Notes on Agonistic Communication by the Neotropical Torrent Frog Hylodes Meridionalis (Hylodidae)
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Herpetology Notes, volume 11: 919-923 (2018) (published online on 11 November 2018) Notes on agonistic communication by the Neotropical torrent frog Hylodes meridionalis (Hylodidae) Fábio de Sá1, Nadya Pupin1,* and Célio F. B. Haddad1 Diurnal activity has been suggested as a catalyst for meridionalis (Mertens, 1927) occurs in the extreme the evolution of visual communication in frogs (Hödl southern portion of the distribution of the genus. and Amézquita, 2001). Noisy fast-flowing streams as Herein we report observations of H. meridionalis that breeding and feeding sites may facilitate the evolution were made in the field in Parque das Oito Cachoeiras, of complex visual communication in frogs as a way to municipality of São Francisco de Paula, Rio Grande avoid interference from environmental sound (Haddad do Sul State, Brazil, a region predominantly covered and Giaretta, 1999; Hödl and Amézquita, 2001). We by Atlantic Forest. We observed and described the have observed that frogs of the family Hylodidae previously unknown behaviour of males of this species Günther, 1858, exhibit elevated levels of complexity using the focal animal sampling method (Altmann, in their visual communication, as has been found for 1974) in Arroio do Padre, a fast-flowing stream bellow Crossodactylus schmidti Gallardo, 1961; Hylodes japi the Escondida waterfall (29.4511°S, 50.5577°W; de Sá et al., 2015; H. heyeri Haddad et al., 1996; and 900 m a.s.l.). Our field procedures were approved H. phyllodes Heyer and Cocroft, 1986 (Lingnau, 2003; by the Instituto Chico Mendes de Conservação da Hartmann et al., 2006; Beltramin, 2014; Caldart et al., Biodiversidade/Instituto Brasileiro do Meio Ambiente 2014; de Sá et al., 2016). Diurnal Neotropical torrent e dos Recursos Naturais Renováveis (ICMBio/ frogs (i.e., hylodids) have served as model species for IBAMA; license numbers 30181–1 and 57098–1). We understanding communication, particularly with regard filmed behaviours with a Sony DSC-H9 camera. We to the evolution of visual communication in frogs (see considered behavioural events to be intraspecific visual Caldart et al., 2014; de Sá et al., 2016). displays following the approach proposed by Hödl and Hylodes Fitzinger, 1826 is the most speciose genus Amézquita (2001) and identified the displays using the of the monophyletic family Hylodidae (Grant et al., terminology of previous reviews (Hödl and Amézquita, 2006; Pyron and Wiens, 2011). Twenty-six species 2001; Hartmann et al., 2005; de Sá et al., 2016). We are currently known for the genus, which occur in collected seven individuals as voucher specimens after association with the Brazilian Atlantic Forest, from the filming, which are housed in the Célio F. B. Haddad state of Espírito Santo to the state of Rio Grande do Sul collection (CFBH), Departamento de Zoologia, Instituto (Frost, 2017). Species of Hylodes are rheophilic, with de Biociências, UNESP, Rio Claro, São Paulo, Brazil their reproductive biology being obligatorily associated (CFBH 30368–30374). with fast-flowing streams, where they lay eggs and their On 21 November 2011 (around 14:00 h) we observed tadpoles develop (e.g., Nascimento et al., 2001; Pombal aggressive interactions among three males of H. et al., 2002; de Sá et al., 2015). The species Hylodes meridionalis that were agonistically competing for breeding territories on emergent rocks in the middle of the fast-flowing Arroio do Padre stream. One male (A), stimulated by the presence of a conspecific male (B), was performing several visual displays (toe trembling, toe flagging, toes posture, foot shaking, foot flagging, 1 Universidade Estadual Paulista, Instituto de Biociências, arm lifting, arm waving, and body jerking) while Departamento de Zoologia and Centro de Aquicultura (CAUNESP), Avenida 24 A, 1515, CEP 13506-900, Rio periodically emitting advertisement calls. Male A Claro, São Paulo, Brazil. moved in the direction of male B, and then positioned * Corresponding author. E-mail: [email protected] himself on B. Male A then positioned and maintained 920 Fábio de Sá et al. Figure 1. Three males of Hylodes meridionalis interacting during a territorial dispute in a fast-flowing stream (see text for details). (a) Male A is positioning and maintaining his right hand on the dorsum of male B while performing advertisement calls and the agonistic visual display called toe flagging (indicated by the arrow); male B is motionless in a submissive posture called body lowering. (b) Male A is performing the visual display called foot-flagging as an agonistic message for male B. (c) Male B is adopting body lowering next to male A, while male C is emitting an advertisement call. (d) Male C is keeping his right hand on the dorsum of male A while emitting an advertisement call; male B had jumped away. Parque das Oito