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Habitat, egg-laying behaviour, eggs and tadpoles of four sympatric species ofPseudopaludicola (Anura, Leiuperidae)Ariovaldo A. Giaretta a; Kátia G. Facure a

a Laboratório de Comportamento, Ecologia e Sistemática de Anuros Neotropicais, Universidade Federal deUberlândia, Uberlândia, Minas Gerais, Brazil

Online Publication Date: 01 April 2009

To cite this Article Giaretta, Ariovaldo A. and Facure, Kátia G.(2009)'Habitat, egg-laying behaviour, eggs and tadpoles of foursympatric species of Pseudopaludicola (Anura, Leiuperidae)',Journal of Natural History,43:15,995 — 1009

To link to this Article: DOI: 10.1080/00222930802702456

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Habitat, egg-laying behaviour, eggs and tadpoles of four sympatricspecies of Pseudopaludicola (Anura, Leiuperidae)

Ariovaldo A. Giaretta* and Katia G. Facure

Laboratorio de Comportamento, Ecologia e Sistematica de Anuros Neotropicais, UniversidadeFederal de Uberlandia, CEP 38400–902, Uberlandia, Minas Gerais, Brazil

(Received 2 October 2007; final version received 11 November 2008)

In contrast to most leiuperid frogs, Pseudopaludicola falcipes does not lay eggs infoam nests; this could represent a reversion to the primitive state. We found thatin four other Pseudopaludicola species, eggs were also not embedded in foam nestsand had a well-defined outermost jelly layer. The females also constantly movedor dived and males lacked vigorous ‘‘wiping/kicking’’ leg motions while eggs werebeing laid, features that make foam nesting difficult. The tadpoles of three specieshave two gaps in the marginal papillae along the lower labium and two posteriorrows of labial teeth; the tadpoles of one species had three gaps and three rows, apattern resembling that of some Physalaemus (Leiuperidae) species. Our data ontadpole morphology and reproductive behaviour do not allow us to rule out theparaphyletic nature of Physalaemus in relation to Pseudopaludicola but theyprovide some support against the ‘‘foam-loss hypothesis’’ in Pseudopaludicola.

Keywords: tadpole; foam nest; morphology; systematics; Leptodactylidae

Introduction

Pseudopaludicola are tiny [,22 mm snout–vent length (SVL)] frogs that are widely

distributed in South America. Twelve species are recognized (Frost 2007) with most

of them occurring in open vegetation such as Llanos, Chaco and Cerrado (Cei 1980;

Frost 2007; Giaretta et al. 2008). Brief accounts on the reproductive biology are

available for Pseudopaludicola falcipes (Hensel, 1867) which, unlike most other

leiuperid/leptodactylid frogs, does not lay eggs in foam nests (Barrio 1945, 1953;

Gallardo 1968).

Several authors have drawn attention to the possible paraphyly of the genus

Physalaemus in relation to Pseudopaludicola (Lynch 1989; Cannatella and Duellman

1984; Lobo 1995). The presence of a gap in the posterior row of marginal papillae of

the tadpoles is a supposedly derived feature shared by species of Physalaemus of the

Physalaemus cuvieri group and Pseudopaludicola falcipes. If, in reality,

Pseudopaludicola is nested within Physalaemus, the absence of foam nesting in P.

falcipes necessarily represents a reversion to the primitive condition (Cannatella and

Duellman 1984; Lynch 1989; Lobo 1995).

Here we present data on the reproduction of four Pseudopaludicola species,

including information on habitat, seasonality, spawning behaviour, egg number, egg

size and egg and tadpole morphology. We also address comments on the evolution of

*Corresponding author. Email: thoropa@inbio.ufu.br

Journal of Natural History

Vol. 43, Nos. 15–16, April 2009, 995–1009

ISSN 0022-2933 print/ISSN 1464-5262 online

# 2009 Taylor & Francis

DOI: 10.1080/00222930802702456

http://www.informaworld.com

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foam-nesting behaviour among terrestrial Neotropical frogs, arguing particularly

against the ‘‘foam-loss hypothesis’’ in Pseudopaludicola.

