Desvendando o desconhecido: diversidade, distribuição e diversificação de anuros no interflúvio Purus-Madeira

The Purus-Madeira Interfluve (PMI) represents one of the less known areas of Brazilian Amazonia. Despite it is extremely threatened by anthropic actions, the knowledge about the taxonomic identity of anurans inhabiting the PMI and the processes driving their distribution and diversification are poorly known. The main goals of this thesis were to investigate the hidden diversity in anurans, provide bases to ecological and conservation studies through the description of new taxa, and illuminating the role of environment on species distribution and diversification along the PMI. In the first chapter, we integrated morphology, bioacoustics, and genetics to explore if there was hidden diversity in anurans of the genus Scinax along 1000 km of landscapes in the PMI. Integrative analyses revealed that approximately 82% of the regional richness in Scinax was unknown to science. Results highlighted how much the PMI faunal diversity is poorly known and its need for conservation actions. In the second chapter, we formally described the most widely distributed new species of Scinax in the PMI and tested if its geographic distribution and abundance were driven by environmental variables. Scinax ruberoculatus is easily distinguished from its congeners through morphological (adults and tadpoles) and bioacoustical characters. Differing from the predicted for aquatic breeding anurans, its distribution and abundance along the PMI is positively driven by silt content and not by forest structure (tree density). It is suggested that this habitat-association is driven by the species’ reproductive needs once reproductive sites in silty soils may be less ephemeral, favouring the survival of tadpoles of the new species. In the third chapter, we described a new species of Scinax with distribution apparently restricted to the central portion of PMI. Despite it is close related to species of the Scinax wandae clade, the new species is distinguished from all other Amazonian Scinax through morphology and colouration, as well as by the advertisement call. The species’ habitat is deeply threatened by the anthropic pressure due to property speculation as result of the reconstruction of the BR-319 highway. In the fourth chapter, Scinax onca was described based in specimens from two distinct populations in the PMI, one living in dense forests and the other in open forests. Phylogenetic analyses of the first chapter recovered these populations as reciprocally monophyletic. Differences in colour pattern, as well as its evolutionary relationship, led us to hypothesize that environmental gradients of the PMI may be responsible by observed differentiation in these populations. However, data collected along its distribution are necessary to elucidate if the observed differentiation is really influenced by environmental gradients. In the fifth chapter, we used a diminutive terrestrial anuran (Phyzelaphryne miriamae) and widely distributed in the PMI as a model to test if the gene flow along the landscape can be explained by the ecological gradient hypothesis. For the first time in Amazonia, genomic landscape analyses and thousands of single nucleotide polymorphisms (SNPs) were used to test this hypothesis. Genetic structure analyses estimated five ancestral populations in P. miriamae. Results indicated that the effect of environmental gradients on gene flow of the target species was pronounced. After accounting the effect of geographic distance, the explanation of environmental variables ranges from 24.7 % (silt content) to 30.2% (temperature seasonality). On the other hand, geographic distance explained just 2.3–3.7% of the gene flow. Although there is an effect of geographic distance on gene flow in P. miriamae, it is restricted to short and long distances, being null in moderated distances.O interflúvio entre os rios Purus e Madeira (IPM) compreende uma das regiões mais desconhecidas da Amazônia brasileira. Mesmo