Chiroptera Neotropical 2014 - 20(2): 1271-1279 1271 Dental anomalies: New cases of Artibeus lituratus from Colombia and a review of these anomalies in bats (Chiroptera) Camilo López-Aguirre Pontificia Universidad Javeriana, Bogotá D.C., Colombia - Carrera 7 No. 40 * Email: cernesto.laguirre@gmail.com ARTICLE Manuscript history: Submitted in 17/Mar/2014 Accepted in 25/Oct/2014 Available on line in 20/Dec/2014 Section editor: Ludmilla M.S. Aguiar Abstract. Unusual variations in the dentition of mammals have been reported many times, however the understanding of the occurrence and evolution of these anomalies remains mainly unknown due to the lack of a comprehensive approach and compiling information. Dental anomalies in bats are of special interest because the wide range of morphological variation among them specifically at the craniofacial region, findings include the first case of a living mammal with bilateral symmetry that has an asymmetrical dental formula. At the Neotropic, Artibeus lituratus is the bat species with the highest number of records of dental anomalies. In this paper it is reported the first evidence of both polyodontia and oligodontia from a single population of bats, in two individuals of Artibeus lituratus from Colombia. Also, after a deep bibliographical research, compiled data from the last 50 years is presented and analysed and a list of bats species reported with dental anomalies worldwide is presented. The list of bat species with cases of dental anomalies rise to 64 species. It was evident the predominance of insectivorous species, especially from the genus Myotis. Keywords: Polyodontia, oligodontia, atavism, Phyllostomidae, Neotropic All Chiroptera Neotropical content can be freely accessed at http://chiropteraneotropical.net. ISSN 2317-6105 (online) | 1413-4403 (printed) Introduction Dental abnormalities are frequently found among mammals, however, variations in dental formula not due to mechanical stress or physical injury are rarely present and documented, thus, the understanding of these conditions remains mostly unknown (Martin 2007). There are two types of variations in dental formula that can be identified: (1) polyodontia (=hyperodontia, hyperdontia) which is the presence of extra teeth, and (2) oligodontia which is the lack or absence of one or more teeth (Wolsan 1984a). Of this two, oligodontia is the most commonly reported due to the many ways that could occur besides genetic and ontogenic factors, like malnutrition, disease, injury, or abnormal attrition (Butler 1995). Despite that oligodontia is the most frequent between these two, only a few studies have focused in analysing the evolution, genetics and development of this anomaly in mammals (Knyazev et al. 2003; Line 2003; Jogahara et al. 2007; Asahara et al. 2012). Yet, to this point the information available indicates that oligodontia is strongly related with mutations in the PAX9 gene among other genetic traits, like mutations in the MSX1 gene (Line 2003) or inheritance (Knyazev et al. 2003; Jogahara et al. 2007). Evolutionary traits have also been found in populations with high incidence of oligodontia, attributed to the increasing genetic drift typical in marginal populations (Asahara et al. 2012). There are two different hypotheses that explain most of the presence of polyodontia, attributing this to evolutionary and ontogenic factors (Wolsan 1984a); the first one explain the presence of extra teeth as a result of the development of an extra tooth germ, which is due to the expression of some rare genes present in the gene pool of a given species (Wolsan 1983); these genes were frequently present in the gene pool of ancestral species of the same group, this case is known as atavism (Hall 2003). The second hypothesis attributes polyodontia to the presence of supernumerary tooth germ as a result of the splitting of a tooth germ derived either from a mutation or inheritance (Wolsan 1984b). According to Hall (1984) there are four criteria for recognising an atavism: (1) Presence of anomalies in adult individuals; (2) its absence in related species and recent ancestor; (3) presence of anomalies in only a little proportion of the population, and (4) resemblance to a character possessed by all individuals of an ancestral population.