​​​​​​​The so-called arc of deforestation is a major agricultural and industrial frontier in southern Amazonia and northern Cerrado of Brazil. As arboreal mammals, the primates in this region are therefore threatened by forest loss and fragmentation. At the same time, knowledge about the taxonomic diversity and distribution ranges of these taxa is incomplete, which might hamper efficient conservation measurements. New species have been recently discovered in this region, and their ranges remain imprecise because only a few occurrence records are available for each species. Here we present 192 new records of 22 species and subspecies of Alouatta, Aotus, Ateles, Cebus, Chiropotes, Lagothrix, Leontocebus, Pithecia, Plecturocebus, Saimiri, and Sapajus, collected in 56 different localities during 10 field expeditions across the arc of deforestation between 2015 and 2018. Based on these new records, we extend the ranges of Alouatta puruensis, Ateles chamek, and Saimiri collinsi; identify potential hybridization zones between A. puruensis and A. discolor, and between At. chamek and At. marginatus; redefine the range of Plecturocebus moloch; and clarify the ranges of P. baptista and P. hoffmannsi. Moreover, these results and the dataset are valuable for further research on, for example, species distribution and habitat use modeling, for assessing species extinction risks, and for supporting efforts for the conservation of species increasingly threatened on a global deforestation frontier.

Masturbation is a common auto-sexual behaviour in humans but is not explicitly known in a major portion of non-human primates. We report the first masturbatory behaviour in a male Phayre's langur, Trachypithecus phayrei, observed in a semi-evergreen forest in northeastern Bangladesh. Like other Asian colobines, the multi-male-multi-female groups of the Phayre's langur suggest a multilevel social organization and a complex hierarchy among males. The lack of sexual opportunity could result in masturbation and sperm competition among males. However, sperm competition is reported to be low in such non-seasonal breeders. Hence, we suggest an adequate characterization of the socio-sexual behaviour and reproductive strategies of this globally endangered primate in order to demonstrate the causes, cost and consequences of masturbation. We also urge further scientific exploration into masturbation among primates due to its evolutionary and conservational significance.

This study aimed to investigate the effect of estrogen withdrawal on bonetissue in adult female marmoset monkeys. In a 1-year follow-up study we usedquantitative computer tomography to measure total bone mineral density (BMD)of the proximal tibia and the second-last lumbar vertebral body (L5/L6)before and 1, 3, 6, and 12 months after ovariectomy. Body mass did notsignificantly change during the 1-year observation period. However, asignificant decline of total BMD after ovariectomy was observed in theproximal tibia but not in L5/L6. In addition, regression analysis showed asignificant positive relationship between BMD and body mass in both tibiaand L5/L6. The results of our study support the idea that ovariectomizedmarmoset monkeys may serve as a model to investigate bone loss related todecline of estrogen production.

Aging Western societies are facing an increasing prevalence of chronicautoimmune-mediated inflammatory disorders (AIMIDs) for which treatments that are safe and effective are scarce. One of themain reasons for this situation is the lack of animal models, which accurately replicateclinical and pathological aspects of the human diseases. One important AIMID is theneuroinflammatory disease multiple sclerosis (MS), for which the mouse experimentalautoimmune encephalomyelitis (EAE) model has been frequently used in preclinicalresearch. Despite some successes, there is a long list of experimental treatments thathave failed to reproduce promising effects observed in murine EAE models when they weretested in the clinic. This frustrating situation indicates a wide validity gap betweenmouse EAE and MS. This monography describes the development of an EAE model in nonhumanprimates, which may help to bridge the gap.

Human immunodeficiency virus (HIV) comorbidities have becomeclinically more important due to antiretroviral therapy. Although therapyincreases life expectancy, it does not completely suppress immune activationand its associated complications. The simian immunodeficiency virus(SIV)-infected rhesus macaque (Macaca mulatta) represents a valuablemodel for the investigation of SIV-associated diseases. Althoughcardiovascular (CV) changes are common in HIV-infected patients, there areonly a few reports on the incidence of CV findings in SIV-infected animals.In addition, potential associations between pathohistological findings andhematological parameters are still unclear.We therefore conducted a retrospective analysis of 195 SIV-infected rhesusmacaques that were euthanized with AIDS-related symptoms at the GermanPrimate Center, Goettingen, over a 25-year period. Pathological findingswere correlated with hematological data.The main findings included myocarditis (12.8 %), endocarditis(9.7 %),and arteriopathy (10.3 %) in various organs. Thrombocytopenia occurredmore frequently in macaques with endocarditis or arteriopathy than inmacaques without CV disease (80 % in animals with endocarditis, 60 %in animals with arteriopathy, and , respectively).Further investigations of the interaction between coagulation markers,proinflammatory cytokines, and biomarkers associated with endothelialdysfunction (e.g., D-dimers) and histological data (vascular wall structure)may unravel the mechanisms underlying HIV/SIV-associated CV comorbidities.

