Marine Decapod Research Articles

Tracking genetic and phylogenetic diversity across Brazilian ecoregions: A molecular ecology approach using marine decapod crustaceans

Abstract Genetic diversity is shaped by life history traits and environmental factors across the marine ecoregions of the world (MEOW), a condition that serves as a valuable framework to enhance our understanding of gene flow processes and identifying priority conservation centers among populations in different regions. We investigated the genetic and phylogenetic diversity of 13 decapod crustacean species distributed across the marine ecoregions of Brazil. We hypothesized that ecoregions act as barriers to gene flow, creating distinct population structures and varying genetic diversity levels. We examined how habitat type, bathymetry, geographical distribution, and larval development affect genetic diversity. Mitochondrial markers from 13 species of the four major decapod groups (Anomura, Brachyura, Caridea, and Penaeoidea) were analyzed using nucleotide diversity, haplotype networks, pairwise FST, and linear mixed-effects models (LMER). Results show no significant genetic structuring among ecoregions. Genetic diversity correlates with habitat type (P < 0.05), with species from less impacted areas, especially intertidal zones like rocky shores and estuaries, displaying higher diversity. Phylogenetic diversity (PD) and species richness (SR) varied, with the highest PD in eastern Brazil and the highest SR in southeastern Brazil. Intertidal zones showed the highest genetic diversity, likely due to their complex microhabitats and environmental variability. Our findings indicate that environmental and geographical barriers defined by the ecoregions do not significantly impede genetic connectivity among decapod crustaceans, which suggests that high dispersal potential of larval stages facilitates genetic flow across ecoregions. The results underscore the need for conservation strategies that consider the high genetic connectivity and diversity of marine species across broad spatial scales.

MiR-34 negatively regulates the expression of Dmrt and related genes in the testis of mud crab Scylla paramamosain

The mud crab (Scylla paramamosain) is a commercially significant marine decapod crustacean. Due to its obvious sexual dimorphism, the mechanism of sex differentiation and gonadal development has attracted significant research interest. The Dmrt (double-sex and mab-3 related transcription factor) genes are vital in animal gonadal development and sex differentiation. In the present study, miR-34 was predicted to target the 3′ end of Dmrt-1, idmrt-2, Dmrt-3, Dsx and Dmrt-like genes by prediction software, and the interactions between miR-34 and these Dmrt genes were validated by in vivo and in vitro experiments. Dual luciferase assay results indicated that miR-34 mimics/inhibitors co-transfected with plasmid vectors with 3′ end of Dmrt-1, idmrt-2, Dmrt-3, Dsx and Dmrt-like, respectively, led to a significant decrease/increase of fluorescence activity in HEK293T cells. In vivo experiments showed that injection of agomir-34 significantly inhibited Dmrt-1, idmrt-2, Dsx and Dmrt-like expression, while injection of antagomir-34 caused the opposite result. However, Dmrt-3 expression was not affected by injection of miR-34 reagents. Meanwhile, the expression of spermatogenesis and testicular development-related molecular marker genes (IAG, foxl2 and vasa) in mud crabs was significantly changed after injecting the miR-34 reagent in vivo. Furthermore, the result of immunoblotting proved that the expression level of Dmrt-like protein can be regulated by miR-34. These results imply that miR-34 is indirectly involved in sex differentiation and testicular development of S. paramamosain by regulating Dmrt-1, idmrt-2, Dsx and Dmrt-like genes.

Marine and estuarine crustacean diversity and assemblage structure in eastern Brazil three years after the Fundão mining dam failure

The present study investigates the spatial and temporal patterns of species richness and assemblage structure of decapod and stomatopod crustaceans in the area impacted by the Fundão dam collapse (Rio Doce basin, Brazil) in November 2015. From October 2018 to September 2019, monthly bottom-trawl samples were collected in estuarine and marine waters of the Rio Doce (directly impacted area) and three other localities. Forty-one crustacean species were recorded, with the overall community structure dominated by six species. The seabob shrimp Xiphopenaeus kroyeri was the most common species, with the coastal marine area near to the Rio Doce mouth being an important fishery ground. Species composition changed significantly among localities, habitats, and seasons, with marine and estuarine assemblages shaped by freshwater discharge. Distribution patterns of species were significantly influenced by the environmental variables potentially altered by tailings, such as turbidity and pH. Species richness and abundance differed among localities; as expected, they were generally higher on the inner shelf than in estuaries and higher during the dry season than the rainy season. Due to the lack of information before the disaster, the low number of species found in the Rio Doce estuary cannot be solely attributed to the disaster but also its freshwater condition. This is the first broad study of the estuarine and coastal marine decapod and stomatopod crustaceans in the region, and we suggest the need for long-term monitoring considering that the effects of this disaster are not easy to detect and probably need multi-year study to be evidenced.

