Genus Scinax Research Articles

A new snouted treefrog (Anura, Hylidae, Scinax) from fluvial islands of the Juruena River, southern Brazilian Amazonia.

Southern Amazonia is one of the less-explored regions by anuran taxonomists. We describe a small new species of snouted treefrog, genus Scinax, from this region, from a fluvial archipelago in the Juruena River, state of Mato Grosso, Brazil. The description is based on external morphology of adults and tadpoles, advertisement call and molecular data. The species is phylogenetically related to other snouted treefrogs of the Scinax cruentomma species group and shows the most southeastern distribution in Amazonia among its close relatives. It is distinguished from congeners mainly by its larger adult body size and bilobate vocal sac that reaches the level of the pectoral fold, a reddish-brown horizontal stripe on the iris, dark melanophores or blotches on the vocal sac and the throat of females, and the uniformly brown posterior portion of the thigh. The advertisement call comprises one pulsed note emitted at regular intervals, with a duration of 189-227 ms, 30-35 pulses/note and a dominant frequency of 2,250-2,344 Hz. The type locality is suffering several environmental impacts, including illegal mining, overfishing, unsustainable agriculture, uncontrolled logging and degradation associated with the construction of new hydroelectric dams. Further study of the biology and regional distribution of the new species is required to propose mitigation measures needed for its conservation.

New insights into a poorly known parasite, Dero lutzi (Oligochaeta: Naididae), associated with tree frogs of the genus Scinax: morphological evaluation and genotypic data.

The oligochaete Dero lutzi follows a life strategy that alternates between free-living periods in aquatic environments and endoparasitic phases. Most occurrences of D. lutzi in anurans are reported in species with arboreal habits, with studies limited to the recording of the oligochaete's presence in the host. Our study recovered specimens of D. lutzi from the tree frogs Scinax fuscovarius and Scinax. nasicus. We performed a morphological assessment of the parasite using light microscopy, for the first time, scanning electron microscopy. Molecular characterization of D. lutzi was carried out using the mitochondrial gene 16S rRNA and the nuclear gene 28S rRNA. Additionally, a phylogenetic tree was constructed to assess the species´position in relation to other group members. In our results, we confirmed the phenotypic morphological characteristics of the endoparasitic phase of D. lutzi. We also presented its phylogenetic position with other oligochaetes in the group, demonstrating the proximity between the endoparasite D. lutzi and the free-living oligochaete D. superterrenus.

A NEW SNOUTED TREEFROG OF THE GENUS SCINAX (ANURA, HYLIDAE) FROM THE WHITE-SAND FORESTS OF CENTRAL AMAZONIA

We describe through integrative taxonomy a new species of snouted treefrog of the genus Scinax from white-sand forests of the Rio Negro Sustainable Development Reserve in Central Amazonia, Brazil. The new species is phylogenetically related to other Scinax with striped eyes and pulsed advertisement calls. It differs from other Amazonian species mainly by having snout–vent length 21.6–25.4 mm (n= 11) in adult males and 24.8–27.0 mm (n= 9) in females, snout subacuminate in dorsal view, a dark brown lateral stripe on each flank (fading posteriorly), brown tadpoles with labial keratodont row formula 2(2)/3 and keratodont row P-2 longer than P-1 and P-3, and an advertisement call consisting of a single pulsed note with a call duration of 502–652 ms, 79–105 pulses/note and a dominant frequency of 3,811–4,543 Hz. The new species clusters within a major, well-supported phylogenetic clade grouping several candidate and recently described species as well as species previously included in the former Scinax staufferi species group (viz., S. cruentomma, S. fuscomarginatus, S. staufferi, and S. wandae). The phylogenetic relationships and structural pattern in the advertisement calls of these species highlight the need for a redefinition and reevaluation of the monophyly of the S. staufferi species group.

DNA barcode reveals candidate species of Scinax and Ololygon (Anura: Hylidae) in Atlantic Forest.

