Intraoceanic and interoceanic dispersal of a marine invader: revealing an invasion in two ocean basins

Recent collection efforts along the Brazilian coast revealed a Haliclona species preliminarily identified as a likely new species. However, sequencing of the 28S rRNA C-Region, a barcode marker in sponges, showed its high genetic similarity with a Haliclona sp. from Hawaiʻi (GenBank MW016137–MW016139). We applied an integrated morphological and molecular assessment, which allowed us to identify both Brazilian and Hawaiian specimens as H. (Reniera) laubenfelsi, a species with an Indo-Pacific distribution. We postulate this species to be exotic both in the Brazilian coast and in Hawaiʻi. Our evidence is based on the arrival of the species in Brazil after 2001, being first registered next to an international port. In turn, the species is distributed discontinuously in Hawaiʻi, being mainly restricted to sheltered bays and vicinities of ports, showing a predilection for anthropogenic substrates, which strengthen the hypothesis of its exotic origin. Recent collections in Hawaiʻi (2016–2018) failed to find this species in natural habitats, though it was an abundant pioneer species in Autonomous Reef Monitoring Structures. Its capacity to colonize artificial substrata may indicate either a cryptobenthic nature or an invasive potential. We highlight the need of monitoring its abundance, spatial distribution, and biotic interactions along the Brazilian coast to assess its potential environmental impacts. The full morphological description, and the molecular sequences we provided certainly will speed up the identification of this species, allowing to track its range extension.