The lowest diploid number (2n=16) yet found in any primate:: Callicebus lugens (Humboldt, 1811)

Morphologic, molecular and karyologic analyses of Callicebus lugens (Humboldt, 1811) of known geographic origin supported the proposition that this is a valid species. Morphologic and morphometric analyses showed evident differences between C lugens and two other related taxa of the same group (Callicebus purinus and Callicebus torquatus). Cytochrome b DNA analyses (maximum parsimony, neighbour joining and maximum likelihood) were congruent in showing a strong association between C lugens and Callicebus sp. of the torquatus group in one branch and a sister branch further divided into two clades: one with species of the personatus group and another, with species of the moloch group. Karyotypic analysis showed that C lugens has the lowest diploid chromosome number of the primate order (2n = 16). Comparisons with other congeneric species clearly supported the proposition that C. lugens is karyotypically similar to others of the torquatus group. Copyright (C) 2003 S. Karger AG, Basel.