Molecular species delimitation methods are efficient tools to identify species, including the discovery of new taxa and cryptic organisms, thus being useful to biodiversity studies. In the present work, 16S mitochondrial sequences and cytochrome oxidase I (COI) were used to evaluate the richness of species in the genus Scinax and Ololygon from a biodiversity hotspot in Atlantic Forest. A total of 109 specimens formally belonging to eight species of Scinax and three species of Ololygon were collected in 13 localities along the state of Bahia (northeastern Brazil) and one site in Espírito Santo (southeastern Brazil). Of the Scinax species collected in this study, three were morphologically differentiated from other described species and identified as putative new species (Scinax sp.1, Scinax sp.2 and Scinax sp.3). The species delimitations were inferred using three different methods: ABGD, PTP and mPTP which allowed recognizing 11 Scinax species and five Ololygon species. Scinax sp. 1, Scinax sp. 2 and Scinax sp. 3, have been confirmed as new putative species and Ololygon argyreornata possibly contains cryptic species. We suggest additional studies, including morphological and bioacoustic data to validate these new putative species.

Buccopharyngeal morphology of the tadpoles of Scinax v-signatus/, with comments on larval characters of the S. perpusillus/ species group(Amphibia: Anura: Hylidae).

The Neotropical genus Scinax Wagler currently comprises 127 species of small treefrogs distributed from southern Mexico to Argentina and Uruguay, including some islands such as Trinidad and Tobago, and St. Lucia (Frost 2020). Two major clades are recognized within Scinax, the S. catharinae and the S. ruber clades. The former is composed of two species groups, the S. catharinae and the S. perpusillus groups (Faivovich 2002; Faivovich et al. 2005). The S. perpusillus species group currently comprises 13 species: S. alcatraz (Lutz); S. arduous Peixoto; S. atratus (Peixoto); S. belloni Faivovich, Gasparini Haddad; S. cosenzai Lacerda, Peixoto Feio; S. faivovichi Brasileiro, Oyamaguchi Haddad; S. insperatus Silva Alves-Silva; S. littoreus (Peixoto); S. melloi (Peixoto), S. peixotoi Brasileiro, Haddad, Sawaya Martins; S. perpusillus (Lutz Lutz); S. tupinamba Silva Alves-Silva; and S. v-signatus (Lutz). These species are endemic of the Brazilian Atlantic Forest and are recognized by their intimate association with bromeliads (Fig. 1), in which adults breed and lay their eggs, and tadpoles develop (Peixoto 1987, 1995; Alves-Silva Silva 2009).

A neotype for Hyla x-signata Spix, 1824 (Amphibia, Anura, Hylidae)

The uncertain identity of Hyla x-signata Spix, 1824 has been a pervasive problem in the taxonomy of the genus Scinax. A species supposedly distributed from northeastern Brazil northwards to Colombia and Venezuela, described in a few lines without much information and with an accompanying figure, and its type specimen lost during World War II, combined to produce a curious situation. Twenty-one of the 39 species of the S. ruber Clade described in the last 50 years were considered to require a diagnosis from S. x-signatus by their authors. In most cases these had no other alternative than to gather information about this species from indirect sources, frequently pointing out the problems associated with its uncertain identity. In this paper, we review the taxonomic history of Hyla x-signata, designate a neotype, provide a redescription including advertisement call and sequence data, and diagnose it from all other species of the S. ruber Clade.

Treefrogs with distinct advertisement calls produce similar territorial signals

ABSTRACT The advertisement call contains important spectral and temporal information for species-specific recognition and is generally related to sexual attraction. On the other hand, the territorial call is emitted to defend a specific territory from conspecifics or heterospecifics. Therefore, we hypothesised that the territorial call of sympatric and close related species is more similar to each other (as a result of convergence or lack of divergence) than their advertisement calls. In order to test this hypothesis, we examined the territorial and advertisement calls of five anuran species of the genus Scinax. These species are sympatric and two of them were previously observed displaying heterospecific territorial communication. We redescribed the advertisement and territorial calls of these five species, compared them with cluster analyses and found that acoustic characteristics of the territorial calls were more similar to each other than that of their advertisement calls. These results could be indicative of a convergent selective pressure for the territorial call in opposite to a divergent selective pressure for the advertisement call. This pattern may be more widespread than reported and future directions are proposed.