Anthropogenic and biological sound effects on the maternal care behavior of a key crab species

IntroductionMaternal care in marine decapods involves eggs caring in the brood compartment until the larvae hatch. This behavior mainly allows embryo mass oxygen supply, ensuring healthy embryonic development. The present study aimed to analyze the effect of different sound sources (anthropogenic and biologic) and their temporal patterns (low and high rate: 1 min of the sound stimulus + 5 min of silence and 1 min of the sound stimulus + 1 min of silence, respectively) on the maternal care of the key crab species, Neohelice granulata.MethodsIn the laboratory, three acoustic stimuli were played back: an artificial white noise (10 Hz – 20 kHz), and two sounds obtained from the crabs´ natural habitat, motorboat passages and biological signals from a crabs’ predator fish. Three behavioral variables were quantified: still position, and two maternal care behaviors: abdominal flapping and chelae probing.ResultsResults demonstrated that the high rate anthropogenic stimuli, white noise and motorboat, affected all behavioral variables, increasing the still position and diminishing the maternal care behaviors. Otherwise, the predatory stimulus did not affect the still position although diminished the maternal care behaviors (high rate).DiscussionThe different behavioral response depending on the sound stimuli may indicate that crabs distinguish sound sources. The anthropogenic noise is suggested to cause distraction that is linked to the increased still position, while the predator stimulus would be associated with an alert behavior not affecting the locomotion behavior. The sound stimuli effect on the maternal care behavior revealed a negative effect that potentially could affect offspring survival. This is important considering the ecosystem engineering function of the studied key crab species. The reduction of the noise emission pattern rate is suggested as a mitigation action to diminish sound impact effects in the crab’s natural habitat. The study contributes the first to assessing the effect of different sound sources on the maternal care behavior of a crustacean species.

Review of the concept of Profilicollis Meyer, 1931 with a description of Profilicollis rancoensis n. sp. (Acanthocephala: Polymorphidae) from the freshwater crab, Aegla abtao Schmitt, 1942 (Decapoda: Anomura) in Chile, with a key to congeneric species.

Profilicollis rancoensis n. sp. is the tenth species of Profilicollis Meyer, 1931 which includes 9 other species mostly known from marine decapod crabs and shore birds. Cystacanths of P. rancoensis are described from the dominant freshwater crab Aegla abtao in Ranco Lake, Chile and are morphologically distinguished from cystacanths of the 9 other species based on a combination of 4 characters. These are body size, number of proboscis hook rows, number of hooks per row, and length of the largest anterior 2-4 hooks. Male and female cystacanths of P. rancoensis are 2.10-3.33 mm long having an ovoid proboscis with 14 rows of 6-7 hooks per row, with the largest anterior 2-4 hooks being 105-110 micrometers long; the anterior trunk has many small spines in 70-80 concentric rings, each with 50-60 spines around them; hook roots are simple, directed posteriorly, about as long as the blades anteriorly with unremarkable anterior manubria; the cephalic ganglion are in mid-receptacle just anterior to the level of the anterior trunk; the lemnisci are long and slender; the testes are in the anterior trunk, posterior trunk, or one in each; the primordia of 2 tubular cement glands are evident; strong bundles of fibers link the anterior and posterior trunk; and the posterior trunk has a corrugated surface cuticula. Molecular analysis (COI and 18S) sequences coincided with the morphology and support its taxonomy. The phylogenetic profile revealed that P. rancoensis n. sp. fell into the Profilicollis clade. Both sequences showed low genetic variation, and three different haplotypes were found. The new species was more closely related to P. botulus (Van Cleave, 1916) Witenberg, 1932 than to other Profilicollis species.

