ABSTRACT Aim We evaluate the phylogenetic relationships and taxonomic validity of Atlantic species of Labrisomus , identifying the lineages currently assigned to L. nuchipinnis , and assessing the role of biogeographic barriers in shaping the evolutionary history and geographic distribution of the genus. Location Atlantic Ocean. Taxon Labrisomus . Methods We assembled an extensive mitochondrial and nuclear DNA dataset of Atlantic species of Labrisomus to perform multi‐locus phylogenetic divergence‐time and historical biogeographic analyses, reconstruct haplotype networks, estimate genetic distances, implement lineage delimitation tests and estimate migration rates. Results Labrisomus nuchipinnis is a species complex comprising three deeply divergent lineages: one broadly distributed in the western Atlantic, another restricted to Florida (USA), and a third mostly distributed in the eastern Atlantic. A new usage of L. nuchipinnis is proposed, with the species restricted to the western Atlantic, and with the revalidation of Clinus canariensis (as L. canariensis ) for the mostly eastern Atlantic lineage. Despite their anatomical similarity, L. nuchipinnis and its Atlantic congeners diverge significantly genetically. Unusual genetic connectivity between samples of L. canariensis from the eastern Atlantic and southern Brazil suggests a potential trans‐Atlantic genetic pathway. Main Conclusion The deep genetic divergence among lineages previously included in the L. nuchipinnis complex contrasts with their anatomical similarity, making Labrisomus one of the most challenging cases of cryptic diversification among reef fishes. The evolutionary history of the genus likely involved spatial segregation driven by ecological niche overlap. Ecological factors may influence distribution patterns among species of the genus more strongly than geographic distance. The apparently isolated population of L. canariensis off southern Brazil provides a well‐documented case of disjunct distribution of a reef fish species between the eastern Atlantic and south Brazil, highlighting the potential of this region as a melting‐pot of biodiversity.

The recent review by Veron et al. (2025) posits that quantitative genomic evidence used to understand coral evolution should be secondary to species hypotheses derived from expert opinion based on field experience. The authors argue that morphological “biological entities” should take precedence over molecular evidence when conflicts arise. This perspective required the rejection of extensive, independent molecular datasets that have progressively converged on a robust evolutionary framework for reef corals. Here, we reaffirm how prioritising subjective visual assessments over quantitative genetic and genomic data is methodologically unsound and scientifically regressive. We reject the framing of this perspective as “morphology versus molecules”. Rather, it is a fundamental divergence between two opposing philosophies: a static system anchored in non-reproducible expert judgement, and an integrative framework where genetic data provide the necessary independent test of morphological hypotheses. We show how a reliance on “field entities” obscures true morphological patterns by failing to distinguish between phenotypic plasticity, convergence, and evolutionary divergence. Effective taxonomy requires species hypotheses to be testable, and to stand or fall on the strength of reproducible evidence. Such a framework does not replace morphology; it validates it by providing an explicit, testable basis for evaluating morphological hypotheses. The integration of testable, reproducible molecular analysis with other lines of evidence including morphology is the benchmark of modern taxonomy across all Kingdoms of Life. We address the logical inconsistencies in the general arguments put forward by Veron et al. (2025) and refute their specific rejection of recent Acropora species-level revision with reproducible data.

Manta and devil rays comprise a vulnerable animal group with a complex nomenclatural history and a somewhat unresolved taxonomy. The existence of a putative undescribed species of manta ray in the Atlantic Ocean has been proposed for over 15 years. Molecular assessments have been crucial for improving our understanding of the evolutionary history and, therefore, species delimitation of this threatened group. Herein, morphological and molecular data from Western Atlantic specimens support the formal description of a new taxon assigned to the genus Mobula Rafinesque, 1810. Morphologically, this new mobulid species differs from its closest congeners (i.e., Mobula birostris and Mobula alfredi) on the stellate-shaped dermal denticle form and non-bifurcate ramification, the characteristic dorsal surface with V-shaped supra-branchial patches, ventral colour patterns, presence and feature of a caudal bulb with a residual spine, 9 to 13 rows of teeth, and overall morphometrics. Based on nearly complete mitochondrial genome and nuclear data, phylogeny reconstructions recovered the new species as a monophyletic lineage closely related to M. birostris and M. alfredi. To date, the new manta ray species has been recorded only in Atlantic waters, inhabiting oceanic islands and archipelagos as well as coastal and estuarine regions, areas under major threats due to pollution, boat strikes, coastal fisheries, and habitat degradation. Unfortunately, the species has been reported caught as bycatch, being either discarded, shared, or sold, in addition to boat strike and entanglement reports, suggesting that this new mobulid species, like all other mobulids, is likely threatened.