The tadpole of Scinax camposseabrai (Bokermann) (Amphibia, Anura, Hylidae).

The treefrog Scinax camposseabrai (Bokermann) is endemic to the Brazilian semiarid region and known from the municipalities of Maracás, Igaporã and Curaçá, in the state of Bahia, and from the municipality of Matias Cardoso, northern Minas Gerais state, Brazil (Frost 2019). It was removed from the synonymy of Scinax x-signatus (Spix), recognized as a valid species, and placed in the S. ruber clade (sensu Faivovich et al. 2005) by Caramaschi Cardoso (2006). Taxonomic changes proposed by Duellman et al. (2016) for the genus Scinax were discussed by Lourenço et al. (2016) and Faivovich et al. (2018), and we follow here their suggestion to consider Ololygon and Julianus (erected for the S. uruguayus group) as synonyms of Scinax. This large genus Scinax currently would include 123 species (Frost 2019), many of which have had their larval morphology formerly described. Here, we describe the external morphology of the previously unknown tadpoles of S. camposseabrai.

A review of the elusive bicolored iris Snouted Treefrogs (Anura: Hylidae:Scinaxuruguayus group).

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.

Una nueva rana de huesos verdes del género Scinax (Anura: Hylidae) asociada a los bosques subandinos de la cuenca del río Magdalena, Colombia

Biota colombiana es una revista científica, que publica artículos originales y ensayos sobre la biodiversidad de la región neotropical, con énfasis en Colombia y países vecinos, arbitrados mínimo por dos evaluadores externos. Incluye temas relativos a botánica, zoología, ecología, biología, limnología, conservación, manejo de recursos y uso de la biodiversidad. El envío de un manuscrito implica la declaración explícita por parte del (los) autor (es) de que este no ha sido previamente publicado, ni aceptado para su publicación en otra revista u otro órgano de difusión científica. El proceso de arbitraje tiene una duración mínima de tres a cuatro meses a partir de la recepción del artículo por parte de Biota Colombiana. Todas las contribuciones son de la entera responsabilidad de sus autores y no del Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, ni de la revista o sus editores.

A new species of Amazonian snouted treefrog (Hylidae: Scinax) with description of a novel species-habitat association for an aquatic breeding frog.

The genus Scinax is one of the most specious genera of treefrogs of the family Hylidae. Despite the high number of potential new species of Scinax revealed in recent studies, the rate of species descriptions for Amazonia has been low in the last decade. A potential cause of this low rate may be the existence of morphologically cryptic species. Describing new species may not only impact the taxonomy and systematics of a group of organisms but also benefit other fields of biology. Ecological studies conducted in megadiverse regions, such as Amazonia, often meet challenging questions concerning insufficient knowledge of organismal alpha taxonomy. Due to that, detecting species-habitat associations is dependent on our ability to properly identify species. In this study, we first provide a description of a new species (including its tadpoles) of the genus Scinax distributed along heterogeneous landscapes in southern Amazonia; and secondly assess the influence of environmental heterogeneity on the new species’ abundance and distribution. Scinax ruberoculatus sp. nov. differs from all nominal congeners by its small size (SVL 22.6–25.9 mm in males and 25.4–27.5 mm in females), by having a dark brown spot on the head and scapular region shaped mainly like the moth Copiopteryx semiramis (or a human molar in lateral view, or a triangle), bicolored reddish and grey iris, snout truncate in dorsal view, bilobate vocal sac in males, by its advertisement call consisting of a single pulsed note with duration of 0.134–0.331 s, 10–23 pulses per note, and dominant frequency 1,809–1,895 Hz. Both occurrence and abundance of the new species are significantly influenced by silt content in the soil. This finding brings the first evidence that edaphic factors influence species-habitat association in Amazonian aquatic breeding frogs.

