Phylogenetic relationships in the genus Cheracebus (Callicebinae, Pitheciidae)

Cheracebus is a new genus of New World primate of the family Pitheciidae, subfamily Callicebinae. Until recently, Cheracebus was classified as the torquatus species group of the genus Callicebus. The genus Cheracebus has six species: C. lucifer, C. lugens, C. regulus, C. medemi, C. torquatus, and C. purinus, which are all endemic to the Amazon biome. Before the present study, there had been no conclusive interpretation of the phylogenetic relationships among most of the Cheracebus species. The present study tests the monophyly of the genus and investigates the relationships among the different Cheracebus species, based on DNA sequencing of 16 mitochondrial and nuclear markers. The phylogenetic analyses were based on Maximum Likelihood, Bayesian Inference, and multispecies coalescent approaches. The divergence times and genetic distances between the Cheracebus taxa were also estimated. The analyses confirmed the monophyly of the genus and a well-supported topology, with the following arrangement: ((C. torquatus, C. lugens), (C. lucifer (C. purinus, C. regulus))). A well-differentiated clade was also identified within part of the geographic range of C. lugens, which warrants further investigation to confirm its taxonomic status.

The complete mitochondrial genome of Menticirrhus littoralis (Sciaenidae, Perciformes) and its phylogeny

We describe the mitochondrial genome of the Menticirrhus littoralis and infer the phylogenetic position of Menticirrhus in the family Sciaenidae. The genome contains 16,499 base pairs distributed in gene regions (13 protein-coding regions, 2 rRNAs and 22 tRNAs) and a control region (CR). Our phylogenetic analysis suggests, with strong statistical support, that Menticirrhus is a sister group of the other sciaenids.

Genetic diversity and structuring in the arapaima (Osteoglossiformes, Osteoglossidae) population reveal differences between the Amazon and the Tocantins-Araguaia basins

Arapaima is a widely-distributed fish of enormous economic importance in the Amazon region. In the present study, a total of 232 specimens were sampled, 121 from five sites in the Amazon basin and 111 from five sites in the Tocantins-Araguaia basin. The analyses investigated fragments of the Cytochrome b, Control Region, Cytochrome Oxidase I, NADH dehydrogenase subunit 2 and seven loci microsatellites. The analyses revealed the existence of two mitochondrial lineages within the general area, with no haplotypes shared between basins, and genetic variability significantly higher in the Amazon than in the Tocantins-Araguaia basin. Two divergent, but sympatric mitochondrial lineages were found in the Amazon basin, but only a single lineage in the Tocantins-Araguaia basin. The existence of these two mitochondrial lineages indicates that past events, probably occurring during the Pleistocene, resulted in the separation of the populations of this species and molded its evolutionary history, which is reflected directly in its mitochondrial DNA. The analysis of the arapaima population structure identified distinct levels of diversity within the distribution of the species, indicating specific geographic regions that will require special attention for the development of conservation and management strategies.

New insights about species delimitation in red snappers (Lutjanus purpureus and L. campechanus) using multilocus data

Lutjanus campechanus and Lutjanus purpureus are two commercially important lutjanid fishes (snappers) with non-sympatric distribution throughout Western Atlantic. Even though both taxa have traditionally been regarded as valid species, their taxonomic status remains under debate. In the present study, we used phylogeographic approaches and molecular methods of species delimitation to elucidate the taxonomic issues between both species, based on 1478 base pairs from four genomic regions. We found haplotypes shared between the two species, particularly in relation to nuclear DNA (nuDNA) sequences. The molecular delimitation of species supported the discrimination of L. purpureus and L. campechanus as distinct evolutionary units. Nonetheless, a unidirectional gene flow was found from L. campechanus towards L. purpureus. Therefore, it seems plausible to infer that L. campechanus and L. purpureus are two evolutionary units in which the apparent sharing of haplotypes should be driven by introgression.