Material and methods

All species were studied in the municipalities of Uberlandia (about 18u559S,

48u179W) and Monte Alegre (about 18u569S; 49u019W) in the region of the Triangulo

Mineiro, State of Minas Gerais, Brazil. The original Cerrado vegetation (Oliveira

and Marquis 2002) can still be found as scattered patches in the region. We refer to

human-generated areas of reproduction as those in which the natural vegetation has

been removed and often covered by short (,1 m tall) grass or grass-like plants. The

regional climate is rainy and hot from September to April and dry and mild with

occasional frosts for the remainder of the year. The annual mean precipitation is

about 1550 mm (750–2000 mm; Giaretta and Kokubum 2004).

Weekly behavioural observations were made from November 2000 to April 2004;

sporadic observations between 1998 and 2008 (including dry season months) were

also included. The daily pattern of calling activity was determined occasionally

during 24-h periods. Courting or egg-laying pairs were found by scanning breeding

choruses and the most relevant events were noted through continuous recording

(Martin and Bateson 1986). Naturalistic observations and photographs of egg-

releasing behaviours were made at 20–40 cm from the amplectant pairs. Video

sequences of egg-laying behaviour were made (DVD Sony Handycam; 8006digital

zoom; about 365 cm visual field) of Pseudopaludicola mystacalis (Cope, 1887) (n53)

and Pseudopaludicola ternetzi Miranda-Ribeiro, 1937 (n52). Preserved adults were

analysed for secondary sexual characters. Tadpoles were preserved in 5% formalin;

adults were killed in 10% alcohol solution and preserved in 10% formalin.

The SVL of the smallest calling individual was used to set the lower size limit to the

adult male category; for females, it was the SVL of the smallest individual bearing

mature eggs or found in amplexus. Egg numbers were determined by counting ovarian

eggs from females with hypertrophied and convoluted oviducts and from egg clutches

obtained by keeping couples overnight in plastic bags with water. Tadpoles were

identified by raising them to metamorphosis in aquaria. When in captivity, tadpoles

were fed with ornamental fish food and cooked lettuce. References to tadpole stages

follow Gosner (1960). For morphological description, tadpoles collected in the field

were preferred. Morphological nomenclature follows Altig and McDiarmid (1999a;

2007). Size [SVL and total length (TL)] measurements were taken with callipers to the

nearest 0.1 mm; the eggs were measured with a micrometer on a stereomicroscope.

Considering the presumed close phylogenetic relationship between

Pseudopaludicola and Physalaemus of the Ph. cuvieri group (Cannatella and

Duellman 1984), we also describe and compare the oral disc morphology of the

tadpoles of Physalaemus centralis Bokermann, 1962 and Ph. cuvieri Fitzinger, 1826

(specimens from Uberlandia). In our sample, the tadpoles and early juveniles of Ph.

cuvieri were indistinguishable from those of Ph. centralis. Because Ph. cuvieri

reproduces in places where Ph. centralis is absent (the reverse not being true; Menin

and Giaretta 2003; personal observation) its tadpole could be identified confidently;

we based our description of Ph. centralis tadpoles only on reared specimens.

We collected amplectant pairs of Pseudopaludicola in the field and held them

overnight in plastic bags containing shallow (0–10 mm deep) water (about 100 ml)

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and checked the next day to see whether the restricted movements during egg-laying

would result in foam; this procedure is quite effective to obtain foam nests of severalPhysalaemus species (A.A. Giaretta, personal observation). Pairs kept in bags were

also observed in their egg-laying behaviour, and the eggs were checked for

fertilization.

Two species of Pseudopaludicola lay eggs in places occupied by the predatory

tadpoles of Leptodactylus labyrinthicus (Spix, 1824) (Leptodactylidae) (Silva et al.

2005). To test for egg predation, we placed two groups of 30 eggs of

Pseudopaludicola aff. canga Giaretta and Kokubum 2003 in two aquaria with two

predatory tadpoles (50 mm TL) each; the experiments were carried out overnight and

the guts of the predatory tadpoles were analysed.

