Thesea pyrrha sp. nov., a new shallow-water octocoral (Cnidaria, Anthozoa) from southwestern Atlantic, and implications on the systematics of the genus.

The family Plexauridae Gray, 1859 is characterized by grouping octocorals that have thick branches and coenenchyme. However, due to their relatively simple body plan, the establishment of homologous and, therefore, systematically informative morphological characters is a challenge for the systematics of Octocorallia. During the last decade, molecular studies suggested that Plexauridae is polyphyletic, with representatives grouping with Acanthogorgiidae Gray, 1859 and also Gorgoniidae Lamouroux, 1812. Represented by 22 extant species, mostly of which occur in the Atlantic Ocean, the plexaurid genus Thesea Duchassaing Michelotti, 1860 has also been purported to be polyphyletic, with a Pacific lineage related to the former Paramuriceidae and an Atlantic lineage more closely related to Gorgoniidae. Thus, aiming to further improve our understanding of the evolutionary position of the Southwestern Atlantic Thesea, sequencing of the extended Octocorallia barcode reinforces the need for a re-evaluation of the position of the genus within plexaurids. Molecular and macro and micromorphological analyzes indicate the occurrence of an undescribed species distributed from Rio de Janeiro to Santa Catarina, here named Thesea pyrrha sp. nov. Results presented herein also suggest that T. pyrrha is close related to Adelogorgia and Psammogorgia, both genera exclusive to the Pacific Ocean.

Revised nomenclature of the sea pen genus Balticina Gray, 1870 (= Halipteris Kölliker, 1870) (Anthozoa: Octocorallia).

The pennatulacean genus Balticina has had a long and confusing taxonomic history, with serious nomenclatural problems that remain unresolved. Owing to disagreements about authorships and dates of publication, the names Pavonaria, Norticina and Halipteris have all been used as valid in place of Balticina, or else been regarded as its junior synonyms, even simultaneously. In this paper, after an extensive literature review, we determine the authorships and dates for all the taxa involved in accordance with the provisions of the International Code of Zoological Nomenclature and establish Balticina Gray, 1870 (=Halipteris) and Balticinidae Balss, 1910 (=Halipteridae) as the valid genus and family names, respectively, for this group of sea pens. We also propose the replacement name Rakollikeria for the preoccupied genus name Pavonaria Kölliker, 1870 (Balticinidae) (nec Schweigger, 1819 - Funiculinidae).

Erythropodium caribaeorum (Duchassaing and Michelotti, 1860) (Cnidaria: Alcyonacea), an additional alien coral in the Southwestern Atlantic.

Invasive species may compromise biodiversity and ecosystem services, and represent a steadily growing concern for coastal marine ecosystems. The marine aquarium trade (MAT) is the source of some of the world's worst aquatic invasions, inflicting multimillion-dollar losses in infected regions. In the Southwestern Atlantic (SWA), two Indo-Pacific coral species were recently introduced as a result of the MAT and already dominate the substrate at the introduction site in Southeastern Brazil (Praia Vermelha, Angra dos Reis, Rio de Janeiro State). Herein, based on morphological and molecular evidence, we report a Caribbean native coral species likely introduced by the MAT in Praia Vermelha, Erythropodium caribaeorum (Duchassaing Michelotti 1860). While the eradication of coral species that already have a pest status in the SWA is unlikely, we propose that the eradication of the three species still contained to their introduction sites, including E. caribaeorum, is still feasible and depends on a rapid and integrated embracement of the task by core stakeholders. Priority actions for the regulation of MAT and hobbyism in Brazil are proposed.