QH 1 9, No. 19, pp. 259-264 12 October 1976 B4X f^^ PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON A JACANA FROM THE PLIOCENE OF FLORIDA (AVES: JACANIDAE) By Stores L. Olson Smithsonian Institution, Washington, D.C. 20560 The seven or eight hving species of jacanas (Jacanidae) form a distinctive pantropical charadriiform family, highly specialized for locomotion on floating vegetation. A single genus, Jacana, is found in the New World, where it is endemic. Its forms extend from Argentina north through Mexico to southernmost Texas and the Greater Antilles. The only Tertiary bird ever thought to be related to the Jacanidae was Rhegminornis calohates Wetmore from the Lower Miocene of Florida. Wetmore (1943) made this the type of a new family, the Rhegminornithidae, which Brod-korb (1967) later retained as a subfamily of the Jacanidae. The affinities of Rhegminornis were subsequently determined to lie with the Meleagrididae in the order Galliformes ( Olson and Farrand, 1974). The only remaining fossil record of the Jacanidae is a late Pleistocene occurrence of the living species Jacana spinosa in Brazil (Winge, 1888). The discovery of a jacana among the avian material collected at a Middle Pliocene locality in north-central Florida is therefore of con-siderable interest. In the present paper, the name Jacana spinosa is used in the broad sense to include all living forms of the genus. The populations from western Panama northward (/, spinosa, sensu stricto) are often considered specifically distinct from those to the south (/. jacana), and the exact nature of the interaction between these forms where they come in contact in Panama is not yet fully understood (Wetmore, 1965). If indeed two species are involved, they are very closely re-lated and certainly constitute a superspecies. The compara-19— Proc. Biol. Soc. Wash., Vol. 89, 1976 (259) // CD C/' Ir-c:> * so oo I^; J> o CZ-il , -^ ■V ^—•'1 '^SZ' .<^' '\<^' \\a> a\'