Rocas Atoll Research Articles

Diel vertical migration and seamount stepping stones promote species connectivity from coastal to offshore insular systems in the Tropical Southwestern Atlantic

AbstractThe recruitment of marine species in isolated oceanic island systems can be challenged by prevailing currents, as exemplified by the Tropical Southwestern Atlantic. In this region, the Fernando de Noronha ridge hosts several seamounts, the Rocas Atoll and the Fernando de Noronha Archipelago, which are home to great marine biodiversity. However, along the ridge, the central branch of the South Equatorial Current (cSEC), flowing westward, poses a challenge to the recruitment of organisms toward Fernando de Noronha. To unveil critical insights into the intricate processes shaping biodiversity in these insular ecosystems, we use a dispersal Lagrangian tool to explore the role of diel vertical migration (DVM) to depth strata influenced by the South Equatorial Undercurrent (SEUC), which flows eastward bellow the cSEC, in shaping species dispersal and metacommunity dynamics. Our results show that while not a direct journey, the DVM into SEUC‐influenced strata increases the possibility that the seamounts and the Rocas Atoll act as stepping stones between the continental shelf and Fernando de Noronha. Propagules of organisms originating primarily from the continental shelf are transported to the western seamounts of the ridge. Upon reaching the western seamounts, organisms can find suitable habitats to recruit. The progeny of these communities that migrate to SEUC‐influenced strata have the opportunity to reach suitable habitats at the Rocas Atoll and the Eastern seamounts, ultimately connecting to the Fernando de Noronha archipelago. These results provide scientific fundaments for the development of a functional network of marine protected areas in the Tropical Southwestern Atlantic.

Pseudoscorpiones (Arachnida) of the Brazilian oceanic islands

Pseudoscorpiones are compose an ancient order of arachnids, occur in a wide variety of terrestrial habitats worldwide, with representatives of various genera occurring exclusively in insular habitats. The primary objective of this study was to determine the composition and distribution of Pseudoscorpiones within the Brazilian equatorial oceanic islands. To determine Pseudoscorpiones communities and distribution in coastal environmental habitats of the Brazilian equatorial oceanic islands (Fernando de Noronha archipelago, Rocas Atoll and St. Peter and St. Paul rocks), was defined three zones along the insular environmental gradient in the Brazilian equatorial oceanic islands. These zones include the Sand Beach (SB) closest to the intertidal zone, the Slope Forest (SF) with a sloping terrain and the Top Forest (TF) farthest from the beach. Collecting points were distributed in each zones (SB, SF, and TF) at distances greater than 1 km, with four samples collected at each point approximately 12.5 m apart from each other. The TF zone is observed only in Fernando de Noronha. In our study we found pseudoscorpions exclusively on the islands of the Fernando de Noronha archipelago. We collected 5 species from the Hesperolpiidae and Syarinidae families. The SF habitats exhibited greater species richness, while the Upper Forest habitats showed greater population abundance. Notably, we recorded pseudoscorpions (Ideoblothrus amazonicus) in bird nests (Sula dactylatra) on Rata Island, suggesting the use of nests as habitat, reproduction, and, possibly, occasional transport to and from other habitats. No pseudoscorpions were found in SB environments. Landscape changes and tourism can threaten this incredible newly discovered community, vital for monitoring environmental changes in this delicate ecosystem.

Toxoplasma gondii antibodies in tropical seabirds from the Rocas Atoll Biological Reserve, Brazil.

Toxoplasma gondii is a coccidian that infects almost all warm-blooded animals, including birds. Rocas Atoll Biological Reserve, located in the northeast of Brazil, is the only atoll in the South Atlantic, and home to the largest population of seabirds in the western Atlantic. In this study the occurrence of T. gondii antibodies in seabirds from Rocas Atoll were determined. Birds were manually captured, blood samples were taken, and antibodies detected by the modified agglutination test (>5). In total, 267 birds of seven species belonging to three families (Sternidae, Fregatidae and Sulidae) and two orders (Charadriiformes and Suliformes) were sampled. Out of the 267 samples, 20 (7.3%) were seropositive: nine out of 48 brown noddies (Anous stolidus), one out of 26 black noddies (Anous minutus), three out of 20 magnificent frigatebirds (Fregata magnificens), five out of 95 sooty terns (Onychoprion fuscatus) and two out of 20 red-footed boobies (Sula sula). None of the 33 masked boobies (Sula dactylatra) and the 25 brown boobies (Sula leucogaster) were seropositive. The antibody titers were 5 (n=6), 10 (n=4), 20 (n=3), 40 (n=6) and 160 (n=1). Due to the uniqueness of this environment, monitoring the seabirds is suggested to maintaining this Conservation Unit.

