Anisophylly in South American Acanthaceae

: Attention is drawn to the nature and occurrence of anisophylly in South American species of Acanthaceae. Consultation of existing scientific literature and herbarium records has enabled the compilation of an extensive list of Acanthaceae species known to exhibit the phenomenon within the region, where it is most common in Justicia L., Lepidagathis Willd., Sanchezia Ruiz & Pav., and Pseuderanthemum Radlk. Some insights are drawn into the occurrence, systematic patterns, and potential ecological implications of anisophylly in this family, but the character is shown to be of limited use in species diagnosis. Six new species of Justicia from Peru, Ecuador and Colombia that exhibit this unusual morphological characteristic are described, J. impar J.R.I.Wood & P.Gallego, J. imparifolia J.R.I.Wood & P.Gallego, J. maynasana J.R.I.Wood & P.Gallego, J. microcalyx J.R.I.Wood & P.Gallego, J. obliqua J.R.I.Wood & P.Gallego and J. yariguiorum P.Gallego & J.R.I.Wood. The paper is illustrated with maps and line drawings. Notes on related species, distribution and conservation are provided.