DNA barcoding is a recently proposed global standard in taxonomy based on DNA sequences. The two main goals of DNA barcoding methodology are assignment of specimens to a species and discovery of new species. There are two main underlying assumptions: i) reciprocal monophyly of species, and ii) intraspecific divergence is always less than interspecific divergence. Here we present a phylogenetic analysis of the family Potamotrygonidae based on mitochondrial cytochrome c oxidase I gene, sampling 10 out of the 18 to 20 valid species including two non-described species. Potamotrygonidae systematics is still not fully resolved with several still-to-be-described species while some other species are difficult to delimit due to overlap in morphological characters and because of sharing a complex color patterns. Our results suggest that the family passed through a process of rapid speciation and that the species Potamotrygon motoro, P. scobina, and P. orbignyi share haplotypes extensively. Our results suggest that systems of identification of specimens based on DNA sequences, together with morphological and/or ecological characters, can aid taxonomic studies, but delimitation of new species based on threshold values of genetic distances are overly simplistic and misleading.

The neotropical cichlid genus Astronotus currently comprises two valid species: A. ocellatus Agassiz, 1831 and A. crassipinnis Heckel, 1840. The diagnosis is based on color pattern and meristics counts. However, body color pattern is highly variable between regions and the meristic counts show a considerable overlap between populations differing in color patterning. They do not represent true synapomorphies that diagnose species. Purportedly the only truly diagnostic character is the presence or absence of one or more ocelli at the base of the dorsal fin, diagnosing A. ocellatus and A. crassipinnis, respectively. Using the 5′ portion of the mitochondrial COI gene and EPIC nuclear markers, the validity of the dorsal ocelli as diagnostic character was tested in individuals sampled from ten localities in the Amazon basin. Analyses rejected the hypothesis that dorsal ocelli are diagnostic at the species level. However, they revealed the existence of five hypothetical, largely allopatrically distributed morphologically cryptic species. The phylogeographic structure is not necessarily surprising, since species of the genus Astronotus have sedentary and territorial habits with low dispersal potential. The distribution of these hypothetical species is coincident with patterns observed in other Amazonian aquatic fauna, suggesting the role of common historical processes in generating current biodiversity patterns.

We describe a new species of Ischnocnema from the Cerrado (Brazilian savanna) of the Triângulo Mineiro region, state of Minas Gerais. Comparisons were made with those species historically thought to be closely related to I. juipoca. Topotype males (14.9–18.7 mm SVL) of the new species are smaller than those of Ischnocnema juipoca, I. octavioi, Eleutherodactylus heterodactylus, Pristimantis dundeei, and P. crepitans. Different from E. heterodactylus and P. crepitans, the new species does not have expanded discs on finger III and IV. The new species is different from P. dundeei by lacking finger/toe discs and nuptial pads. A marked sexual dimorphism in size is absent in P. crepitans and present in the new species. Different from the new species, I. verrucosa is coarsely tuberculate on dorsal surfaces. Ischnocnema verrucosa, I. octavioi, and P. dundeei are primarily forest dwellers while the new species is common in open areas. The advertisement call of the new species has more (1.5–2.5 times) pulses and higher (1.3–1.8 times) pulse repetition rate than that of I. juipoca.

Uma semente, trazida pelo vento, pousa sobre o solo e lá fica até as primeiras chuvas. Ao germinar, suas raízes começam a se desenvolver, e logo surge o primeiro ramo, e outro a partir deste, e mais outro, até o vicejar de uma árvore, com muitos galhos e folhas. [...]