Records of non-native species in the Southwestern Atlantic reefs have increased alarmingly within the last two decades. Here, we provide the first report in the Southwest Atlantic of Neopomacentrus cyanomos (Bleeker, 1856), Regal Damselfish, a small reef species native to the Indian ocean and western Pacific, based on underwater observations made from three coastal islands in S & atilde;o Paulo State. Outside its natural range, N. cyanomos was previously recorded in the Northwest Atlantic and Southeast Atlantic, where it is often associated with oil and gas platforms, a pathway via which N. cyanomos probably was introduced to Brazil.

The family Madreporidae Ehrenberg, 1834 (Anthozoa, Scleractinia), includes some of the most important mesophotic and deep-sea habitat-forming species of stony corals. However, molecular data are completely lacking for some of its species, preventing the test of their phylogenetic position. The integration of molecular and morphological data in scleractinian taxonomy has revealed the presence of several para- or polyphyletic lineages, which in most cases are still waiting for a revision. Here, using a genomic approach that couples nuclear ultraconserved and exon loci and complete mitochondrial genome features, we investigate the phylogenetic position of three Madrepora Linnaeus, 1758 species - sequenced for the first time - and the genus Thalamophyllia Duchassaing, 1870. The latter has been historically assigned to the family Caryophylliidae Dana, 1846, but recent molecular studies have found it more closely related to the phylogenetically distant family Agariciidae Gray, 1847. Here, we present congruent nuclear and mitochondrial results placing the species Madrepora carolina (Pourtalès, 1871) and the genus Thalamophyllia inside the family Agariciidae. Specifically, both taxa present the canonical mitochondrial gene order - shared with the family Agariciidae and the majority of stony corals - while lacking the specific gene transpositions characteristic of the families Madreporidae and Caryophylliidae, respectively. The genus Thalamophyllia and the species M. carolina are, therefore, formally moved to the family Agariciidae, and M. carolina is accommodated in a new genus (Pseudomadrepora Vaga Quattrini gen. nov.). The results of this study uncover another case of macromorphological skeletal convergence in the order, while untangling the relationship of some deep-water scleractinian taxa.

Anthropogenic climate change combined with the 2023–24 El Niño-Southern Oscillation triggered the fourth global bleaching event, affecting coral reefs worldwide. However, the extent of its impacts on the unique and extensive reef environments in the Southwestern Atlantic remained unquantified. Here, we report results from the first large-scale, standardized bleaching monitoring effort in the Southwestern Atlantic, encompassing 18 reef sites across a broad latitudinal range (3°-27°S). The intensity and duration of the thermal stress experienced were evaluated using the Degree Heating Week metric, obtained through remote-sensing data. Bleaching and coral cover loss were monitored through photoquadrat surveys conducted before, during, and after the event. Our results revealed widespread thermal anomalies that often exceeded 20 °C-weeks and lasted 3–5 months. Bleaching incidence reached 96

Critical knowledge gaps hamper effective conservation of threatened cold‐water coral (CWC) ecosystems, facing cumulative anthropogenic and climate pressures. This review provides a strategic roadmap for urgent, informed intervention. This review synthesizes global expert consensus to identify and prioritize key knowledge gaps impeding CWC conservation and restoration. Our objective is to provide a strategic roadmap for research, funding, and policy over the next decade. Through literature synthesis and a global expert panel (i.e. the authors), we identified and prioritized critical knowledge gaps in CWC conservation and restoration. Priorities were defined as challenges addressable within a decade through focused international collaboration and funding. We identified 10 knowledge gaps across five themes, including CWC status and distribution, community composition, early life history, metapopulation dynamics and connectivity, growth, and food dynamics. We then provide recommendations for international policy that would support CWC protection. Addressing these research priorities is a prerequisite for effective conservation strategies. A coordinated international effort is crucial over the next decade to translate this knowledge into actionable plans and prevent irreversible biodiversity loss.

