Species and generic delimitation in Bikinia and Tetraberlinia

Abstract

We have assessed the monophyly and internal topology of Bikinia and Tetraberlinia along with some other systematic and methodological questions using AFLP analyses. In addition to AFLP analyses we tried to determine the sister group of these two genera by adding additional sequences to an existing ITS data set. Our analyses suggest Julbernardia is the closest related genus, but also Icuria is a candidate since the position of this genus remains unclear. Although ITS provides us with some good resolution at the generic level, we have to conclude ITS is not a good marker in this group due to the presence of several non-homologous copies. Evidence for a monophyletic Bikinia is quite strong. However, more evidence is needed to test the monophyly of Tetraberlinia. Within Bikinia, only a clade consisting of B. aciculifera and B. durandii was supported by a jackknife analysis. We show that B. le-testui and B. pellegrinii are separate species. Aberrant Bikinia material from the Crystal Mountains in Gabon proved to be a new species. A sapling collected under a tree of B. le-testui could be identified as a hybrid between this species and B. media. Another new species, T. apiphila, is clearly related to Tetraberlinia, although it also shares some morphological characters with Bikinia. We demonstrated that AFLP results can be reproduced and that the errors of such replications fall within the variation present at the population level. AFLP can discriminate between different populations of a single species, even with high jackknife support. In the sample of genera studied here the AFLP technique provides high resolution at generic level and we even expect it to work between several closely related genera. Finally, we describe how the AFLP technique can be used to identify hybrids