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We describe a new species of the Scinax cruentomma species group, with a red streak in the iris and a weakly bilobate vocal sac. It is known from oligotrophic soils in the sedimentary basin of the Ucayali River near Jenaro Herrera (province of Requena, Peru) and Ro Blanco (buffer zone of the Matses Indigenous territory and reserve). The new species can be distinguished from the other species of the S. cruentomma group by its small snout-vent length, body and iris color patterns, weakly bilobate vocal sac, myological characters, and the number of notes and pulses of the advertisement call. It is morphologically most similar to S. strussmannae, from which the advertisement call, nostril, canthus rostralis, and loreal region can distinguish it.

The most ventral muscles of the head (the mm. submentalis, intermandibularis, and interhyoideus) provide support to the gular region and lift the buccal floor during ventilation and feeding. These muscles show limited variation in most gnathostomes, but in Anura they exhibit a surprising diversity. The few studies that have explored this character system highlighted its potential as a source of phylogenetic information. In this paper we explored the diversity of this character system studying specimens of 567 anuran species and reviewing published data to cover a total of 1321 species, belonging to 53 of the 54 currently recognized anuran families, as well as caudates and caecilians. We defined 27 discrete characters including the number of muscle bellies, supplementary layers, hypertrophy and diversity of elastic fibres, and pigmentation, among others, and optimized them on a comprehensive phylogenetic hypothesis. We recognized 223 unambiguously optimized synapomorphies for numerous clades on different scales, including three for Anura and many for suprafamiliar clades with poor phenotypic support. Finally, we discussed the evolution of this highly diverse character system, including homology, development, and its functional role in vocalization and feeding. Interestingly, the striking levels of variation in some structures contrast with the amount of phylogenetic inertia, allowing us to recognize several general patterns. Supplementary elements of the m. intermandibularis evolved first as broad layers occuring in more than half of extant anuran species and then concentrated forming discreet bellies in several clades. The anterior portion of the gular region is not sexually dimorphic, and is likely related to ventilation and tongue protraction. Conversely, the diversity of the m. interhyoideus is strongly linked to vocal sacs, which are present only in adult males, suggesting the presence of two independent modules., (© The Willi Hennig Society 2021.)

We describe a new species of the Scinax ruber clade from Northeastern Brazil that occurs in widely separated geographic areas in the Atlantic Forest of southern Bahia state and the Highland Humid Forest of Serra de Baturité, northeast Ceará state. Scinax tropicalia sp. nov. (holotype coordinates: -14.795694°, -39.172645°) is diagnosed from all 75 currently recognize species of the S. ruber clade by bioacoustical and morphological adult traits, such as duration (0.11-0.31 s) and dominant frequency (1.59-1.85 kHz) of the advertisement call, snout shape rounded, nearly rounded, or semi-circular in dorsal view and rounded to slightly protruding in profile, bilobate vocal sac, absence of pectoral glands and spicule-shaped papillary epidermal projections on nuptial pads, and color pattern on the dorsum of body and hidden surfaces of hindlimbs.

The Neotropical hylid genus Sphaenorhynchus includes 15 species of small, greenish treefrogs widespread in the Amazon and Orinoco basins, and in the Atlantic Forest of Brazil. Although some studies have addressed the phylogenetic relationships of the genus with other hylids using a few exemplar species, its internal relationships remain poorly understood. In order to test its monophyly and the relationships among its species, we performed a total evidence phylogenetic analysis of sequences of three mitochondrial and three nuclear genes, and 193 phenotypic characters from all species of Sphaenorhynchus. Our results support the monophyly of Sphaenorhynchus with molecular and phenotypic evidence, with S. pauloalvini as the earliest diverging taxon, followed by S. carneus, as the sister taxon of all remaining species of the genus. We recognize three species groups in Sphaenorhynchus (the S. lacteus, S. planicola and S. platycephalus groups), to facilitate its taxonomic study; only three species (S. carneus, S. pauloalvini and S. prasinus) remain unassigned to any group. Sequence data were not available for only two species (S. bromelicola and S. palustris) for which we scored phenotypic data; wildcard behaviour was detected only in S. bromelicola nested inside the S. platycephalus group. On the basis of the resulting phylogenetic hypothesis, we discuss the evolution of oviposition site and a number of phenotypic characters that could be associated with heterochronic events in the evolutionary history of this group., (© The Willi Hennig Society 2018.)

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., Competing Interests: The authors have declared that no competing interests exist.