Additions to the marine decapod (Crustacea: Decapoda) fauna of South Africa

This report adds five previously unreported species to the decapod crustacean fauna of South Africa, as well as removing one species previously listed in error. It also documents locality (and/or reference specimen) data for 12 other species, most of which had been depicted in regional field guides, but without reporting when and where they had been collected. Almost all the species added were already known from adjacent African countries and their ranges are here extended into South Africa. Although some of these records are based on photographs, rather than collected specimens, it is argued that such records should be accepted as adequate evidence for inclusion of at least visually-distinctive crustacean species into the regional fauna.

Ecology and Diversity of Marine Decapod Crustaceans

Decapods are one of the most diverse crustacean orders, with around 17,500 extant species [...]

Size dependent egestion of polyester fibres in the Dublin Bay Prawn (Nephrops norvegicus)

Microplastics (MPs) are an extensive global contaminant in the marine environment, known to be ingested by marine organisms. The presence of MPs in the commercially important marine decapod crustacean Nephrops norvegicus (Dublin Bay Prawn) has been documented for the North-East Atlantic and the Mediterranean, however, uncertainties remain about retention times of MPs in the gastrointestinal tract (GIT) of this species. This study aims to investigate the retention times of polyester MP fibres of three sizes (3, 5, and 10 mm in length) and to determine whether the egestion of MP fibres is size and time dependent. Results suggest that MP fibres of different lengths are retained for different periods of time, with larger MP fibres being retained for longer periods (e.g., minimum 96 h for 10 mm fibres). The present study also assesses for the first time, the size dependent relationship of MP fibres under controlled conditions for N. norvegicus.

Long-Term Ammonia Toxicity in the Hepatopancreas of Swimming Crab Portunus trituberculatus: Cellular Stress Response and Tissue Damage

Ammonia is the most common contaminant in aquaculture systems. Due to the unexpected deterioration of natural seawater quality caused by harmful alga blooms in summer, the water exchange cycle for the culture ponds of the swimming crab Portunus trituberculatus, an important aquaculture species in China, is often much longer, and the crabs may be exposed to long-term ammonia stress. However, less information is available regarding the long-term effects of ammonia in marine decapod crustaceans. Therefore, it is of great significance to understand the toxic effects of prolonged ammonia in decapods. In this study, alteration of histology, cellular stress responses (CSRs), and apoptosis in the hepatopancreas of P. trituberculatus, an important aquaculture species, during ammonia stress (5, 15, and 45 mg⋅L–1) for 1, 7, and 15 days and recovery at the normal condition for 7 days, were analyzed. Our results demonstrated a serious impact of long-term (15 days) ammonia stress by depressing crab CSR especially when ammonia concentration exceeds 15 mg⋅L–1. Overall, short- (1 day) and medium-term (7 days) ammonia stress induced CSR, evidenced by upregulated expression of the genes involved in antioxidant defense (SOD, CAT, and GPX), apoptosis (p53, Bax, and Caspase-3), heat shock response (HSR) (Hsp70 and Hsp90), unfolded protein response (UPR) (IRE1, ATF6, and XBP1), and DNA damage response (DDR) (ATR and DNA-PKcs). However, long-term (15 days) ammonia stress, especially when exposed to the ammonia of 15 and 45 mg⋅L–1, resulted in a higher level of apoptosis and severe damage of hepatopancreas, which may be related to the depressed CSR including antioxidant defense, HSR, UPR, and DDR. Notably, after recovery, the expressions of many genes involved in apoptosis, antioxidant response, HSR, UPR, and DDR in the groups exposed to ammonia at 15 and 45 mg⋅L–1 were still significantly different to that of the control group. In summary, care should be taken when P. trituberculatus is exposed to ammonia over 15 mg⋅L–1 especially when exposure duration is longer than 15 days, as the CSR could be compromised. This study provides a reference for a comprehensive understanding of CSR in decapod crustaceans under ammonia stress and will be beneficial for management in the intensive culture of the swimming crab.

Metabolic changes in antennal glands of Caribbean spiny lobsters Panulirus argus infected by Panulirus argus virus 1 (PaV1).

