Documenting the early stages of invasion of Matthiola parviflora and predicting its spread in North America

We identify Matthiola parviflora, native to the Mediterranean, as a newly discovered exotic plant in the Sonoran Desert in southwestern United States. We used morphological and molecular characteristics to distinguish M. parviflora from its naturalized congener Matthiola longipetala. Comparison with Internal Transcribed Spacer sequences from GenBank confirmed identification as M. parviflora. To predict the potential for broad-scale invasion, we used repeated censuses and maximum-entropy modeling with MaxEnt software. Censuses from 2008-2010 documented localized spread through an undisturbed biological reserve, and the modeling predicted a large area of suitable habitat in southwestern United States and northern Mexico. This record represents the first reported occurrence of M. parviflora in the Western Hemisphere and characterizes the species as well established near Tucson, Arizona, with a significant potential for spread.