New species and record of Dodecaceria (Annelida: Cirratulidae) the Biological Reserve of Rocas Atoll, Brazil, the only atoll in the South Atlantic Ocean.

The polychaete Family Cirratulidae is one of the most abundant and diverse groups of Annelida, although it remains poorly known worldwide. Dodecaceria Ørsted, 1843 is one of the least described genera of Cirratulidae. The present report is the first taxonomic study of the genus Dodecaceria for the Brazilian coast. Cirratulidae were collected at Rocas Atoll, the first Brazilian marine protected area and the only atoll in the South Atlantic Ocean. We described one new species, Dodecaceria zelinhae n. sp., and a new record of D. dibranchiata Blake & Dean, 2019, previously only known from Panama. The new species is distinguished from other Dodecaceria species by having lateral tentacles, a smooth peristomium, 3-5 pairs of branchiae, hooks from chaetiger 11 in notopodia and 9 in neuropodia. Dodecaceria dibranchiata, a Caribbean species, is here recorded for the first time in the South Atlantic Ocean.

Daily variability of pH and temperature in seawater from a near-pristine oceanic atoll, Southwest Atlantic

The study of pH and temperature variability in reef environments, and the underlying processes that control this variability, is of great importance for ocean acidification research. Therefore, in the reef environment of Rocas Atoll, we conducted continuous monitoring of pH and temperature and periodic sampling of carbonate chemistry, and we hypothesize that seawater temperature is not the determining factor in the daily variability of pH at this atoll. Our results showed that the seawater of the atoll presented a high daily variability in pH, [H+], and temperature. The cycles of variations occurred primarily with a periodicity of ∼24 h, related to the daily light cycle, and secondarily with a periodicity of ∼12 h, associated with the semi-diurnal tidal cycles of the atoll. The results indicate that the relative balance of net organic carbon metabolism is the main process modulating carbonate chemistry on the atoll throughout the day.

Genetic diversity patterns of lionfish in the Southwestern Atlantic Ocean reveal a rapidly expanding stepping-stone bioinvasion process

In 2020, multiple lionfish (Pterois spp.) records along the equatorial Southwestern (SW) Atlantic revealed a new expansion of these potentially damaging invasive populations, which could impact over 3500 km of Brazilian coastline over the next few years, as well as unique ecosystems and marine protected areas in its path. To assess the taxonomic status, invasion route, and correlation with other centres of distribution, we investigated the genetic diversity patterns of lionfish caught in 2022 at the Amazonia, Northeastern Brazil, and Fernando de Noronha and Rocas Atoll ecoregions, using two molecular markers, the mitochondrial COI and the nuclear S7 RP1. The data indicate that all studied lionfish belong to what is generally accepted as P. volitans, and share the same genetic signature as lionfish present in the Caribbean Sea. The shared haplotypes and alleles indicate that the SW Atlantic invasion derives from an active movement of adult individuals from the Caribbean Sea into the Brazilian coast. The Amazon mesophotic reefs likely served as a stepping-stone to overcome the biogeographical barrier represented by the Amazon-Orinoco River plume. New alleles found for S7 RP1 suggest the onset of local genetic diversification, heightening the environmental risks as this bioinvasion heads towards other South Atlantic ecoregions.

