It now appears that gibbons and siamangs (Hylobates, Nomascus and Symphalangus) are monophyletic with respect to the clade that includes gorillas, chimpanzees, orangs and us. I have reproduced the relevant part of the image in the PLoS article to the left. About them, the authors of the article write:
The eight species included in this study form three clades that coincide with genus designation (absent is Hoolock; nodes 64–69) that diverged rapidly 8.9 MYA. Moreover, Nomascus species appear more recent than Symphalangus and Hylobates, with node divergence dates estimated at less than 1 MY (Table 3, Table S9, Figure 2). Thus, Hylobatidae exhibits episodes of rapid divergence perhaps related to excessive genome re-organization and warrants additional investigation.Another piece of the puzzle.
Hat Tip to Bill Myers.
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