Molecular phylogeny of Ochrosia sensu lato (Apocynaceae) based on ITS sequences data: An evidence for the inclusion of Neisosperma

Molecular phylogeny of <I>Ochrosia</I> sensu lato (<I>Ochrosia</I> sensu stricto and <I>Neisosperma</I>) was investigated by maximum parsimony analysis of sequence data from the internal transcribed spacer (ITS) of nuclear ribosomal DNA. Twenty-one species including two varieties (25 accessions), were defined as the ingroup. Three outgroup species were selected from tribe Vinceae (<I>Kopsia arborea, K. flavida</I>, and <I>Rauvolfia serpentina</I>). The ITS sequence data showed that <I>Ochrosia</I> s.l. is a highly defined monophyletic group (supported with 100% bootstrap value). As shown in the strict consensus tree, all <I>Neisosperma</I> species were placed at the basal part of the tree with <I>N. glomerata</I> and <I>N. nakaiana</I> as the basalmost taxa. All species belong to <I>Ochrosia s.str.</I> were grouped into one clade and nested within <I>Neisosperma</I> resulting in monophyletic <I>Ochrosia</I> s.str. and paraphyletic <I>Neisosperma</I>. This suggested that <I>Neisosperma</I> should be included into <I>Ochrosia</I>, and the two groups are treated as a single genus. The analysis also showed that subdivision of <I>Ochrosia s.l.</I> into sections based on fruit morphology (fibrous vs. massive and thick endocarp) is not supported.