Cachoeiras, municipality of São Francisco de Paula, Rio Grande do Sul State, Brazil. his right hand on the dorsum of male B while performing toe flagging, arm lifting, and arm waving). Male B calls and visual displays (toe flagging and toes posture; then jumped away and male A kept performing visual Fig. 1a). Male B remained motionless in a submissive displays (toe flagging and foot flagging) and emitting posture (body lowering). After a little more than one advertisement calls, while in a natural calling posture. minute, and while still under male A, male B moved While all these interactions were occurring, two other and abandoned the submissive posture to adopt a calling males were periodically emitting advertisement calls, posture, from which he emitted one advertisement call. but from distinct emergent rocks (approximately one Next, male A positioned himself to the side of male meter from the first two males that were being filmed). B and adopted a submissive posture (body lowering). Male A, likely still visually stimulated by the proximity Male B performed some visual displays with his toes of male B, started to move again (initially displaying (toe trembling and toe flagging), which seemed to truncated walking) in the direction of the new position provoke male A to perform some visual displays as of male B, and then jumped to within a few centimetres well (toe trembling) and to move closer to the intruder of male B. While moving, male A was calling and (moved displaying truncated walking associated with performing visual displays (toe flagging, toes posture, Notes on agonistic communication by a Neotropical torrent frog 921 and arm waving). Escaping from male A, male B jumped male C was calling. At this moment, the three males (A, away, stopping at another rock. Still pursuing male B, and C) were on the same rock and positioned very B, male A called and performed visual displays (toe close to each other, with male B adopting a submissive trembling, toe flagging, foot shaking, and foot flagging), posture (body lowering; Fig. 1c). Male A pursued male and then jumped and approached male B again. Male B and performed visual displays (toes posture and foot A called, performed visual displays (toe flagging, arm shaking) and made an advertisement call. When male waving, and upright posture), and touched the dorsum A called, male C jumped on the dorsum of male A, of male B with his left hand. Male B then jumped into and started to emit advertisement calls. Males A and C the water, but quickly returned to the same rock behind adopted submissive postures (body lowering) and male male A. Male A kept performing visual displays (toe B jumped away. Male C then adopted a natural calling trembling, foot shaking and, more distinctly, foot- posture and kept his right hand on the dorsum of male A flagging; see Fig. 1b). Male A turned to face male B while calling (Fig. 1d). Males A and C performed visual and touched him on the snout with his gular region. displays with their toes simultaneously (toe trembling Male B immediately jumped away, stopping at the rock and toe flagging). When observing the three males where male A was initially, but now occupied by a third interacting, a fourth male was heard calling. male (C), which was calling and disputing the breeding Advertisement calls were always emitted with the use area. Male C called, performed visual displays (toe of both vocal sacs, with the exception of one occasion trembling and toe flagging), and jumped on the dorsum when male C started to call with only the left vocal sac of male B, which immediately moved slightly forward. and only inflating his right vocal sac together with the Subsequently, male A returned to the same rock while left to complete the end of the call (see de Sá et al., 2016, and Elias-Costa et al., 2017, for an explanation of the selective use of vocal sacs in Hylodes). All visual displays performed by each male are presented in Table 1. Sometimes visual displays were performed Table 1. Visual displays performed by three males of Hylodes in temporal association with advertisement calls, which meridionalis who were agonistically competing for territories. are marked with an asterisk (*) in Table 1. Male C was The behaviours occurred in a relatively small area on emergent rocks in the middle of a fast-flowing stream. We considered larger than male A, which was larger than male B. behavioural events to be intraspecific visual displays, None of the males emitted aggressive calls during our following the approach proposed by Hödl and Amézquita observations. (2001) and identified the displays based on the terminology The area of the fast-flowing stream where the of previous reviews (Hödl and Amézquita, 2001; Hartmann observations were made had a high number of densely et al., 2005; de Sá et al., 2016). Displays with an asterisk distributed reproductively active Hylodes meridionalis (*) were sometimes performed in temporal association with males.