Panulirus argus virus 1 (PaV1) (Family Mininucleoviridae) causes chronic and systemic infection in wild juvenile spiny lobsters Panulirus argus (Latreille, 1804), ending in death by starvation and metabolic wasting. In marine decapods, the antennal gland is involved in osmoregulation and excretion. In this compact organ, fluid is filtered from the hemolymph, and ions are reabsorbed to produce a hypotonic urine. Although PaV1 is released with the urine in infected individuals, little is known regarding the metabolic effect of PaV1 in the antennal gland. The objective of this study was to perform a comparative evaluation of the metabolic profile of the antennal gland of clinically PaV1-infected lobsters versus those with no clinical signs of infection, using proton nuclear magnetic resonance analysis. Overall, 48 compounds were identified, and the most represented metabolites were those involved in carbohydrate, amino acid, energy, and nucleotide metabolism. Most of the metabolites that were down-regulated in the infected group were essential and non-essential amino acids. Some metabolites involved in the urea cycle and carbohydrate metabolism were also altered. This study represents a first approach to the metabolic evaluation of the antennal gland. We broadly discuss alterations in the content of several proteinogenic and non-proteinogenic amino acids and other key metabolites involved in energetic and nucleotide metabolism.

An annotated and illustrated checklist of the porcelain crabs of Panama (Decapoda: Anomura).

The present study is the first exhaustive checklist of porcelain crabs (Porcellanidae) distributed on the Pacific and Atlantic (Caribbean) coasts of Panama, based on literature records and material collected between 2006 and 2019. The Panamanian porcellanid fauna is currently composed of a total of 76 species, with 26 species reported from the Caribbean coast, 45 species reported from the Pacific coast, and five species reported from both sides of the Central American Isthmus (Isthmus of Panama). In other words, the Caribbean and Pacific coasts of Panama each harbour, respectively, 31 and 50 species of porcellanid crabs. However, this total includes two problematic porcellanid records from Panama, viz. Clastotoechus nodosus (Streets, 1872) and Petrolisthes brachycarpus Sivertsen, 1933, as well as a putatively undecribed taxon reported as Pachycheles sp. The following four species are recorded for the first time from Panama, viz. Euceramus panatelus Glassell, 1938, Pachycheles riisei (Stimpson, 1859) [also being new for Mexico], Petrolisthes dissimulatus Gore, 1983 and P. tonsorius Haig, 1960. In addition, Minyocerus kirki Glassell, 1938 is newly recorded from Colombia, extending its previously known distributional range significantly southwards. Most species are illustrated in colour, several for the first time, based on material from Panama or other localities. At least 20 further species (16 in the Atlantic, 5 in the Pacific, and 1 in both oceans) are suspected to occur in Panamanian waters, based on their records from the neighbouring Costa Rica and/or Colombia, or their wide distribution in the Caribbean Sea or the tropical eastern Pacific. The presence of several cryptic or pseudocryptic species (at least some of them presumably undescribed), especially in the taxonomically challenging Petrolisthes galathinus (Bosc, 1802) species complex, or the eventual species splitting within some taxa currently seen as transisthmian, will likely further increase the total number of species present in Panama. The porcellanid fauna of Panama is also ecologically remarkably diversified. Most Panamanian porcelain crabs are free-living under rocks, in crevices of rocks, dead coral heads, coralline algae, coral rubble etc., or on mud, among mangrove roots. Euceramus panatelus lives in possibly self-dug burrows in soft mud or muddy sand, whereas its congener E. transversilineatus (Lockington, 1878) may occasionally be found in association with holothuroids. At least 15 further porcellanid species occurring in Panama live in permanent or facultative associations with a variety of other marine organisms, including sponges, cnidarians (octocorals), echinoderms (sea urchins, sea stars, sea cucumbers), polychaetes (parchment worms) and other decapod crustaceans (hermit crabs), making them one of the most attractive groups for studies of symbiosis-related behaviour and evolution.

Population level differences in overwintering survivorship of blue crabs (Callinectes sapidus): A caution on extrapolating climate sensitivities along latitudinal gradients.

