Taxonomic Survey of Ascidians (Tunicata: Ascidiacea) in the Parque Natural Municipal Marinho Recife de Fora Natural, Porto Seguro, Bahia, Brazil

Ascidians (Ascidiacea) are sessile marine invertebrates found in coastal and reef environments, occurring in both solitary and colonial forms. Despite their ecological relevance as filter feeders and bioindicators, their diversity in tropical reef environments from Southwest Atlantic remains poorly understood. This study presents a taxonomic survey of ascidians from the Parque Natural Municipal Marinho Recife de Fora (PNMRF), a marine reef protected area located on the southern coast of Bahia, which is recognized as the third largest center of marine biodiversity in Brazil. Sampling was conducted through free diving and manual collection on coralline substrates. Specimens were fixed in 4% formalin and preserved in 70% ethanol for subsequent morphological analysis, based on external, internal, and larval characteristics, with the support of specialized taxonomic literature for the Atlantic. A total of 21 species were identified, with a predominance of the genus Didemnum. Among the recorded taxa, highlights include new records for the Brazilian coast, including representatives of Diplosoma, the possible range expansion of non-native species such as Pyura gangelion and Styela canopus, and the distribution extension of native species such as Eudistoma recifensis and Polycarpa spongiabilis. These results underscore the still underexplored richness of ascidians in reef environments and provide essential data to support taxonomic studies, biological monitoring, and conservation strategies in PNMRF and other tropical coastal ecosystems.