Voucher specimens are in the frog collection (AAG-UFU) of the Universidade

Federal de Uberlandia, as follows. Pseudopaludicola saltica (Cope, 1887): adults

AAG-UFU 2606–7, tadpoles AAG-UFU 2601 (eight tadpoles); P. mystacalis:

adults AAG-UFU 2604–5, tadpoles AAG-UFU 2603 (six tadpoles); P. aff. canga:

adults AAG-UFU 2608–9, tadpoles AAG-UFU 2602 (10 tadpoles); P. ternetzi: adults

AAG-UFU 2625–7; Ph. centralis: adult AAG-UFU 2286, tadpoles AAG-UFU 2611

(142 tadpoles); and Ph. cuvieri: adults AAG-UFU 2031–2, tadpoles AAG-UFU 2610

(64 tadpoles).

Results

Males of all four species of Pseudopaludicola were smaller than females (Table 1),had nuptial asperities on the thumbs, and distended subgular vocal sacs. Size of eggs

and fecundity of the four species are also summarized in Table 1. The ova of all

species were dark grey and there were at least two jelly layers, the outermost being

quite firm (not fluid). Within a clutch, most eggs were free or loosely attached to one

another. The reproductive season was coincident with rains (August/September to

March/April) for P. saltica, P. mystacalis, and P. ternetzi; males of P. mystacalis

were also heard sporadically in the middle of the dry season (June 2003; 15:00 h; air

24uC, water 23uC). Pseudopaludicola aff. canga could reproduce continuously all

Table 1. Adult sizes and egg size/number of four syntopic Pseudopaludicola species from the

Cerrado Biome, Uberlandia, Minas Gerais, Brazil.

Species Males SVL

Mean¡SD

Range (n)

Females SVL

Mean¡SD

Range (n)

Egg number

range (n*)

Diameter of

yolk (range)

Diameter of

jelly capsule

(range)

Pseudopaludicola

saltica

16.1¡1.2 20.8¡1.0 45–139 (2) 1.30–1.30 3.6–4.0

14.6–18.0 (10) 20.5–22.0 (4)

Pseudopaludicola

mystacalis

13.8¡0.6 16.2¡0.9 74–164 (2) 0.75–0.85 1.7–2.5

12.8–14.7 (11) 15.2–17.0 (5)

Pseudopaludicola

aff. canga

13.6¡0.7 15.9¡0.9 11–40 (4) 1.20–1.40 2.1–3.0

12.7–14.9 (11) 14.6–16.1 (12)

Pseudopaludicola

ternetzi

15.4¡0.9 18.8¡0.9 41–52 (3) 1.20–1.70 2.3–3.3

15.1–17.0 (5) 17.5–20.1 (9)

Measurements are given in mm. SVL, snout–vent length.

*Egg clutches, 10 measured eggs each.

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year around (n57 years), but calling activity was restricted to sunny hours during the

hotter days of the drier, colder months. The calling period of all species started about

1–3 h before sunset and continued into the night in P. mystacalis, P. saltica and P.

ternetzi; P. aff. canga called at any time of day or night during the rainy months.

In all four species the amplexus was axillary (n>4 for all species; Figure 1).

Species account

Pseudopaludicola saltica

Reproduction took place in human-generated open areas (n56) with a shallow

(,10 mm) slow-flowing film of clean water; vegetation at these sites was short

(,30 cm tall) grass-like herbs. The reproductive activity extended to 1–2 days after

heavy rains. Pseudopaludicola mystacalis was found calling syntopically at one site.

Figure 1. Egg-releasing behaviour of two Pseudopaludicola species. Upper panel, an

amplectant pair of Pseudopaludicola saltica. The female has her front and hind limbs

extended and the male has his feet close to their cloacae; note also that the oviposited eggs are

within a circle around the couple (arrows); the egg jelly layers were not yet hydrated. This

couple was laying eggs in water about 5 mm deep. Lower panel, an amplectant pair of

Pseudopaludicola mystacalis. The couple is completely underwater, the female has her hind legs

a little bit extended and the male has his feet in close contact with their cloacae.

