VOCAL REPERTORY OF TWO SPECIES OF THE LEPTODACTYLUS PENTADACTYLUS GROUP (ANURA, LEPTODACTYLIDAE)

INTRODUCTION Among frogs, acoustic signals are related to female attraction, territorial demarcation, and predator avoidance (Gerhardt and Huber 2002). The advertisement, courtship, territorial, encounter, reciprocation, release and distress calls are main kinds of anuran vocalizations (Duellman and Trueb 1994; Gerhardt and Huber 2002). Besides advertisement call, some species of Leptodactylus of the L. pentadactylus group (sensu Heyer 1979, 2005) present reciprocation, release and distress calls (Heyer 1979; Hödl and Gollmann 1986; Hero and Galatti 1990; Kaiser 1994; Davis et al. 2000; Heyer and Thompson 2000; Heyer 2005; Toledo et al. 2005). The vocal repertory of L. labyrinthicus includes advertisement, courtship, distress, and territorial calls (Márquez et al. 1995; Toledo et al. 2005; Zina and Haddad 2005). Males of L. syphax produce advertisement and aggressive calls and non-vocal clicks (Cardoso and Heyer 1995). Herein we report and describe for the fi rst time a reciprocation call in L. syphax and show that its advertiseABSTRACT: Among frogs, vocalizations play important roles in their social interactions. Herein we describe fi ve new types of vocalizations for two foam-nesting species of the Leptodactylus pentadactylus group, L. syphax and L. labyrinthicus. Behavioral observations and recordings were done in four localities within the Cerrado biome, at southeast and central Brazil. Before emitting advertisement calls, males of L. syphax often started producing a sequence of notes, which gradually turned into the advertisement call. These different notes may be an introductory call, which would serve to prepare the vocal structures for the emission of the high-frequency/amplitude advertisement calls. A male of L. syphax was emitting advertisement calls when a female approached and started to emit brief and low-amplitude calls; these vocalizations probably are reciprocation calls. Males of L. labyrinthicus involved in agonistic interactions can emit vocal cracks (encounter call) and deep rough sounds (territorial calls). Five courting males of L. labyrinthicus released screams with their mouth slightly opened in response to the approach of human observers. We conclude that these screams do not represent distress or territorial calls.

Herein we report and describe for the fi rst time a reciprocation call in L. syphax and show that its advertise-ABSTRACT: Among frogs, vocalizations play important roles in their social interactions. Herein we describe fi ve new types of vocalizations for two foam-nesting species of the Leptodactylus pentadactylus group, L. syphax and L. labyrinthicus. Behavioral observations and recordings were done in four localities within the Cerrado biome, at southeast and central Brazil. Before emitting advertisement calls, males of L. syphax often started producing a sequence of notes, which gradually turned into the advertisement call. These different notes may be an introductory call, which would serve to prepare the vocal structures for the emission of the high-frequency/amplitude advertisement calls. A male of L. syphax was emitting advertisement calls when a female approached and started to emit brief and low-amplitude calls; these vocalizations probably are reciprocation calls. Males of L. labyrinthicus involved in agonistic interactions can emit vocal cracks (encounter call) and deep rough sounds (territorial calls). Five courting males of L. labyrinthicus released screams with their mouth slightly opened in response to the approach of human observers. We conclude that these screams do not represent distress or territorial calls.  and a Sennheiser MKH816T microphone were also used. All recordings were made from distances less than two meters from the calling individual. Audiospectrograms were produced using Sound Ruler software (Gridi-Papp 2004); sample rate was set at 44,100 Hz, with 16-bit resolution, and FFT (Fast Fourier Transformation) length at 1024 was used. The analog recording was digitized at a 22,050 Hz sampling rate. The sound fi les presented in the results do not correspond exactly to the call sections pictured in the fi gures (sonograms). The terminology used for the description of the vocalizations essentially follows Heyer et al. (1990).
The advertisement calls we describe are in agreement with those presented by Cardoso and Heyer (1995). The calls we interpreted as introductory (Figure 1, middle) were obtained by Cardoso and Heyer (1995) by playbacking advertisement calls to a male. These authors recognized these calls as aggressive (territorial), because they failed to fi nd intermediate notes in their sample (such as that we present in fi gure 1, lower). In our records, the increasing intensity of the calls emitted prior to the advertisement calls and the existence of transitional sounds indicate that they may be introductory vocalization, which would serve to prepare the vocal structures for the emission of the high-frequency/amplitude advertisement calls. Considering the contradictory interpretation of the function of these calls, further stud-ies are necessary to determine precisely their function.
Reciprocation call A male was observed emitting advertisement calls when a conspecifi c female approached (< 5 cm) and started to release brief and low-amplitude calls (n = 32) (Figure 2). The male kept emitting advertisement calls while the female was vocalizing (3 min.). We kept observing the pair by fi ve hours, but amplexus did not occur. We captured and examined the female and found that she was bearing mature eggs. Her calls (n = 11 analyzed) have a fundamental frequency of 1012.4 Hz (± 21.2; 969 -1048) and last 19.1 ms (± 4.1; 11.6 -25.1). The inter-call intervals average 3.9 s (± 2.4; 1.9 -8.9; n = 9 measurements).
These vocalizations are reciprocation calls (sensu Duellman and Trueb 1994; Gerhardt and Huber 2002), because a receptive female emits them in response to advertisement calls of a conspecifi c male in a close-range interaction. As L. syphax males are territorial and have sharp-horny spines in their chest and thumbs (Heyer 1979;Cardoso and Heyer 1995; personal observation), we suggest that females could emit reciprocation calls to signalize their sex and receptivity to prevent male attacks (review in Schlaepfer and Figeroa-Sandí 1998). The reciprocation call was reported for few anuran species (Schlaepfer and Figeroa-Sandí 1998;Bernal and Ron 2004). As for L. syphax, the reciprocation call of L. fallax (L. pentadactylus group) consists of brief and low-amplitude sounds (Davis et al. 2000).

