Geissmann, T. (2003). Circumfacial marking in siamangs and evolution of the face ring in the Hylobatidae. International Journal of Primatology 24: 143-158.
T. Geissmann
Institute of Zoology, Tierärztliche Hochschule Hannover, Germany
Key words: Symphalangus syndactylus;
siamang; gibbon; face ring; fur coloration; evolution
Abstract: The occurrence of a white brow band in siamangs is documented for
the first time. The characteristic occurs in 4.4% of the 250 siamangs examined for
this study. Among adult siamangs, the characteristic was found more often in females
than in males (11.3% of 71 females vs. 1.4% of 73 males, respectively). In a particular
family lineage of captive siamangs (not included in the numbers above), the characteristic
was unusually frequent (42.9% of 14). The trait appears to be inherited (possibly
an autosomal dominant inheritance). Additional white markings occur in at least one
of the study animals on hands, feet, and in a corona above the ears. In contrast
to other studies, the results of the present paper suggest that the presence of white
facial markings, and possibly also of white hands and feet and of a bright corona
are primitive gibbon traits. In addition, some degree of sexual dichromatism in the
circumfacial markings appears to have occurred in the common ancestor of all gibbons.
Site by Thomas Geissmann.
For comments & suggestions, please email to
webmaster@gibbons.de
Gibbon Research Lab. Home: |
![]() |