Winter mortality can strongly affect the population dynamics of blue crabs (Callinectes sapidus) near poleward range limits. We simulated winter in the lab to test the effects of temperature, salinity, and estuary of origin on blue crab winter mortality over three years using a broad range of crab sizes from both Great South Bay and Chesapeake Bay. We fit accelerated failure time models to our data and to data from prior blue crab winter mortality experiments, illustrating that, in a widely distributed, commercially valuable marine decapod, temperature, salinity, size, estuary of origin, and winter duration were important predictors of winter mortality. Furthermore, our results suggest that extrapolation of a Chesapeake Bay based survivorship model to crabs from New York estuaries yielded poor fits. As such, the severity and duration of winter can impact northern blue crab populations differently along latitudinal gradients. In the context of climate change, future warming could possibility confer a benefit to crab populations near the range edge that are currently limited by temperature-induced winter mortality by shifting their range edge poleward, but care must be taken in generalizing from models that are developed based on populations from one part of the range to populations near the edges, especially for species that occupy large geographical areas.

Dietary preferences of brachyuran crabs from Taiwan for marine or terrestrial food sources: evidence based on fatty acid trophic markers

BackgroundTrophic interactions are key processes, which determine the ecological function and performance of organisms. Many decapod crustaceans feed on plant material as a source for essential nutrients, e.g. polyunsaturated fatty acids. Strictly herbivorous feeding appears only occasionally in marine decapods but is common in land crabs. To verify food preferences and to establish trophic markers, we studied the lipid and fatty acid composition of the midgut glands of two marine crab species (Grapsus albolineatus and Percnon affine), one semi-terrestrial species (Orisarma intermedium, formerly Sesarmops intermedius), and one terrestrial species (Geothelphusa albogilva) from Taiwan.ResultsAll species showed a wide span of total lipid levels ranging from 4 to 42% of the dry mass (%DM) in the marine P. affine and from 3 to 25%DM in the terrestrial G. albogilva. Triacylglycerols (TAG) were the major storage lipid compound. The fatty acids 16:0, 18:1(n-9), and 20:4(n-6) prevailed in all species. Essential fatty acids such as 20:4(n-6) originated from the diet. Terrestrial species also showed relatively high amounts of 18:2(n-6), which is a trophic marker for vascular plants. The fatty acid compositions of the four species allow to clearly distinguish between marine and terrestrial herbivorous feeding due to significantly different amounts of 16:0, 18:1(n-9), and 18:2(n-6).ConclusionsBased on the fatty acid composition, marine/terrestrial herbivory indices were defined and compared with regard to their resolution and differentiating capacity. These indices can help to reveal trophic preferences of unexplored species, particularly in habitats of border regions like mangrove intertidal flats and estuaries.

Unexpected Absence of Population Structure and High Genetic Diversity of the Western Atlantic Hermit Crab Clibanarius antillensis Stimpson, 1859 (Decapoda: Diogenidae) Based on Mitochondrial Markers and Morphological Data

Recent studies on genetic variability have revealed different patterns of genetic structure among populations of marine decapod species with wide geographical distribution. The hermit crab Clibanarius antillensis has a broad distribution along the western Atlantic Ocean, from south Florida (United States) to Santa Catarina (Brazil). This factor, in addition to differences in larval morphology and in adult coloration, makes this species a good model for studies on intraspecific variations. Therefore, we evaluated the molecular and morphological variability of C. antillensis along its distribution in order to check the levels of population structure. The results were based on the morphological analyses of 187 individuals and 38 partial sequences of the mitochondrial gene 16S rRNA and 46 of cytochrome c oxidase subunit I (COI) from specimens whose locations covered the whole species distribution. The molecular analyses did not show any apparent population structure of C. antillensis. This result was corroborated by the morphological analyses since the characters analyzed did not show any pattern of variation. Our results may be explained by a set of factors, such as the dispersive potential of the species and the absence of barriers that could prevent gene flow. In addition, high genetic diversity was observed, mainly for COI, which may be explained by the historical processes of the species, which seem to be in almost constant expansion in the last 700,000 years and experienced no genetic bottleneck. Apparently, this species was little affected by the climate fluctuations of Pleistocene. Additionally, our morphological analyses allowed us to present herein a redescription of the studied species since we noted differences from the characters in the diagnosis.