The roles of vicariance and dispersal in the differentiation of two species of the Rhinella marina species complex

The high levels of Neotropical biodiversity are commonly associated with the intense Neogene-Quaternary geological events and climate dynamics. Here, we investigate the evolutionary history of two species of Neotropical closely related amphibians (R. horribilis and R. marina). We combine published data with new mitochondrial DNA sequences and multiple nuclear markers, including 12 microsatellites. The phylogenetic analyses showed support for grouping the samples in two main clades; R. horribilis (Central America and Mexico) and R. marina (South America east of the Andes). However, the phylogenetic inferences also show an evident mito-nuclear discordance. We use Approximate Bayesian Computation (ABC) to test the role of different events in the diversification between the two groups recovered. We found that both species were affected primarily by a recent Pleistocene divergence, which was similar to the divergence estimate revealed by the Isolation-with-Migration model, under persistent bidirectional gene flow through time. We provide the first evidence that R. horribilis is differentiated from the South American R. marina at the nuclear level supporting the taxonomic status of R. horribilis, which has been controversial for more than a century.

Range distribution and contributions to taxonomy of Elops smithi (ELOPIFORMES: ELOPIDAE)

This study presents the first record of Elops smithi for northern Brazil. The evidence suggests this species is being misidentified incorrectly as Elops saurus in estuaries of the Western Atlantic Ocean. Here, morphological, molecular, and cytogenetic evidence identified all ladyfish specimens from one estuary in the region as E. smithi. Thus, at least Elops smithi occurs in the northern coast of Brazil and it is recommended that specimens from this region identified as E. saurus be further investigated with genetic and cytogenetic tools in order to assure a correct species identification.

The largest fish in the world's biggest river: Genetic connectivity and conservation of Arapaima gigas in the Amazon and Araguaia-Tocantins drainages

Arapaima, pirarucu or paiche (Arapaima gigas) is one of the largest freshwater fish in the world, and has a long history of commercial exploitation in the Amazon region. To estimate levels of genetic variability and historical and recent connectivity in Arapaima, we examined variation in eleven microsatellite DNA markers in individuals from 22 localities in Brazil, Colombia, and Peru. The results of analysis of molecular variance, Bayesian clustering and discriminant analysis of principal components showed that Arapaima in our samples represents two major populations, one in the Amazonas and one in the Araguaia-Tocantins River basins. The Amazonas population is further structured by isolation-by-distance with the hydrologically largely unconnected Amapá locality representing the eastern-most extreme of this continuum; gene flow predominates at distances of less than 1500 km with localities separated by over 2000 km dominated by genetic drift and effectively forming different populations. We saw no evidence of multiple species of Arapaima in the Amazonas basin, and analysis of pairwise genetic divergence (F_ST) with Mantel tests and correlograms indicated that this largest population exhibits a large-scale pattern of isolation-by-distance, with which results from MIGRATE-N agreed. The degree and significance of genetic divergence indicates that most sampled localities represent demographically independent sub-populations, although we did identify several recent migration events between both proximal and more distant localities. The levels of genetic diversity were heterogeneous across sites, including low genetic diversity, effective population sizes, and evidence of genetic bottlenecks in several places. On average the levels of gene diversity and rarefied allelic richness were higher for localities along the Amazonas mainstem than in the tributaries, despite these being the areas of highest fishing pressure, while the lowest values were found in tributary headwaters, where landscape modification is a significant threat. We recommend that managers consider the regional and local threats to these populations and tailor strategies accordingly, strategies which should ensure the ability of young A. gigas to disperse through floodplain corridors to maintain genetic diversity among otherwise sedentary adult sub-populations.

Forensic analysis reveals fraud in fillets from the "Gurijuba" Sciades parkeri (Ariidae - Siluriformes): a vulnerable fish in Brazilian Coastal Amazon

The utilization of molecular tools for the certification of fishery products has been increasing over the last years. In general, economically important species are replaced by less valuable species, characterizing a commercial fraud. We evaluated the authenticity of 107 frozen fillets tagged as Gurijuba (Sciades parkeri) and Uritinga (Sciades proops) from local markets in northern amazon coast by sequencing two mitochondrial genes: Cytochrome oxidase subunit I and cytochrome b (Cyt b). About 16% of fillets putatively related to S. parkeri were replaced by S. proops. The Gurijuba faces high fishing pressure, being currently listed by the International Union for Conservation of Nature as vulnerable. Forensic analysis with DNA markers, proved to be highly efficient in the discrimination of the processed seafood products, providing unequivocal identification of species, revealing commercial fraud in the fillets of the Gurijuba, and revealing the utility of Cytb sequences as barcode in fishes.

