Pithecoctenium Mart. ex Meisn. is a genus of four species in the tribe Bignonieae. All the species are lianas, and can be recognized by their acutely hexangular branchlets, bifoliolate leaves with a trifid or, more frequently, additionally trifurcately-branched terminal tendril, arching corollas that are coriaceous, white, and pubescent, and echinate fruits (except in P. falcatum (Vell.) A. Pool) with seeds surrounded on three sides by a clearly demarked, hyaline-membranous wing. Relationships with similar genera are discussed, and a key to the species of Pithecoctenium, their descriptions, and distribution maps are provided. The relationships of the species are also discussed. Lectotypes are designated for Bignonia squalus Vell., P. echinatum var. tomentosum Hassl., P. vitalba f. glabratum Hassl., and P. vitalba f. intermedium Hassl., a lectotype and epitype are designated for B. falcata Vell., and a new combination, P. falcatum (Vell.) A. Pool, is proposed. The following are presented as new synonyms of P. crucigerum (L.) A. H. Gentry: B. botryoides Cham., B. vitalba Cham., B. vitalba var. extratropica Cham., P. catharinae DC., P. echinatum var. tomentosum Hassl., P. echinatum var. tomentosum f. grandiflorum Hassl., P. hexagonum var. brasilianum DC., P. vitalba f. glabratum Hassl., P. vitalba f. intermedium Hassl., and P. echinatum var. intermedium Hassl. Pithecoctenium cynanchoides DC., Anemopaegma clematideum Griseb., and P. cynanchoides var. pellucidum Hassl. are presented as new synonyms of P. carolinae (Lindl.) G. Nicholson. Pithecoctenium cordifolium DC. (including the nomina nova for P. cordifolium DC.: Neves-armondia cordifolia K. Schum. and P. hatschbachii A. H. Gentry) is presented as a new synonym of P. falcatum (Vell.) A. Pool.