Southwestern Atlantic reefs are experiencing increased bleaching-associated mortality, prompting the proposal of active coral restoration as a solution. However, this approach faces challenges such as genetic bottlenecks, cost, scale, survival amidst local and global impacts, and long-term efficacy. Thus, we reviewed the major attributes of Southwestern Atlantic reefs and their coral species to assess the feasibility of active coral restoration in this unique biological and oceanographic setting. We also examined existing restoration techniques and their applicability to Southwestern Atlantic coral species and reef sites. Few species meet both suitability and priority criteria for restoration, with only Millepora alcicornis, Mi. braziliensis, and Mi. nitida, and, to a lesser extent, Mussismilia braziliensis emerging as relevant candidates. In this low-diversity region, suitable species are scarce, and identifying suitable restoration sites is challenging due to widespread local impacts and ineffective policy enforcement. We propose that practitioners (i) master species-specific fragmentation, handling, care, and monitoring techniques; (ii) align restoration practices with scientific knowledge; (iii) avoid combining multiple interventionist techniques; (iv) acknowledge potential conflicts of interest in restoration practices; and that (v) government agencies oversee restoration activities, and that transparency reports be generated. Southwestern Atlantic reefs need custom-designed conservation measures, and baseline data is essential for identifying suitable restoration sites. Although few species are viable candidates for restoration, and its effectiveness in restoring degraded reefs is unproven under current climate conditions, following the proposed ethical and ecological guidelines may help sustain threatened species and ecosystem services in degraded areas until climate change policies take effect.

Azooxanthellate scleractinian corals, a group of species that lack a symbiotic relationship with dinoflagellates, are influenced by environmental variables at various scales. As the global commitment to sustainably manage ocean ecosystems and resources rises, there is a growing need to describe biodiversity trends in previously unsampled areas. Benthic invertebrate research in South Africa is a developing field, and many taxa in deep water environments remain inadequately characterized. Recently, the South African azooxanthellate scleractinian fauna was taxonomically reviewed, but their distributional correlations with physical parameters have not been studied. Here we aim to understand the biodiversity gradients of the South African azooxanthellate coral fauna by analysing the environmental correlates of museum samples. The associated coordinate data were georeferenced and depth obtained from a national bathymetric dataset, prior to undertaking a multivariate analysis. This analysis encompassed several steps, including the grouping of the longitude and depth data (environmental data), identifying families characteristic of the group variability, and examining the correlation of the associated data with the biological data. Additionally, the analysis involved quantifying diversity patterns along the environmental gradients. Overall, our results confirmed two longitudinal groups (eastern margin [Group A] vs southern and western margin [Group B]) and 11 depth categories represented within two bathymetric zones (shallow [50-200 m] and deep [300-1000 m]). Caryophylliids, flabellids, and dendrophylliids contributed the most towards distinguishing longitudinal and depth gradients. Both abiotic variable (longitudinal and depth) partially explained coral distribution patterns, with depth being highly correlated to the species variation observed. Data limitations within our data set resulted to unexplained variance, however, despite these limitations, the study demonstrates that historical museum samples provide a valuable data source that can fill research sampling gaps and help improve the understanding of biodiversity patterns of the coral fauna in under sampled marine ecosystems.