Non-invasive MRI Studies of Ventilatory and Cardiovascular Performance in Edible Crabs Cancer pagurus During Warming Under Elevated CO2 Levels.

The thermal tolerance of marine decapod crustacea is defined through their capacities for oxygen uptake and distribution. High ambient CO2 levels were previously shown to reduce hemolymph oxygen levels at enhanced cardiac performance during warming. This study investigated the impacts of warming under two CO2 levels on ventilation and hemolymph circulation in edible crabs Cancer pagurus. It also highlights changes in the ventilatory and cardiac pauses displayed by Decapoda under routine metabolism. Animals were exposed to step-wise, sub-critical warming (12–20°C over 5 days) under control (470 μatm) and high (1,350 μatm) water PCO2. Flow-through respirometry was combined with magnetic resonance imaging and infra-red photoplethysmography to allow for simultaneous, non-invasive measurements of metabolic rates (), ventilation and cardiovascular performance. Crabs spent significantly more time in a low state (metabolic pause), when experiencing high CO2 conditions above 16°C, compared to normocapnic warming. Heart rates leveled off beyond 18°C at any CO2 level. Cardiac output continued to increase with high-CO2-warming, due to elevated cardiac stroke volumes. Consequently, temperature-dependent branchial hemolymph flow remained unaffected by CO2. Instead, a suppressing effect of CO2 on ventilation was found beyond 16°C. These results indicate constrained oxygen uptake at stable cardiovascular performance in a decapod crustacean.Cancer pagurus: urn:lsid:zoobank.org:act:B750F89A-84B5-448B-8D80-EBD724A1C9D4

The positive effect of coexisting ecosystem engineers: a unique seaweed-mussel association provides refuge for native mud crabs against a non-indigenous predator.

In marine sedimentary bottoms, mussels and macroalgae have long been recognized as important autogenic engineers that create habitat and modify abiotic conditions. The structural complexity added by bivalves and macroalgae may also mediate intraguild predation amongst marine decapod crustaceans. While spatial distributions of these ecosystem engineers frequently overlap, there is limited understanding of compounded effects when more than one engineer is present. Here we demonstrate that the coexistence of two ecosystem engineers may create habitat valuable for the survival of a small native species, the Atlantic mud crab (Panopeus herbstii), in the presence of the invasive green crab (Carcinus maenas). Using laboratory and field habitat mimics, we measured mud crab survival rates as a proxy for refuge quality. We compared the refuge provided by a unique association between shells of blue mussels (Mytilus edulis) and the giant strain of Irish moss (Chondrus crispus) to that provided by bare substrate, and by each engineer alone. These experiments revealed that the association of giant Irish moss with blue mussel shells positively and non-additively increased mud crab survival compared to the other less complex habitat mimics. In contrast, parallel experiments revealed that high habitat complexity was less important for young green crabs to survive predation from large conspecifics. These results suggest that the impact of ecosystem engineers on trophic dynamics should be considered in a broader, whole-community context encompassing multiple habitat-forming species present.

Shape matters: relevance of carapace for brachyuran crab invaders

The increasing trend of biological invasions is one of the most concerning threats for ecosystems functioning. The identification of optimal characters determining the invasive potential of non-native species has always been a challenge in conservation studies. Morphological features can be used as a good proxy to address the invasive success in fish species, assuming that anatomical differences in comparison to native species can provide to newcomers ecological opportunities increasing their probability to become successful. Considering this, the present study constitutes the first applicative attempt of a model based on geometric morphometrics to demonstrate the importance of the carapace shape in the invasive ability in marine decapod crustaceans. The study was performed on the native brachyuran community of Alfacs Bay, in the Ebro Delta, the largest estuarine zone along the north-western Mediterranean, in which two recently established non-native crab species coexist: Dyspanopeus sayi and Callinectes sapidus. Results suggested that invaders with extreme carapace traits located peripherally in the community morphospace, such as C. sapidus, usually possess ecological advantages contributing to understand their success. Conversely, intermediate morphologies within the morphospace, such as D. sayi, imply ecological overlapping with native species reducing their community relevance. Besides, we also assessed the effect on the community morphospace of a hypothetical future invasive event from another crab species (Portunus segnis) with high probabilities to also colonize the community. Our outcomes confirm that the morphometric approach could be an alternative tool for assessing the potential ability of invasive crab species. However, further studies at different spatial and temporal scales, including additional traits and quantitative data from invasions, would be necessary to confirm the efficacy and usefulness of the methodology.

