Studies of Neotropical Compositae—XIX. Sciadocephala gentry (Eupatorieae), a New Species from Pasco, Peru

Sciadocephala gentryi Pruski & R. Ortiz (Compositae: Eupatorieae: Adenostemmatinae) is a newly described serrate-leaved understory herb endemic to Pasco, Peru, that we compare to its congeners. The second of two Peruvian species is S. amazonica R. M. King & H. Rob., herein newly reported for Peru and vouchered by entire-leaved material found near Iquitos, Loreto. In Peru, each of these two species was first collected and identified to genus by Alwyn Gentry, and these are the only species of Sciadocephala Mattf. with pinnately veined leaf blades and pubescent nectaries. Previously, the two Peruvian collections of S. amazonica were determined in the literature as S. schultze-rhonhofiae Mattf., a trinervate-leaved Ecuador endemic herewith excluded from the flora of Peru. A key to the species of Sciadocephala, a distribution map of Sciadocephala, and preliminary conservation assessments of the two species in Peru are given. Sciadocephala gentryi has several floral characters that have been associated with wind pollination in Eupatorieae.