Herpetology Notes, volume 10: 283-285 (2017) (published online on 29 May 2017) Interspecific combat between Nymphargus aff. grandisonae and Espadarana prosoblepon (Anura, Centrolenidae) Anton Sorokin1,* and Emma Steigerwald2 There are approximately 150 species composing the are considered derived, as they are not seen in any other family Centrolenidae, commonly referred to as the frogs (Guayasamin et al., 2009). There are two classes glassfrogs (Frost, 2016). Though principally arboreal, of combat grasps, described as the primitive and derived during breeding season they descend to riparian habitat, states. In the primitive state, males are positioned in a mating epiphyllously and typically depositing eggs on back-to-venter, or amplexus-like, position. In contrast, vegetation overhanging the water (Guayasamin et al., in the derived state, males hang from vegetation by 2009). During breeding season, some glassfrog species their hind limbs, clasping each other venter-to-venter engage in male-to-male combat as they defend their (Bolivar et al., 1999). territories from conspecifics (Hutter et al., 2013). On 15 We provide the first observation of interspecific November 2014, at roughly 2100h, we observed a male combat between glassfrog species Nymphargus aff. Nymphargus aff. grandisonae (Cochran and Goin, 1970) grandisonae and Espadarana prosoblepon. To the on an upper leaf engaged in amplexus-like combat with best of our knowledge, our observation is also the first a male Espadarana prosoblepon (Boettger, 1892) on a record of any interspecific combat in Centrolenidae. lower leaf (Fig. 1). The animals were hanging above a Espadarana prosoblepon cooccurs with N. grandisonae stream in Buenaventura Reserve in El Oro Province, across the latter’s range. Though N. grandisonae inhabits Ecuador. The observation took place at 3.6350°S, a higher elevational band than E. prosoblepon, they 79.7490°W, WGS 84, 1040 m a.s.l. We detected overlap significantly (Amphibiaweb, 2016) and appear neither eggs nor females nearby. The individuals did to share similar habitat requirements. Nymphargus aff. not vocalize or inflate their vocal sacs at any time grandisonae and N. grandisonae are very closely related during the observation, which lasted approximately 10 species, and it can reasonably be expected that their minutes. Though unconfirmed, it is possible that the N. behavior is similar. The ranges of N. aff. grandisonae aff. grandisonae was using his humeral spines. Neither and E. prosoblepon also overlap, and the elevational animal was visibly injured after separation. range of N. aff. grandisonae is nested within that of E. Among frogs, combat is not unique to centrolenids. prosoblepon (Szekely pers comm. 2016). It remains Frog species from many lineages combat with unclear how often glassfrogs interact interspecifically, conspecifics to defend their territory, protecting their potentially competing for scarce suitable riparian share of limited resources and reproductive opportunities vegetation. Better understanding how and with whom (Wells, 1977). They may fight to defend a preferred glassfrogs engage in combat could elucidate niche oviposition site, or a preferred site for broadcasting partitioning in their complex neotropical ecosystems. their call to potential mates (Toledo and Haddad, 2005; Combat is sparsely documented in Centrolenidae. Vilaça et al., 2011; Wells, 1977). However, the combat Most of what we know comes from anecdotal reports in behaviours observed in certain species of centrolenids 11 species (Rojas-Runjaic and Cabello, 2011). Bolivar et al. (1999) hypothesized that combat behaviour could be used as a taxonomic character for this family, allowing for the discrimination of constituent species by subfamily. In this initial conception, “derived” combat 1 Department of Biology, East Carolina University, NC, USA. 2 Department of Environmental Science, Policy, and behaviour was the ancestral state for the family, and only Management, University of California Berkeley, CA, USA. the subfamily Hyalinobatrachinae engaged in primitive * Corresponding author e-mail: [email protected] combat (Guayasamin et al., 2009). Therefore, when both 284 Anton Sorokin & Emma Steigerwald Figure 1. Nymphargus aff. grandisonae grips Espadarana prosoblepon in a primitive combat state in Buenaventura Reserve, Ecuador (A and B). Photos by Anton Sorokin. primitive and derived combat were described (Rojas- Acknowledgements. We are grateful to Paul & Diana Szekely for Runjaic and Cabello, 2011) in Centrolene daidaleum, their helpful suggestions and edits. these observations contradicted the standing hypothesis. The hypothesis was further attenuated two years later by References similar observations (Hutter et al., 2013) in Nymphargus Amphibia Web: Information on amphibian biology and conservation. grandisonae. Our observation corroborates Hutter et (2016): [Web application]. AmphibiaWeb, Berkeley. Available al. (2013) in finding Nymphargus aff. grandisonae, a at www.amphibiaweb.org. Last accessed December 2016 close relative of N. grandisonae, engaged in primitive- Bolivar, W.G., Grant, T., Osorio, L.A. (1999): Combat behavior state combat behavior. As suggested by Rojas-Runjaic in Centrolene buckleyi and other Centrolenid frogs. Alytes: and Cabello (2011), the initial combat-systematics International Journal of Batrachology 16(3–4): 77–83. Frost, D.R. (2016): Amphibian Species of the World: an Online hypothesis was based on anecdotal observations from Reference. Version 6.0 (24 March 2017). Electronic Database a small fraction of glassfrog diversity. Data more accessible at http://research.amnh.org/herpetology/amphibia/ comprehensively representative of centrolenid diversity index.html. American Museum of Natural History, New York, will be required to understand the value of combat USA. behaviour for informing systematics and phylogeny. Guayasamin, J.M., Castroviejo-Fisher, S., Trueb, L., Ayarzagüena, J., Rada, M., Vilà, C. (2009): Phylogenetic systematics of Glassfrogs (Amphibia: Centrolenidae) and their sister taxon Allophryne ruthveni. Zootaxa 2100: 1–97. Combat between Nymphargus aff. grandisonae and Espadarana prosoblepon 285 Hutter, C.R., Esobar-Lasso, S., Rojas-Morales, J.A., David, P., Gutiérrez-Cárdenas, A., Imba, H., Guayasamin, J.M. (2013): The territoriality, vocalizations and aggressive interactions of the red-spotted glassfrog, Nymphargus grandisonae, Cochran and Goin, 1970 (Anura: Centrolenidae). Journal of Natural History 47: 47–48. https://doi.org/10.1080/00222933.2013.792961 Rojas-Runjaic, F.J.M., Cabello, P. (2011): A glassfrog with primitive and derived combat behavior. Zootaxa 2833: 60–64. Toledo, L.F., Haddad, C.F.B. (2005): Reproductive biology of Scinax fuscomarginatus (Anura, Hylidae) in south-eastern Brazil. Journal of Natural History 39(32): 3029–3037. https:// doi.org/10.1080/00222930500221403 Vilaça, T. R. A., Silva, J. R. do S., & Solé, M. (2011): Vocalization and territorial behaviour of Phyllomedusa nordestina Caramaschi, 2006 (Anura: Hylidae) from southern Bahia, Brazil. Journal of Natural History 45: 29–30. https://doi.org/10. 1080/00222933.2011.561018 Wells, K. D. (1977): The social behaviour of anuran amphibians. Animal Behavior, 25: 666–693. Accepted by Igor Kaefer.