Herpetology Notes, volume 13: 1025-1026 (2020) (published online on 14 December 2020)

Unusual necrophilic amplexus in Rhinella marina (Linnaeus, 1758)

Thainá Najar1 and Lucas Ferrante2,*

Explosive breeding is a fairly common reproductive by external characteristics in this sexually dimorphic strategy in frogs and toads, and unusual cases of species, but we do not know the specific cause of death amplexus have been reported for explosively breeding or how long the female was dead when observed. After anurans (Duellman and Trueb, 1996; Wells, 2007), our brief observation, the males continued in amplexus including at least one case of necrophilic amplexus with the dead female. (Jennier and Hardy, 2015). An instance of necrophilic Distinguishing aberrations from adaptive behaviour amplexus in the Amazonian toad Rhinella proboscidea is a challenge and no criteria are known to distinguish was treated as a functional reproductive strategy one from the other. We believe that our observation because males promoted the ejection of oocytes from constitutes a behavioural aberration because the the abdominal cavities of dead females and fertilised amplexus did not lead to reproductive success since them (Izzo et al., 2012). Cane toads, Rhinella marina the presence of eggs was not recorded at the site. In (Linnaeus, 1758), are explosive breeders with a wide amphibians, males usually attract females for breeding distribution and an ability to invade exotic locales (Zug (Duellman and Trueb, 1994; Wells, 2007), however and Zug, 1979; Shine, 2012). In South America, its there are exceptions, such as in the Amazon Treefrog native habitat, the species is known to breed throughout Callimedusa tomopterna (Najar and Ferrante, 2018). the year, with explosions during the rainy season (Lima Here we raise the hypothesis that females may perhaps et al., 2012). We here report an observation involving excrete hormones in the water to attract males, what amplexus of two male R. marina and a dead female. would explain our observation because these hormones The amplexus was observed on 17 December 2017, could continue to be expelled after death. In this way, it which coincide with the rainy season in the region. The observation occurred in the Fazenda Experimental da Universidade Federal do Amazonas, Municipality of Manaus, Amazonas State, northern Brazil (-2.6544ºS, -60.0545ºW), which includes an artificial reservoir destined for fish farming. The trio was floating at few centimetres from the edge of the reservoir and the two males were engaged in a dispute over access to the body of a dead female in attempts to perform axillary amplexus (Fig. 1). The female could be sexed

¹ Curso de Graduação em Ciências Biológicas, Universidade do Estado do Amazonas (UEA), Manaus, Amazonas 69050-030, Brazil. 2 Programa de Pós-Graduação em Ecologia, Instituto Nacional de Pesquisas da Amazônia (INPA), Manaus, Amazonas 69060-000, Brazil. Figure 1. Necrophilic amplexus between two males of * Corresponding author. E-mail: [email protected] Rhinella marina and a dead female. Photo by Thainá Najar. 1026 Thainá Najar & Lucas Ferrante would be important that future studies evaluate whether References anuran females that breed in aquatic environments Brito, L.B.M., Joventino, I.R., Ribeiro, S.C., Cascon, P. (2012): expel pheromones to attract males. Thus, these small Necrophiliac behavior in the “cururu” toad, Rhinella jimi evidences, can be a puzzle piece of amphibian’s natural Stevaux, 2002, (Anura, Bufonidae) from Northeastern Brazil. history, as observed by Najar and Ferrante (2018) and North-Western Journal of Zoology 8: 121206. reveal that the attraction in amphibian’s reproduction is Duellman, W. E., Trueb, L. (1996): Biology of Amphibians. not exclusive to males. The necrophiliac amplexus has Baltimore, Maryland, USA The Johns Hopkins University Press. been observed in other species of the genus Rhinella, Izzo, T.J., Rodrigues, D.J., Menin, M., Lima, A.P., Magnusson, W.E. including R. proboscidea (see Izzo et al., 2012) and (2012): Functional necrophilia: a profitable anuran reproductive R. jimi, a species of the R. marina group (Brito et al., strategy? Journal of Natural History 46: 2961–2967. 2012). This is the first observation of this phenomena Jennier, J.C., Hard, L.M. (2015): Natural history notes. Anaxyrus in R. marina, thus increasing the knowledge about this woodhousii (Woodhouse’s Toad). Necrophilia. Herpetological behaviour in Rhinella and suggesting that it may be Review 46: 73. Lima, A.P., Magnusson, W.E., Menin, M., Erdtmann, L.K., more widespread, if uncommon, in the genus. Rodrigues, D.J., Keller, C., Hodi, W. (2012): Guia de Sapos da Reserva Adolpho Ducke. Second Edition. Manaus, Amazonas, Acknowledgements. The authors are grateful to Igor Kaefer Brasil, Áttema Design Editora. for reviewing this manuscript and Cathelen Felix and Thalita Najar, T., Ferrante, L. (2018): The journey of life of the Tiger- Geovanna for invaluable help with fieldwork, as well as the striped Leaf Frog Callimedusa tomopterna (Cope, 1868): Notes Fazenda Experimental da Universidade Federal do Amazonas of sexual behaviour, nesting and reproduction in the Brazilian for the assistance during field work and the Conselho Nacional Amazon. Herpetology Notes 11: 531–538. de Desenvolvimento Científico e Tecnológico for the financial Shine, R. (2012): Invasive species as drivers of evolutionary change: support. cane toads in tropical Australia. Evolutionary Applications 5: 107–116. Wells, K.D. (2007): The Ecology and Behavior of Amphibians. Chicago, Illinois, USA, University of Chicago Press. Zug, G.R., Zug, P.B. (1979): The marine toad, Bufo marinus: a natural history resumé of native populations. Smithsonian Contributions to Zoology 284: 1–58.

Accepted by Fabrício Oda