The genus Steenisia (Rubiaceae) and its taxonomic position

Steenisia, with 5 species in Borneo and the Natuna Islands, is proposed to be removed from the tribe Argostemmateae (Rubioideae – Rubiaceae) to the tribe Rondeletieae (Cinchonoideae s. str. – Rubiaceae). The contorted aestivation of the corolla, the structure of the testa, the general absence of raphides, and the type of placentation are characters indicating this position. A key and descriptions, distribution maps and illustrations of all species are provided.