Phylogeny of the genus Hypophthalmus Cuvier, 1829 (Pimelodidae - Siluriformes), based on a multilocus analysis, indicates diversification and introgression in the Amazon basin

The genus Hypophthalmus encompasses four valid South American freshwater catfish species: H. marginatus, H. edentatus, H. fimbriatus, and H. oremaculatus. More recently two new species were proposed Hypophthalmus n. sp. 1 and Hypophthalmus n. sp. 2. While Hypophthalmus species are a fundamentally important resource for the commercial fisheries that operate in the continental waters of the Amazon basin, their phylogenetic relationships and the true diversity of the genus have yet to be defined conclusively. Given this, the present study analyzed sequences of the mitochondrial COI gene and four nuclear markers (RAG2, Myh6, Plagl2 and Glyt) to evaluate the phylogenetic relationships and the diversity of the species of this genus. All the analyses showed that Hypophthalmus is monophyletic, and the species delimitation tests recovered all the Hypophthalmus taxa as distinct species. The putative new species Hypophthalmus n. sp. 1 and Hypophthalmus n. sp. 2 presented mean genetic divergence similar to or greater than that observed between valid Hypophthalmus taxa. All the analyses showed that H. oremaculatus is the sister group of H. n. sp. 1, which together group with H. fimbriatus. This clade is the sister group of the clade containing H. edentatus and H. n. sp. 2. One specimen, morphologically identified as H. oremaculatus, presented the nuclear genome of this species and the mitochondrial genome of H. n. sp. 1; while another specimen, morphologically identified as H. n. sp. 2, presented the nuclear Myh6 of H. n. sp. 2 and the mitochondrial and RAG2 genome of H. edentatus. These results indicate that hybridization and introgression has occurred between species in Hypophthalmus. The findings of this study indicate that the diversity of the Hypophthalmus is underestimated, emphasize the need for a taxonomic review of the genus, and a more systematic evaluation of the hybridization patterns found, to understanding the role of hybridization and introgression in the evolution of the genus.

First cytogenetic information for Lonchothrix emiliae and taxonomic implications for the genus taxa Lonchothrix + Mesomys (Rodentia, Echimyidae, Eumysopinae)

The taxonomic identification of Lonchothrix emiliae (Rodentia, Echimyidae, Eumysopinae) is problematic because of the overlap of morphological characters with its sister clade represented by species in the genus Mesomys which, like L. emiliae, is distributed throughout the Amazonian biome. Cytogenetic studies reported the karyotype of L. emiliae as 2n = 60/FN = 116, but this karyotype and samples were later designated as M. hispidus. To evaluate the karyotype diversity of Lonchothrix and Mesomys, and to provide data useful as karyological diagnostic characters, in the present study we made a comparative analysis of specimens of L. emiliae and M. stimulax collected from two Brazilian Amazonian localities, using C-banding, G-banding, FISH using rDNA 45S and telomeric probes, and Cytochrome-b (Cytb) sequences. The results indicate that L. emiliae has 2n = 64♀, 65♂/FN = 124 and a multiple sexual system (XX/XY₁Y₂), while M. stimulax has 2n = 60/FN = 116. The Neo-X system found in L. emiliae also occurs in two Proechimys species, but cytogenetic analysis indicated an independent origin for these systems. The rDNA 45S analysis showed interstitial signals at one autosomal pair for each species, while an ITS found in L. emiliae was not coincident with the NOR. The molecular analysis confirmed Lonchothrix and Mesomys are sister genera, and the high level of intraspecific genetic divergence (7.1%) in M. stimulax suggests that it may be a species complex.

Surveying cephalopod diversity of the Amazon reef system using samples from red snapper stomachs and description of a new genus and species of octopus

The cephalopod fauna of the southwestern Atlantic is especially poorly-known because sampling is mostly limited to commercial net-fishing operations that are relatively inefficient at obtaining cephalopods associated with complex benthic substrates. Cephalopods have been identified in the diets of many large marine species but, as few hard structures survive digestion in most cases, the identification of ingested specimens to species level is often impossible. Samples can be identified by molecular techniques like barcoding and for cephalopods, mitochondrial 16S and COI genes have proven to be useful diagnostic markers for this purpose. The Amazon River estuary and continental shelf are known to encompass a range of different substrates with recent mapping highlighting the existence of an extensive reef system, a type of habitat known to support cephalopod diversity. The present study identified samples of the cephalopod fauna of this region obtained from the stomachs of red snappers, Lutjanus purpureus, a large, commercially-important fish harvested by fisheries using traps and hook-and-line gear that are capable of sampling habitats inaccessible to nets. A total of 98 samples were identified using molecular tools, revealing the presence of three squid species and eight MOTUs within the Octopodidae, representing five major clades. These include four known genera, Macrotritopus, Octopus, Scaeurgus and Amphioctopus, and one basal group distinct from all known octopodid genera described here as Lepidoctopus joaquini Haimovici and Sales, new genus and species. Molecular analysis of large predatory fish stomach contents was found to be an incredibly effective extended sampling method for biodiversity surveys where direct sampling is very difficult.