998 A.A. Giaretta and K.G. Facure

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Oviposition was observed for four pairs. After being amplexed, a female took up

to 4 h to start releasing eggs. One couple found in amplexus was followed for about

450 min until the male dismounted the female. All the eggs were released within a 40-

mm radius. When ready to release a group of eggs, the female raised her head by

extending the front legs and extended her hind legs a little. When the female’s head

was up, the male brought his feet close to her cloaca with his toes in medial contact.

At this time both individuals had their cloacae in close contact (Figure 1); the couple

remained in this egg-releasing position for 2–3 s before the male relaxed and

sometimes performed a few (one to three) slow (about 1 s) movements of extending

and retracting his partially opened (thighs at about 120u) legs. The times between the

egg-releasing sessions were variable (3–120 s), and fewer than 10 eggs appeared to be

released in each session. The egg-releasing behaviour, from the time when the female

extended her hind legs until she returned to the normal position, lasted about 3–4 s.

During the egg-releasing intervals, the female frequently jumped over the oviposited

eggs, which resulted in sand and detritus adhering to the eggs’ jelly layer (Figure 2).

Tadpoles (Figures 3A, 4A and 5A) that were examined were in Gosner stages 36–

38. Labial tooth row formula was 2(2)/2(1), the anterior gap broader than the

posterior; oral apparatus anteroventral; one broad anterior and two narrow

posterior gaps in the marginal papillae row; submarginal papillae absent; lateral

disc emarginate; upper jaw sheath arc-shaped, serrated; lower jaw sheath U-shaped,

serrated; nostrils closer to the eyes than to the tip of snout; nostril diameter smaller

than that of pupil; vent tube dextral, with a free border; eyes dorsolateral; spiracle

slightly before the mid-length of the body and at the midline of body height, distal

portion forming a short free tube; tail straight or slightly curved upwards; dorsal fin

low, margin almost straight, greatest height at mid-length of tail, originating beyond

the tail–body junction; ventral fin lower than the dorsal, margin almost straight; tail

tip round; body ovoid in dorsal view, depressed and ovoid in lateral view, back grey;

tail translucent with small grey spots, belly transparent. Total length was 23–28 mm;

body 30–38% of TL. Newly metamorphosed individuals averaged 8.9 mm (SD50.6;

n54) SVL.

Figure 2. An egg clutch of Pseudopaludicola saltica. Individual eggs (arrows) can be seen as

the spheres covered with sand grains. Scale about 15 mm.

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Pseudopaludicola mystacalis

Reproduction took place in human-generated habitats (n56) with sparse, short

(,30 cm tall) grasses. The species reproduced in both permanent water bodies [lakes

and slow-flowing shallow (,20 cm deep) creeks] and temporary water bodies

(,30 cm deep). The males called while sitting close (,10 cm) to the water or slightly

submerged. Pseudopaludicola aff. canga, P. ternetzi and P. saltica (n51 site each)

could call syntopically.

One complete and 12 partial oviposition sequences were observed. The complete

sequence lasted 4.2 h after starting at 16:50 h. The amplexed females moved around

constantly in or among pools. At the moment of egg release, the female dived

(keeping at least her head under water) and partially extended her hind legs, while

the male brought his toes close to their cloacae (Figure 1B); both froze in this

position for 2–3 s. After a group of eggs was released, the male made a few (two or

three) movements of extending and retracting his legs for a short period (about 1 s);

while moving the legs the male kept them at an angle of about 120u from each other.

Just after the male finished the leg movement, the female surfaced and moved

forward for either another egg releasing session or for a rest period. The female

moved underwater for distances of up to 1 m. The egg release occurred at the

moment the male had his toes close to their cloacae. The intervals between the egg

releasing sessions were quite variable, with an observed minimum of 3 s. During each

Figure 3. Left side view of the tadpole of the Pseudopaludicola species studied. (A)

Pseudopaludicola saltica, (B) Pseudopaludicola mystacalis, (C) Pseudopaludicola aff. canga,

(D) Pseudopaludicola ternetzi. Specimens from Uberlandia, MG, Brazil. Scales 11.5, 9.0, 10.0

and 10.0 mm for A, B, C and D, respectively.

