Generic Relationships and Classification of Tribe Paullinieae (Sapindaceae) with a New Concept of Supertribe Paulliniodae

The current study examines all genera of Sapindaceae tribe Paullinieae sensu Acevedo-Rodriguez et al. (2011). Based on molecular phylogenetic analyses of trnL intron and ITS sequence data along with critical evaluation of morphology, supertribe Paulliniodae is newly recognized and morphologically characterized by zygomorphic flowers, thyrses with lateral cincinni, corollas of 4 petals, and alternate leaves with a well-developed distal leaflet. Paulliniodae contains four successively nested subclades designated as tribes Athyaneae, Bridgesieae, Thouinieae, and Paullinieae. Athyaneae contains Athyana and Diatenopteryx, and is composed of trees with exstipulate pinnately compound leaves, and isopolar, spherical, colporate pollen grains. Bridgesieae contains the monospecific shrub genus Bridgesia with exstipulate, simple leaves, and isopolar, spherical, tricolporate pollen grains. Thouinieae is resurrected and amended to include three genera of trees or shrubs with exstipulate trifoliolate or unifoliolate leaves. Paullinieae is circumscribed to include only six genera (Thinouia, Lophostigma, Cardiospermum, Paullinia, Serjania and Urvillea) of climbers or climber-derived shrubs with stipulate leaves and a pair of inflorescence tendrils. Guindilia, previously considered a member of this clade, is shown to be more distantly related and not part of supertribe Paulliniodae. The following 14 new combinations are made to incorporate the results of our findings: Serjania biternata, Serjania cristobaliae, Serjania dissecta, Serjania guerrerensis, Serjania macrolopha, Serjania serjanioides, Serjania sonorensis, Serjania spinosa, Serjania tortuosa, Thinouia trifoliata, Urvillea cuchujaquense, Urvillea oliveirae, Urvillea procumbens, and Urvillea pterocarpa.