Triaenonychidae is a family of Opiliones distributed in the southern continents. In this paper we focused on the South American triaenonychids, aggregating sequences of three markers (18S rRNA, 28S rRNA and cytochrome c oxidase subunit I), re-examining the position of additional South American species. In addition, we describe a new genus Adrianonyx gen. nov. and two new species, Adrianonyx contulmo sp. nov. from the Monumento Natural Contulmo and Adrianonyx crypticus sp. nov. from the Parque Nacional Nahuelbuta, are described.

The species of the sponge genus Oscarella are difficult to define because they have no skeleton, and some species may be highly variable. We found nine types of Oscarella co-existing in south-east Brazil and we combined genetic, morphological, anatomical, cytological, microbiological, reproductive and ecological information to determine how many species are there. As a result, we described three new species of Oscarella, of which one is highly variable.

The Rhinocylapus Poppius, 1909 complex is a small group in the rare, mainly tropical plant-bug subfamily Cylapinae Kirkaldy, 1903. Supplementing the molecular and morphological data of a previous study allowed us to obtain a more resolved and supported phylogeny of the complex and test the relevance of total-evidence analysis in cases that lack molecular data. We also provide illustrations of habitus and genitalic structures, a key to the genera and generic synopsis. The current study is an important step for understanding phylogenetic relationships of the poorly known and diverse subfamily Cylapinae.