Evidence of the Atlantic nurse shark (Ginglymostoma cirratum) population shrink at Rocas Atoll, Southwestern Atlantic

Abstract The Atlantic nurse shark, Ginglymostoma cirratum, was recently listed as Vulnerable by IUCN Red List, however, as highlighted, little is known about its populations in the Southwestern Atlantic. Therefore, population studies are essential to propose status evaluations and new conservation measures. Natural marks present on the animals' bodies are used as an alternative non‐invasive method rather than the usual tagging system for individual identification, thus avoiding the need for animal handling. This study aimed to evaluate the population size trend of G. cirratum at the Rocas Atoll Marine Biological Reserve, the only atoll located in the South Atlantic. Data were collected through underwater filming, photo‐identification, and visual censuses. Three expeditions were carried out in 2018 and the abundance of sharks was sampled in the inner part of Rocas Atoll Marine Biological Reserve. Sharks were identified individually with the aid of the software Interactive Identification System – Contour (I3S). Based on the re‐sightings of identified animals, two capture–recapture estimators of population size were used (Petersen–Bailey; Jolly–Seber). The estimates were then compared to the only previous estimate made 20 years before, which employed the same number of expeditions and estimators. A total of 139 sharks were identified from 444 sightings in 63 h of diving effort. Population estimates varied from 200 to 205 sharks, which are significantly lower than the previous estimate (339–368 sharks) made 20 years ago, suggesting a demographic decline in Southwestern Atlantic populations. Population studies and movement of G. cirratum are essential to inform the implementation of additional protective measures, including the establishment of protected corridors between marine protected areas and the recovery of G. cirratum populations. It is crucial to consider that the distribution of individuals may extend beyond the borders of the non‐take marine protected area. Therefore, the observed decline in the local population could potential indicate a broader decline across the Southwestern Atlantic.

Haemoproteus jenniae (Haemoproteidae, Haemosporida) infects gulls (Larus spp.) in South Africa, with redescription of Haemoproteus skuae.

Haemoproteus spp. are dipteran-borne protozoa that infect erythrocytes and reticulo-endothelial cells of birds. These parasites are not usually transmitted between birds belonging to different orders. The suborder Lari (order Charadriiformes) comprises ~170 avian species, the majority of which are aquatic, including gulls, terns, auklets, murres and skuas, among others. In spite of the diversity of this avian group, there is limited known diversity of haemosporidian parasites, with only 4 recorded Haemoproteus morphospecies thus far. We examined the blood smears of 21 kelp gulls (Larus dominicanus) captured at a breeding colony in South Africa, as well as Haemoproteus-positive archival blood smears of 15 kelp gulls and 1 Hartlaub's gull (Larus hartlaubii) sampled while under care at seabird rehabilitation facilities in South Africa. Haemoproteus sp. infection was detected in 19% of wild-caught kelp gulls. All parasites from the gulls were morphologically identified as Haemoproteus jenniae, a species previously recorded in Lari birds at the Galapagos Islands (Ecuador), Rocas Atoll (Brazil) and Poland. Gene sequencing uncovered a new cytochrome b lineage, LARDOM01, which was closely related to the previously reported H. jenniae lineage CREFUR01. Additionally, we evaluated a hapantotype blood smear of Haemoproteus skuae, which had been described infecting a brown skua (Catharacta antarctica) in South Africa. We provide a redescription of H. skuae and discuss the morphological characters distinguishing it from H. jenniae. Further research is necessary to improve our knowledge about the host and geographic distribution, health effects and phylogeny of H. jenniae and H. skuae.

Habitat use, non-breeding groupings and chromatic pattern in Johngarthia lagostoma (H. Milne Edwards, 1837) (Decapoda, Gecarcinidae) in Trindade Island, South Atlantic Ocean

