There are several field observations of predation on vertebrates by large or medium-sized cursorial spiders in the families Ctenidae, Lycosidae, Pisauridae, Sparassidae, Theraphosidae, and Trechaleidae (e.g., Menin et al., 2005; Maffei et al., 2010; Nyffeler and Pusey, 2014). On the other hand, predation on vertebrates by orbicular web spiders (Nephilidae and Araneidae) seems to be less common (Nyffeler and Knörnschild, 2013), whereas predation by small spiders using diffuse webs is apparently rare (Werger, 1978; Garb et al., 2004). Herein we report the first record of a brown widow spider, Latrodectus geometricus C.L. Koch, 1841 (Theridiidae), preying on a neotropical snake Tantilla melanocephala (Linnaeus, 1758). Latrodectus geometricus is widespread in Africa and the Americas (mainly Central and South America) and has been introduced to some others countries around the world (Levi, 1959; Garb et al., 2004); it is generally considered to be of little medical importance (Vetter and Isbister, 2008; Almeida et al., 2009). The species is commonly found in urban habitats around houses, buildings, gardens, and other anthropogenically- modified areas, such as agricultural plots (e.g., Lamoral, 1968; Anderson, 1972), but it also occurs in natural environments like cerrado (open savannah) in Central Brazil (Motta, 2014). This species is the largest theridiid spider in the Brazilian cerrado biome, with females varying from 0.7–1.2 cm in length and possessing a beige to black brown globose abdomen (depending on local luminosity; Motta, 2014). This species can be identified easily by having characteristic dorsal spots and ventrally an orange or reddish hourglass mark, and also by its spiked egg sacs. These spiders live in a small, cone-shaped silk retreat from which they build an irregular, framed web (Benjamin and Zschokke, 2003). Generally at night, brown widows extrude diffuse threads impregnated with glue droplets at their terminal ends onto the substrate (Lamoral, 1968; Foelix, 2011). Prey animals become glued to the threads at a touch and, while trying to wrestle free, neighbouring trapping threads are contacted and the prey becomes progressively more entangled, capturing the prey (Levi, 1959; Garb et al., 2004; Foelix, 2011). Latrodectus geometricus is a generalist that can feed on a wide range of animals, but it mainly consumes insects and other ground-dwelling arthropods, including spiders, scorpions, and centipedes (Rossi and Godoy, 2005; Lira and Costa, 2014; Rosa et al., 2016). Tantilla melanocephala is a small (19–25 cm in total length) snake with a large range in the Neotropics, occurring from Guatemala to northern Argentina and Uruguay (Santos-Costa et al., 2006) and showing both diurnal and nocturnal habits. This snake is found in many localities in the cerrado, but at low abundance (Marques and Puorto, 1998; França and Araújo, 2006; Braz and França, 2016). Tantilla melanocephala feeds on centipedes (Myriapoda: Chilopoda), which are immobilized and killed, and ingested always beginning with the head (Marques and Puorto, 1998; Oliveira, 2016). These snakes commonly use soil debris, termite mounds, or fallen logs as shelters in cerrado habitats Herpetology Notes, volume 10: 647-650 (2017) (published online on 10 November 2017) Predation of the snake Tantilla melanocephala (Squamata: Colubridae) by the spider Latrodectus geometricus (Araneae: Theridiidae) in Central Brazil Clarisse R. Rocha 1, *, Paulo César Motta 2 , Alexandre S. Portella 3 , Marcus Saboya 1 and Reuber Brandão 1,3 1 Centro de Estudos do Cerrado na Chapada dos Veadeiros, Universidade de Brasília, Alto Paraíso, 73770-000 Goiás, Brazil 2 Laboratório de Aracnídeos, Departamento de Zoologia, Universidade de Brasília, Brasília, 70910-900 Distrito Federal, Brazil 3 Laboratório de Fauna e Unidades de Conservação, Departamento de Engenharia Florestal, Universidade de Brasília, Brasília, 70910-900 Distrito Federal, Brazil * Corresponding author e-mail: rocha.clarisse@gmail.com