Debido a la ambigua definición de sus caracteres diagnósticos, las anémonas de mar chilenas Anthopleura hermaphroditica y Bunodactis hermafroditica han sido confundidas en reiteradas ocasiones. Examinando la anatomía externa e interna de varios ejemplares recolectados entre Antofagasta y Chiloé, se re-describe y compara ambas especies en relación a su historia sinonímica. Aun siendo muy similares, A. hermaphroditica y B. hermafroditica pueden ser distinguidas por los patrones de coloración del disco oral, el desarrollo de las verrugas, la presencia de zooxantelas y los cnidocistos de la columna y filamentos mesenteriales. En base a estos criterios, la autoría de Bunodactis hermafroditica pertenece a Carlgren (1959) pero debido a que el material tipo no corresponde con la descripción, se designa un neotipo que contiene las características señaladas por dicho autor. Aunque se cuestiona la validez de los acrorragios para diferenciar géneros, se proponen modificaciones a la terminología empleada en las diagnosis de Anthopleura y Bunodactis. A partir de esto se rechaza la sinonimización de los géneros Gyractis y Bunodactis, considerando este último un género válido hasta que se realice una adecuada revisión del material tipo de Aulactinia. Por otro lado, las marcadas diferencias anatómicas observadas entre poblaciones de Anthopleura hermaphroditica sugieren la presencia de al menos dos especies distintas.

Anthopleura hermaphroditica is an intertidal anemone that lives semi-buried in soft sediments of estuaries and releases its brooded embryos directly to the benthos, being exposed to potentially detrimental ultraviolet radiation (UVR) levels. In this study, we investigated how experimental radiation (PAR: photosynthetically active radiation; UVA: ultraviolet A radiation; and UVB: ultraviolet B radiation) influences burrowing (time, depth and speed) in adults and juveniles when they were exposed to PAR (P, 400–700 nm), PAR + UVA (PA, 315–700 nm) and PAR + UVA + UVB (PAB, 280–700 nm) experimental treatments. The role of sediment as a physical shield was also assessed by exposing anemones to these radiation treatments with and without sediment, after which lipid peroxidation, protein carbonyls and total antioxidant capacity were quantified. Our results indicate that PAB can induce a faster burial response compared to those anemones exposed only to P. PAB increased oxidative damage, especially in juveniles where oxidative damage levels were several times higher than in adults. Sediment offers protection to adults against P, PA and PAB, as significant differences in their total antioxidant capacity were observed compared to those anemones without sediment. Conversely, the presence or absence of sediment did not influence total antioxidant capacity in juveniles, which may reflect that those anemones have sufficient antioxidant defenses to minimize photooxidative damage due to their reduced tolerance to experimental radiation. Burrowing behavior is a key survival skill for juveniles after they have been released after brooding.

New in situ records of the sublittoral sea anemone Oulactis coliumensis (Riemann-Zürneck & Gallardo, 1990) are provided from different localities of northern Chile and Peru. Specimens were generally observed buried in shallow soft bottoms (3–25 m depth), near port cities and in areas with a high organic load. This is the first report of the species outside its type locality (off the Bay of Coliumo, Chile; ~36°S), extending its range of distribution to lower latitudes.

Non-indigenous species represent a significant threat to marine biodiversity, and accurate taxonomic identification is critical for effective management. This study revisits the long-standing record of the Australian sea anemone Oulactis muscosa in Argentina, which has been cited in numerous studies for nearly 50 years. We conducted a comprehensive taxonomic revision of specimens from Mar del Plata, Argentina, using both morphological and molecular analyses. Our findings reveal a persistent taxonomic error: the specimens belong to a different species. Detailed morphological comparisons and genetic sequencing of mitochondrial and nuclear markers re-identified the specimens as Anthopleura correae. This species is native to Brazil and is distributed from Ceará to Santa Catarina. This represents the first record of an Anthopleura species in Argentina, extending its known distribution. Genetic analyses confirmed the re-identification, showing no significant divergence between the Argentine and Brazilian specimens, while revealing notable differences from O. muscosa. We highlight the importance of rigorous taxonomic approaches integrating both morphological and molecular data to prevent misidentifications, which is particularly crucial when identifying potential invasive species. This study clarifies the taxonomic status of a regionally distributed species and contributes to the accurate inventory of sea anemones in Argentina.

The present review provides an in-depth look into the complex topic of delimiting species in sea anemones. For most part of history this has been based on a small number of variable anatomic traits, many of which are used indistinctly across multiple taxonomic ranks. Early attempts to classify this group succeeded to comprise much of the diversity known to date, yet numerous taxa were mostly characterized by the lack of features rather than synapomorphies. Of the total number of species names within Actiniaria, about 77% are currently considered valid and more than half of them have several synonyms. Besides the nominal problem caused by large intraspecific variations and ambiguously described characters, genetic studies show that morphological convergences are also widespread among molecular phylogenies. On the contrary, spatial distribution has been emerging as a more reliable parameter to explain cryptic relationships among sea anemones. Integrative approaches and genome-wide data have been especially helpful to unveil the mechanisms behind the speciation process, which is typically marked by large genetic differences among populations, even from neighbouring localities. This paper further discusses current gaps in our knowledge and offers some future directions on how to address the issue of species delimitation in the extremely polymorphic group of sea anemones.