A new species of Scinax from the Purus-Madeira interfluve, Brazilian Amazonia (Anura, Hylidae).

A new tree frog species of the genus Scinax from the interfluve between the Purus and Madeira rivers, Brazilian Amazonia, is described and illustrated. The new species is diagnosed by medium body size, snout truncate in dorsal view, ulnar and tarsal tubercles absent, nuptial pads poorly developed, skin on dorsum shagreen, dorsum light brown with dark brown spots and markings, white groin with black spots, anterior and posterior surfaces of thighs black, and iris bright orange. The advertisement call consists of a single short note, with 16−18 pulses and dominant frequency at 1572−1594 Hz. Tadpoles are characterized by body ovoid in dorsal view and triangular in lateral view, tail higher than body, oral disc located anteroventrally and laterally emarginated, dorsum of body uniformly grey-brown with dark brown eye-snout stripe in preservative, fins translucent with small to large irregular diffuse dark brown spots.

Comparative analysis based on replication banding reveals the mechanism responsible for the difference in the karyotype constitution of treefrogs Ololygon and Scinax (Arboranae, Hylidae, Scinaxinae).

According to the recent taxonomic and phylogenetic revision of the family Hylidae, species of the former Scinax catharinae (Boulenger, 1888) clade were included in the resurrected genus Ololygon Fitzinger, 1843, while species of the Scinax ruber (Laurenti, 1768) clade were mostly included in the genus Scinax Wagler, 1830, and two were allocated to the newly created genus Julianus Duellman et al., 2016. Although all the species of the former Scinax genus shared a diploid number of 2n = 24 and the same fundamental number of chromosome arms of FN = 48, two karyotypic constitutions were unequivocally recognized, related mainly to the distinct size and morphology of the first two chromosome pairs. Some possible mechanisms for these differences had been suggested, but without any experimental evidence. In this paper, a comparison was carried out based on replication chromosome banding, obtained after DNA incorporation of 5-bromodeoxiuridine in chromosomes of Ololygon and Scinax. The obtained results revealed that the loss of repetitive segments in chromosome pairs 1 and 2 was the mechanism responsible for karyotype difference. The distinct localization of the nucleolus organizer regions in the species of both genera also differentiates the two karyotypic constitutions.

Comparative analysis based on replication banding reveals the mechanism responsible for the difference in the karyotype constitution of treefrogs Ololygon and Scinax (Arboranae, Hylidae, Scinaxinae)

According to the recent taxonomic and phylogenetic revision of the family Hylidae, species of the former Scinaxcatharinae (Boulenger, 1888) clade were included in the resurrected genus Ololygon Fitzinger, 1843, while species of the Scinaxruber (Laurenti, 1768) clade were mostly included in the genus Scinax Wagler, 1830, and two were allocated to the newly created genus JulianusDuellman et al., 2016. Although all the species of the former Scinax genus shared a diploid number of 2n = 24 and the same fundamental number of chromosome arms of FN = 48, two karyotypic constitutions were unequivocally recognized, related mainly to the distinct size and morphology of the first two chromosome pairs. Some possible mechanisms for these differences had been suggested, but without any experimental evidence. In this paper, a comparison was carried out based on replication chromosome banding, obtained after DNA incorporation of 5-bromodeoxiuridine in chromosomes of Ololygon and Scinax. The obtained results revealed that the loss of repetitive segments in chromosome pairs 1 and 2 was the mechanism responsible for karyotype difference. The distinct localization of the nucleolus organizer regions in the species of both genera also differentiates the two karyotypic constitutions.

High Species Richness of Scinax Treefrogs (Hylidae) in a Threatened Amazonian Landscape Revealed by an Integrative Approach.

