Hedysarum langranii sp. nov. (Fabaceae, Hedysareae), a New Species From China, and Supplementary Descriptions of H. smithianum and H. dentatoalatum

ABSTRACT Hedysarum langranii sp. nov. (Fabaceae, Hedysareae) is described and illustrated from Shaanxi, Henan and Gansu, China. This new species is morphologically similar to H. smithianum , but can be distinguished by its glabrous stipules (vs. sparsely pubescent), standard petal 9–11 mm long (vs. 12–13 mm long), keel petals 12–13 mm long (vs. 14–15 mm long), androecium 13–15 mm long (vs. 16–17 mm long), loment articles 4–5 mm wide (vs. 5–7 mm wide). The new species can be easily distinguished from H. dentatoalatum by its papyraceous leaflets (vs. membranaceous), corolla pale purple or pink (vs. pale yellow); loment articles 5–7 × 4–5 mm, without prickle on the veins, with minute irregular teeth along both sutures (vs. 8–12 × 10–12 mm, with prickles on the veins, with wings and prominent teeth along both sutures). The phylogenetic tree based on the nuclear sequences shows that H. langranii is sister to H. dentatoalatum , while the tree based on the plastid sequences shows that H. langranii is sister to a clade consisting of H. smithianum and H. dentatoalatum. The new species and H. dentatoalatum are both diploids with a chromosome number 2 n = 14. Supplementary descriptions of H. smithianum and H. dentatoalatum are also provided. The incongruent phylogenetic position of H. dentatoalatum could be explained by an ancient hybridization hypothesis, but requires further investigation to determine the reason for this incongruence.