Overview of the order Zoantharia (Cnidaria: Anthozoa) in Brazil

Zoantharia (Hexacorallia) is an order of benthic cnidarians, which are known to play an important ecological role in many marine ecosystems. Although the order has a cosmopolitan distribution, including the tropical southwestern Atlantic, research on Brazilian zoantharian species diversity and distribution patterns is lacking. In order to start addressing this gap, we conducted shallow-water coastal and oceanic island sampling in parallel with an extensive literature review to summarize the knowledge of the order Zoantharia from Brazil. Additionally, mitochondrial 16S ribosomal DNA and cytochrome oxidase subunit I (COI) sequences from specimens were determined to confirm their identity and phylogenetic position within the order. Our results show the presence of at least 13 zoantharian species in Brazilian waters, including first records of Palythoa aff. clavata and Zoanthus aff. pulchellus. Moreover, range extensions were confirmed for Palythoa caribaeorum, P. grandiflora, P. variabilis, Zoanthus pulchellus, and Parazoanthus swiftii. We also present the first report on the distribution patterns for all studied species in Brazil. The current study is expected to provide a baseline for further surveys in the tropical southwestern Atlantic, where Zoantharia species richness is still understudied and therefore very likely underestimated.