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Background: Caryophylliidae is one of the most diverse scleractinian families, however it was recovered as polyphyletic in multiple molecular studies. Recently, the mitochondrial gene order was proposed as a character for a taxonomic revision of the family. Here we describe the first mitogenome of the caryophylliid genus Crispatotrochus, whose phylogenetic position remains uncertain. Methods and results: The complete mitochondrial genomes of Crispatotrochus rubescens and Crispatotrochus rugosus were sequenced, assembled, and annotated. The two mitogenomes are identical and circular, have a length of 16,536 bp, a GC content of 35.9%, and contain 13 protein-coding genes, 2 ribosomal RNAs and 2 transfer RNAs. Both species have a transposition of a three gene block - cob, nad2, and nad6 - similarly to a group of caryophylliid genera that were recovered as monophyletic, including the type genus (Caryophyllia) of the family. The phylogenetic analyses recovered Crispatotrochus within the clade that presents the gene rearrangement and specifically as sister taxa of the genus Caryophyllia, a result consistent with previous studies and the similar gross morphology of the two genera. Conclusions: We determined the mitochondrial genomes of the genus Crispatotrochus to investigate their relations within Scleractinia. Results from this study provide insights on the phylogenetic position of the genus and corroborate that the mitochondrial gene order could be used as taxonomic character for the family Caryophylliidae. [ABSTRACT FROM AUTHOR]

Containing 51 extant genera and over 300 species, the family Caryophylliidae Dana, 1846 is reported from Antarctica to the Arctic, ranging from shallow to deep waters. Even though most caryophylliids are solitary, the majority of the most extensive deep-water reefs have their main engineers in colonial representatives of this family. However, several of these colonial species are small-sized and are usually found in shallow waters. Based on a study of colonies collected during scuba diving at Alcatrazes Archipelagos’ main island (São Paulo State) and Ilha Rasa (Rio de Janeiro), Brazil, a new species belonging to the genus Coenocyathus Milne Edwards & Haime, 1848 is described as C. sebroecki sp. nov. The species identity and its phylogenetic position within the Caryophylliidae could be distinguished by using morphological and genetic data. Also, the description of the cnidom of this species and remarks on its biology are provided, as well as a brief discussion on the polyphyly of the Caryophylliidae and an identification key for all extant Coenocyathus species. [ABSTRACT FROM AUTHOR]

Coral reefs globally are threatened by climate change, but reef assemblages at high latitudes may serve as refugia. Marginal coral communities located in the subtropical Southwestern Atlantic are poorly studied, but were subject to an unprecedented heatwave and associated coral bleaching in 2019. Record values of 18.5 and 20.5 °C-weeks were registered for coastal and insular sites, which are the highest ever documented for a reef in the South Atlantic. As a consequence, approximately 80% and 20% of the population of the reef-building coral Mussismilia hispida (1116 colonies surveyed) underwent bleaching in coastal and insular sites, respectively. However, mortality (2%) was far lower than for episodes of similar magnitude in other regions, particularly in the Indo-Pacific. Therefore, the subtropical Southwestern Atlantic MCC displayed low mortality and remarkable tolerance when exposed to the most intense bleaching episode ever recorded for the region, reinforcing its potential as a refugium. [ABSTRACT FROM AUTHOR]

Accidental introduction through ballast water and biofouling are currently the main factors responsible for spreading non-indigenous species in the marine realm. In the Southwestern Atlantic, two scleractinian corals, Tubastraea coccinea and T. tagusensis, have been introduced by opportunistic colonization in 1980 and are now widespread along more than 3,500 km of coastline. To better understand the invasion process and the role of vectors in spreading these species, we sampled 306 and 173 colonies of T. coccinea and T. tagusensis from invaded sites, possible vectors and one native population. Analyses revealed a higher diversity of multi-locus genotypes (MLGs) on vectors, suggesting that they were contaminated prior to their arrival in the Southwestern Atlantic, and a high proportion of clones at invaded sites, with few genotypes spread over ~2,000 km. This broad distribution is most likely a result of secondary introductions through the transport of contaminated vectors. Results also suggest the occurrence of multiple invasions, mainly in the northernmost sites. In summary, clonality, secondary introductions, and multiple invasions are the main reasons for the broad spread and invasive success of Tubastraea spp. in the Southwestern Atlantic. Consequently, the correct control of vectors is the most effective approach for management and prevention of new invasions. [ABSTRACT FROM AUTHOR]