Reproductive ecology and behaviour of a species of Adenomera (Anura, Leptodactylinae) with endotrophic tadpoles: Systematic implications

Abstract

The species of the Leptodactylus fuscus group and those of the genus Adenomera lay their eggs in underground chambers. According to current systematic arrangement of these genera, this behaviour is convergent. Here we describe reproduction, courtship, tadpole morphology, calls, chamber structure, and populational phenology of an Adenomera species, and compare some of these features with those of other species of the genus and with species of Leptodactylus of the fuscus and pentadactylus groups. We tested the tadpoles of the Adenomera sp. and those of Leptodactylus labyrinthicus (pentadactylus group) for their foam‐making abilities. There was sexual dimorphism in size; males averaged 22.0 mm and females 24.3 mm in snout–vent length. Males called from late September to late February; calling often began about 2–3 h before sunset. Males called exclusively in open (non‐forest) areas. Egg clutches were found around male calling sites. Males excavated spherical chambers which had a direct entrance. During mating, the male led the female towards a previously excavated chamber. Territorial interactions (aggressive calls and fights) occurred when an intruder male approached a calling male. Late‐stage tadpoles and newly metamorphosed juveniles were found within underground chambers. Clutch size averaged 10.6; eggs averaged 3.7 mm in diameter and were cream coloured. Tadpoles had horny beaks, but no labial tooth; spiracle was present. All tested groups of tadpoles generated foam within 10 h. As we report for Adenomera sp., the males of Leptodactylus species of the fuscus group lead the female to a previously excavated chamber. Tadpole foam‐making behaviour was reported in Leptodactylus of the fuscus group and was previously unknown for any species of Adenomera or for Leptodactylus of the pentadactylus group. The way in which the tadpoles of Adenomera sp., Leptodactylus spp. (of the fuscus group) and L. labyrinthicus made foam was quite similar. The foam‐making behaviour of the studied tadpoles may act to avoid compaction of the tadpoles at the bottom of the basin or underground chamber, avoiding overcrowding and increasing respiratory and excretory efficiency. As presently recognized, the phylogenetic position of Adenomera suggests that reproductive major behavioural features are convergent with some Leptodactylus species. Alternatively, our data point to close phylogenetic relationships between Adenomera and Leptodactylus of the fuscus and pentadactylus groups, reinforcing the paraphyletic nature of the genus Leptodactylus.

Keywords:

• Adenomera
• Anura
• Leptodactylidae
• Leptodactylus
• phenology
• reproduction
• systematics

Acknowledgements

We thank colleagues of the Laboratório de Ecologia e Sistemática de Anuros Neotropicais for assistance in the field. J. M. Vielliard loaned us the Nagra tape recorder. The Companhia Energética do Estado de Minas Gerais (CEMIG) financially supported field works at Perdizes. Marcelo Menin, W. Rodrigues Silva, Kátia G. Facure, and Ariadne Angulo critically read early versions of the manuscript. Grants by CNPq (132465/2000‐0) and FAPEMIG (DC/SOT 2185/2002) to M.N.C.K.

Notes

Habitats: F, forest; F/O, forest and open areas; O, just open areas; NR, not reported.

^aImmature ovarian eggs?