Atlantic reef-building corals and coral reefs continue to experience extensive decline due to increased stressors related to climate change, disease, pollution, and numerous anthropogenic threats. To understand the impact of ocean warming and reef loss on the estimated extinction risk of shallow water Atlantic reef-building scleractinians and milleporids, all 85 valid species were reassessed under the IUCN Red List Categories and Criteria, updating the previous Red List assessment of Atlantic corals published in 2008. For the present assessment, individual species declines were estimated based on the modeled coral cover loss (1989-2019) and projected onset of annual severe bleaching events (2020-2050) across the Atlantic. Species traits were used to scale species' relative vulnerability to the modeled cover declines and forecasted bleaching events. The updated assessments place 45.88%-54.12% of Atlantic shallow water corals at an elevated extinction risk compared to the previous assessments conducted in 2008 (15.19%-40.51%). However, coral cover loss estimates indicate an improvement in reef coverage compared to the historic time-series used for the 2008 assessments. Based on this, we infer that, although remaining dangerously high, the rate of Atlantic reef coral cover decline has surprisingly slowed in recent decades. However, based on modeled projections of sea-surface temperature that predict the onset of annual severe bleaching events within the next 30 years, we listed 26 (out of 85) species as Critically Endangered in the IUCN Red List. Each of these species had previously been listed under a lower threatened category and this result alone highlights the severe threat future bleaching events pose to coral survival and the reef ecosystems they support.

Deep waters (>150 m) shelter half of the extant diversity of scleractinian corals, including framework reef- forming species. However, to date, the relationship between microorganisms and corals has focused mainly on their zooxanthellate shallow-water counterparts. Here, using 16S rRNA gene amplicon sequencing, we explore the microbiome of all major Atlantic deep-water scleractinian reef framework engineers ( Desmophyllum pertusum, Solenosmilia variabilis, Madrepora oculata, and Enallopsammia rostrata), and correlated them with environmental characteristics. Colony fragments of each coral species used in the present study were sampled from three sedimentary basins off the Southeastern coast of Brazil, including two water masses (Antarctic Intermediate Water and South Atlantic Coastal Water). Although representing distant scleractinian evolutionarily lineages, some evolving apart for more than 300Ma, our results suggest a taxonomic homogeneity in their microbial profile. The species-specific microbial core, as well as the core common to all examined species, were identified. Such cores are composed of bacterial genera that have already been observed in other coral species, including those from zooxanthellate species. Such a pattern suggests an active selection of the microbial community by their hosts, a phenomenon that seems to be fundamental for holobiont fitness, especially in long-lived species, such as corals. Besides the microbial core, for all examined species, part of the determined microbiome was flexible and responded to environmental drivers. This flexibility is most probably related to the host's ability to adapt in ecological time scales. Taken together, these holobiont abilities may be crucial to its success in both ecological and geological timescales.

Endemic to the Brazilian fauna, the brain coral Mussismilia hispida is the second most widespread zooxanthellate coral of the South-west Atlantic and, most importantly, is within the main reef-building species of the region. Counterintuitively, M. hispida has one of its most abundant populations near its southernmost distributional limit, the Alcatrazes Archipelago off the coast of São Paulo State. On this archipelago, colonies thrive from 2 to over 20 m deep, and in some localities, M. hispida covers more than 50

The limited temporal completeness and taxonomic accuracy of species lists, made available in a traditional manner in scientific publications, has always represented a problem. These lists are invariably limited to a few taxonomic groups and do not represent up-to-date knowledge of all species and classifications. In this context, the Brazilian megadiverse fauna is no exception, and the Catalogo Taxonomico da Fauna do Brasil (CTFB) (http://fauna.jbrj.gov.br/), made public in 2015, represents a database on biodiversity anchored on a list of valid and expertly recognized scientific names of animals in Brazil. The CTFB is updated in near real time by a team of more than 800 specialists. By January 1, 2024, the CTFB compiled 133,691 nominal species, with 125,138 that were considered valid. Most of the valid species were arthropods (82.3%, with more than 102,000 species) and chordates (7.69%, with over 11,000 species). These taxa were followed by a cluster composed of Mollusca (3,567 species), Platyhelminthes (2,292 species), Annelida (1,833 species), and Nematoda (1,447 species). All remaining groups had less than 1,000 species reported in Brazil, with Cnidaria (831 species), Porifera (628 species), Rotifera (606 species), and Bryozoa (520 species) representing those with more than 500 species. Analysis of the CTFB database can facilitate and direct efforts towards the discovery of new species in Brazil, but it is also fundamental in providing the best available list of valid nominal species to users, including those in science, health, conservation efforts, and any initiative involving animals. The importance of the CTFB is evidenced by the elevated number of citations in the scientific literature in diverse areas of biology, law, anthropology, education, forensic science, and veterinary science, among others.

