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The study of early development in Neotropical Leiuperinae frogs (Anura, Leptodactylidae) has been addressed by several works in recent times. However, a comparative developmental approach under a phylogenetic context was not available. Herein we analyzed the morphological and ontogenetic diversity of embryos belonging to 22 species of the three largest genera in Leiuperinae. We find that in most cases, variations fit with the phylogeny at the inter- and intrageneric levels. Embryo kyphosis and whitish color are synapomorphies for the clade grouping Physalaemus and Engystomops. The presence of a third lower tooth row on the oral disc is plesiomorphic for Leiuperinae, only changing in derived clades. The configurations and developmental trajectories of the lower lip are exceptionally diverse. The developmental sequences optimized on the phylogenetic tree recover an early differentiated first lower tooth row a synapomorphy of Pseudopaludicola and Physalaemus, and an early differentiated second row as synapomorphy of Pleurodema. On the other hand, few features are highly conserved in the subfamily, such as the adhesive glands universally present in a type-C configuration. Our results also suggest that the morphology and ontogeny of embryos is in some cases associated to the environment where they develop. A large body size, poorly developed transient respiratory structures, large yolk provision and delayed development of the digestive tract occur convergently in embryos inhabiting cold, oxygenated environments. Embryos that develop in warmer water bodies in xeric environments show more complex and persistent transient respiratory structures and an early onset of hind limbs development. Our survey highlights that morphology and early development of anurans can be a valuable source of information for phylogenetic studies, and provide fundamental bases to explore and discuss how evolutionary changes can be shaped by environmental conditions.

The genus Scinax currently includes more than 120 species, recovered in two major clades, the S. catharinae and the S. ruber clades. The latter comprises 75 species, most of which remain unassigned to any species groups, while 12 are included in the S. rostratus and S. uruguayus groups. In this paper we present a taxonomic review of the two species currently included in the S. uruguayus group, discussing some putative phenotypic synapomorphies of this group. Although S. pinima and S. uruguayus have been considered as distinct species, this has been based on scant evidence, and several authors doubted of their distinctiveness. Our study of available specimens of S. pinima and S. uruguayus corroborates that both are valid and diagnosable species based on phenotypic evidence. Furthermore, our results show that S. pinima previously known only from its type locality, has a much widespread distribution than previously thought (including the Brazilian states of Paraná, Santa Catarina, and Rio Grande do Sul), which, added to the biological information presented here allows to suggest the removal of this species from the \"Data Deficient\" IUCN Red List category to \"Least Concern\". Also, we describe a new species formerly reported as S. aff. pinima and S. uruguayus from NE Argentina and some localities from the Brazilian State of Rio Grande do Sul. All species are diagnosed and characterized using adult and larval morphology, osteology, vocalizations, cytogenetics, and natural history.

A new species of Leptodactylus frog (Anura: Leptodactylidae) from the South American Gran Chaco, morphologically similar and previously confused with the widespread Leptodactylus mystacinus, is described through the use of multiple sources of evidence (molecular, external morphology, coloration, osteology, bioacoustics, and behavior). The phylogenetic analysis with partial sequences of mitochondrial rDNA genes (12S and 16S) recovered the new species within the L. fuscus group, being highly divergent (>3% genetic distance in 16S). The new species was recovered as sister taxa of L. mystacinus, from which it is distinguished by tympanum coloration, cephalic index, dorsum and legs coloration, and some osteological differences in nasals and prevomers. This new frog is characterized by a moderate body size (SVL 46.80?66.21 mm), distinctive color pattern (reddish dorsal surfaces of body with noticeable black stripes in the dorsolateral folds), a circular and dark tympanum with dark tympanic annuli, and behavior of males that call on top of fallen logs and tree branches close to the ground.

[This corrects the article DOI: 10.1371/journal.pone.0222131.].

Observations on stereotyped defensive behaviours are presented for 7 frog species of the Neotropical genus Odontophrynus from Argentina and Uruguay. Seven stereotyped postures were observed, among which the most common observed were puffing up the body, contracting, and crouching down. Newly reported behaviours include tongue protrusion, eye protection, and some combinations of postures. We provide an account of defensive behaviours already described in Odontophrynus and discuss the correspondence between the terminology used by previous authors and recently proposed classifications. In addition, we highlight defensive mechanisms associated with the body raising posture in Neotropical anurans, which may include intimidating predators, body shape disruption, warning signaling, and exposure of skin macroglands.

The holotype of Odontophrynus americanus collected by Alcide d’Orbigny in northern Patagonia, Argentina differs morphologically from the tetraploid frogs repeatedly assigned to this species and that are distributed from central Argentina and Uruguay to the north to Brazil and Paraguay (probably also Bolivia). Surprisingly, the external characteristics of the holotype match with the morphology of the adult syntype and specimens currently referred to as Odontophrynus occidentalis distributed in central, western, and southern Argentina. On the basis of resemblance in position, number, size, and shape of the glandular warts, we propose that O. americanus should be considered a senior synonym of O. occidentalis. Consequently, we realize that the tetraploid frogs currently called O. americanus were all too often misidentified under this name. After reviewing all the available names applicable to this tetraploid species, we recognize Hyperoodon asper described by Rodolfo A. Philippi as valid, resurrecting this nominal species within the genus Odontophrynus, with the designation of a neotype from Montevideo, Uruguay. We also propose that Ceratophrys argentina Philippi is a nomen dubium. To update the taxonomy of the genus Odontophrynus, we provide partial chresonymies, morphologic diagnoses, cytogenetic and bioacoustic characters, and geographic distribution maps for both O. americanus and O. asper.