1000 A.A. Giaretta and K.G. Facure

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session it appeared that one to five eggs were released; egg groups were spread

throughout a large area, up to 8 m between extremes. The released eggs were loose

on the bottom or adhered to underwater vegetation. Egg clutches produced in plastic

bags reached 100% fertilization and no trace of foam was found (n54 couples). In

the bags, the male performed the typical behaviours of bringing his feet close to the

cloacae and making a few leg movements after the egg release.

Figure 4. Diagram of the oral apparatuses of the studied Pseudopaludicola and Physalaemus

tadpoles. (A) Pattern found in Pseudopaludicola saltica, Pseudopaludicola mystacalis,

Pseudopaludicola ternetzi and a few Pseudopaludicola aff. canga. (B) Most common pattern

found in most Pseudopaludicola aff. canga. (C) Pattern found in both Physalaemus cuvieri and

Physalaemus centralis. Specimens from Uberlandia, MG, Brasil. Corresponding pictures in

Figure 5.

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Tadpoles (Figures 3B, 4A and 5B) examined were in Gosner stage 37–40. Oral

apparatus was as described for P. saltica (Figure 4A and 5B). Nostrils not visible in

lateral view, closer to the eyes than to tip of snout, diameter smaller than that of

pupil; vent tube dextral, with a free border; eyes dorsolaterally positioned; spiracle at

the mid-length of body, slightly below the midline of height, with a short free tube;

dorsal fin arched with the greater height at mid-length of tail, inserted at the tail–

body junction; ventral fin lower than dorsal, almost straight; tail tip round; body

ovoid in dorsal and lateral views; grey back; translucent tail with large grey mottling;

belly transparent. Total length was 21–24 mm; body 37–40% of TL. Newly

metamorphosed individuals were 7.0–8.4 mm SVL (n52).

Figure 5. Oral discs of the tadpoles of Pseudopaludicola and Physalaemus. (A) Pseudopaludicola

saltica, (B) Pseudopaludicola mystacalis, (C) Pseudopaludicola ternetzi, (D) Most common

pattern of Pseudopaludicola aff. canga, (E) Physalaemus cuvieri and (F) Physalaemus centralis.

Specimens from Uberlandia, MG, Brasil. Diagrams and scale shown in Figure 4.

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Pseudopaludicola aff. canga

Reproduction took place in human-generated habitats (n54) and along veredas

(Palm marshes; n53) bordered by short (,100 mm tall) grasses. The males calledfrom slow flowing, shallow (,45 mm) streamlets with clear water and a muddy

bottom; they called sitting in or close to (,10 mm) the water. The eggs were released

in several small groups (,10 eggs) in places with slow water flow or in small (,15 cm

diameter) marginal pools. The couple normally left the water while moving from one

egg laying site to the next. At the moment of egg release, the female often dived (20–

45 mm deep) beneath mud or plants for 5–8 s. At the moment of egg release the male

brought his toes close to their cloacae for 1–2 s. The end of diving (egg releasing) was

preceded by two to four slow movements of his hind legs (1–2 s). The released eggsremained at the bottom. Egg clutches produced in plastic bags reached 100%

fertilization and no trace of foam was found (n53 couples). In the bags, the male

performed the typical behaviours of bringing toes close to the cloacae and making a

few movements with the legs after egg-laying.

The predatory tadpoles of Leptodactylus labyrinthicus ate all the exposed eggs;

each one was swallowed as a unit.