Hyalophysa lynni n. sp. (Ciliophora, Apostomatida), a new pathogenic ciliate and causative agent of shrimp black gill in penaeid shrimp

The parasitic ciliate causing shrimp black gill (sBG) infections in penaeid shrimp has been identified. The sBG ciliate has a unique life cycle that includes an encysted divisional stage on the host’s gills. The ciliature of the encysted trophont stage has been determined and is quite similar to that of the closely related apostomes Hyalophysa bradburyae and H. chattoni. Hyalophysa bradburyae is a commensal ciliate associated with freshwater caridean shrimp and crayfish, while H. chattoni is a common commensal found on North American marine decapods. Based on 18S rRNA gene sequence comparisons, the sBG ciliate is more closely related to the marine species H. chattoni than to the freshwater species H. bradburyae. The unique life cycle, morphology, 18S rRNA gene sequence, hosts, location, and pathology of the sBG ciliate distinguish this organism as a new species, Hyalophysa lynni n. sp.

Decapod crustaceans from the continental shelf of Sergipe, northeastern Brazil.

We evaluated the taxonomic composition of decapod crustaceans from the continental shelf of the Brazilian state of Sergipe. The specimens were collected during two field campaigns that covered the entire shelf length, at depths of 5-30 m. In the first campaign ("Petro-UFS"), four samplings took place between 1999-2000. In the second one ("Penaeid"), monthly samplings were carried out in 2013-2014, and covered an area at and between two important estuaries. Overall, we examined 74,387 decapod crustacean specimens. These specimens belonged to 27 families and 78 species, of which 26 species are newly recorded from Sergipe. Considering these results and previous records, Sergipe now has 121 species of marine decapod crustaceans, which represents only ~20% of the species recorded in the northern and northeastern Brazil. This gap indicates that the crustacean richness of Sergipe is probably underestimated and likely to increase with further samplings, especially on artificial rocky shores, rhodoliths and algae banks, small coralline formations, and other unexplored estuarine habitats.

New records of marine decapods and stomatopods in \xc1rea de Conservaci\xf3n Guanacaste (ACG): four years of marine biodiversity inventorying

The marine area of Área de Conservación Guanacaste (ACG) contains a 43,000 ha formal marine protected area, a 732 ha special management zone in Bahía Santa Elena, and 150 km of wild protected coastline. In an effort to broaden the biodiversity knowledge of all marine taxa present in the area, an inventory was started in 2015 (BioMar-ACG Project). This initiative is being funded by the Guanacaste Dry Forest Conservation Fund (GDFCF) in collaboration with government staff at ACG, and is carried out by Centro de Investigación en Ciencias del Mar y Limnología (CIMAR, Center for Research in Marine Science and Limnology) and Museo de Zoología (Zoology Museum), both from Universidad de Costa Rica (UCR). After four years of the project, 2650 specimens of marine decapod crustaceans and stomatopods have been collected, belonging to 209 species, out of which 99 are new records for ACG, four may be new species and nine (Cyrtoplax panamensis, Glyptoxanthus labyrinthicus, Pachyches marcortezensis, Petrolisthes donadio, Pylopagurus holmesi, Synalpheus pinkfloydi, Typton granulosus, Zenopontonia soror, Neogonodactylus pumilus) are new records for Costa Rica. With this contribution the total number of decapods (257 spp.) and stomatopods (14 spp.) for ACG is 271 species, more than half the species reported for Costa Rica, and more than a quarter of all crustaceans reported for the eastern tropical Pacific. The high concentration of species in ACG may be attributed to the diversity of habitats, the seasonal upwelling and to the recent sampling efforts. In only four years, the BioMar-ACG has increased the number of species in these groups of crustaceans by 37% over the past 85 years of previous studies in the ACG.