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Foam nests have evolved independently in several amphibian groups as an adaptive response to prevent predation and desiccation in dry environments. Nests are normally laid on ponds, or in underground galleries, humid forest leaf litter or terrestrial bromeliads. They are built when males or females beat a foam precursor associated with the egg masses extruded by the female. The spawning process requires the synchronic actions of the mating pair to obtain a hemispheric nest that protects the offspring. Herein, we describe the spawning behaviour of Engystomops pustulatus based on videos from 13 nesting couples from the lowlands of western Ecuador. Three variables were measured as indicators of male effort: duration of mixing events, duration of resting periods, and number of kicks per mixing event. We consider that not only male physical effort but also female behaviour influences nest structure. We suggest that nest building requires prolonged and intense physical activity by the male as well as th...

We describe the diet of adult and juvenile Engystomops pustulatus from three populations in the Ecuadorian Choco. Analysis of the items recovered from the gastrointestinal tracts of 95 individuals showed that E. pustulatus has a diverse diet. We identified 52 prey types among 1211 items. The numeric niche breadth, as measured by the Simpson's Index, was 5.37 while the volumetric niche breadth was 5.48. Among juveniles at Cerro Blanco we found a high proportion of small prey items, including termites and ants. Larger items, including snails, coleopterans, and isopods, were most frequent in adults at Patricia Pilar and La Mana. We hypothesize that dietary niche breadth is correlated with the presence of teeth in Engystomops. Engystomops pustulatus has teeth and has a more generalist diet than the termite and ant specialist species E. pustulosus, E. petersi, and E. freibergi, which lack teeth.

We present a phylogeny of the Neotropical genus Engystomops (= Physalaemus pustulosus species group) based on sequences of approximately 2.4 kb of mtDNA, (12S rRNA, valine-tRNA, and 16S rRNA) and propose a phylogenetic nomenclature. The phylogeny includes all described taxa and two unnamed species. All analyses indicate that Engystomops is monophyletic and contains two basal allopatric clades. Clade I (Edentulus) includes E. pustulosus and the Amazonian E. petersi + E. cf. freibergi. Clade II (Duovox) includes all species distributed in W Ecuador and NW Peru. Brevivox, a clade of small-sized species is strongly supported within Duovox. Populations of Engystomops pustulosus fall into two well-supported clades, each of which occupies two disjunct portions of the species range. Overall, our phylogeny is congruent with most previous hypotheses. This study is among the few published species-level phylogenies of Neotropical amphibians derived from molecular datasets. A review of the proportion of new species detected by similar studies suggests that the increasing use of molecular techniques will lead to the discovery of a vast number of species of Neotropical amphibians.

We describe Engystomops puyango sp. nov. from the lowlands of southwestern Ecuador. The new species is closely related to E. pustulatus from which it differs in skin texture, advertisement call, and karyotype features. The new species also differs from E. pustulatus at genes 12S and 16S of mitochondrial DNA (6.5%–6.8% of sequence divergence). A phylogeny based on mtDNA shows that E. sp. nov. is part of a clade of Engystomops distributed below 1300 m in western Ecuador and northwestern Peru. The new species occurs in Evergreen Lower Montane Forest and Foothill Semideciduous Costa Forest. The karyotype of the new species has 2n = 20 chromosomes which represents the first known reduction in chromosome number in Leiuperidae (2n = 22). Its advertisement calls as well as those of E. pustulatus have a facultative component that resembles the chuck in calls of E. pustulosus but that are less discrete and have lower acoustic complexity.