A Taxonomic Synopsis of Aldina, a Florally Distinctive and Poorly Collected Amazonian Genus of Papilionoid Legumes

We present a taxonomic synopsis of Aldina (Leguminosae, Papilionoideae), a poorly known Neotropical genus of predominantly Amazonian trees with unusual, non-papilionate flowers. Aldina is characterized by the combination of odd-foliolate leaves and flowers with radial symmetry, free and undifferentiated petals, an entire calyx, and free, numerous stamens. Difficulty accessing species in remote areas has led to poor representation in herbaria, and species descriptions based on scant material have led to a doubtful and confused taxonomy. Eighteen species are recognized here: A. aurea, A. auyantepuiensis, A. barnebyana, A. berryi, A. discolor, A. diplogyne, A. elliptica, A. heterophylla, A. insignis, A. kunhardtiana, A. latifolia, A. macrophylla, A. microphylla, A. occidentalis, A. paulberryi, A. petiolulata, A. polyphylla, and A. reticulata. The names A. amazonica, A. latifolia var. pubescens, A. insignis var. retusa, A. stergiosii, A. aquae-negrae, A. rio-negrae, and A. speciosa are newly synonymized. We lectotypify A. discolor, A. heterophylla, A. macrophylla, A. occidentalis, and A. polyphylla, and make a new combination, Aldina auyantepuiensis. All Aldina species are found in the Amazon basin. An identification key for all species, a color plate, diagnostic illustrations, and a map of geographic distribution of the genus are also presented.