Here we document an exceptional and previously unreported event: the stranding of a false killer whale, Pseudorca crassidens, newborn in northeastern Brazil resulting from a fatal collision with an Indo-Pacific sailfish, Istiophorus platypterus. Detailed necropsy, pathological examination, and genetic identification of the embedded foreign structure demonstrate unequivocally that the trauma was caused by the bill of an Indo-Pacific sailfish. To our knowledge, this represents the first confirmed case of interaction between these two species for the Brazilian coast, and one of the very few documented worldwide, providing valuable insight into the ecological dynamics of pelagic predators in the Southwestern Atlantic. This case also underscores the importance of long-term beach monitoring programmes for detecting unusual biological events and improving our understanding of marine mammal ecology, behaviour, and mortality sources.

The dendrophylliid ‘sun corals’ are a group of highly dispersive scleractinians that became invasive in the Atlantic Ocean. A recent study, focusing on the corallite macro- and micromorphologies, remarkably expanded the number of Tubastraea species in the Southwestern Atlantic, including the description of four new corals to the world: Tubastraea grandidentata, T. megalostoma, T. columnata, and T. ramosa, which are validated in the present study. The increasing biodiversity of sun corals demands the application of alternative tools, such as molecular markers, to corroborate findings at the morphological level. Hence, a DNA analysis based on COI, IGR, and ITS1-5.8S-ITS2 rDNA regions is used to infer the phylogeny of the new species described from Brazil. The rDNA is the most variable region and dramatically impacts the phylogenetic reconstruction, supporting the species identity of the ‘Brazilian’ Tubastraea and indicating two major clades: branched and unbranched corals. The most robust phylogeny is obtained by concatenating the three genetic regions using Bayesian inference. Genetic polymorphisms and fixed differences are observed within and between species. Data also support the identity of Atlantia caboverdiana from the Northeastern Atlantic. Finally, the unprecedented biodiversity of sun coral species in the Tropical Atlantic raises concerns about all previous identifications and the mechanisms involved in the dispersion of Tubastraea across the world. Moreover, multiple introductions, gene flow, and larval competency period remain misunderstood, challenging the management policies hitherto adopted to control these exotic dendrophylliids.

Extending over warmer environments in the Brazilian waters, the exotic vermetid Eualetes tulipa was first recorded from Ceará State (3°S) in 2005. In 2009, it was reported in cold-water environments in Rio de Janeiro State (22°S). Seven years later, E. tulipa was recorded from Rio Grande do Norte State (6°S) on rocky pools in sandstone reefs. In the present study, E. tulipa is for the first time recorded from Bahia State (12°S), associated with a biofouling community in the Todos-os-Santos Bay, co-occurring with exotic dendrophylliid corals (Tubastraea). The vermetid community recorded from Bahia State shows a great diversity of epibionts, mostly bivalves, cirripeds and sponges. The co-occurrence of Eualetes and Tubastraea corals must be monitored, once these exotic species are co-occurring in a protected environmental area, bringing concern on possible impacts on native benthic fauna.

Didiscus gladius sp. nov. is described from Bahia State (Brazil). The sponge is thinly encrusting to lump-shaped and has a glassy, translucent appearance, through which the spiculation is clearly visible. The megascleres are styles and two categories of oxeas. The microscleres are discorhabds. Colour is beige or brown in ethanol. Didiscus verdensis is the nearest relative in the Atlantic which differs from the new species in a series of traits (e.g. absence of true styles and presence of strongyles). A key to species of Didiscus is given.