Tracing individuals and populations of the tambaqui, Colossoma macropomum (Cuvier, 1818), from Brazilian hatcheries using microsatellite markers

BACKGROUND

In recent years, tracing of alimentary produce of animal origin has become increasingly important, for economic, food safety and ecological reasons. The tambaqui, Colossoma macropomum, is the native fish most farmed in Brazil. The reliable identification of the origin of tambaquis (wild or farmed) offered for sale to the general public has become necessary to satisfy regulatory norms and uphold consumer confidence. Molecular methods based on the analysis of DNA sequences have often been used to evaluate the potential for tracing farmed fish, given their reliability and precision.

RESULTS

Full likelihood and Bayesian approaches proved to be the most efficient for the identification, respectively, of individuals and populations for most of the fish sampled from seven hatcheries and one wild stock. The exclusion method and genetic distances were the least effective approaches for the identification of individuals and populations. The Bayesian method identified correctly more than 99% of the fry from most stocks, except those of the Santarém hatchery and River Amazon wild stock, which presented the best results for individual identification.

CONCLUSIONS

The identification of populations was effective for most hatcheries, although the identification of individuals from most stocks was hampered by the reduced genetic variability. © 2018 Society of Chemical Industry.

Comparative analysis of the transcriptome of the Amazonian fish species Colossoma macropomum (tambaqui) and hybrid tambacu by next generation sequencing

Background

The C. macropomum is a characiform fish from the Amazon basin that has been hybridized with other pacu species to produce commercial hybrids, such as the tambacu. However, little is known of the functional genomics of the parental species or these hybrid forms. The transcriptome of C. macropomum and tambacu were sequenced using 454 Roche platform (pyrosequencing) techniques to characterize the domains of Gene Ontology (GO) and to evaluate the levels of gene expression in the two organisms.

Results

The 8,188,945 reads were assembled into 400,845 contigs. A total of 58,322 contigs were annotated with a predominance of biological processes for both organisms, as determined by Gene Ontology (GO). Similar numbers of metabolic pathways were identified in both the C. macropomum and the tambacu, with the metabolism category presenting the largest number of transcripts. The BUSCO analysis indicated that our assembly was more than 40% complete. We identified 21,986 genes for the two fishes. The P and Log2FC values indicated significant differences in the levels of gene expression, with a total of 600 up-regulated genes.

Conclusion

In spite of the lack of a reference genome, the functional annotation was successful, and confirmed a considerable difference in the specificity and levels of gene expression between the two organisms. This report provides a comprehensive baseline for the genetic management of these commercially important fishes, in particular for the identification of specific genes that may represent markers involved in the immunity, growth, and fertility of these organisms, with potential practical applications in aquaculture management.

Multiloci analyses suggest synonymy among Rhomboplites, Ocyurus and Lutjanus and reveal the phylogenetic position of Lutjanus alexandrei (Lutjanidae: Perciformes)

ABSTRACT Lutjanidae comprises 21 genera and 135 species widespread throughout Atlantic, Indian and Pacific oceans. Nonetheless, the phylogenetic relationships of Lutjaninae remain uncertain. Furthermore, phylogenetic hypotheses for Lutjanus alexandrei, an endemic species from northeastern Brazilian coast, in Lutjanidae are absent so far. Therefore, we carried out multiloci analyses, combining both mitochondrial and nuclear DNA sequences in Lutjaninae species from Western Atlantic focusing on the controversial relationships among Lutjanus, Rhomboplites, and Ocyurus. Besides, we determined the phylogenetic position and dated the origin of L. alexandrei. The phylogenetics trees based on the 4.4 kb for 11 species corroborated the synonym among Lutjanus and the putative monotypic genera. For the dating of L. alexandrei, another nucleotide dataset (3.0 kb; 40 species) validated the genetic identity of this species that diverged from the sister taxon L. apodus between 2.5 - 6.5 Mya, probably as a result of the barrier caused by the muddy outflow from Orinoco and Amazon rivers along the coastal zone. This report is the most robust multiloci analysis to confirm the synonymy of the three genera of Lutjaninae from Western Atlantic and the first reliable inference about the phylogenetic relationships and origin of L. alexandrei.

