Aspectos da biologia reprodutiva e descriÁ„o do girino de Adenomera aff. simonstuarti (Anura: Leptodactylidae) de florestas de areia branca na AmazÙnia Central, Brasil

Abstract

Knowledge on anuran breeding biology may support the comprehension of ecological and evolutionary patterns, as well as new species descriptions. Moreover, it may be fundamental to support conservation actions, since anurans are the most globally threatened vertebrates. Leptodactylidae is one of the Neotropical anuran families with the most diverse and well-documented breeding biology. Among its members, Adenomera is the only genus with species presenting endotrophic tadpoles, which makes it an interesting study system in the field of breeding biology. In the present study, we describe aspects of the breeding biology and the external morphology of tadpoles of Adenomera aff. simonstuartia species being formally described from white-sand riparian forests in central Amazonia. An 800 m2 grid of transects was implanted in the Rio Negro Sustainable Development Reserve (Iranduba, Amazonas, Brazil) for data acquisition regarding breeding aspects of the target species. The peak of breeding activity of Adenomera aff. simonstuarti occurs in the rainy season, but reproductive events also occur at a lower intensity in the dry season. Males are vocally active mostly at dusk and dawn but also vocalize sporadically throughout the day. Males are also territorials and responsible for building the underground chambers used for oviposition. Females are guided into the chambers by males, while males emit courtship calls along the course. The courtship call is similar in structure to the advertisement call, while the territorial call presents greater structural complexity. The amplexus occurs within the previously-excavated chamber, which is round or elliptical and has 25–32 mm diameter by 18–22 mm depth. The nest comprises a viscous and dense foam, where 5–7 yellowish-cream eggs are laid. Evidences suggests that the foam where eggs are laid is produced jointly by the couple. Tadpoles have a dark dorsum and have a large amount of yolk in the belly. The tadpole morphology is similar to that of other species of Adenomera, except for the presence of a spiracle, which is unusual in endotrophic tadpoles of this genus. Larval development is completed 16 days after oviposition. The average body length of metamorphs just after leaving the nest is approximately 6.12 mm and their weight 0.0285 ± g. The breeding biology of Adenomera aff. simonstuarti described here resembles that of other congeners. However, the presence of a spiracle in their endotrophic tadpoles may represent an evolutionary adaptation to the habitat occupied by the species, which undergoes frequent flooding during the rainy season. This morphological structure is commonly present in exotrophic tadpoles that complete their development freely in water, but not in endotrophic tadpoles.