The active NOR-bearing chromosomes found in the karyotypes of the Pithecopus species and the broader phylogenetic context of the genus. Two possible scenarios to explain NOR variation are shown in inset (see details in discussion). The phylogenetic arrangement was reconstructed from Duellman et al (2016) and Haga et al. (2017). Chromosomes within brackets present additional NOR sites in the polymorphic condition within the population. The NOR site of the underlined pairs (black lines) was confirmed by FISH using the rDNA probe. Species with unknown karyotypes are indicated by the “?” symbol. Species suspected to contain cryptic diversity are represented by triangles. The letters within brackets indicate the following references: [a] Present study; [b] Bruschi et al. (2012); [c] Barth et al. (2009); [d] Paiva et al. (2009); [e] Bruschi et al. (2013); [f] Morand and Hernando (1997); [g] Barth et al (2013); [h] Bruschi et al. (2014a); [i] karyotype described by Bruschi et al. (2013) and recognized as a new species by Haga et al. (2016). The asterisks (*) represent the heteromorphic condition resulting from the paracentric inversion found in the Alta Floresta population by Bruschi et al. (2013).