The Dendropsophus decipiens clade comprises four species: D. berthalutzae, D. decipiens, D. haddadi, and D. oliveirai. Tadpoles of these species were described, but data on their internal morphology are lacking. We provide the first description of the buccopharyngeal anatomy, chondrocranial morphology, and cranial, hyoid and hyobranchial musculature of the tadpole of D. decipiens. Larvae of D. decipiens are characterized by the absence of lingual papillae, presence of fan-like papilla on the buccal floor, presence of a single-element suprarostral cartilage, presence of a small triangular process at the basis of the processus muscularis, m. levator mandibulae lateralis inserted on the nasal sac, and m. subarcualis rectus II-IV with a single, continuous slip. Tadpoles are likely macrophagous, although not as specialized as those of other species of the genus, suggesting some degree of diversification on the feeding habits within Dendropsophus., Competing Interests: The authors have declared that no competing interests exist.

In this article, we describe a new species of Scinax from the state of Paraná, southern Brazil, based on the external morphology of adults and their advertisement calls. The new species is diagnosed by the size of its males (SVL 27.8-31.6 mm); the snout subovoid in the dorsal view and slightly acuminate in profile; the vocal sac subgular and ventrally not reaching the pectoral region; and the advertisement call composed of a single pulsed note with 7-13 pulses, and a duration of 0.16-0.25s. This new species occurs in natural highland grassland formations, in the threatened ecosystem of the Atlantic Forest in the state of Paraná, southern Brazil.

A new species of the Scinax ruber Clade is described from Municipality of Barra do Garças, State of Mato Grosso, Brazil. It is diagnosed by its size (SVL 29.4-35.4 mm in males); dorsum with a background that varies from light and dark gray to dark brown, with round and irregular dark blotches; hidden surfaces of thigh and shank light or dark brown, with lighter, large and irregular blotches (yellow in life); and nuptial pad that covers the medial margin of Metacarpal I, and obscures the posterior portion and the outer margin of the inner metacarpal tubercle. It is most similar with Scinax rupestris, from which it differs by having larger adult males; less developed nuptial pad; and hidden surfaces of thigh and light or dark brown, with lighter, large and irregular blotches (yellow in life). The new species occurs near the headwaters of permanent or temporary streams, where males call from vegetation or rocks at the margins of small streams.

A new species of Sphaenorhynchus is described from the Municipality of Mariana, State of Minas Gerais, Brazil. It is characterized by the vocal sac moderately developed, single, subgular, with longitudinal folds; white canthal and dorsolateral lines delimited below by a dorsolateral black line from the tip of snout extending beyond the eye to gradually disappearing up to the flanks; and premaxilla and maxilla almost completely edentulous, each bearing 1-5 extremely small teeth. It is most similar with Sphaenorhynchus orophilus, from which it can be distinguished by having a less robust forearm in males; glandular subcloacal dermal fold; premaxilla and maxilla almost completely edentulous; and larvae with large marginal papillae in the oral disc. The new species occurs in natural ponds over ironstone outcrops (known as canga) on flat terrain, where males call from the floating vegetation.

A new species of the Scinax ruber clade is described from Chapada dos Veadeiros region, Central Brazil. The new species is diagnosed by having SVL 21.9-27.7 mm in males and 26.7-31.7 mm in females; snout acuminate in dorsal view and rounded in profile; medium-sized tympanum; vocal sac single, median, subgular, that does not reach the pectoral region; iris iridescent yellow, with some thin, darker reticulations; tadpoles with ventral oral disc; P-3 regular and unmodified as a labial arm; absence of keratinized and colored plates on the sides of the lower jaw-sheath; presence of a keratinized and colored spur on each side behind the lower jaw-sheath; dorsolateral eyes, ventrally invisible; and advertisement call composed of 8-14 notes each with 4-18 pulses, and duration of 290-420 ms. The new species uses temporary creeks in rock meadows above 1.000 m a.s.l. and males calls from rock outcrops. The dorsal color pattern enables this species to camouflage in this kind of surfaces.

We describe the tadpole of Sphaenorhynchus caramaschii. It differs from tadpoles of other species of Sphaenorhynchus in having a short spiracle, submarginal papillae, and alternating short and large marginal papillae in the oral disc. Some larval characteristics, like morphology and position of the nostrils, length of the spiracle, and size of the marginal papillae on the oral disc are discussed for tadpoles of other species of Sphaenorhynchus.