The sponge genus Oscarella is very important for the understanding of the early evolution of Metazoa, but the identification of its species is particularly difficult due to the absence of a skeleton and high polymorphism, leading to an underestimate of its diversity. The discovery of nine distinct morphotypes of Oscarella co-existing in cryptic habitats in south-east Brazil represents a taxonomic puzzle that requires an integrative taxonomic approach for species delimitation. Here we combined genetic (cox-1 and cob genes), morphological, anatomical, cytological, microbiological, reproductive and ecological datasets to delimit and describe three new species of Oscarella, one of which is highly polymorphic. Oscarella aurantia, sp. nov. is orange, microlobate, with metachromatic vacuolar cells, granular cells, and microgranular cells. Oscarella carollineae, sp. nov. is intertidal, cream or red, microlobate, with granulo-vacuolar cells, dense globular cells, and granular cells. Oscarella ruthae, sp. nov. is highly polymorphic, with tubular or papillate lobes; colour violet, pink, purple, red, orange or cream, often with shades of cream or green at the base; abundant clusters of vacuolar cells type 1, and rare vacuolar cells type 2 and microgranular cells. No single character was sufficient for species delimitation due to high intraspecific variation. Integration of multiple datasets was essential to delimit species of Oscarella and would also be helpful for the taxonomy of other polymorphic sponges.

Triaenonychidae is a family of Opiliones with almost 500 described species distributed in the southern continents. Recent work has provided a solid phylogenetic foundation based on Sanger and ultraconserved element molecular sequence data that resulted in a global reorganisation of the family. In this study, we turn to 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 and confirming the existence of a new genus. We provide novel information regarding the external morphology of 10 of the 11 South American genera of Triaenonychidae, based on stereomicroscope and SEM images of the body and genitalia. In addition, a new genus Adrianonyx gen. nov. and two new species, Adrianonyx contulmo sp. nov. from the Monumento Natural Contulmo (Chile) and Adrianonyx crypticus sp. nov. from the Parque Nacional Nahuelbuta (Chile) are described.