We review the taxonomy of two historically problematic taxa of Neotropical frogs belonging to the Physalaemus cuvieri group: P. albonotatus and P. cuqui. A thorough revision of morphological, bioacoustic, cytogenetic, and genetic characters throughout their ranges indicated that P. cuqui is a junior synonym of P. albonotatus. In addition, our analyses allowed the identification and description of a new taxon that was historically confused with the latter. The new species is externally indistinguishable from P. albonotatus, and both species are allopatric. Their distinction can be made only with their advertisement calls and on molecular grounds. Finally, to help stabilize the complex taxonomy of the P. cuvieri group, we provide a redescription of P. albonotatus with a neotype designation. This decision is based on the fact that we were unable to track extant type specimens in different herpetological collections that would be associated with the original description of this taxon, which is actually a composite of species. A comprehensive list of works dealing with both species is included, indicating whether they are referred to either P. albonotatus or the new species.

The holotype of Odontophrynus americanus collected by Alcide d´Orbigny in northern Patagonia, Argentina differs morphologically from the tetraploid frogs repeatedly assigned to this species and that are distributed from central Argentina and Uruguay to the north to Brazil and Paraguay (probably also Bolivia). Surprisingly, the external characteristics of the holotype match with the morphology of the adult syntype and specimens currently referred to as Odontophrynus occidentalis distributed in central, western, and southern Argentina. On the basis of resemblance in position, number, size, and shape of the glandular warts, we propose that O. americanus should be considered a senior synonym of O. occidentalis. Consequently, we realize that the tetraploid frogs currently called O. americanus were all too often misidentified under this name. After reviewing all the available names applicable to this tetraploid species, we recognize Hyperoodon asper described by Rodolfo A. Philippi as valid, resurrecting this nominal species within the genus Odontophrynus, with the designation of a neotype from Montevideo, Uruguay. We also propose that Ceratophrys argentina Philippi is a nomen dubium. To update the taxonomy of the genus Odontophrynus, we provide partial chresonymies, morphologic diagnoses, cytogenetic and bioacoustic characters, and geographic distribution maps for both O. americanus and O. asper.

In recent decades, a renewed interest in comparative studies of embryonic ontogeny in anurans is taking place. Toad embryos are often employed as model organisms, and scarce attention has been put on interspecific variations. In this work we analyze the development of transient embryonic and larval structures in 21 species in five genera of Bufonidae. These species vary in their ovipositional mode and the type of environments where the embryos and tadpoles develop, including ponds, streams, and axils of leaves of terrestrial or epiphytic plants. Comparative anatomical studies and sequence heterochrony analyses show that primary morphological variations occur in the morphology at the tail-bud stage, the arrangement and development of the external gills, adhesive gland type and division timing, growth of the dorsal hatching gland on the head, configuration of the oral disc, emergence and development of the hind limbs, and presence of the abdominal sucker. Some of these transformations are best explained by phylogeny (e.g., early divergent taxa of bufonids have embryos with kyphotic body curvature, Type C adhesive glands, and a very small third pair of gills). Other traits might be correlated with reproductive modes (e.g., phytotelmata embryos hatch comparatively late and show an accelerated development of hind limbs). Because these actual variations are not well studied (e.g., less than the 10% of the known diversity of bufonids has been studied from this perspective), comprehensive analyses are required to interpret character evolution and the relationship with reproductive modes within the family.

In this work, we studied chromosome morphology, Ag-NOR, and C-banding patterns in the Neotropical leiuperid frogs that compose the Physalaemus henselii species group: Physalaemus fernandezae, Physalaemus henselii, and Physalaemus riograndensis. The chromosome diploid complement in all species was 2n  =  22 and consisted of seven large to medium and four small chromosome pairs. Chromosome fundamental number (FN) varied, because pair 11 was metacentric in P. henselii and P. riograndensis (FN  =  44) but telocentric in P. fernandezae (FN  =  42). Each species presented a single pair of Ag-NORs, which are located in the secondary constriction of pair 11 in the case of P. fernandezae, in pair 8 in P. riograndensis (as in many other Physalaemus species), and in pair 5 in P. henselii, which is a unique character state among leiuperids. There were no substantial interspecific differences in C-banding pattern, and the heterochromatic bands were mainly located in the centromeric regions of all chromosomes. Noncentromeric C-bands adjacent to NORs were detected in P. riograndensis and P. fernandezae, as already reported for other species of this genus. The karyotype of P. fernandezae was quite similar to that of species in the P. signifer group and of the leiuperid Eupemphix nattereri. Neither karyotypic data nor adult and larval morphology support the P. henselii species group as currently defined.