Rhinella dorbignyi (dorbigny’s toad). Defensive behavior.

JUNGBLUT LD; POZZI AG

HERPETOLOGICAL REVIEW

Society for the Study of Amphibians and Reptiles

Lugar: Texas; Año: 2022 vol. 53 p. 300 - 301

0018-084X

Rhinella dorbignyi belongs to the Rhinella granulosaspecies group, which is composed of small to medium-sizedspecies that present rough skin, well-developed and keratinized cranial crests, and small parotoid glands, and is distributed in open areas in southeastern Brazil, Uruguay, and northeastern Argentina, being a rather common species in grasslands of the Pampas region in Argentina (Pereyra et al. 2016. Cladistics 32:36–53). During fieldwork, we observed stiff-legged behavior in adult male and female R. dorbignyi from two different populations separated by ca. 400 km in the southeastern and Fig. 1. Various color morphs of Raorchestes shillongensis from Shillong, Meghalaya, India: grey dorsum with ‘)-(’ shaped or ‘) (’ mark (A, C, F, H, I); dark brown dorsum with no distinct markings (B); black dorsum with no distinct markings (D); irregular dorsal markings (E, N); hourglass marking on dorsum (G, K–M); grey or slaty dorsum with sharp northwestern parts of Buenos Aires Province, Argentina. The first site was a flooded area located between Provincial Route 88 and agricultural crops in the district of Lobería, Buenos Aires, Argentina (38.4746°S, 58.5763°W; WGS 84; 28 m elev.). Between 2000 and 2200 h on 10 November 2020, we traversed the margins of a semi-permanent body of water and located two female (71.2, 77.5 mm SVL) and one male (58.1 mm SVL) R. dorbignyi. When holding them to take photographs, they stretched their limbs laterally and flattened the trunk of the body ventrally, maintaining a rigid posture (Fig. 1A). When the specimens were left on the ground, this stiff-legged behavior ceased almost immediately, or after a few seconds. The second site was a semi-natural area located in the Municipal Park of Alberti, Buenos Aires, Argentina (35.0274°S, 60.2842°W; WGS 84; 72 m elev.). Between 2100 h and 2300 h on 23 December 2020, we located three female R. dorbignyi (64.4, 56, and 62.4 mm SVL) feeding in an open grassy area. Before capturing them, we disturbed them first with gentle touches and later with more intense touches. The animals tried to escape, but in no case did they display the stiff-legged posture during the disturbance, rather this posture was only observed when we grabbed the animals. One of the females stretched her hind legs posteriorly and inflated her lungs, increasing her body volume notably (Fig. 1B). As before, this rigid posture ceased within seconds after releasing the animals. Stiff-legged behavior was originally described in twounrelated frog species (Stereocyclops parkeri and roceratophrys appendiculata) that live in the leaf-litter of coastal rainforests in southeastern Brazil (Sazima 1978. Biotropica 10:158). This behavior has been previously reported in other leaf-litter species (de Mira-Mendes et al. 2016. Herpetol. Notes 9:91–94). It is suggested that by displaying this behavior frogs could mimic fallen leaves, confusing visually oriented predators (Sazima 1978, op. cit.). Nevertheless, R. dorbignyi inhabits open grasslands, an environment where resembling a fallen leaf is likely to providelittle advantage. In addition, adults spend most of the timeunderground or are frequently observed on the margins oftemporary ponds. The stiff-legged behavior has been reported in other species that inhabit open phytophysiognomies, including R. granulosa (Mângia and Santana 2013. Herpetol. Notes 6:45–46), R. pygmea (Figueiredo-De-Andrade and Da Silveira 2018. Herpetol. Notes 11:205–207), Odontophrynus americanus (Maffeid and Ubaid 2016. Neotrop. Biol. Conserv. 11:195–197), and Pleurodema bibroni (Kolenc et al. 2009. Zootaxa 1969:1–35, reported as death feigning), suggesting that more studies are necessary to better understand the adaptive role of this postural defense in anurans.