Tadpoles (Figures 3C, 4B and 5D) examined were at Gosner stage 25–39. In most

individuals, labial tooth row formula 2(2)/3(1), anterior gap broad and the posteriornarrow; P3 row short or very short; oral apparatus anteroventral; one broad anterior

and three narrow posterior gaps in the marginal papillae row, the medial gap may be

shorter than the laterals; no submarginal papillae; lateral disc emarginate; upper jaw

sheath arc-shaped, serrated; lower jaw sheath U-shaped, serrated; nostrils not visible

in lateral view, diameter smaller than that of pupil; vent tube dextral, with a short

free border; eye positioned dorsolaterally; spiracle short, at the mid-length of body,

slightly below the midline of height, with a short free tube; dorsal fin arched with its

greater height at mid-length of tail, inserted at the tail–body junction; ventral finlower than dorsal, almost straight; tail tip round; body globoid in dorsal and lateral

views; body grey; tail translucent with or without grey spots; belly transparent or

whitish. Maximal observed total length was 27.7 mm; body comprising 33–37% of

TL. Variation: Three out of 23 specimens had a labial tooth row formula of 2(2)/2(1)

and two posterior gaps in the marginal papillae row (Figure 4A). Newly

metamorphosed individuals averaged 8.1 mm (SD50.57; n56) in SVL.

Pseudopaludicola ternetzi

Reproduction took place in human-made environments with wet grasslands (,30 cm

tall) with slow-flowing and shallow (15–50 mm deep) water (n52 sites). Tadpoles

were collected in waters less then 10 cm deep. Pseudopaludicola mystacalis was

present syntopically at both sites; P. aff. canga was also present at one site.

Three partial sequences of egg laying behaviour were observed. Eggs were laid in

shallow (,15 mm) portions of the water body and the females did not dive to releaseeggs. Egg release occurred when the female extended her hind legs and the male

brought his toes close to their cloacae. After a group of eggs was released, the male

sometimes made slow movements for one to three times by extending and retracting

his legs; while moving the legs, males kept them at an angle of about 120u from each

other. The female moved around constantly while laying eggs.

Tadpoles (Figures 3D, 4A and 5C) examined were in Gosner stage 25–36. Oral

apparatus as described for P. saltica (Figure 4A and 5C). Nostrils closer to the eyes

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than to tip of snout, diameter smaller than that of pupil; vent tube dextral, with a

short free border; eye dorsolateral; spiracle at mid-length and mid-height of body,

with a short free tube; dorsal fin almost straight with greater height at mid-length of

tail, inserted beyond the tail–body junction; ventral fin lower than dorsal, straight;

tail tip round; body ovoid in dorsal and depressed ovoid in lateral views; body grey;

tail translucent pale pink with small grey spots; belly transparent or whitish.

Maximal observed total length was 22 mm; body comprising 32% TL. A newly

metamorphosed individual measured 8.1 mm in SVL.

The oral structures of Ph. cuvieri (Figure 4C and 5E) and Ph. centralis (Fig. 4C

and 5F) were indistinguishable from one another in stages 36–38. Labial tooth row

formula 2(2)/3(1), anterior and posterior gaps narrow; P3 row shorter than rows A1–

2 and P1–2. Oral apparatus anteroventral. Marginal papillae gaps: one broad

anteriorly and three narrower posteriorly, with the more lateral ones shorter than the

medial. Submarginal papillae absent. Disc emarginate laterally. Nostril diameter

larger than that of pupil.

Discussion

Most Pseudopaludicola are seasonal breeders active during the rainy season (Barrio

1945, 1953; Castro 1964; Cei 1980). In our region, three Pseudopaludicola are

prolonged breeders; P. aff. canga potentially reproduce all year around. Most

Pseudopaludicola species live in open areas (Barrio 1953; Castro 1964; Gallardo

1968; Giaretta and Kokubum 2004; Dure et al. 2004; present work); as an exception,

Gascon (1996) and Rodrıguez and Duellman (1994) reported Pseudopaludicola

ceratophryes Rivero and Serna, 1985 in forest habitats. Males of Pseudopaludicola

boliviana Parker, 1927 (Dure et al. 2004) and the four species considered here call

from shallow, slow-flowing water; P. falcipes (Barrio 1945, 1953) and P. mystacalis

can also use ponds. Pseudopaludicola mystacalis, P. aff. canga and P. ternetzi appear

to have similar ecological requirements because they can be found calling side by

side. Tadpoles of all species can be regarded as exotrophic benthic (sensu Altig and

McDiarmid 1999a); those of P. saltica have relatively depressed bodies and long tails

with low fins in concordance with the habits of using shallow, flowing water.

