Numerical phenetic analysis of Olinia rochetiana sensu lato (Oliniaceae)

Abstract

Previous circumscriptions of Olinia rochetiana A. Juss. (Oliniaceae) presented a taxonomically variable and widespread species complex in central and tropical East Africa. Results of numerical phenetic analyses of morphological variation within O. rochetiana sensu lato indicate the existence of four taxa which are recognisable at specific rank corresponding to O. huillensis Welw. ex A. & R. Fern., O. ruandensis Gilg, O. rochetiana A. Juss. sensu stricto and O. usambarensis Gilg ex Engl. The analyses also indicate that O. huillensis, hitherto reported to occur only in Angola, occurs widely in southern Africa and shows geographic segregates characterised as O. huillensis Welw. subsp. huillensis, O. huillensis subsp. burttdavii Sebola and O. huillensis subsp. discolor Sebola (Map 2). The major delimiting characters were found to be the shapes of petals and leaves, presence or absence of indumentum and the degree of hairiness on floral parts, and the form of inflorescence units (i.e. being either compact or spreading). Phenetic and ecological concepts of species are applied at the specific and subspecific ranks, respectively. Keys to distinguish between the species and infraspecific taxa are presented, and full descriptions and citations of examined specimens are provided.