The land crab Johngarthia lagostoma is endemic to Trindade Island, Atol das Rocas, Fernando de Noronha and Ascension Islands. The natural history of the species in non-breeding periods is little known. Therefore, here we reported the formation of non-breeding groups and evaluated the chromatic populational pattern of J. lagostoma in Trindade Island. Records were obtained between April and June 2015. The groups were characterized according to their location, terrain elevation, environmental characteristics and specimens’ behavior. The chromatic pattern was defined by the classification of individuals between yellow and purple, and the proportion of each color was compared between populational units (previously defined based on genetic differences). Non-breeding groups were recorded in four locations in Trindade Island, at altitudes < 40 m, and all of them were in locations with food resources and sediment suitable for the construction of shelters. Isolated individuals or the absence of the species were observed in the most inhospitable places, indicating that the maintenance of the species depends on portions of suitable habitat amid the currently arid matrix. Yellow individuals (96.4%) were predominant on Trindade Island and the chromatic pattern differed from the other populations. Color patterns seem to follow genetic differences between populations, and the founder effect may account for current patterns. From the data obtained, we emphasize that the maintenance of the species may depend on food, sediment suitable for shelters construction, humidity and shade. Due to the significant population decline in other regions, the need to define guidelines for the conservation of the species on Trindade Island is highlighted. In this context, the regeneration of insular vegetation and prohibiting the known anthropic consumption of individuals may represent important strategies for the maintenance of the species.

Influencing factors for microplastic intake in abundant deep-sea lanternfishes (Myctophidae)

Plastic debris is ubiquitous in the hydrosphere. Yet, we lack an understanding of contamination among deep-sea species and primarily how each trait can influence microplastic intake. We investigated microplastic contamination in the digestive tract of hyper-abundant mesopelagic lanternfishes (n = 364 individuals) from the Southwestern Tropical Atlantic, captured from 90 to 1000 m depth. Overall, microplastics were detected in most individuals analysed (frequency of occurrence = 68 %). Large microplastics, mostly of a filamentous shape were the most frequent, followed by smaller fragments and foams. Microplastics made of high-density polymers (PET, PVC, PA, SBR rubber) were more prevalent than low-density ones (PE, EVA and PBD rubber), especially under deeper layers. Larger microplastics were detected in lanternfishes captured off the northeastern Brazilian coast (mean 0.88 ± SE 0.06 mm) compared to those from around the Rocas Atoll and Fernando de Noronha Archipelago (0.70 ± 0.07 mm; p≤ 0.05), ∼350 km from the continent. Moreover, lanternfishes that migrate from the upper mesopelagic (200–500 m) to the epipelagic layers (<200 m) had simultaneously the highest intake and the smallest particles (1.65 ± 0.17 particles individual-1 and 0.55 ± 0.07 mm; p≤ 0.05). Biological mediated transport of microplastics from the epipelagic to the mesopelagic waters was evinced, but fishes foraging in shallower layers had the lowest intake (1.11 ± 0.10 part. ind.-1; p≤ 0.05). Furthermore, the jaw length was positively associated with an increment in microplastic intake (Incidence Rate Ratio = 1.1; p≤ 0.05). The lanternfishes that preferably prey upon fish larvae are more prone to microplastic intake than their counterparts, which forage mostly on crustaceans and gelatinous zooplankton (p≤ 0.05).

Extension of the known range of the snapping shrimp Alpheus christofferseni Anker, Hurt and Knowlton, 2007 (Caridea: Alpheidae)

Alpheus christofferseni Anker, Hurt and Knowlton, 2007 was described based on four specimens from Atol das Rocas, northeastern Brazil, and one specimen from Bocas del Toro, the Caribbean coast of Panama. Here, we report the collection of two specimens from Pernambuco, Brazil (~ 8°41’S), thus increasing the knowledge on species distribution along the Brazilian coast by approximately five latitudinal degrees south of its type locality (Atol das Rocas, Rio Grande do Norte, ~ 3°51'S). We also report a substantial increase in the known bathymetric distribution from shallow intertidal to approximately 51 m. Notes on morphological variation are provided based on the new material, and the first sequence of the 16S ribosomal subunit gene for the Brazilian coast is provided and compared with congeners.

New data on abundance of lemon shark Negaprion brevirostris (Poey, 1868) at Lama Bay, Rocas Atoll, Brazil

New data on abundance of lemon shark Negaprion brevirostris (Poey, 1868) at Lama Bay, Rocas Atoll, Brazil

New records of rare deep-sea fishes (Teleostei) collected from off north-eastern Brazil, including seamounts and islands of the Fernando de Noronha Ridge.

