RCAAP Repository

Abstract The aim of this study was to investigate the spatial and temporal distribution of Exhippolysmata oplophoroides and relate its abundance to various environmental variables (bottom water temperature and salinity, texture of sediment and percentage of dissolved organic matter). The sampling of shrimp and abiotic factors was carried out monthly from July 2012 to June 2014, in seven trawling stations (S1-S7), four of them in the marine area and three in the estuary (southern coast of the state of São Paulo, Brazil). The distribution of individuals showed significant differences between stations and between the two years of study (ANOVA, p < 0.05), but not among seasons (p > 0.05). A total of 2005 shrimp were collected, with the highest abundance being found in S4 (n= 937). Bottom salinity and sediment texture were the environmental factors with significant influence on the distribution of the species in the studied region. The low salinity values at S6 and S7, and the low capacity for osmoregulation of E. oplophoroides limit its distribution in the marine environment. High concentrations of silt+clay found at S4 contributed to the accumulation of organic matter, which influenced the high abundance of shrimp there. The information gathered in our study provides valuable results for the knowledge of this species in its area of distribution and contributes to a better understanding of the life history.

Abstract The purpose of this study was to describe the structure of the midgut (hepatopancreas and intestine) in the endemic species, Macrobrachium carcinus. Thirty specimens were collected, and the midgut was fixed in Bouin's solution for histological and histochemical analyzes by light microscopy. The hepatopancreas consists of two lobes that connect to the end of the stomach by primary ducts, which originate secondary tubules or hepatopancreatic ducts, that branch into hepatopancreatic tubules. The hepatopancreatic duct presents a columnar epithelium composed of R- and F- cells with evident brush borders for absorption and storage. The hepatopancreatic tubule is lined by epithelium with five cell types (E, F, R, B, and M). The distal region presents all cell types, with a predominance of E-cells that correspond to epithelial renewal. The middle region presents F- and B- cells, characteristic of extracellular and intracellular digestion. The proximal region, with B- and R- cells, performs the final digestion, storage, and extrusion of the cells with waste material. The intestine is lined by a single cell type with an evident brush border, suggesting luminal absorption. This cellular arrangement along the length of the midgut proposes distinct morpho-functional characteristics of digestion, absorption, and storage in this species.

Abstract Alpheus platycheirus Boone, 1927 (Decapoda, Alpheidae) is a snapping shrimp widely distributed in the western Atlantic, from the Gulf of Mexico to eastern Brazil. This shrimp usually inhabits muddy marine bottoms; however, here we record for the first time A. platycheirus in association with Thalassia testudinum and Halodule wrightii meadows at an unusually shallow depth in northwest Venezuela. This record extends the known habitat and distribution of A. platycheirus in the Caribbean. Moreover, it represents an additional alpheid species for Venezuela, bringing the known total to 34 species.

ABSTRACT The relationship between color and size supports the hypothesis that color is an important signal for some crab species during mating rituals or agonistic interactions. Thus, the objective of this study was to describe the color variation of D. pagei and its relationship with sex and sexual maturity. The crabs were placed on a surface for photographic recording of the body parts: cephalothorax, chelipeds, abdomen and pereiopods using a digital camera installed on a photographic table. Images were converted to the spectrum of red, green, blue and also of them combined (RGB). The values of each spectrum revealed that the color variation of the cephalothorax and chelipeds were different between adults and juveniles. The abdomen and pereiopods showed color variation in both sexes and at developmental stages. The pattern of color variation observed in juveniles ranged from light to dark brown and adults are from orange to intense red. The change in color of the cephalothorax and chelipeds could be used as a character to determine the onset of sexual maturity. The high color variation of the abdomen and pereiopods in both sexes and at developmental stages, though, indicates individual variation which probably is associated with other factors, such as molt stage or even the quality of food available.

