A New Species of Echinopepon from Argentina and Taxonomic Notes on the Subtribe Cyclantherinae (Cucurbitaceae)

Echinopepon disjunctus, a new species of the Echinopepon torquatus species-group from the Yungas rainforest of Jujuy (Argentina), is described and illustrated. Echinopepon coulteri is here excluded from the E. torquatus group on inflorescence and floral characters; a key to the remaining species of the group is included. In addition, the floral structure of the monotypic genus Pseudocyclanthera and four species of Rytidostylis is reviewed. The aestivation of the corolla, invagination at the base of the hypanthium, nectar-secreting trichomes, synanther, and pollen morphology support a closer relationship between Pseudocyclanthera and Rytidostylis than between Pseudocyclanthera and Cyclanthera. The receptacular nature of the trichomatous base of the androecial column and style seems to be distinctive for Rytidostylis. A key to the genera Cyclanthera, Pseudocyclanthera, and Rytidostylis is also included.