Herpetology Notes, volume 13: 393-395 (2020) (published online on 26 May 2020)

First report of xanthism in Bothrops jararacussu Lacerda, 1884 (Serpentes: Viperidae)

Lucas R. Mendonça¹,*, Leandro de A. Oliveira¹, Clodoaldo L. Assis¹, Jhonny J. M. Guedes¹,2, and Renato N. Feio¹

Chromatic anomalies are known to occur in all pigment called xanthine, being a rare anomaly in snakes major terrestrial vertebrate groups, such as mammals, (Cardoso and Parpinelli, 2006). Chromatic anomaly was birds, amphibians and reptiles (e.g., De-Carvalho et well documented for a specimen of Epicatres cenchria al., 2015; Lucati and López-Baucells, 2017; García- (Linnaeus, 1758) (Hoge and Bulloumini, 1957), though Padrón and Bosch, 2019), including snakes (Sazima other cases are known in the literature, including reports and Di-Bernardo, 1991; Ortiz et al., 2017). It may be for Dipsas mikanii (Schlegel, 1837), Crotalus durissus related with adaptive advantages to the environment (Linnaeus, 1758), Bothrops jararaca (Wied-Neuwied, when the individual has a darker colouration (Gibson 1824), B. alternatus Duméril et al., 1854, and B. cotiara and Falls, 1979), but, on the other hand, individuals with (Gomes, 1913) (see Sueiro et al., 2010). Regarding lighter colour patterns may have their fitness reduced Bothrops jararacussu Lacerda, 1884, there is one case (Krecsák, 2008). Among several known anomalies, of albinism reported in the literature for three newborn albinism refers to the total absence of melanin, however, females (Ortiz et al., 2017). This snake is the second it may also be expressed less intensely, being named as largest pitviper in Brazil, reaching up to 2.20 meters in xanthism, piebaldism or leucism (sensu Sazima and total length (Marques, 1998). It occurs in forested areas Di-Bernardo, 1991). These conditions are caused by of the Atlantic Forest, from the states of Bahia to Rio genetic mutations and may be related, for example, Grande do Sul, also reaching Paraguay and Argentina with environmental factors during the embryological (Marques, 1998; Campbell and Lamar, 2004; Bernarde, development (Bechtel, 1978). In general, the cause of 2014; Nogueira et al., 2020). This species also presents albinism is generally attributed to a mutation in the sexual dimorphism, where adult females have dark sequencing gene of tyrosinase enzyme, a key component brown or black adornments on a yellow background, in the formation of melanin (Bechtel, 1978; Griffiths et and adult males have less contrasting adornments, on a al., 1998; Alberts et al., 2004). Therefore, the xanthism brown or greyish background (Melgarejo, 2013). Herein, might occur through a mutation in the sequencing gene we report a specimen with a very distinct colour pattern, that depresses the presence of melanophores, but does which can be classified as xanthism, representing, by the not interfere with the expression of the xanthophores, best of our knowledge, the first case of this chromatic so the final result is a yellowish individual, as it occurs anomaly in B. jararacussu. in salmonid skin (Colihueque, 2010). Xanthism is, On April 2016, an adult male B. jararacussu was therefore, characterized by the presence of a yellow donated to the Museu de Zoologia João Moojen (MZUFV) at Universidade Federal de Viçosa. The specimen (Fig. 1) was collected in the municipality of Viçosa (-20.754600°S, -42.882500°W), Minas Gerais state, Brazil. It was euthanized, fixed in formalin 10%, ¹ Museu de Zoologia João Moojen, Departamento de Biologia stored in alcohol 70%, and housed in the herpetological Animal, Universidade Federal de Viçosa, Vila Gianetti, nº32, collection of the MZUFV (voucher #2457). After 36570-977, Viçosa, Minas Gerais, Brazil. fixation, the specimen weighed 0.213 kilograms, and 2 Current address: Programa de Pós-Graduação em Ecologia e presented the following morphometric and meristic Evolução, Departamento de Ecologia, Universidade Federal de Goiás – Campus Samambaia, Goiânia, GO, 74690-900, characteristics: snout-vent length = 816 mm; tail length Brazil. = 136 mm, 180 ventral scales, 23/21/17 dorsal scale * Corresponding author. E-mail: [email protected] rows, 54 subcaudals, 6 intrasupraoculars, 8 supralabials, 394 Lucas R. Mendonça et al.

and the postorbital stripe were light brown (Fig. 1). Xanthism, among others chromatic anomalies recorded for snakes, are mainly observable in nocturnal or cryptic species (Sazima and Di-Bernardo, 1991) which is the case of the species reported here. In diurnal species, there would be selection against such anomalies due to the loss of protective (or cryptic) colouration that would favour visually-oriented predators (Sazima and Di-Bernardo, 1991). Therefore, xanthism and other anomalies that induce lighter colour patterns may reduce the fitness of the carrier specimen, as suggested by Krecsák (2008). Despite their rarity, reports of chromatic anomalies are important to improve our understanding about the distribution and frequency of such anomalies in natural populations. Finally, such record is a necessary first step towards developing systematic studies about the evolution of colour pattern variation among animal groups, as well as how such anomalies may affect survivorship and reproduction.

Acknowledgements. We would like to thank Daniela Pinto- Coelho and Rodrigo Castellari Gonzalez for their valuable contributions in a previous draft of this manuscript.

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Accepted by Rodrigo Gonzalez