Further notes on the natural history of the South American pepper frog, Leptodactylus labyrinthicus (Spix, 1824) (Anura, Leptodactylidae)

Abstract

Leptodactylus labyrinthicus tadpoles reach a large size in the nest through consumption of trophic eggs. We previously suggested that the trophic eggs are laid just after amplexus has finished, but our new data do not support this hypothesis. We also present further details on the natural history of the species with regard to breeding activity, spawning site, retreats and the ability of tadpoles in preying upon fully-growth heterospecific tadpoles. We also show that the tadpoles are mainly nocturnal and take diurnal refuges. We collected the data in Brazil in three localities within the Cerrado Biome. We examined burrows used by L. labyrinthicus males, verified if females still contained mature eggs just after released from amplexus, and tested the ability of tadpoles in preying fully-growth heterospecific tadpoles. Field observations and experiments were conducted on tadpole activity time, hiding behaviour and level of susceptibility to predation by the bird leaf-scrapers in four sheltering situations. Reproduction could start before the first rains; this may be advantageous by allowing the tadpoles to exploit eggs of other frogs. We found one floating nest built in a temporary pool. The nest of the species is normally circumscribed in an excavated basin beside the water body. Adult males were found during the day with their head-out of the entrance of underwater burrows, which were perforations through dense root mats beside calling/spawning sites. Probably, these burrows in permanently water-filled soil are actively excavated by males. Females released all their eggs during the amplexus, so trophic eggs are not produced by the currently-accepted mechanism. Fully-grown heterospecific tadpoles were not preyed upon by L. labyrinthicus tadpoles, which can prey only slow-moving newly hatched ones. Field tadpoles took shelter under mud/dead leaves during daylight and became exposed on the bottom at night. Free-ranging leaf-scrapers removed dead leaves from a pool with their beaks and preyed upon tadpoles. In the experiments, the tadpoles sheltered under gravel/leaves during daylight, but they were exposed at night. Leaf-scrapers ate all exposed tadpoles, but no tadpole of the gravel/leaves trays was consumed. Hence the nocturnal habits and use of diurnal refuges may protect the tadpoles from visual predators, such as the leaf-scrapers.Keywords: Leptodactylus pentadactylus group, reproduction, retreats, trophic eggs, tadpoles. Notas complementares sobre a história natural da rã-pimenta sul-americana,Leptodactylus labyrinthicus (Anura, Leptodactylidae) ResumoGirinos de L. labyrinthicus crescem parcialmente no ninho consumindo ovos tróficos. Sugerimos anteriormente que os ovos tróficos seriam postos logo após o amplexo, porém nossos novos dados não corroboram esta hipótese. Apresentamos também mais detalhes da história natural da espécie relacionados à estação reprodutiva, local de desova, abrigos e capacidade dos girinos em predar girinos heteroespecíficos plenamente desenvolvidos. Demonstramos ainda que os g...

Species composition and reproductive modes of anurans from a transitional Amazonian forest, Brazil

“…Furthermore, species in the Leptodactylus pentadactylus group, such as L. labyrinthicus, exhibit extra strategies that guarantee larval survival in unpredictable habitats, such as trophic eggs to feed the larvae (e.g. PRADO et al 2005a, SILVA & GIARETTA 2008.…”

“…Additional information on the reproductive modes of the species was obtained from HEYER (1969HEYER ( , 1974, DUELLMAN (1985), HÖDL (1990), HERO (1990), ZIMMERMAN & SIMBERLOFF (1996), ETEROVICK & SAZIMA (2000), PRADO et al (2002PRADO et al ( , 2005a, KOKUBUM & GIARETTA (2005), POMBAL & HADDAD (2005, 2007, and SILVA & GIARETTA (2008, 2009). Some of the species identified in this study, in particular those with an ample geographic distribution -e.g.…”

Effect of hydric stress on locomotion and morphology of tadpoles from temporary ponds

“…Desiccation resistance was evidenced in descriptive notes (Black, ; Candelas, Ortiz, Vasquez, & Fellix, ; Downie, ; Jones, ; Valerio, ) where some species of aquatic tadpoles have been shown to survive for up to 5 days out of water, congregated on damp mud under rocks or dead leaves. Such a resistance capacity might represent an advantage because it could be sufficient for the ponds to be restored by new rainfall (Black, ; Candelas et al, ; Downie, ; Jones, ; Silva & Giaretta, ; Valerio, ). In Leptodactylidae species lay their eggs in foam nests build by adults during oviposition.…”

“…These foam nests can be made on the water (aquatic nest), in basins (on the edge of ponds) or in underground chambers excavated by adults (terrestrial nest) (reproductive modes 11, 13, 30, respectively, according to Haddad & Prado, . The capacity of leptodactylid tadpoles to resist desiccation has been evidenced exclusively in species with terrestrial nests (e.g., Leptodactylus fuscus , Leptodactylus poecilochilus, Leptodactylus riveroi, Leptodactylus knudseni, Leptodactylus pentadactylus, and Leptodactylus labyrinthicus ; Candelas et al, ; Downie, ; Rocha, Passos, & Magnusson, ; Silva & Giaretta, ; Valerio, ).…”

“…A consequence of dehydration for adult anurans is a significant loss of water from the nervous system (Churchill & Storey, ), thereby indirectly affecting an animal's locomotor performance through a reduced central control of locomotion (Preest & Pough, ). Locomotion is important not only to forage or to escape predators (Laurila & Kujasalo, ; McCollum & Leimberger, ; Watkins, ), but also appears to be important for the survival of tadpoles in drying ponds by enabling the tadpoles to move to humid refuges (Black, ; Candelas et al, ; Downie, ; Jones, ; Silva & Giaretta, ; Valerio, ). Locomotion analysis by video tracking has been used for comprehending how some factors can affect the integrity of organisms (Delcourt, Denoël, Ylieff, & Poncin, ; Denoël et al, ), hence, using this tool allows us to understand to which degree hydric stress influences a tadpole's locomotor performance.…”