host plant in the Australian region (i.e. where the plant is introduced but the moth native). In addition to comparing the morphology of immature and adult moths, we sequenced a partial region of the cytochrome oxidase subunit I gene from putative specimens from the Azapa Valley, and reconstructed a Bayesian phylogeny using representative species from different groups of Elachista as terminals. The specimens from Chile fell within the lineage of E. synethes, with 0% of genetic divergence. Thus, we hypothesize that this leaf-miner species was accidentally introduced into northern Chile, and has established there due to the existence of suitable host plants in that area.