Here we report on new data on the occurrence and distribution of rare deep-sea fishes (Teleostei) collected from off north-eastern Brazil, including seamounts and oceanic islands of the Fernando de Noronha Ridge (Rocas Atoll and Fernando de Noronha Archipelago). Collections were made by the French RV Antea during the ABRACOS (Acoustics along the BRAzilian COaSt) expeditions between 29 September and 21 October 2015, and 9 April and 10 May 2017. Occurrences of Photostylus pycnopterus (Alepocephalidae), Gigantura chuni (Giganturidae), Ahliesaurus berryi (Notosudidae), Benthalbella infans, Rosenblattichthys hubbsi, Scopelarchoides danae (Scopelarchidae), Scopelengys tristis (Neoscopelidae), Zu cristatus (Trachipteridae), Stylephorus chordatus (Stylephoridae) and Pseudoscopelus cordilluminatus (Chiasmodontidae) are reported for the first time or confirmed in the Brazilian Exclusive Economic Zone. Photostylus pycnopterus and G. chuni are also recorded for the first time in the western South Atlantic, whereas records of P. cordilluminatus are the first in the western Atlantic. Other records of rare species of those families are also reported and discussed.

Brachyuran crabs (Crustacea, Decapoda) from the remote oceanic Archipelago Trindade and Martin Vaz, South Atlantic Ocean.

Forty species of shore and shallow water brachyuran crabs are reported from the remote oceanic Archipelago Trindade and Martin Vaz (TMV), 11 of which were previously known from Trindade Island, 28 are recorded from the Archipelago for the first time, and one is a new species, Epialtus parvulus sp. nov. This brings the total known shore and shallow water decapod fauna of TMV to 99 species. The opportunity is taken here to elaborate on the taxonomy of the species reported from TMV. One new genus, Mecataleptodius, is recognized for two species, Cancer parvulus Fabricius, 1793, its type species, and Cataleptodius olsoni Manning Chace, 1990, endemic to Ascension Island. The following seven nominal species are synonymized: Acanthonyx dissimulatus Coelho in Coelho Torres, 1993; A. scutiformis (Dana, 1851a); Dromia gouveai Melo Campos Junior, 1999; Epialtus portoricensis Rathbun, 1923; Ranilia guinotae Melo Campos Junior, 1994; R. saldanhai H. Rodrigues da Costa, 1970; and Omalacantha garthi (Lemos de Castro, 1953). TMV is a subset of the western Atlantic crab fauna (23 species or 57.5%), also including 8 (20%) amphi-Atlantic species, 3 (7.5%) amphi-American, 3 (7.5%) endemic, 2 (5%) cosmopolitan, 1 (2.5%) known from both sides of the Atlantic and the Indo-West Pacific. The crab fauna of TMV, Ascension (AS) and Saint Helena (SH) are compared with one another as well as with that of the oceanic islands Fernando de Noronha (FN) and the Rocas Atoll (RA) by means of nonmetric multidimensional scaling (NMDS) applied to a dissimilarity matrix generated by Jaccards coefficient. TMV-FN-RA and AS-SH clustered into two distinct groups according to the composition of their crab fauna. The NMDS analysis ranked the species that cause segregation of the crab faunal assemblages among TMV, AS, and SH, while revealing a gradient in species composition between the two groups of islands (TMV-FN-RA and AS-SH) formed by the amphi-Atlantic species. Island isolation, age and size alone do not explain the existing differences in species richness among TMV, AS and SH. The taxonomic composition of the shallow water fauna in these islands is likely to have been determined by several variables that were interwoven differently along their evolutionary history.

Ocean temperature and density dependence as key drivers of the population dynamics of an intertidal crab at the Brazilian oceanic islands