Mobulidae is a monophyletic family within the Myliobatiformes that comprises pelagic species represented by manta and devil rays. Among the genus Mobula, the Atlantic Pygmy Devil Ray - Mobula hypostoma - is reported in coastal regions exclusively in tropical and subtropical Atlantic Ocean from 1 to 100 m deep. In Brazil, M. hypostoma is one of the least studied Mobula species. It is regularly misidentified, especially as Mobula thurstoni, and is commonly listed as bycatch, in fishery inventories, or related to opportunistic sightings in the national territory. Here, we describe the complete nucleotide sequence of the mitochondrial genome (mitogenome) from Mobula hypostoma, which is 18,141 bp in length and comprises 13 protein-coding, two ribosomal RNA, and 22 transfer RNA genes. The M. hypostoma mitochondrial genes organisation and mitochondrial genome length are similar to other Mobula species, and the phylogenetic reconstruction indicates M. hypostoma as closely related to Mobula munkiana. The Brazilian mitogenome of M. hypostoma is expected to be a valuable resource for molecular-based species identification, and evolutionary and phylogeography studies.

Once considered the most speciose mostly azooxanthellate scleractinian group, the family Caryophylliidae is found to be highly polyphyletic based on molecular data and is undergoing a process of systematic revision. High-throughput sequencing methods coupled with morphological analyses have facilitated revision of several scleractinian lineages, including the aforementioned family. In previous studies that relied on few mitochondrial and nuclear markers, the caryophylliid genera Stephanocyathus and Vaughanella were phylogenetically recovered in separate clades from the lineage that includes the type genus of the family, Caryophyllia, which is considered the 'true' Caryophylliidae. To help untangle the relationship among taxa of this family, here a new deep-sea scleractinian family (Stephanocyathidae Vaga, Cairns & Kitahara fam. nov.) is proposed based on phylogenomic reconstructions coupled with molecular features, specifically gene order, of the complete mitochondrial genome. Evolutionary reconstructions were based on both mitochondrial and nuclear ultraconserved elements (UCEs) and exon loci data sets and confirmed the divergent position of the genera Stephanocyathus and Vaughanella. The new family shows a specific gene transposition in the mitochondrial genome, not present in the 'true' caryophylliid lineage, but instead already observed for the species Paraconotrochus antarcticus, recovered as sister taxon of the here proposed new family. Although its phylogenetic position is unknown, the genus Ericiocyathus is also added to the new family, based on macromorphological similarities. This study represents a step forward in our understanding of deep-sea corals relationships and provide further information (e.g., mitochondrial gene order) that will aid in future efforts of assessing the systematic of caryophylliid lineages.

Corals are early-branching animals highly reliant on diverse symbionts for growth and reproduction. Most coral groups, including stony corals and hydrocorals, exhibit deep genetic divergence between the Atlantic (ATO) and Indo-Pacific (IPO) oceans, hampering their direct comparison. Although sibling zoanthid species (Hexacorallia: Zoantharia) deviate from this pattern, their symbioses have so far only been studied on local scales. Here, we examined the microbiomes of Palythoa caribaeorum from the ATO and P. tuberculosa from the IPO. Our extensive geographical sampling and metabarcoding revealed that Palythoa microbiomes have similar alpha diversity in both oceans. The primary exceptions are the symbiodiniacean Cladocopium and Chlamydiae bacteria, which mirror the global diversity patterns of corals. Despite distinct overall microbial compositions between oceans, some regions shared remarkably similar communities, hinting at the importance of both symbiont phylogeny and function. Finally, we explore the shift from commensal/mutualistic microbes to opportunistic pathogens, crucial amid the ongoing en-vironmental changes. ### Competing Interest Statement The authors have declared no competing interest.

