Phylogeny and phylogeography of the genus Gymnocladus and its close relatives.

Abstract In this chapter, an attempt has been made to understand the phylogeny and phylogeography of the genus Gymnocladus and its close relatives. Gymnocladus is a small archaic genus belonging to the family Leguminosae, having very few species and showing interesting patterns of distribution. The genus was first described by Lamark with two species G. canadensis and G. arabicus from eastern Canada and Egypt, respectively. Guilandina dioica is an earlier name for the Canadian species Gymnocladus canadensis, which is again synonymized to Gymnocladus dioica. Another sister genus of Gymnocladus is Gleditsia, which was described by Linnaeus with a single species Gleditsia triacanthos from Virginia (North America). Currently, there are approximately 14 species in the world out of which 10 species are found in temperate Asia, 2 or 3 in North America, G. amorphoides in South America and G. caspica around the Caspian Sea. In India, the genus Gleditsia is represented by G. assamica and G. delavayi and is also restricted to the northeastern region of India. Occurrence of Gymnocladus burmanicus from Arunachal Pradesh in India is also highlighted in this chapter.