Abstract A new behavior related to shell care was recently reported for the intertidal hermit crab Clibanarius erythropus (Latreille, 1818) in the Gulf of Cádiz (southwestern Europe). It also has been observed in other species of the diogenid genera Clibanarius Dana, 1952, and Calcinus Dana, 1951, however, it has not been described as an active behavior. In the present study, intertidal hermit crabs from different species and localities were sampled to assess if air-exposure is a shell cleaning behavior restricted to some species of intertidal hermit crabs or if it is a more generalized behavior among species inhabiting intertidal habitats. The results revealed that air-exposure is an active behavior in species of Clibanarius and Calcinus, since we observed it also in Clibanarius albidigitus Nobili, 1901, and Calcinus obscurus Stimpson, 1859, from the Pacific coast of Costa Rica, although not in other intertidal species studied by us. We found interspecific differences in tolerance to physical stress of emerged hermit crabs. This air-exposure tolerance can be interpreted as a physiological adaptation to desiccation stress and is also related to the shell type they inhabit. Also, we provide additional features and details of the air-exposure behavior, combining observations of the first description in 2015 with our new field observations.

Abstract The influence of salinity on the survival of the larvae of Leptuca leptodactyla (Rathbun, in Rankin, 1898) from zoea (Z) to megalopa (M) stage was analyzed in order to deduce the larval dispersal strategy of the species. Larvae were obtained from 10 ovigerous females captured in the mangrove of Guaratuba Bay, southern Brazil. Five salinity treatments were conducted from 0 to 35 PSU (S0, S5, S15, S25 and S35). The larvae were individually raised in plastic cell culture plates, totaling 120 experimental units per treatment, kept under natural photoperiod (12:12 h) and water constant temperature (26.3 ± 0.82°C), and fed with microalgae, rotifers and Artemia nauplii. While all larvae died at S0, S5 and S15, complete larval development until the M stage was only observed at S25 and S35. The highest survival rate was recorded at S35 (18 M from 120 newly-hatched Z, survivorship 15%) and the lowest at S25 (2 M, 1.66%). No significant difference in the total duration was observed between S25 (28.5 ± 0.70 days) and S35 (23.61 ± 3.05 days). The life cycle of L. leptodactyla is based on a larval exportation strategy as they need to perform ontogenetic migrations to the coastal area.

Abstract A new genus and new species of caprellid, Parapseudaeginella n. gen., and Parapseudaeginella australiensis n. sp., is described from shallow water of Ningaloo Reef, south of Tantabiddy, reef front, Western Australia. The new genus is very similar to Pseudaeginella Mayer, 1890, but can be easily distinguished by the pereonites 6 and 7 being clearly fused (separated in Pseudaeginella) and by the absence of a pair of proximal grasping spines on the propodus of pereopods 5-7 (present in Pseudaeginella). The new species is characterised by acute dorsal projections on head, pereonite 1 and 2, and acute lateral projections near the coxa of gnathopod 2 in males. The new taxon has probably been overlooked in the past due to its tiny size. Further efforts to sample and describe the smaller caprellids is needed to fully understand the global diversity and relationships of caprellids.

Abstract Relative growth can help to identify dimorphism between individuals, and it is also used to determine changes in ontogeny related to sexual maturity. The morphometric variables recorded were width, length and height in carapace and chelae. The abdomen width was taken only in females. Data analysis was made separating males and females. Exploratory analysis used maximum, minimum and mean values and compared these values between sexes using MANOVA, ANOVA and LSD-Fisher methods. A weight-size relationship was also determined. Relative growth was estimated using a multi-model approach. Six models were applied, and the best was selected using Akaike and Bayesian information criteria. Residual versus predicted graphics were also produced based on the selected models. The mean sizes were similar between sexes, but the maximum values were observed in males. The weight-size relationships showed a negative allometry. The best model varied by morphometric variables and sex, but the type of relative growth was principally isometric and negative allometry. Biometric characteristics in Menippe frontalis A. Milne-Edwards, 1879 did not show abrupt changes in the relative growth. The threshold was not assumed as an indicator of morphometric sexual maturity however, they may be used for establishing legal minimum size in M. frontalis.

