Stenostephanus (Acanthaceae) in Peru

An account of the hill forest genus Stenostephanus Nees in Peru is presented. The salient characteristics and distribution of the genus are outlined to provide a wider context for the Peruvian species. Five new species, S. antiquorum J.R.I.Wood, S. atrocalyx J.R.I.Wood, S. cuscoensis J.R.I.Wood, S. densiflorus J.R.I.Wood and S. wasshausenii J.R.I.Wood are described as well as two varieties, var. angustissimus J.R.I.Wood and var. hirtiflorus J.R.I.Wood of S. longistamineus (Ruiz & Pav.) V.M.Baum. A key to all species occurring in Peru is provided together with diagnostic summaries of their salient characteristics and maps of their distribution. The new taxa are illustrated with line drawings and their conservation status is assessed.