AbstractUnderstanding how climatic and density‐dependent processes affect demography is crucial for predicting population responses to climate change. For marine invertebrates with complex life cycle such as decapod crustaceans, increasing temperatures might affect survival and development of early pelagic stages, whereas high density can increase competition and thus reduce growth and fecundity of older life stages. In this study, we investigate the effects of warm ocean events, body size and density on the population dynamics of the intertidal Sally lightfoot crab (Grapsus grapsus) at the Brazilian oceanic islands. Firstly, we assessed the trends of marine heatwaves (MHW) and positive temperature anomalies (ΔSST+) at the equatorial St Peter and St Paul (SPSP) Archipelago and Rocas Atoll and the subtropical Trindade Island. We then jointly analyzed short‐term count, capture‐recapture and fecundity data, and long‐term population monitoring data (2003–2019) using an integrated population model. Warm ocean events have become more frequent and intense only at the equatorial islands. Increasing MHW frequency positively influenced recruitment in the high‐density SPSP population, while MHW intensity and ΔSST+ frequency had negative impacts. Conversely, no climatic effects were observed for the low‐density Rocas population, which has the largest crabs. Despite a lack of warming in Trindade, this subtropical population with intermediate density and body size was negatively affected by ΔSST+. Our findings revealed population‐specific responses to climate change when accounting for local life history and ecology. Thus, environmental and density‐dependent effects should be broadly considered in future conservation studies regarding ocean warming impacts on marine invertebrate populations.

Modern sedimentation and morphology of the Rocas Atoll shelf, and the role of Quaternary sea-level changes

The Rocas Atoll is in the Fernando de Noronha Fracture Zone South Atlantic Ocean and was developed on top of an ancient oceanic volcano, mainly during the Holocene. Quaternary sea-level fluctuations, especially during the last transgression, left geomorphic marks on the atoll and its surrounding shelf. This study investigated the shelf of Rocas Atoll based on single-beam, sonography, grabbed bottom sediments, and multi-temporal satellite imagery. The Rocas Atoll has a surrounding shelf with general E–W orientation, predominantly flat with a water depth of 25 m. The shelf break occurs between 45 and 50 m water depth, reaching up to 80 m locally on northwestern. Inner and outer shelf zones are marked by step-terrace features. The deepest break in relief (T1) occurs at ∼70 m water depth, a terrace (T2) at 40 m, and another terrace (T3) occurs at 30 m. Most of the hard-bottoms are reefs. Close to the atoll, in shallow depths, reefs occur aggregated, forming a tridimensional structure of low relief mounds and paths. As the water depth increases toward the outer shelf, the reefs occur isolated. The geomorphologic patterns of this shelf are analogous to the northeast Brazilian shelf, reflecting the influence of Pleistocene/Holocene sea-level oscillations. Furthermore, multi-temporal satellite images between 2001 and 2019 reveal that modern processes of reef erosion, as a response to decadal climate phenomena, intensify the shelf sedimentation, and the South Equatorial Currents shape the modern shelf and affect seasonally the sediment transport and sand body dimensions.

Paleo-sea levels, Late-Holocene evolution, and a new interpretation of the boulders at the Rocas Atoll, southwestern Equatorial Atlantic

Rocas Atoll is a remote place and the only atoll in the southwestern Atlantic Ocean. This study presents new paleo-sea level reconstructions and a new interpretation on former ones. The new data indicate that sea level was higher at the Late-Holocene than it is at present and that the hydrodynamic factors overlap with sea-level changes, precluding more precise paleo-sea level reconstructions. According to previous works, the Rocas Atoll presents one of the most conspicuous paleo-sea level indicators, represented by reef remains. But, in this paper, these supposedly reef remains are reinterpreted as algal-reef boulders detached from the atoll reef-front by high-wave energy events and deposited over the reef rim, where they remain detached or are cemented and, sometimes, mushroom shaped. It is considered that the bigger boulders may have been deposited in their current position by the cumulative effects of past energetic wave events. Furthermore, the use of beachrocks as paleo-sea level indicators in former studies is discussed, leading to the conclusion that they actually indicate beach progradation and lateral accretion resulting from a positive sand budget. Finally, a schematic morphological evolution of the atoll during the Late-Holocene is proposed. At the atoll, leveling with RTK and imagery with laser scanner were collected, and eleven radiocarbon ages were measured by accelerator mass spectrometry (AMS).