Overall, diseases of the vascular system are rarely observed entities among nonhuman primates that are commonly associated with systemic infections, septicemia or bacteremia. Rhesus monkeys infected with simian immunodeficiency virus (SIV) may develop a chronic occlusive arteriopathy of unknown etiology in late stages of the disease. This SIV associated arteriopathy is the only well-known specific vascular entity described in nonhuman primates. We herein report a unique case of granulomatous arteritis in a grey mouse lemur affecting multiple organs, which is not comparable to other disease entities formerly described in nonhuman primates. The features of the entity most closely resemble disseminated visceral giant cell arteritis in humans. A concise description of the disease is given, and the differential diagnoses are discussed. An idiopathic pathogenesis is suspected.

Humans and African great apes (AGAs) are naturally infected with several species of closely related malaria parasites. The need to understand the origins of human malaria as well as the risk of zoonotic transmissions and emergence of new malaria strains in human populations has markedly encouraged research on great ape Plasmodium parasites. Progress in the use of non-invasive methods has rendered investigations into wild ape populations possible. Present knowledge is mainly focused on parasite diversity and phylogeny, with still large gaps to fill on malaria parasite ecology. Understanding what malaria infection means in terms of great ape health is also an important, but challenging avenue of research and has been subject to relatively few research efforts so far. This paper reviews current knowledge on African great ape malaria and identifies gaps and future research perspectives.

Data on spontaneous pathology are substantially scarce for commonmarmosets, compared to other laboratory animals, but is essential for theinterpretation of histological findings in the context of toxicological andexperimental studies. Especially if common marmosets are used asexperimental animals in respiratory research, detailed knowledge on thespectrum, occurrence, and incidence of spontaneous histopathologicalpulmonary lesions in this non-human primate species is required. In thisstudy, lung tissue of 638 common marmosets from the marmoset colony of theGerman Primate Center was examined histologically. The analysis revealed ahigh incidence of predominantly mild and multifocal interstitial pneumonia(32.99 %) of unknown etiology in most cases. Only few marmosets exhibitedlobar pneumonia (1.41 %) and bronchopneumonia (0.94), which were mainlycaused by bacterial pathogens such as Bordetella bronchiseptica andKlebsiella pneumoniae. Lung immaturity and atelectasis were commonhistological findings in newborn marmosets. Typical background lesionsincluded anthracosis (8.15 %), hemosiderosis (1.72 %), extramedullaryhematopoiesis (11.6 %), mineralization (10.97 %), and inflammatorycell foci (10.34 %). In addition, three cases of pulmonary arteriopathy (0.47 %)and 1 case of foreign-body granuloma (0.16 %) were detected in themarmoset study cohort. The high prevalence of circulatory disturbances(congestion, edema, hemorrhage) and changes in air content (secondaryatelectasis, alveolar emphysema) could partly be explained byeuthanasia-related artifacts or agonal changes. The present study provides acomprehensive overview of the range and incidence of spontaneous pulmonaryhistopathology in common marmosets, serving as valuable reference data forthe interpretation of lung lesions in toxicological and experimentalmarmoset studies.

Abstract. Although non-human primates (NHPs) represent only a minor fraction of all animals used in biomedical research, there is a continuous effort to further reduce, refine and replace research with NHPs in accordance with the principles of the three R's. Most of the NHP model species are genetically highly diverse, and significant variation occurs among populations of different geographic origins, particularly in macaques. Since such differences can considerably affect the outcome of biomedical experiments, genotyping represents a promising tool to refine research approaches and to reduce the number of NHPs in biomedical research. Accordingly, the European Primate Network (EUPRIM-Net) developed an anonymous online survey to evaluate possibilities and potential hindrances for the application of genotyping in NHP research. On the one hand, our results point to the importance of genetic variation in NHPs and the need to consider the genetic background for future research approaches. On the other hand, our survey identified several hindrances and limiting factors for the application of genotyping and its incorporation in research, primate husbandry and breeding. We provide some fundamental recommendations on how to meet these challenges and how genotyping can be efficiently used to refine NHP research and to reduce the number of NHPs in biomedical research in the long term.