Phenotypic and life-history diversification in Amazonian frogs despite past introgressions.

The advent of genomics in phylogenetics and population genetics strengthened the perception that conflicts among gene trees are frequent and often due to introgression. However, hybridization occurs mostly among species that exhibit little phenotypic differentiation. A recent study delineating species in Anomaloglossus, a frog genus endemic to the Guiana Shield, identified an intriguing pattern in the A. baeobatrachus species complex. This complex occurs in French Guiana and Amapá (Brazil) and comprises two sympatric phenotypes contrasting not only in body size, habitat, and advertisement call, but also in larval development mode (endotrophic vs exotrophic tadpoles). However, molecular and phenotypic divergences are, in some cases, incongruent, i.e specimens sharing mtDNA haplotypes are phenotypically distinct, suggesting a complex evolutionary history. Therefore, we genotyped 106 Anomaloglossus individuals using ddRADseq to test whether this phenotype/genotype incongruence was a product of phenotypic plasticity, incomplete lineage sorting, multiple speciation events, or admixture. Based on more than 16,000 SNPs, phylogenetic and population genetic approaches demonstrated that exotrophic populations are paraphyletic. Species tree and admixture analyses revealed a strikingly reticulate pattern, suggesting multiple historical introgression events. The evolutionary history of one exotrophic population in northern French Guiana is particularly compelling given that it received genetic material from exotrophic ancestors but shows very strong genetic affinity with the nearby endotrophic populations. This suggests strong selection on larval development and mating call after secondary contact and hybridization. The case of A. baeobatrachus represents a striking example of introgression among lineages that are phenotypically distinct, even in their larval development mode, and highlights how high-resolution genomic data can unravel unexpectedly complex evolutionary scenarios.

On the distinctiveness of Amapasaurus, its relationship with Loxopholis Cope 1869, and description of a new genus for L. guianensis and L. hoogmoedi (Gymnophthalmoidea/Ecpleopodini: Squamata).

Amapasaurus is a monotypic genus of forest lizards never accessed molecularly and, based on morphological similarities, suggested to be closely related to species of the former Leposoma parietale group Ruibal 1952, currently in the genus Loxopholis Cope 1869. Two other species, formerly allocated in Arthrosaura (A. guianensis and A. hoogmoedi), were tentatively moved to Loxopholis in an extensive molecular revision of Gymnophthalmoidea. Here we add mitochondrial and nuclear sequence data (12S, cyt b, ND4, c-mos and NT3) of Amapasaurus to previously published and new data of all Ecpleopodini genera (except for Adercosaurus), in order to test: i) the close relationship between Amapasaurus and Loxopholis and ii) the position of Loxopholis guianensis and Loxopholis hoogmoedi with three different phylogenetic methods, expanding the knowledge on the current taxonomy of Ecpleopodini. Concatenated analyses of mitochondrial and nuclear data (2303 bp) under Bayesian Inference, Maximum Likelihood and Maximum Parsimony methods recovered a strongly supported sister relationship between Amapasaurus tetradactylus Cunha 1970 and species of Loxopholis. Genetic divergence between Amapasaurus and this assemblage of Loxopholis is high in both mitochondrial (~18% for cyt b) and nuclear (~12% for c-mos) regions, supporting its generic distinctiveness. Differing from the current taxonomy of the Ecpleopodini tribe, our analyses recovered Lo. guianensis and Lo. hoogmoedi as a distinct clade that is sister to all other Loxopholis plus Amapasaurus. Supplemented by external and hemipenial morphology data available from the literature along with DNA sequences, we restrict Loxopholis to the species of the former parietale group of Leposoma and describe a new genus to allocate Lo. guianensis and Lo. hoogmoedi.

Cryptic diversity in the Hypsiboas semilineatus species group (Amphibia, Anura) with the description of a new species from the eastern Guiana Shield.

We used molecular and morphological data to investigate the hidden diversity within the Hypsiboas semilineatus species group, and more specifically within H. geographicus, an allegedly widespread species in northern South America. As a result, the identity of H. geographicus was clarified, several candidate species were detected and one of them, from the eastern Guiana Shield, is described herein as a preliminary step to resolve the taxonomy of the group. Hypsiboas diabolicus sp. nov. is mainly distinguished from closely-related species by an acuminate snout in lateral view, well-developed webbing between fingers and toes, and unspotted carmine/crimson colouration on the concealed surfaces of legs, feet and hands in life. The tadpole of the new species is described and is characterized by a large A-2 gap, a mostly single row of large marginal papillae, and a dark brown to black colouration. We also describe the advertisement call of the new species, which is defined as a soft call consisting of short clusters of 2-3 chuckles with a dominant frequency ranging between 1.11-1.19 kHz. Hypsiboas diabolicus sp. nov. is currently known only from the eastern Guiana Shield, and is probably endemic to that region. The new species' range overlaps broadly with another candidate species referred to as H. aff. semilineatus 1. Our preliminary results stress out a high cryptic diversity in that species group and the need for a formal redescription of Hypsiboas geographicus based on more topotypic material than what is currently available  to properly sort out the taxonomic status of several lineages in that clade.

Description and phylogenetic relationships of a new genus and two new species of lizards from Brazilian Amazonia, with nomenclatural comments on the taxonomy of Gymnophthalmidae (Reptilia: Squamata).

We describe a new genus and two new species of gymnophthalmid lizards based on specimens collected from Brazilian Amazonia, mostly in the "arc of deforestation". The new genus is easily distinguished from other Gymnophthalmidae by having very wide, smooth, and imbricate nuchals, arranged in two longitudinal and 6-10 transverse rows from nape to brachium level, followed by much narrower, strongly keeled, lanceolate, and mucronate scales. It also differs from all other Gymnophthalmidae, except Iphisa, by the presence of two longitudinal rows of ventrals. The new genus differs from Iphisa by having two pairs of enlarged chinshields (one in Iphisa); posterior dorsal scales lanceolate, strongly keeled and not arranged in longitudinal rows (dorsals broad, smooth and forming two longitudinal rows), and lateral scales keeled (smooth). Maximum parsimony, maximum likelihood, and Bayesian phylogenetic analyses based on morphological and molecular data indicate the new species form a clade that is most closely related to Iphisa. We also address several nomenclatural issues and present a revised classification of Gymnophthalmidae.

Two new endangered species of Anomaloglossus (Anura: Aromobatidae) from Roraima State, northern Brazil.

We describe two new species of Anomaloglossus from Roraima State, Brazil, that are likely endemic to single mountains currently isolated among lowland forest and savanna ecosystems. The first species, Anomaloglossus tepequem sp. nov. was collected in 1986 and 1992 along a single stream at >500 m elevation on a tepui-like mountain named Tepequém, but was not detected during recent investigations. It is mainly diagnosed from other Anomaloglossus species by its well developed foot webbing, immaculate cream abdomen colouration and small body size (males: 18.2-20.1 mm, females: 21.7-24.5). The second species, Anomaloglossus apiau sp. nov. was found along several streams between 500 and 1400 m elevation on Serra do Apiaú, and is mainly diagnosed from congeners by its weakly webbed feet, males with swollen third finger and ventrolateral stripe formed by white dots, and its advertisement call; a long trill (up to almost 40 s) consisting of pairs of very short pulses. The discovery of these two apparently microendemic species suggests that additional Anomaloglossus species remain to be described in the Guiana Shield. Both species should be considered critically endangered given their seemingly reduced range size, association with highland habitat, and the anthropogenic pressure they currently face.