Rising habitat loss is one of the main drivers of the global amphibian decline. Nevertheless, knowledge of amphibian diversity needed for effective habitat protection is still highly inadequate in remote tropical regions, the greater part of the Amazonia. In this study we integrated molecular, morphological and bioacoustic evidence to evaluate the species richness of the treefrogs genus Scinax over a 1000 km transect across rainforest of the Purus-Madeira interfluve, and along the east bank of the upper Madeira river, Brazilian Amazonia. Analysis revealed that 82% of the regional species richness of Scinax is still undescribed; two nominal species, seven confirmed candidate species, two unconfirmed candidate species, and one deep conspecific lineage were detected in the study area. DNA barcoding based analysis of the 16s rRNA gene indicates possible existence of three discrete species groups within the genus Scinax, in addition to the already-known S. rostratus species Group. Quantifying and characterizing the number of undescribed Scinax taxa on a regional scale, we provide a framework for future taxonomic study in Amazonia. These findings indicate that the level to which Amazonian anura species richness has been underestimated is far greater than expected. Consequently, special attention should be paid both to taxonomic studies and protection of the still-neglected Amazonian Scinax treefrogs.

A new species of the Scinax catharinae group (Anura: Hylidae) from southeastern Brazil.

We describe a new species of the Scinax catharinae group from coastal forest in the State of São Paulo, Brazil. We also describe the karyotype and the advertisement call of the new species, which is composed by a multipulsed note. The chromosome morphology of the new species shows the nucleolar organizer region (NOR) on Pair 6, a putative synapomorphy previously inferred for the S. catharinae clade. We report, for the first time, the presence of mental glands in a species of the genus Scinax. Additionally, we provide a brief discussion about the occurrence of glandular tissue on the mental and inguinal regions of the species of the S. catharinae clade.

The karyotypes of five species of the Scinax perpusillus group (Amphibia, Anura, Hylidae) of southeastern Brazil show high levels of chromosomal stabilization in this taxon.

Based on morphological, bioacoustics, and morphological traits, the genus Scinax has been subdivided into two major clades: S. catharinae and S. ruber. The first clade includes S. catharinae and S. perpusillus groups, whereas the second clade includes S. rostratus and S. uruguayus groups. Chromosome morphology, NOR and C-banding patterns of variation support these clades. This study aims the cytogenetic characterization of five species currently included in the S. perpusillus group: Scinax sp. (gr. perpusillus), S. arduous, S. belloni, S. cosenzai, and S. v-signatus, including standard cytogenetic techniques and repetitive DNA FISH probes. All species had 2n=24 chromosomes. Nucleolar organizing regions occurred in chromosome pair 6 in all species, but differed in their locations among some species, suggesting a putative synaponomastic character for the clade. In S. belloni, the first chromosome pair was a metacentric, contrasting with the submetacentric first pair reported in all other species of the genus. Scinax sp. (gr. perpusillus) and S. v-signatus had similar karyotypic formulae, suggesting they are related species. Scinax cosenzai had a divergent C-banding pattern. Repetitive DNA probes hybridized more frequently in chromosomal subtelomeric regions in all species indicating recent cladogenesis in these species. Karyotypic evidence indicates unreported high levels of stabilization within S. perpusillus and in S. catharinae clade, resulting in a wealth of characters potentially informative for higher phylogenetic analyses.

A new species of Scinax Wagler, 1830 (Anura: Hylidae) from the middle Amazon river basin, Brazil

A new species of the hylid genus Scinax is described and illustrated. The new taxon was found in the Amazonian rainforest of northern Brazil, municipalities of Maués and Careiro da Várzea, state of Amazonas. The new species is characterized by its moderate size (male mean snout-vent length 36.3mm); body robust; large, orange, black-bordered axillary and inguinal spots; and bilobate vocal sac. This new species was found in primary and secondary forest on branches of shrubs or trees in, or next to, permanent ponds and flooded areas.