sendo uma região extremamente ameaçada pelas ações do homem, pouco se conhece sobre a identidade taxonômica dos anuros que habitam a região e os processos responsáveis por determinar padrões de distribuição e diversificação de espécies. O objetivo geral desta tese foi investigar a diversidade escondida de anuros, fornecer subsídios para estudos ecológicos e de conservação através da descrição de novos taxons, e revelar processos ecológicos responsáveis pela distribuição e diversificação de espécies no IPM. No primeiro capítulo, integramos dados morfológicos, bioacústicos e moleculares para investigar a existência de diversidade escondida em anuros do gênero Scinax ao longo de 1000 km de paisagens no IPM e áreas circunvizinhas. Análises integrativas revelaram que aproximadamente 82% da riqueza regional de espécies de Scinax era composta por espécies desconhecidas para a ciência. Os resultados evidenciaram o quanto o IPM é pouco conhecido do ponto de vista faunístico e a necessidade de ações conservacionistas na região. No segundo capítulo, descrevemos formalmente a espécie de Scinax com maior distribuição ao longo do IPM e investigamos se sua distribuição geográfica e abundância são influenciadas por variáveis ambientais. Scinax ruberoculatus é facilmente distinta das demais congêneres por caracteres morfológicos (adultos e girinos) e bioacústicos. Diferente do que se esperava para anuros de reprodução aquática, sua distribuição e abundância ao longo do IPM é influenciada positivamente pela porcentagem de silte no solo e não pela estrutura da floresta (densidade de árvores). Sugere-se que está associação espécie-habitat seja guiada pelas necessidades reprodutivas da espécie, uma vez que sítios reprodutivos em solos siltosos podem ser menos efêmeros, favorecendo assim a sobrevivência dos girinos da nova espécie. No terceiro capítulo, descrevemos formalmente uma nova espécie de Scinax com distribuição aparentemente restrita à porção central do IPM. Apesar de ser proximamente relacionada com espécies do clado Scinax wandae, a nova espécie se distingue de todas estas por caracteres morfológicos e de coloração, bem como por seu canto de anúncio. Sua área de ocorrência passa por forte pressão antrópica em decorrência do desmatamento influenciado pela especulação imobiliária decorrente da reconstrução da BR-319. No quarto capítulo, Scinax onca foi descrita com base em espécimes provenientes de duas populações distintas do IPM, uma distribuída em florestas densas e a outra em florestas abertas. Análises filogenéticas do primeiro capítulo mostraram que estas populações formam clados reciprocamente monofiléticos. As diferenças no padrão de coloração entre as duas populações, juntamente com suas relações evolutivas, nos levaram a levantar a hipótese de que variações ecológicas do IPM podem ser os responsáveis pela diferenciação destas duas populações. Entretanto, dados coletados ao longo de sua distribuição se fazem necessários para elucidar se a diferenciação observada é influenciada pelos gradientes ambientais. No quinto capítulo, utilizamos uma espécie diminuta de anuro terrícola (Phyzelaphryne miriamae) amplamente distribuída no IPM como modelo para testar se o fluxo gênico ao longo da paisagem pode ser explicado pela hipótese de gradientes ambientais. Pela primeira vez na Amazônia, utilizamos análises genômicas de paisagem e milhares de polimorfismos de nucleotídeos únicos (SNPs) para testar esta hipótese. Análises de estrutura genética estimaram cinco populações em P. miriamae. Os efeitos dos gradientes ambientais no fluxo gênico da espécie alvo foram pronunciados. Os valores de explicação das variáveis ambientais, após corrigidas pelo efeito da distância geográfica, variaram entre 24.7% (teor de silte no solo) e 30.2% (sazonalidade da temperatura). Enquanto que a distância geográfica explicou apenas 2.3–3.7% do fluxo gênico. Embora haja efeito da distância geográfica no fluxo gênico de P. miriamae, este se limita apenas a pequenas e longas distâncias, sendo nulo em distancias intermediarias

