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Representatives of three subgenera of Hylobatidae, Hylobates (Symphalangus) syndactylus, H. (Nomascus) concolor and H. (Hylobates) agilis were compared karyotypically by G-banding, and silver staining. A greater degree of similarity (30-55%) was found among these groups than previous reports suggest; however, these figures are still considerably lower than chromosome similarities characteristic of all other catarrhine groups. Inversion, translocation, fission, and fusion have all played a role in restructuring hylobatid chromosomes since a common hominoid ancestor. H. syndactylus and H. concolor show the greatest G-band correspondence, and in addition share an unusual C-band distribution and an extremely rare nucleolar organizing region placement (on the Y chromosome). The latter two are probably shared derived traits, suggesting that these two species shared a common ancestor not shared by other hylobatids. These data suggest a branching order for these three hylobatid groups different from those derived by other morphological and biochemical methods.
Tuinen et al. (Mon,) studied this question.