Taxonomic review of the genus Gymnocladus (Fabaceae: Caesalpinioideae: Gleditsieae) with emphasis on Asian species, including a new species G. sanctus.

A total of six species of the genus Gymnocladus are recognized herein, five of which are distributed in Asia: G. angustifolius, G. assamicus, G. burmanicus, G. chinensis, along with G. sanctus that is described and illustrated as new. The new species resembles the only North American species, G. dioicus, but differs by its generally lanceolate-ovate to oblong (vs. ovate) leaflets, which are thinly coriaceous (vs. chartaceous), pinkish (vs. white to greenish-white) flowers, and generally smaller and thicker (8–12 × 3–4.5 × 2.5–3 cm vs. 12–25 × 3–7 × 0.6–0.8 cm), sparsely puberulent (vs. glaucous) pods. Additionally, a lectotype is designated for G. assamicus. An updated key encompassing all six species and a distribution map for the five Asian species are also provided.