Cebus (Sapajus) libidinosus Spix, 1823

Gutierrez, Eliecer E. & Marinho-Filho, Jader, 2017, The mammalian faunas endemic to the Cerrado and the Caatinga, ZooKeys 644, pp. 105-157 : 113-114

Cebus (Sapajus) libidinosus Spix, 1823

Distribution.

Cebus libidinosus is endemic to the Cerrado and the Caatinga, and has been recorded in the Brazilian states of Bahia, Ceará, Goiás, Maranhão, Minas Gerais, Paraíba, Piauí, Pernambuco, Rio Grande do Norte, São Paulo, Tocantins, and Distrito Federal ( Pontes et al. 2006, Vilela 2007, Canale et al. 2009, Bruna et al. 2010, Lynch-Alfaro et al. 2012a, 2014, Feijó and Langguth 2013, Fragaszy et al. 2013, Gomes et al. 2015, Mendes et al. 2015, Nova et al. 2015).

Nomenclature.

We regard libidinosus as a member of the genus Cebus , subgenus Sapajus , and advocate for the use of the name Sapajus at the subgenus-level (contra Lynch-Alfaro et al. 2012a, 2012b, 2014). The division between the gracile (untufted) and robust (tufted) groups of capuchin monkeys has been known for over a century (see Elliot 1913, Hershkovitz 1949, 1955), and the names Cebus and Sapajus have been applied to them at the subgenus-level, respectively (e.g., Silva-Junior 2001, Ferreira et al. 2009, Casado et al. 2010). Lynch-Alfaro et al. (2012a) recommended elevating Sapajus to the genus-level based on their estimated age for the split between the gracile and robust lineages of Cebus (95% highest posterior density = 4.21-7.86 Ma). This estimate resulted from the analysis of sequence data from two mitochondrial genes. Subsequently, Lynch-Alfaro et al. (2012b) summarized known morphological and behavioral differences between gracile and robust lineages, restated the gene-tree argument of Lynch-Alfaro et al. (2012a), and advocated for elevating Sapajus at the genus level; 'expert opinions’ have been invoked to promote this view ( Lynch-Alfaro et al. 2014). Although several NGOs, ecologists, and ethologists started to adopt this proposal, dissent exists (e.g., Rosenberger 2012, Feijó and Langguth 2013, this study). Clearly, the differences and phylogenetic split between the two lineages of capuchin monkeys should be recognized with Linnean nomenclature; however, the most suitable action to do so, at least provisionally, is to use Sapajus and Cebus as subgenera of Cebus . At least three reasons support this view, as follows (see also Voss et al. 2014, Garbino 2015a):

(1) Elevating Sapajus to the genus level is unnecessary, as it does not accomplish anything than using the name at the subgenus level could not.

(2) At least for now, using the age since the split between Sapajus and Cebus as an argument to elevate Sapajus at the genus level is flawed for two reasons. First, because the age of that split, as estimated by Lynch-Alfaro et al. (2012a), was inferred based on data from a single locus, it should be considered a preliminary one (i.e., a working hypothesis). Secondly, the artifactual current taxonomy of platyrrhine monkeys (see Rosenberger and Matthews 2008, Rosenberger 2012, Garbino 2015a and references therein) prevents sensible comparisons of age of splits among pairs of platyrrhine sister genera. This is a consequence of the wide, dogmatic acceptance of genera that have been proposed on the basis of criteria that are typically used to recognize species (at best) in most other groups of mammals. A recent example of this phenomenon is provided by the recent proposal to validate the name Leontocebus as a genus, to contain the nigricollis group of Saguinus , using as an argument the fact that it is sympatric with other tamarin lineage ( Rylands et al. 2016) - note that this same unacceptable criterion (i.e., sympatry) and divergence-time have been used by Byrne et al. (2016) to propose the recognition of Cheracebus as a “genus” and without even considering the more sensible option of regarding Cheracebus as a subgenus of Callicebus ; we herein propose to use Cheracebus

at the subgenus level only. Clearly, the currently inflated taxonomy of New World primates should be fixed, and several proposed genera should be lumped into fewer ones. This process has already begun (e.g., Garbino 2015a, this study), but it is far from completion.

(3) Continuing to recognize the long established, monophyletic genus Cebus , and subgenera Sapajus and Cebus within it, allows for more efficient communication among scientists. First, the use of the genus-(subgenus)-species format (i.e. using the subgenus name, when pertinent) readily confers phylogenetic information. In this case, the genus name Cebus informs about the sister-taxon relationship between the subgenera Sapajus and Cebus - supported by a number of synapomorphies (see Lynch-Alfaro et al. 2012b) - whereas the subgenera names, Sapajus and Cebus , recognize the differences between the two lineages that underwent different evolutionary histories. Furthermore, association of the genus name Cebus with the species epithets of both linages of capuchin monkeys have existed for decades, and unnecessarily disrupting this association (by elevating Sapajus to the genus level) might pose difficulties in scientific communication, for example for literature searches or for merging data from public repositories (e.g., GenBank, Global Biodiversity Information Facility).

We take the opportunity to emphasize the importance of using the subgenus rank to preserve nomenclatural stability, similar to what have been recently done for other groups of mammals ( Giarla et al. 2010, Voss et al. 2014, Díaz-Nieto et al. 2016, Teta et al. 2016). This aspect is especially important for New World primates , whose generic and alpha-level taxonomy should be rectified in the upcoming decades.

Conservation status.

The red list of the IUCN ver. 3.1 assigned the category "Least Concern" to Cebus (Sapajus) libidinosus (see Rylands and Kierulff 2015). The species was not included in the official list of threatened species of Brazil ( ICMBIO-MMA 2016).