Abstract While previous studies on Alpheus formosus Gibbes, 1850 focused on taxonomic and phylogenetic issues, the present study provides information on the biology and ecology of this snapping shrimp, a representative coral reef species widely distributed in the Atlantic Ocean. We studied A. formosus between 2015 and 2016 on two islands in São Paulo state, Brazil: Laje de Santos and Vitoria Island. We analyzed 47 specimens from Laje de Santos and 44 from Vitoria Island. Individuals ranged in size from 2.0 mm to 13.99 mm CL. The mean number of embryos attached to the pleopods of females was 211.28 ± 312.8 in Laje de Santos and 125.2 ± 177.8 in Vitoria Island. This species should be included in monitoring programs of coral ecosystems they inhabit as A. formosus represents a key element in trophic dynamics of these ecosystems.

Abstract In this study, the larval development of Libinia rhomboidea Streets, 1870 under laboratory conditions is described and compared with the description of Libinia spinosa H. Milne Edwards in Guérin, 1832, Libinia dubia H. Milne Edwards, 1834, and Libinia emarginata Leach, 1815 published by other authors. The ovigerous females collected released larvae asynchronously. Two zoeas and one megalopa stage were obtained. Larval development required 13 to 14 days at 20.5 - 22.0°C and 32 - 35 psu of salinity. The differences in L. rhomboidea with respect to the other three species are the following: in the first zoea, the total length and carapace length were greater and the number of setae on the basial endite of the maxillula was different; in the second zoea the size of the endopod and the number of setae on the scaphognathite of the maxilla were greater; in the megalopa, the total length and carapace length were both greater, while the number of setae on the scaphognathite of the maxilla was less. A great similarity between L. rhomboidea and L. dubia was found; however, it is possible to distinguish the larval morphology of L. rhomboidea from the three species compared.

Abstract Increasing global concern with respect to the levels of bioavailable microplastic (<5 mm) contamination in marine environments has led to many studies examining the physiological impacts of microplastic consumption on a range of species. The copepod, Temora longicornis (Müller, 1785), is a common inhabitant of the upper epipelagic zone of gulf and estuarine waters of the North Atlantic which we hypothesised would be regularly exposed to microplastic contaminated marine environments. They are therefore at risk of consumption of microplastic pollutants, which could have wider trophic impacts. Microplastic was recorded in all water samples with an average concentration of 8.2 particles/m3. However, there was no significant difference in abundance or size of microplastics sampled from three localities within Chichester Harbour, UK. Individual digestion of ninety copepods found no evidence of consumption of any microplastic contaminants above our observable size range of 23 μm. Whilst microplastic pollution remains of wider ecological concern, our results suggest limited support for the potential for this copepod species to transfer these pollutants to higher trophic levels.

Abstract The loggerhead marine turtle is an ideal substrate for epibionts and presents the highest diversity of associated fauna among marine turtles. Here we report the occurrence of two amphipod species, Caprella andreae Mayer, 1890 and Podocerus chelonophilus (Chevreux and Guerne, 1888) from the carapace of one stranded Caretta caretta (Linnaeus , 1758) in Ubatuba, São Paulo state, Brazil. This is the first record of P. cheloniphilus for Brazil and for the South Atlantic Ocean.

Abstract Freshwater crabs exhibit complex behavioral patterns, including those related to mating, which is generally characterized by the approach of the male towards the female. Kingsleya attenboroughi Pinheiro and Santana, 2016 is a pseudothelphusid freshwater crab endemic to Brazil. As with other species from this family, K. attenboroughi is nocturnal. The main objective of the present study is to describe the mating behavior of K. attenboroughi and to evaluate if the molt cycle stage influences mating. The crabs were allocated to pairs and filmed for 24 hr. The mating behavior of the species was characterized by the physical positioning of the male under the female, with an elaborate courtship occurring prior to copulation. The molt cycle appears to influence mating since mating occurred predominantly between pairs in which males were in the inter-molt stage and females were in the post-molt stage.