Known Pseudopaludicola species lay fewer than 300 eggs at a time (Barrio 1945,

1953; present study) and egg sizes vary from 0.7 mm (Barrio 1945, 1953; present

study) to 1.7 mm (present study); a report on mature oocytes less than 0.5 mm (Dure

et al. 2004) deserves a re-evaluation. The relatively small numbers of eggs we found

(Table 1) may indicate that females can produce several small egg complements

within a reproductive season.

The number of gaps in the posterior row of papillae is variable among leiuperid

frogs (Langone 1989; Kehr et al. 2004; present study), even within a species. In

Physalaemus marmoratus (Reinhardt and Lutken, 1862) the modal number of gaps is

two, but gaps may be absent as well (Nomura et al. 2003; A.A.G. personal

observation). The pattern observed in Ph. marmoratus with two gaps and two

posterior rows of labial teeth resembles the pattern we described in P. saltica, P.

mystacalis, P. ternetzi and some P. aff. canga. The number of gaps in the posterior

row of papillae is variable among Pseudopaludicola species as well (present work); P.

falcipes from Argentina has one gap (Barrio 1945, 1953) and a population from

Uruguay has two (Laufer and Barreneche 2008). The pattern of gaps and the number

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of posterior tooth rows of P. aff. canga and P. falcipes from Uruguay (Laufer and

Barreneche 2008) are more similar to those of Ph. cuvieri (Bokermann 1962; Heyer

et al. 1990) and Ph. centralis than to that of P. saltica, P. ternetzi and P. mystacalis

(present work). Two major differences of the tadpoles of Pseudopaludicola species we

studied and the two analysed species of Physalaemus are in the relative proportions

of body parts; in Pseudopaludicola the gap in the second anterior tooth row is wider

than the first posterior row and the nostrils are smaller in diameter than the pupils.

Some problems regarding the tadpole morphology of leiuperid frogs deserve

further attention. Lobo (1991) described a tadpole that he attributed to P. ternetzi

(there called P. mystacalis), which does not have any gap in the posterior row of

papillae; a similar result was described in early stages of the tadpoles of

Pseudopaludicola mineira Lobo, 1994 (Pereira and Nascimento 2004). The tadpole

of Ph. centralis that we described differs from that described by Rossa-Feres (1993)

by having three posterior gaps. We have not been able to interpret the nature of any

of these differences. The great resemblance between Ph. centralis and Ph. cuvieri is

not surprising because they are close relatives (Lynch 1971; Nascimento et al. 2005).

Our data on the reproduction of the four Pseudopaludicola species are

concordant with those of Barrio (1945, 1953) for P. falcipes; eggs of this species

are not embedded in a foam nest, which appears to be true for all the species of the

genus. If, in fact, leptodactyline frogs represent a monophyletic group (cf. Roelants

et al. 2007) and Pseudopaludicola is phylogenetically nested within Physalaemus

(Cannatella and Duellman 1984; Lynch 1989), the absence of foam nests would

necessarily represent a reversion to the primitive state as observed in most frogs

(Lynch 1971; Heyer 1975).

Foam-nesting leptodactylid and leiuperid frogs normally have a reduced number

of jelly layers around the ovum (Giaretta and Kokubum 2004; Giaretta and Menin

2004; Kokubum and Giaretta 2005), a feature probably related to the conversion of

the oviducal secretions into fluids that can be beaten into foam. As in other frogs,

and in contrast to leptodactylid and most leiuperid frogs, Pseudopaludicola eggs have

well-formed jelly layers, especially the outermost (present study). The normal jelly

layers of Pseudopaludicola indicate that they share the plesiomorphic condition in

relation to most other leiuperid frogs and provide support against the ‘‘foam-loss

hypothesis’’.

