Received: 20 January 2016 | Revised: 4 October 2016 | Accepted: 4 October 2016 DOI 10.1002/ajp.22615 RESEARCH ARTICLE Feeding habits of marmosets: A case study of bark anatomy and chemical composition of Anadenanthera peregrina gum Talitha Mayumi Francisco 1,2 | Karina Lucas Barbosa Lopes-Mattos 3 | Edgard Augusto de Toledo Picoli 3 | Dayvid Rodrigues Couto 4 | Juraci Alves Oliveira 5 | José Cola Zanuncio 6 | José Eduardo Serrão 5 | Ita de Oliveira Silva 1 | Vanner Boere 1 1 Departamento de Biologia Animal, Universidade Federal de Viçosa, Viçosa, Brasil 2 Laboratório de Ciências Ambientais, Universidade Estadual do Norte Fluminense - Darcy Ribeiro, Campos dos Goytacazes, Brasil 3 Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Brasil 4 Museu Nacional do Rio de Janeiro, Departamento de Botânica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil 5 Departamento de Biologia Geral, Universidade Federal de Viçosa, Viçosa, Brasil 6 Departamento de Entomologia/BIOAGRO, Universidade Federal de Viçosa, Viçosa, Brasil Correspondence Talitha Mayumi Francisco, Departamento de Biologia Animal, Universidade Federal de Viçosa, Av. P.H. Rolfs s/n, Viçosa 36570-000, Brasil. Email: talithamayumi@gmail.com Funding information Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG) Primates of the genus Callithrix often obtain exudates from plants of the family Fabaceae. This study characterizes the chemical composition of exudates, and the anatomy and hystochemistry of the secretory ducts in the bark of Anadenanthera peregrina (L.) Speg. var. peregrina (Fabaceae). Exudates from this tree species represent an important component of the diet of hybrid marmosets, Callithrix spp. (Primates: Cebidae). A. peregrina was selected as the focal study tree because it is the only gum tree species exploited by Callithrix groups present within five urban forest fragments in the municipality of Viçosa, Minas Gerais State, Brazil. Gum samples were obtained directly from gouges made by the marmosets, while bark samples were obtained from A. peregrina plants, whether or not they were damaged by the marmosets. Constitutive secretory ducts were present in the bark of ungouged A. peregrina, whereas, marmoset damage caused induced secretory duct formation and an increase in the size of these ducts. The gum produced in the gouges made by the marmosets and in ungouged plants reacted positively to tests for polysaccharides, pectin, mucilage, and proteins. The gum from the gouges exhibited high water (41.0%), carbohydrate (38.2%), protein (19.0%), and mineral (Ca 0.4% and K 0.3%) content. We argue that the relatively high calcium content of A. peregrina gum plays an important nutritional role in, balancing a diet that is otherwise rich in phosphorous and poor in calcium. KEYWORDS calcium, Callithrix, Callitrichinae, food resource, mineral, vegetable exudates 1 | INTRODUCTION The diet of primates may include vegetable exudates, such as gums and saps, which are produced by the secretory ducts of plants (Harrison & Tardif, 1994; Ushida, Fugita, & Ohashi, 2006). Marmosets of the genus Callithrix Erxleben, 1,777 (Cebidae) are reported to consume exudates from several species in the plant family Fabaceae (Smith, 2010), including Anadenanthera colubrina (Vell.) Brenan (= A. macrocarpa (Benth) Brenan.) (Amora, Beltrão- Mendes, & Ferrari, 2013; Scanlon et al., 1989; Stevenson & Rylands, 1988) and Anadenanthera peregrina (L.) Speg. (Corrêa, Coutinho, & Ferrari, 2000; Francisco et al., 2014; Rizzini & Coimbra-Filho, 1981; Thompson et al., 2013). Callithrix is characterized by a set of derived dental and mandibular traits that enable individuals to gouge holes in tree bark and damage the ducts in plant tissues that secrete gum (Canton, Hill, Hume, & Crook, 1996; Coimbra-Filho & Mittermeier, 1976; Ferrari & Martins, 1992). These traits include procumbent lower incisors and incisor form lower canines. In addition the lower incisors lack lingual enamel and therefore maintain a sharp gouging edge as the teeth wear (Natori & Shigehara, 1992; Rosenberger, 1978). Moreover, the marmoset masticatory architecture is characterized by relatively long muscle fibers (masseter and temporalis) resulting in high muscle extension (Taylor & Vinyard, 2004) facilitating a wide gap necessary for tree gouging (Vinyard, Wall, Williams, & Hylander, 2003; Vinyard & Ryan, 2006). The genus Callithrix, along with Cebuella (pygmy marmosets), Am J Primatol 2017; 79: e22615 wileyonlinelibrary.com/journal/ajp © 2016 Wiley Periodicals, Inc. | 1 of 9