Abstract The study of Colombian freshwater crabs has advanced significantly, but species records are scattered across different museums and research institutions. Assuming that museum collections incorporate valuable information in estimating species diversity, a database was organized on the 94 known species of family Pseudothelphusidae, which includes 568 records from 1853 to 2019 in continental Colombia and Gorgona Island. The natural regions of Colombia (Amazonian, Andean, Caribbean, Orinoquian, Pacific) were further subdivided into 75 natural sub-regions according to habitat types used by freshwater crabs. Sub-regions were (i) ranked in terms of species richness, with respective species reported in each sub-region listed accordingly, and (ii) classified into a scale of five categories on the basis of a geometric biodiversity index combining species richness and Simpson index. Species accumulation curves are presented to estimate the current status of knowledge about the diversity of the Colombian pseudothelphusids. Although the available data are not standardized for an adequate assessment of relative abundance, since they are influenced by sampling efforts and natural sub-regions are of different sizes and characteristics, the present study may be useful in future ecological and biogeographic research, as well as for conservation purposes.

Abstract We investigated the abundance and spatial distribution of Callinectes danae Smith, 1869 during the day/night periods and tidal cycles in a coastal area of Brazil. Sex ratio, size class distribution, and mean sizes of males and females were also analyzed. The sampling occurred between February and March 2011 in the estuary-bay complex of São Vicente. Collections occurred in six sampling stations during both daytime and nighttime. A total of 1997 specimens were collected in the bay and 963 specimens in the estuary. The abundance of males and females differed between the bay and estuary, with males more abundant in the estuary and adult females in the bay. Crabs in all demographic categories were more abundant at night. The species distribution was intrinsically related to the interaction between environmental factors. In addition to the higher capture during nocturnal collections, a positive correlation was found between the abundance of reproductive females and salinity, while juveniles were more abundant in shallower stations and at lower salinities. Our results contribute to a better understanding of the influence of day/night periods and tidal cycles on the abundance and distribution of the swimming crab C. danae.

Abstract The genus Pectenoniscus Andersson, 1960 currently presents two described species, one epigean, Pectenoniscus angulatus Andersson, 1960, from Nova Teutônia municipality, Santa Catarina state (Southern Brazil) and the hypogean Pectenoniscus liliae Campo-Filho, Bichuette and Taiti, 2019, found in two caves in the Serra do Ramalho karst area (Carinhanha municipality), Bahia state (northeastern Brazil). Recent surveys in karstic areas of Minas Gerais and Bahia revealed six new cave species from this genus, which are herein described. Two species occur in Minas Gerais state in the transition between the biomes Cerrado (Brazilian savannah) and Caatinga (mesophytic and xeromorphic forests): Pectenoniscus montalvaniensis n. sp. from Abrigo da Ema cave (Montalvânia municipality) and Pectenoniscus juveniliensis n. sp. from Gruta do Tabuleirinho cave (Juvenilia municipality). The other four species were found in Bahia state, in Caatinga biome: Pectenoniscus iuiuensis n. sp. from Baixa da Fortuna cave (Iuiu municipality); Pectenoniscus carinhanhensis n. sp. from three caves in Serra do Ramalho (Carinhanha municipality); Pectenoniscus santanensis n. sp. from Gruta do Padre cave (Santana municipality); and Pectenoniscus morrensis n. sp. from Gruta dos Brejões cave (Morro do Chapéu municipality). Aside from the taxonomic descriptions, we provide ecological notes for each described species, as well as an identification key for Pectenoniscus.