Contrasting Patterns of Gene Flow for Amazonian Snakes That Actively Forage and Those That Wait in Ambush

Knowledge of genetic structure, geographic distance and environmental heterogeneity can be used to identify environmental features and natural history traits that influence dispersal and gene flow. Foraging mode is a trait that might predict dispersal capacity in snakes, because actively foragers typically have greater movement rates than ambush predators. Here, we test the hypothesis that 2 actively foraging snakes have higher levels of gene flow than 2 ambush predators. We evaluated these 4 co-distributed species of snakes in the Brazilian Amazon. Snakes were sampled along an 880 km transect from the central to the southwest of the Amazon basin, which covered a mosaic of vegetation types and seasonal differences in climate. We analyzed thousands of single nucleotide polymorphisms to compare patterns of neutral gene flow based on isolation by geographic distance (IBD) and environmental resistance (IBR). We show that IBD and IBR were only evident in ambush predators, implying lower levels of dispersal than the active foragers. Therefore, gene flow was high enough in the active foragers analyzed here to prevent any build-up of spatial genotypic structure with respect to geographic distance and environmental heterogeneity. © The American Genetic Association 2017. All rights reserved

Different environmental gradients affect different measures of snake β-diversity in the Amazon rainforests

Mechanisms generating and maintaining biodiversity at regional scales may be evaluated by quantifying β-diversity along environmental gradients. Differences in assemblages result in biotic complementarities and redundancies among sites, which may be quantified through multi-dimensional approaches incorporating taxonomic β-diversity (TBD), functional β-diversity (FBD) and phylogenetic β-diversity (PBD). Here we test the hypothesis that snake TBD, FBD and PBD are influenced by environmental gradients, independently of geographic distance. The gradients tested are expected to affect snake assemblages indirectly, such as clay content in the soil determining primary production and height above the nearest drainage determining prey availability, or directly, such as percentage of tree cover determining availability of resting and nesting sites, and climate (temperature and precipitation) causing physiological filtering. We sampled snakes in 21 sampling plots, each covering five km2, distributed over 880 km in the central-southern Amazon Basin. We used dissimilarities between sampling sites to quantify TBD, FBD and PBD, which were response variables in multiple-linear-regression and redundancy analysis models. We show that patterns of snake community composition based on TBD, FBD and PBD are associated with environmental heterogeneity in the Amazon. Despite positive correlations between all β-diversity measures, TBD responded to different environmental gradients compared to FBD and PBD. Our findings suggest that multi-dimensional approaches are more informative for ecological studies and conservation actions compared to a single diversity measure

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 specieshabitat 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 22.6-25.9mmin males and 25.4-27.5mmin 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. © 2018 Ferrão et al

Rediscovery of Osteocephalus vilarsi (Anura: Hylidae): An overlooked but widespread Amazonian spiny-backed treefrog

Osteocephalus vilarsi (Melin, 1941) is an Amazonian treefrog species known for over 75 years from its holotype only. Due to a lack of published data on its morphological diagnostic characters and their variations, as well as the absence of molecular, acoustic and ecological data supporting its identity, a highly dynamic taxonomic history has led this species to be confused and even synonymised with other Osteocephalus species from distinct species groups. The molecular phylogenetic relationships of O. vilarsi were investigated based on recently collected specimens from eight Northwestern Brazilian localities in the state of Amazonas, leading to its removal from the Osteocephalus taurinus species group and placement in the Osteocephalus planiceps species group. Furthermore, detailed data on morphology and colour variation are provided, as well as advertisement call and tadpole descriptions. Finally, the currently known geographic range of O. vilarsi is considerably extended, first data on the natural history of the species are provided, and the possible ecological preference of O. vilarsi for Amazonian white-sand forests is discussed. Copyright 2019 Ferrão et al

A new pale-ventered nurse frog (Aromobatidae: Allobates) from southwestern Brazilian Amazonia

Abstract We use integrative taxonomy to formally describe a candidate species of nurse frog of the genus Allobates from southwestern Brazilian Amazonia. The new species nests within a clade that has been defined historically as A. gasconi, but it has an 8.8–11.0% genetic distance for 16S to samples from the type locality of A. gasconi. The new species differs from congeners mainly by males having a translucent white throat and vocal sac; advertisement calls with a duration of 42–60 ms, two notes separated by an inter-note interval of 8–23 ms, and a dominant frequency of 4,953–6,331 Hz; and exotrophic tadpoles with 2 pyramidal papillae on each end of the upper lip and 10–13 pyramidal and cylindrical papillae surrounding the lower lip. Phylogenetic analyses based on mitochondrial DNA suggest that A. gasconi sensu lato as defined previously represents a complex of as many as seven species, corroborating studies that have shown high levels of cryptic diversity within Allobates