Mass bleaching events are growing in duration and intensity. Besides causing extensive mortality, the progressively shorter time between events disrupts the ability of reefs to recover. The unique reefs of the Southwestern Atlantic are often considered climate refugia as they have suffered less bleaching-related mortality when compared to Indo–Pacific and Caribbean reefs. However, their recovery capacity still requires investigation. In 2019, an unprecedented heatwave triggered the most severe bleaching episode recorded for Southwestern Atlantic reefs. Therefore, this study aimed to (i) document the bleaching incidence and mortality during the heatwave, and (ii) assess coral recovery over 3 years. We measured bleaching incidence and monitored coral cover through surveys in three Southern Bahia (central Brazilian coast) reefs before, during and after thermal stress. Our findings show that coral assemblages were exposed to a 5-month-long thermal anomaly, experiencing thermal stress peaking at 14.1 ºC-weeks. Roughly 70

The integration of morphological and molecular lines of evidence has enabled the family Deltocyathidae to be erected to accommodate Deltocyathus species that were previously ascribed to the family Caryophylliidae. However, although displaying the same morphological characteristics as other species of Deltocyathus, molecular data suggested that D. magnificus was phylogenetically distant from Deltocyathidae, falling within the family Turbinoliidae instead. To elucidate the enigmatic evolutionary history of this species and skeletal microstructural features, the phylogenetic relationships of Deltocyathidae and Turbinoliidae were investigated using nuclear ultraconserved and exon loci and complete mitochondrial genomes. Both nuclear and mitochondrial phylogenomic reconstructions confirmed the position of D. magnificus within turbinolids. Furthermore, a novel mitochondrial gene order was uncovered for Deltocyathidae species. This gene order was not present in Turbinoliidae or in D. magnificus that both have the scleractinian canonical gene order, further indicating the taxonomic utility of mitochondrial gene order. D. magnificus is therefore formally moved to the family Turbinoliidae and accommodated in a new genus (Dennantotrochus Kitahara, Vaga & Stolarski, gen. nov.). Surprisingly, turbinolids and deltocyathids do not differ in microstructural organisation of the skeleton that consists of densely packed, individualised rapid accretion deposits and thickening deposits composed of fibres perpendicular to the skeleton surface. Therefore, although both families are clearly evolutionarily divergent, macromorphological features indicate a case of skeletal convergence while these may still share conservative biomineralisation mechanisms. ZooBank: urn:lsid:zoobank.org:pub:5F1C0E25-3CC6-4D1F-B1F0-CD9D0014678E

Sun corals (Tubastraea spp.) have invaded the SW Atlantic coast in the 1980s, saturating vertical walls at heavily impacted areas. More recently, the boring bivalve Leiosolenus aristatus, another invasive species in the SW Atlantic, was found inhabiting sun corals. Here we show that Tubastraea tagusensis is the main coral host for L. aristatus at an extensively invaded island in Southeastern Brazil. Bivalve biomass adjusted to colony volume was similar between invasive T. tagusensis and native corals. However, when adjusted to colony basal area per reef space, bivalve density was exceptionally higher in sun corals, especially on vertical substrates or those with negative orientation. Therefore, sun corals constitute main doorways for borer bivalves at most invaded reefs. Moreover, and owing to the phaceloid colony morphology of T. tagusensis, boring bivalves reduce, on average, the contact area between sun corals and the substrate in 9.6% (SD = 9.9), ranging from 1 to 44%. Regardless of sampling site and reef inclination, the decrease of such surface contact area causes a drop of sun-coral adhesive strength (from 36 to 22 kgf), that can be described by a general exponential decay function, and explain the accumulation of coral debris at the bottom of invaded reefs. While possibly ceding space for native species in the reef community, dislodgment through bivalve infestation may eventually reduce intraspecific competition among sun-coral colonies and favor resettlement in alternative reef habitats, ultimately contributing to the ongoing invasive process.