De novo transcriptome based on next-generation sequencing reveals candidate genes with sex-specific expression in Arapaima gigas (Schinz, 1822), an ancient Amazonian freshwater fish

Background

The Arapaima (Arapaima gigas) is one of the world's largest freshwater bony fish, and is found in the rivers of the Amazon basin. This species is a potential aquaculture resource, although reproductive management in captivity is limited in particular due to the lack of external sexual dimorphism. In this study, using the 454 Roche platform (pyrosequencing) techniques, we evaluated a major portion of the transcriptome of this important Amazonian species.

Results

Four libraries obtained from the liver and skin tissue of juvenile specimens (representing males and females separately) were sequenced, yielding 5,453,919 high-quality reads. The de novo transcriptome assembly resulted in 175,792 contigs, with 51,057 significant blast hits. A total of 38,586 transcripts were mapped by Gene Ontology using Blast2GO. We identified 20,219 genes in the total transcriptome (9,551 in the liver and 16,818 in the skin). The gene expression analyses indicated 105 genes in the liver and 204 in the skin with differentiated expression profiles, with 95 being over-expressed in the females and 214 in the males. The log2 Fold Change and heatmap based on Reads Per Kilobase per Million mapped reads (RPKM) revealed that the gene expression in the skin is highly differentiated between male and female arapaima, while the levels of expression in the liver are similar between the sexes.

Conclusion

Transcriptome analysis based on pyrosequencing proved to be a reliable tool for the identification of genes with differentiated expression profiles between male and female arapaima. These results provide useful insights into the molecular pathways of sexual dimorphism in this important Amazonian species, and for comparative analyses with other teleosts.

Mutations in the melanocortin-1 receptor (MC1R) gene have no influence on the distinct patterns of melanic plumage found in the manakins of the genus Antilophia (Aves: Pipridae)

The melanocortin-1 receptor gene is the most widely-used marker for the investigation of the genetic determination of melanic plumage patterns. Studies of a number of wild bird species have shown an association between non-synonymous mutations of the MC1R gene and the presence of melanic variants. The genus Antilophia (Pipridae) includes only two manakin species (A. galeata and A. bokermanni), which are distinguished primarily by the differences in the pattern of melanic coloration of the plumage of the mantle in the adult males. In A. galeata, this plumage is black, while in A. bokermanni, it is predominantly white. This study investigates the possible association between mutations of the MC1R marker and the variation in plumage coloration observed in the two species. The MC1R sequences of the two species was analyzed, and the observed nucleotide variation was compared. Six polymorphic sites were identified, representing seven distinct genotypes. Five of these polymorphic mutations were non-synonymous, but were not related to the different phenotypes. Neutral evolution and the absence of any systematic association between the variants of the MC1R and plumage coloration in the Antilophia species indicate that alternative mechanisms regulate the expression of the coloration of the plumage in the adult males.

Phylogenetic relationships among Capuchin (Cebidae, Platyrrhini) lineages: An old event of sympatry explains the current distribution of Cebus and Sapajus

Capuchin monkeys are currently represented by four species of Cebus and eight of Sapajus. This group is taxonomically complex and several questions still need to be clarified. In the current study, using mtDNA markers and a larger sample representation than in previous studies, we seek to understand the phylogenetic relationships among the capuchin lineages and their historical biogeography. All 12 species of capuchins were analyzed for the mitochondrial Control Region and Cytochrome b to test two biogeographical hypotheses: "Reinvasion of the Amazon (ROA)" and "Sympatric Evolution (SEV)". The phylogenetic relationships among distinct lineages within genera is consistent with an evolutionary diversification pattern probably resulting from an explosive process of diversification and dispersal between 2.0 Ma and 3.0 Ma. Also, the analyses show that the ancestral capuchins were distributed in a wide area encompassing the Amazon and Atlantic Forest. Our results support the SEV hypothesis, showing that the current syntopic distribution of Cebus and Sapajus can be explained by a sympatric speciation event in the Amazon. We also indicate that the recently proposed species taxonomy of Cebus is not supported, and that S. cay and S. macrocephalus are a junior synonym of S. apella.