Leptodactylus labyrinthicus vocalizations
Territorial call Two males were heard advertisement calling under rock stones (out of our sight) about one meter apart of one another when one of them started to emit very deep rough calls (Figure 3). These vocalizations have very low frequencies, amplitude modulation and different types of sounds. These calls (n = 10 analyzed) have a dominant frequency of 462 Hz (± 153; 384 -891) and last 0.6 s (± 0.3; 0.3 -1.2). The mean time interval between the calls is 8.1 s (± 10; 1.9 -37; n = 9 measurements). We regard these aggressive vocalizations as territorial calls (sensu Duellman and Trueb 1994;Gerhardt and Huber 2002), because a male produced them in the presence of other conspecifi c male that are also emitting

Frequency (kHz)
The distress call of frogs (sensu Hödl and Gollmann 1986) is a loud scream emitted with mouth wide open, generally when an individual is grasped by a predator. This call has clear harmonic bands and often reaches high frequencies above 6 kHz (Hödl and Gollmann 1986). We conclude that the screams we witnessed do not represent distress calls. First, they were emitted with the mouth just slightly open. Second, the males were not grasped or handled. Third, males emitted advertisement calls alternately, which refl ect sexual excitement and could attract predators instead of scaring them away (Gerhardt and Huber 2002). The distress call of L. labyrinthicus is known (Toledo et al. 2005; personal observation) and it is different from the screams presented here. The distress call of this species is emitted by handled individuals, has clear harmonic bands and the frequencies can reach 9 kHz (Toledo et al. 2005). The screams cannot be regarded as a territorial call either, because they are different (e.g. higher frequencies) from the territorial call of the species (Zina and Haddad 2005;present study) and we have observed close range non-courting males in several occasions and they had never reacted in this way.
Courting males seemed to be disturbed with our presence, because they started screaming only when we approached them, stop screaming and resuming advertisement call when we moved away. Future studies could test the hypothesis that these vocalizations are "intimidatory screams" with the function of repelling heterospecifi c disturbers (not necessarily a predator), which could promote the evasion of receptive females from the reproductive site. Probably, males rely on their large size (up to 195 mm SVL,≈ 750 g) and irritating skin secretions (Heyer 1979;Cei 1980;personal observation) to react this way. Besides, large free-ranging L. labyrinthicus males can confront humans by jumping on or grasping approached hands, feet or long sticks (n = 3 unpublished personal observation). advertisement calls. A different territorial call has being described to this species (Zina and Haddad 2005). In our records, the sound pictured in the fi gure 3b is that which most closely resemble the territorial call previously published. The different kinds of sounds of the territorial call of this species may represent differences in the level of male irritation. Probably, the male was very irritated during the emission of calls with greater amplitude (see Figure 3a).
Encounter call Once we found two males that were close (< 1.5 m), but out of sight of one another. The larger male (hereafter dominant) was emitting advertisement calls and the smaller was silent. Close (< 30 cm) the silent male, we imitated the advertisement calls (an easily reproducible "uuup") what caused the approximation (10 cm) of the larger male, which started to emit vocal cracks ( Figure  4). These sounds were produced with the mouth closed and the emission was coincident with a slight dilation of the vocal sac. The cracks were intercalated with advertisement calls. The silent male remained motionless during the emission of the cracks, but the larger male stopped calling and jumped on him; after this attack, the smaller male run out of sight of his aggressor (> 1 m). Each crack is a single note of very low sound amplitude; it lasts 40 ms (± 10) and has fundamental frequency of 194 Hz (± 12; 170 -205; n = 9 calls analyzed). The time interval between the calls is 4.2 s (± 3.2; n = 6 measurements). These vocal cracks fi t well the defi nition of an encounter call (Duellman and Trueb 1994), because they were emitted by a male just preceding an agonistic interaction. Encounter calls probably are emitted to avoid fi ghts (Wells 1977).

Intimidatory (?) screams
Courting males (n = 5) often release screams in the presence of human observers. Once we observed (20:40 h) a male excavating a basin at the edge of a temporary pool (≈ 200 m², 60 cm deep) and there was a receptive female nearby (< 2 m). When we approached to record this male (< 4 m), he started releasing a sequence of screams ( Figure 5) with his mouth slightly opened. As the screams apparently were directed to the observers, we moved away (10 m) and remained hidden for about 10 minutes. The male stopped screaming and restarted to emit advertisement calls. During a second approach (< 2 m), he restarted screaming. We moved away once more and he stopped screaming again. The screams often were intercalated with advertisement calls. The following day, we returned to that site and encountered an egg clutch in the basin he was building. On four other occasions and localities, courting males released screams as a result of the presence of receptive females and human observers. All these fi ve cases were of males not accustomed to human presence; seven other courting males from areas with intense human visitation (garden around swimming pools; see Silva et al. 2005) did not respond aggressively.
The screams are quite variable in duration and six types of sounds can be recognized ( Figure 5). In general, the screams are low, rough, short and are frequency and amplitude modulated. These screams differ mainly in the amount of sound intensity (amplitude). Each scream (n = 14 analyzed; two males recorded) lasts about 1.6 s (± 0.6; 0.8 -3.1), and has a fundamental frequency of 308 Hz (± 42; 240 -373) and a dominant frequency of 1425 Hz (± 236; 969 -1751). The time intervals between the screams average 2.7 s (± 2.9; 0.4 -11.2; n = 13 measurements).