A new species of Tubella (Porifera: Spongillidae) for the Brazilian Amazon: how misidentification can mask a potential species complex

ABSTRACT Sponges may be among the worst dispersers in the animal kingdom, however, some freshwater sponges produce resting bodies called gemmules, which have been used as the main explanation for the widespread distribution of some of those organisms. This is the case of Tubella pennsylvanica Potts 1882, which was originally described from Pennsylvania, USA, and is reported with a worldwide distribution but with scarce and confusing information to validate its taxonomy and dispersal mechanism. It has been registered in the Amazon and is the first species of Tubella reported outside the Amazon. In order to confirm the taxonomic status of the occurrences in Brazil, we collected specimens from three sites in the Amazon basin and compared their measurements and characteristics with the type material of T. pennsylvanica. Based on this specimen analysis, we consider all records in Brazil of Tubella pennsylvanica to be a different species, which is here described as Tubella manauara n. sp. In addition, we provide the first images of the spicules of the holotype of Tubella pennsylvanica. The new species differs from the type material of Tubella pennsylvanica by presenting larger spines in the megasclere acanthoxeas, and larger size of the spicules. The specimens of Tubella manauara n. sp show morphological variations according to the type of substrate on which the sponge has developed. This study reinforces the need to review South American freshwater sponge species with distributions that stretch to other continents.