Ladenbergia siranensis (Rubiaceae: Cinchoneae), a new species from the Sira Mountains, Eastern Andes of Central Peru, and the identity of Ladenbergia acutifolia

A new species of Ladenbergia (Rubiaceae) has been found in the Cordillera de Sira in the eastern Andes of central Peru. It is here described as Ladenbergia siranensis, and it is morphologically similar to L. acutifolia, L. graciliflora and L. shawistigma. It differs from these by a shrubby habit, coriaceous, narrowly elliptic leaves, few-flowered inflorescences, the hypanthium hirtellous outside, small and deeply lobed calyx, a glabrous style, and fruits with reddened hirtellous pubescence. A key to these four species is provided.