Wave climate and extremes on a mesotidal atoll lagoon

Processes on atolls and coral reef lagoons are defined by local wave and tide climates. Based on the reconstruction of lagoon wave climate by downscaling offshore historical wave information, this study aims to assess the wave climate and wave extremes on a mesotidal atoll lagoon (Rocas Atoll, Brazil). Results show that the transformation of offshore waves, when propagating into the lagoon, results in a different and far more homogeneous wave climate. Atoll morphology and tides play a key role in controlling the directional and energy characteristics of the lagoon wave climate. Refraction processes and the reef passage make the side protected from the dominant SE waves the most energetic zone for lagoon wave propagation. Lagoon waves tend to propagate in opposite directions to offshore wind waves, showing the refraction effect of approaching waves when crossing the atoll rim and the channel. The tidal effect on the dissipation process is also a filter for extreme wave conditions. We highlight the dependence of the resulting lagoon wave climate on atoll morphology, thereby addressing its implications to geomorphological process inside the atoll.

A New Species of Cyphocaris Boeck, 1871 (Amphipoda: Lysianassoidea: Cyphocarididae): Found off the Rocas Atoll, Northeastern Brazil

A new species of the genus Cyphocaris Boeck, 1871, is described. The material examined was collected during the “Acoustics along the Brazilian Coast” (Abraços 1) project, by micronektonic trawls at a targeted depth of 525 m, off the Rocas Atoll, Rio Grande do Norte state, Brazil. Cyphocaris boecki sp. nov. can be grouped with the eyed species in the genus but differs from them—except for C. faurei K. H. Barnard, 1916 and C. latirama, Hendrycks &amp; Conlan, 2003—in presenting a dorsally smooth pereonite 1. However, the new species can be distinguished from both by its maxilliped inner plate with two robust apical setae, pereopod 7 basis with weakly produced posterodistal lobe, telson lobes without setae, spines or apical nails, and other characters that are individually discussed among them. The new species can be readily differentiated from C. pedroi Sorrentino, Alves, Johnsson &amp; Senna, 2016, also described from Brazil, by presenting eyes, a rounded lateral cephalic lobe, very elongated antenna 2 almost reaching body length, and pereopod 5 basis, with apically acute spur reaching about two-thirds of the propodus. This is the second record of the genus for Brazilian waters.

Does the transport of larvae throughout the south Atlantic support the genetic and morphometric diversity of the Sally Lightfoot Crabs Grapsus grapsus (Linnaeus, 1758) and Grapsus adscensionis (Osbeck, 1765) (Decapoda: Grapsidae) among the oceanic islands?

Grapsus grapsus and Grapsus adscensionis are supralittoral crabs that are known to inhabit oceanic islands and depend on surface currents to recruit in the rocky shores. The ornamentation of the cephalothorax is very distinct among species, but morphological differences are controversial, and integrative studies with different approaches are needed. This study investigated the genetic variation among the populations of G. grapsus from Saint Peter and Saint Paul Archipelago (SP), Fernando de Noronha (FN), Rocas Atoll (RA) and Trindade Island (TR) in the western Atlantic, and G. adscensionis from the islands of Ascension (AI) and Saint Helena (SH) in the mid-Atlantic. Morphology was assessed by geometric morphometric analyses of the carapace and chelae, and numerical analyses of tubercles in the frontal plate of SP, FN, RA, TR and AI populations. In addition, dispersal of the larvae in the Atlantic Ocean was simulated performing a Lagrangian analysis using HYCOM reanalysis dataset as the ocean surface velocity field. The data obtained for the mitochondrial D-loop gene confirmed the distinctness of the two putative species and demonstrated the connectivity between the populations of G. grapsus from the three equatorial islands. The TR population presented unique haplotypes, as well as AI and SH. The geometric morphometric analyses showed differentiation between the carapace shapes for G. grapsus and G. adscensionis, however, the chelae shape does not allow to distinguish between the species or the population. The morphometric and molecular results were consistent with the pattern of particles dispersion in the Atlantic ocean. The larvae of SP, FN and RA mix after two months of drift, while the larvae of TR, AI, SH circulate only around the respective islands. The results reinforce the validation of the two species and the isolation of populations of G. grapsus in TR and of G. adscensionis in AI and SH. The populations of these islands might be maintained by self-recruitment, through larval behavior associated with the local current system, and therefore should be the target of conservation measures.