Among foam-nesting leiuperid frogs, the foaming behaviour is performed by the

male vigorously beating female-released fluids and eggs with his hind legs (Ryan

1985; Hodl 1992). For foam-nest production it is essential that the female remains at

a site while the male beats the foam (Hodl 1986, 1990, 1992) or uses the foam of

already built nests as a support to re-start egg laying (Giaretta and Facure 2006). In

the Pseudopaludicola species we studied, the females constantly moved (sometimes

from site to site) while laying eggs, a behaviour that makes foam-nest construction

difficult. The diving behaviour performed by the females of P. mystacalis and P. aff.

canga while ovipositing renders foam-nest construction impossible because air

bubbles cannot be trapped under water. Foam generation is thought to be mostly

dependent on frog behaviour (Heyer 1969; Haddad et al. 1990; Hodl 1990), but our

empirical and experimental data do not support this for Pseudopaludicola because

even restricting the female movement in bags did not result in foam.

The behaviour of the males of Pseudopaludicola bringing the toes close to the

cloacae, may be homologous to that described for Ph. cuvieri (Bokermann 1962),

Journal of Natural History 1005

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Physalaemus pustulosus Cope, 1864 (Heyer and Rand 1977), and Physalaemus

ephippifer Steindachner, 1864 (compare Figure 1 in this study with figure 2D in Hodl

1990), but this feature may be ancestral to a more inclusive group of frogs (Hodl

1990), including bufonids (Miller 1909; Hodl 1990). Other factors, mainly the

absence of a vigorous leg ‘‘wiping/kicking’’ motion performed by most Leptodactylus

and leiuperid frogs (Heyer and Rand 1977; Hodl 1990) at the moment of egg release,may also preclude foam production in Pseudopaludicola species.

The typical small size of the Pseudopaludicola species may not be a problem for

foam generation because small Physalaemus, such as Physalaemus bokermanni

Cardoso and Haddad, 1985, can generate foam (Cardoso and Haddad 1985; A.A.G.

personal observation).

The foam nests of some leptodactylid and leiuperid frogs may have evolved in

response to aquatic predators (Downie 1988; Downie and Smith 2003; Menin and

Giaretta 2003) and appear to have gained excretory, respiratory and anti-desiccation

functions in some lineages, such as that of the Leptodactylus pentadactylus group

(Kokubum and Giaretta 2005). The foam nests of several species of leptodactylidsand leiuperids are infested by arthropods (Bokermann 1957; Villa 1980; Villa et al.

1982; Menin and Giaretta 2003; Giaretta and Menin 2004) or invaded by predatory

tadpoles (Silva et al. 2005). If, in fact, and against the present body of evidence,

Pseudopaludicola has lost the ability to build foam nests, this may have been driven

by predation pressure. At the sites where we studied Pseudopaludicola, the

concentration of a small number of eggs in a necessarily small foam nest could

result in complete offspring destruction by maggot flies (Menin and Giaretta 2003)

and predatory tadpoles (Giaretta and Facure 2006; present study); spreading eggsthrough the environment could minimize egg loss to these predators.

In conclusion, excessive weight has been given to the morphology of the oral

apparatus (which is quite variable) of tadpoles of leiuperid frogs relative to the

interpretation of their phylogenetic relationships. At present, no feature of the

tadpole external morphology, egg morphology or reproductive behaviour unequi-

vocally supports the paraphyletic nature of Physalaemus in relation to

Pseudopaludicola or the supposition that the foam nest was lost in the later lineage.

Acknowledgements

Financial support was supplied by FAPEMIG and CNPq; fellowships were provided by

CNPq (to A.A.G.) and CAPES (to K.G.F.). R.A. Ribeiro, A.P. Rodrigues, M.N. de C.

Kokubum, and M. Menin helped in the field and laboratory. The directors of the Clube Caca

e Pesca allowed us access to their reservation. R.G. Altig critically read the draft and the late

A.S. Rand made helpful suggestions on an early version of the manuscript. Jamil Tanus Neto

prepared the line drawings.

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