Allobates

Abstract: The small nurse frogs of the genus Allobates (Anura, Aromobatidae) represent one of the most challenging taxonomic issues of the Neotropics. During several amphibian surveys in the Middle Tapajos River region, state of Para, Brazil, we collected phenotypic, ecological, and molecular data on species of this genus, leading to the identification of a new species included in the Allobates masniger-nidicola complex. The new species is characterized by a large body size (snout-vent length 19.2-21.7 mm in males and 19.3-22.0 mm in females), finger III not swollen in adult males; cryptic external coloration, with dorsum uniformly ochre; a dark brown lateral stripe and a pale cream ventrolateral stripe; limbs ranging from ochre to orange; throat and chest violaceous in males and yellowish in females. The advertisement call is usually arranged in bouts of four closely spaced notes, which we term 4-pulsed units of repetition (UR), 0.317 s long on average, followed by silent intervals, and an average dominant frequency of 4.163 kHz. The new species also has exotrophic tadpoles with a unique fin morphology, which begins after the body-tail insertion and is deeper posteriorly to half of the caudal length. Sequencing of the 16S and COI regions of the mitochondrial DNA show a genetic p-distance of approximately 6-10% compared to closely related congeners. We discuss the biogeography of the new species based on phylogenetic relationships of the species within the Allobates masniger-nidicola complex and the allopatric geographic distribution in relation to sister taxa. Functional characteristics and geographic restrictions make this species particularly sensitive to the increasing human impact in eastern Amazonia.

Abstract: I describe the seventh species of nurse-frog ( Allobates ) from the Madeira River basin in Brazilian Amazonia. The new species is distinguished from similar congeneric species by its small body size (snout-to-vent length ranging between 14.0–14.7 mm in adult males and between 14.7–14.9 mm in adult females), by the absence of dark brown regular shapes ( e.g . hourglass, “X” or polygon-like marks) on the dorsum, by the absence of transverse dark bars on the dorsal surface of the thigh, and by the light gray to white ventral surfaces, light to dark gray only on throat in live male and female specimens. Males have a distinctive advertisement call characterized by the emission of long (7–11 s) trills of short notes (0.04 s in average) with dominant frequency at 5.9–6.3 kHz and emission rate ranging between 6.7–8.7 notes/s. DNA barcode analyses based on a fragment of the 16S rDNA mitochondrial gene provides additional support to the recognition of the new taxon, which is probably distributed on the east riverbank of the Madeira River, in the interfluve between the Aripuana and Ji-Parana rivers.

Abstract: We describe a new species of nurse-frog (Aromobatidae, Allobates) from Floresta Nacional de Carajas, southeastern Brazilian Amazonia. Allobates carajas sp. nov. is distinguished from similar congeneric species by the combination of the following characters: body-size range (snout-to-vent length 16.5-19.1 mm), dorsal color pattern with a dark brown hourglass-shaped mark, by the absence of a pale dorsolateral stripe and presence of a pale ventrolateral stripe, absence of a pale paracloacal mark, by overall bright yellow ventral colors of live male and female specimens, and by the posterior labium of tadpoles, with a single row of pyramidal papillae medially. The advertisement call of the new species is highly variable, with four possible temporal arrangements of notes (continuous emission of notes separated by regular silent intervals, continuous emission of notes separated by irregular silent intervals, emission of discrete note trills, and sporadic emission of single notes). Duration of notes range between 0.020-0.060 s, and the dominant frequency of notes range from 4.75 to 5.38 kHz. The new species is currently known only from forested habitats within Floresta Nacional de Carajas.

Abstract: Regions of the mitochondrial genome were sequenced and analysed in representative species of poison frogs, in order to investigate phylogenetic relationships within the family Dendrobatidae. Mitochondrial DNA (mtDNA) fragments from three gene regions; cytochrome b, 16S ribosomal RNA (rRNA), and 12S rRNA, provided 1198 base pairs of DNA sequence and 589 informative sites. Phylogenetic analysis using parsimony was used to infer the evolutionary relationships among the species in the survey. Our analysis supported previous partitions of species into the genera Epipedobates, Phyllobates andDendrobates , with two exceptions Epipedobates (Allobates) femoralis was placed outside the clade containing the other toxic dendrobatids, and Minyobates minutus was placed within the genus Dendrobates. Genetic distances estimated between all pairs of taxa using the Kimura 2-parameter model indicated substantial genetic divergence between species, particularly those found in Amazonia. Time of divergence estimates were highly variable depending on gene region, but even the lowest estimates were inconsistent with the Pleistocene Refugia hypothesis.