Abstract The Peripampasic Arc is a set of low mountains / hills that connects the Andes, as it scatters to the East forming mountainous areas of lower heights in north-eastern Argentina, with the Atlantic coastal range of the Serra do Mar in Brazil. Numerous studies proved its important biogeographic connection for plant and animal phylogenies, but no information of this pattern is known to lichens. The aim of this work is to establish if the dispersion route of the lichenbiota follows the previously known Peripampasic Arc. For this reason, a comparative study of each area regarding its similarities was analyzed, with emphasis on the biota of the Buenos Aires’ Sierras. We quantified the similarity and β diversity of 104 saxicolous lichens species. There was a strong similarity between the Sierra de la Ventana and Tandil biota, which in turn is linked to the biotas of Uruguay, the Pampean Sierras and the northwest of Argentina. The lack of subgroups in the Peripampasic Arc implies the arc acts as a functional unit of dispersion, which is the most likely cause for the present lichens’ distribution.

Abstract Erythrodiplax nataliae sp. nov. (5 males), collected in Vereda wetlands (a unique Neotropical savanna environment) in Mato Grosso, Brazil is described and illustrated. The new species fits in Borror’s Juliana Group, and can be distinguished from other species by the combination of the following traits: blue pruinosity on thorax (more dense dorsally); sides of the pterothorax yellowish, darkening dorsally; face ivory, dorsally black with a metallic blue reflection; wings hyaline with a small basal brown spot; vesica spermalis with long lateral lobes, enclosing the median process and median process elongated with a pair of conspicuous rectangular and elongated lateral lobes, with a middle dorso-ventral furrow.

Abstract The American genus Argia, with more than 100 species described, is the most speciose genus of Odonata in the world. In this contribution, the final stadium larva of Argia serva, the southernmost distributed species of Argia, is described and diagnosed based on reared material from Martín García island, Buenos Aires, Argentina. The larva of this species can be easily separated from the other Argentinean Argia by the following combination of characters: sternum of S8 covered with spines (bare in A. translata); antennal segment 3 longer than 1+2 (equal to or shorter than 1+2 in A. joergenseni and A. jujuya); palpal setae absent (present in A. croceipennis). A key to the known larvae of Argia of the Southern Cone is provided.