Rediscovery and taxonomic placement of Solanum polyphyllum Phil. (Solanaceae), a narrow endemic from the Chilean Atacama Desert

Although the original description of Solanum polyphyllum Phil. was made in 1891, this species was not seen until it was re-discovered 128 years later in 2019 in the Atacama Desert. Fruits and seeds were previously unknown and a complete description is provided here. This species was not treated in the most recent monograph of Solanum sect. Regmandra, but it should be incorporated in this section due to its glabrous, sessile and entire leaves, which are decurrent onto the stem. Morphologically, S. polyphyllum is similar to S. paposanum, also of section Regmandra, but differs in the entire leaves (against margins with 4–5 acute lobes in S. paposanum) and glabrous leaves (moderately pubescent adaxially and velutinous abaxially in S. paposanum). The rediscovery of S. polyphyllum at a new locality at the same altitudinal belt as the type, re-affirms its restricted distribution and endemism and supports a potential conservation status as an endangered species.