A new species of terrestrial foam-nesting frog of the Adenomera simonstuarti complex (Anura, Leptodactylidae) from white-sand forests of central Amazonia, Brazil

By using integrative taxonomy, we describe a new species of terrestrial foam-nesting frog of the genus Adenomera from white-sand forests of the Rio Negro Sustainable Development Reserve, Central Amazonia, Brazil. Within the A. andreae clade, the new species belongs to the A. simonstuarti complex where it is sister to the lineage from the lower Juruá River. The new species is assigned to the genus Adenomera by having adult SVL smaller than 34.1 mm, by its lack of fringing and webbing between toes and by the absence of spines on the thumb of adult males. It differs from other Adenomera by the following combination of characters: antebrachial tubercle absent; toe tips flattened or slightly flattened, with visible expansions; nearly solid, dark-coloured stripe on underside of forearm; single-note advertisement call; notes formed by 11–21 incomplete pulses; call duration varying between 100 and 199 ms; fundamental frequency 1,765–2,239 Hz; dominant frequency 3,448–4,349 Hz; and endotrophic tadpoles with spiracle present and labial teeth absent. Over the last decade, we have inventoried many permanent sampling modules in ombrophilous forests in the Manaus Region and in the Purus-Madeira interfluve, but the new species was found only in the white-sand forest from West Negro-Solimões Interfluve. Adenomera sp. nov. may be endemic to, or at least a specialist in, this environment

Two new species of Allobates of the trilineatus clade (Anura: Aromobatidae) from the Eastern Guiana Shield

International audienceThe actual diversity of anurans occurring in Amazonia remains only partly described. This is notably the case of the species of the genus Allobates despite a fast rate of species description in this genus during the last decade. This increasing taxonomic effort has been particularly facilitated by the availability of DNA sequences throughout the region. These data suggest for instance the existence of three lineages in the Guiana Shield that may correspond to unnamed species. We examined morphology and calls of these putative species and compared them to related nominal species, which confirmed that two of these lineages not only differ genetically but also morphologically and bioacoustically. These two species are thus named and described herein. Allobates vicinus sp. nov. from northern Suriname forms a clade with another candidate species from southern Suriname and Northern Pará, (Brazil) and with A. granti that occurs in French Guiana. Allobates ripicolus sp. nov. occurs throughout the eastern Guiana Shield and is nested within the A. tapajos complex which otherwise occurs in southeastern Amazonia and comprises A. tapajos and A. kamilae, along with three additional candidate species

Out of Bound: A New Threatened Harlequin Toad (Bufonidae, Atelopus) from the Outer Borders of the Guiana Shield in Central Amazonia Described through Integrative Taxonomy

We used integrative taxonomy to describe a new species of Atelopus from the lowlands of Central Amazonia in the region of Manaus, Amazonas, Brazil. The new species is geographically isolated from the southernmost species of Atelopus of the Guiana Shield. Atelopus manauensis species nova (sp. nov.) is characterized by the combination of the following characteristics: male snout-vent length range (SVL = 19.1–26.4 mm; n = 11); dorsal and lateral skin smooth; ventral surface entirely white or white with cream-colored gular region; fingers and toes lacking subarticular tubercles and fringes. The advertisement call of the new species has a call duration of 689–840 ms, contains 15–26 pulses, is emitted at an average pulse rate of 25.5 pulses per second, and has a dominant frequency ranging 3088–3610 Hz. The genetic divergence between the new species and its morphologically most similar congeners (A. spumarius and A. pulcher) is greater than 4%. Atelopus manauensis sp. nov. is closely related to species of the A. hoogmoedi complex inhabiting the Guiana Shield. The new species has a small geographic distribution (approximately 4500 km2) in a landscape that is strongly threatened by the growth of Manaus, the largest city in Brazilian Amazonia. The new species is considered critically endangered and in need of urgent conservation measures