Molecular authentication of Pargo fillets Lutjanus purpureus (Perciformes: Lutjanidae) by DNA barcoding reveals commercial fraud

ABSTRACT The Caribbean Red Snapper (Pargo) Lutjanus purpureus is the most economically important snapper in Brazil, which is sold, among other forms, as frozen fillets. During the process of transformation into fillets there is the removal of the distinctive morphological traits, being able to favor the substitution by less valued species. In addition, there is no national legislation requiring the insertion of the specific name on the product label. However, according to a Normative Instruction (IN N ° 29/2015 MAPA) that correlates the common and specific names of the products destined to the national trade, in Brazil only L. purpureus and L. campechanus can be denominated “Pargo”. Thus, the DNA barcode tool was used to identify the fillets sold in north of Brazil, labeled “Pargo”, with the aid of sequences from the public and control databases. The results showed that among 142 fillets examined, 78% was identified as L. purpureus and 22% as Rhomboplites aurorubens, a snapper with low commercial value in the country, revealing commercial fraud. The molecular identification method successfully used in this study to authenticate fillets snappers may also be used by surveillance authorities in the quality control of processed fish products, towards ensuring consumer rights.

Phylogeny of the subfamily Stelliferinae suggests speciation in Ophioscion Gill, 1863 (Sciaenidae: Perciformes) in the western South Atlantic

Phylogenies based on morphological and molecular data confirm the monophyly of the subfamily Stelliferinae; however, there is no consensus on the intergeneric and interspecific relationships in the group. Previous studies suggested the non-monophyly of Ophioscion and Stellifer, and possible cryptic species in Ophioscion punctatissimus. Therefore, we used mitochondrial (16S rDNA and COI) and nuclear (Rhodopsin, EGR1, and RAG1) regions to examine phylogenetic relationships among species of this subfamily. Our results confirmed the monophyly of Stelliferinae and supports the close relationship among Bardiella, Corvula and Odontoscion, which form a sister group to Stellifer and Ophioscion. Notwithstanding, all the results support the non-monophyly of Stellifer and Ophioscion and we suggest that a taxonomic revision should consider Ophioscion as a junior synonym of Stellifer. Moreover, O. punctatissimus was grouped into two clades, with the O. punctatissimus lineage I (LI) being closer to O. scierus from the eastern Pacific than to the O. punctatissimus lineage II (LII). The most recent common ancestor (TMRCA) for the O. scierus and O. punctatissimus LI and O. punctatissimus LII clade dates from 7.2 (HPD: 4.3-10.5) Ma, whereas TMRCA for the O. scierus and O. punctatissimus LI clade dates from 5.3 (HPD: 2.4-8.6) Ma, indicating that speciation processes may be related to the rise of the Isthmus of Panama. Phylogeographic analyses corroborate the hypothesis of speciation in O. punctatissimus. These results suggest that lineages of O. punctatissimus originated from distinct ancestors and, by morphological similarity, were considered the same taxon. A taxonomic revision should be performed to validate the species status of such lineages.

Phylogeny, molecular dating and zoogeographic history of the titi monkeys (Callicebus, Pitheciidae) of eastern Brazil

The titi monkeys belong to a genus of New World primates endemic to South America, which were recently reclassified in three genera (Cheracebus, Plecturocebus and Callicebus). The genus Callicebus, which currently includes five species, is endemic to eastern Brazil, occurring in the Caatinga, Savanna, and Atlantic Forest biomes. In the present study, we investigated the validity of these species and inferred their phylogenetic relationships, divergence times, and biogeographic patterns based on the molecular analysis of a concatenated sequence of 11 mitochondrial and nuclear DNA markers, derived from 13 specimens. We ran Maximum Likelihood (ML) and Bayesian Inference (BI) analyses, and estimated genetic distances, divergence times. Ancestral areas were estimated on BioGeoBears. Our results suggest that at about twelve million years ago, the ancestor of all titi monkeys inhabited a wide area that extended from the Amazon forest to the South of the Atlantic forest. A first vicariant event originated Cheracebus in the West of the Amazon and the ancestor of Callicebus and Plectorocebus which, later were separated by a second one. The diversification of Callicebus occurred during the Plio-Pleistocene (beginning at 5 Ma) probably influenced by climatic fluctuations and geological events. Therefore, the results of the present work confirmed the existence of five species that currently inhabit forested areas under increasing threat from human activities. Thus, a reliable diagnosis of the taxonomic status of species living in endangered environments is extremely important for the development of conservation measures.