Larval Diet in Bromeliad Pools: A Case Study of Tadpoles of Two Species in the Genus Scinax (Hylidae)

Many species of frogs that breed in bromeliads exhibit parental care as females deposit unfertilized eggs to feed the tadpoles. Treefrogs of the genus Scinax are not known to exhibit this behavior, even though they have exotrophic tadpoles. The purpose of this study was to describe qualitatively and quantitatively the diets of tadpoles of hylids S. littoreus and S. perpusillus developing in the phytothelm of Alcantarea glaziouana (Bromeliaceae). We evaluate if there are seasonal and spatial differences (between tadpoles living in the central tank and the lateral tanks) in the diet, and to test for food selectivity of the species. The most abundant items in the diet of tadpoles of both species were, respectively, algae, fungi, and protozoa. Detritus and plant debris were present in the diet of more than 90% of the tadpoles of the two species. The trophic niche breadth for S. littoreus was 1.26, whereas that for S. perpusillus was 1.54. The tadpole diets were seasonally conservative for both tadpole species and spatially similar only for S. perpusillus. Tadpoles of Scinax littoreus showed differences in diet, depending on the microhabitat in which they developed in the bromeliad, and showed electivity favorable for fungi but negative for copepods. Our data suggest that tadpoles of S. perpusillus are, in general, non-selective omnivores feeding on items in a similar proportion to their occurrence in the environment, while tadpoles of S. littoreus are more selective-feeders, avoiding animal items.Muitas espécies de anuros que se reproduzem em bromélias apresentam cuidado parental com fêmeas depositando ovos não fertilizados para alimentar os girinos no fitotelma. Os hilídeos do gênero Scinax não apresentam este comportamento, mesmo apresentando girinos exotróficos. O objetivo do presente estudo foi descrever quali-quantitativamente a dieta dos girinos das espécies S. littoreus e S. perpusillus que se desenvolvem no fitotelma da Alcantarea glaziouana (Bromeliaceae). Avaliamos se há diferenças sazonais e espaciais (entre girinos que residem no vaso central e nos vasos laterais da bromélia) na dieta, além de testar a existência de seleção de itens alimentares pelas espécies de anuros. Os itens mais abundantes na dieta de ambos os girinos foram respectivamente: algas, fungos e protozoários. Detrito e restos vegetais estavam presentes em mais de 90% dos estômagos de ambas as espécies. A amplitude de nicho trófico para S. littoreus foi 1,26 enquanto para S. perpusillus foi 1,54. As dietas foram sazonalmente conservativas para ambas as espécies e espacialmente similar apenas para S. perpusillus. Os girinos de Scinax littoreus apresentaram diferenças na dieta de acordo com o microhabitat em que se desenvolviam na bromélia além de apresentar eletividade positiva para fungos e negativa para copépodos. Nossos dados sugerem que S. perpusillus é, em geral, um onívoro não seletivo, alimentando-se de itens em proporção similar da que estes ocorrem no fitotelma, enquanto os girinos de S. littoreus são mais seletivos evitando itens animais.

Calls of five species of the Scinax ruber (Anura: Hylidae) clade from Brazil with comments on their taxonomy

As currently defined, tree frogs of the genus Scinax comprises the most species-rich genus within Hylinae. Although in the last decades there have been an increasing number of taxonomic studies on Scinax, populations of several species still deserve further studies to assess their taxonomic status. The purpose of this paper is to contribute to the taxonomy and zoogeography of some species of Scinax from Brazil assigned to the Scinax ruber clade through the description/redescription of their advertisement calls. The advertisement call of S. duartei from topotypic specimens and the call of S. acuminatus are described here for the first time. The call of S. duartei is in disagreement with descriptions from the literature what suggests that an unnamed species is hidden under this specific name. Redescriptions of the calls of S. crospedospilus, S. eurydice, and S. hayii are also provided and compared with previous studies. In order to better assess the taxonomic status of species with advertisement calls that present more than one emphasized frequency, as in some species of the Scinax ruber clade, we recommend special attention in the descriptions of the spectral components of these calls.