Abstract Terrestrial isopods are a successful group of terrestrial crustaceans. Their exoskeletal cuticle has been studied in several species. However, it is not known whether the cuticle of these animals becomes thicker or how its structure changes as the animals grow. We aimed to determine the principles of upscaling of the exoskeletal cuticle during growth in the terrestrial isopods Armadillidium vulgare (Latreille, 1804) and Porcellio scaber Latreille, 1804 with scanning electron microscopy. The tergal cuticle becomes thicker with increasing body length. In A. vulgare, which rolls into a ball in defense against predators, the rate of increase of tergite thickness was greater than in P. scaber, which clings to the substrate when threatened. As the cuticles of both species become thicker, the proportion of the endocuticle in the cuticle increases. There is a strong correlation between cuticle thickness and the thickness of endocuticular lamellae. This indicates that in thicker cuticles, chitin-protein fibers in sequential layers change their orientation by a smaller angle. We found no significant differences in morphometric parameters between the cuticles of A. vulgare and P. scaber when controlling for cuticle thickness. This suggests that known differences in cuticle structure and composition between these two species may result from differences in cuticle thickness.

Abstract In this study we analyze both seasonal and inter-annual variations in the community parameters of Brachyura zoea I in the Parque Nacional Sistema Arrecifal Veracruzano. Planktonic samples from four transects were collected during three weather conditions: cold fronts; rainy and dry conditions in 2011 and 2012; and cold fronts and dry conditions in 2013. We measured temperature, salinity, and dissolved oxygen, in situ, to determine whether these parameters could explain the observed variations in the community patterns of brachyuran zoea I. We collected zoeae I of 18 species of brachyurans. The dominant species were Libinia dubia H. Milne Edwards, 1834; Menippe nodifrons Stimpson, 1859; and Callinectes sapidus Rathbun, 1896. The temperature and dissolved oxygen were the highest during the rainy conditions and the salinity during the dry conditions in the southern transects. The highest species richness (14) and diversity (2.97 bits individual-1) were found in central transects during cold front conditions. However, we found the highest species richness and diversity during the dry conditions, in the southern transects. Libinia dubia presented the highest density during cold fronts with 1592 ± 127 zoeae 100 m−3 in the northern transect, followed by C. sapidus in the north-central transect, this was observed for both species in the offshore zone. In conclusion, the parameters of the community of zoea I were influenced by the physical parameters measured in each sampling zone.

Abstract The offshore mysid Neobirsteiniamysis inermis (Willemoes-Suhm, 1874) is reported for the first time in western Mexico. A large series of specimens (168 specimens: 44 males, 124 females) was obtained from samples taken with a large benthic sled in as many as 28 localities distributed off the west coast of the Baja California Peninsula (15), in the Gulf of California (11), and off SW Mexico (2). Only one ovigerous female was collected. A complete description of the material, based on a mature specimen, is provided, including SEM images of the mandibles, which are described in detail, and of the eyes.

Abstract Zoological collections are fundamental repositories of biodiversity and have an important role in scientific dissemination. The National Institute of Mata Atlântica (INMA, previously called Professor Mello Leitão Biology Museum) founded by Augusto Ruschi is situated in Santa Teresa, Espírito Santo, Brazil, within the Atlantic Forest Biome, being a relevant source for the development of research in this habitat. The aim herein is to inventory the crustacean collection of INMA with a complete list of the species and their habitat. This collection is not yet digitized or available online. The collection totals 52 species in 41 genera, belonging to 26 families and comprises major crustacean groups, with a particular focus on Decapoda. All holdings are from Brazil. It consists of 443 specimens included in 131 records, representing mostly the Espírito Santo carcinofauna. Without online publication of the specimen data, the visibility and use of the collection would likely remain limited. Sourcing specimens through online databases will facilitate the production of guides and taxonomic training, and also more information can be passed on to the community as a whole. Thus, a proposal for future management of the Crustacea collection of INMA is to digitize the data through photos of the specimens and associated labels.