A REEVALUATION OF THE TRIBES HIPPOTIDEAE AND TAMMSIEAE (RUBIACEAE)

The genera Hippotis, Pentagonia, Sommera, and Tammsia, the hippotides, have recently been removed from their traditional position in the tribe Isertieae and proposed to form two separate tribes, Hippotideae (the three former genera) and Tammsieae (the latter one). In the most recent overview of the classification of the Rubiaceae, the position of these tribes was considered uncertain. The morphology and micromorphology of representatives of all genera were reexamined and data were analysed cladistically. It is concluded that the original distinction between the Hippotideae and Tammsieae was based on faulty observations, the hippotides being uniform in ovary morphology. The cladistic analysis suggests that the hippotides form a monophyletic group, within which Tammsia is nested. It is therefore proposed that Tammsieae should be reduced to a synonym of Hippotideae. There are no indications that the hippotides should be reunited with the Isertieae. The genus Wiasemskya Klotzsch is shown to be synonymous with Tammsia, and it is argued that the genus Striolaria Ducke is synonymous with Pentagonia.