Abstract Aim The aim of this study was to investigate the isotopic signature of P. brasiliana captured in three different points along the river flow toward the sea of the Prumirim River, northern coast of the state of São Paulo/Brazil in order to test the hypothesis of similarity between isotopic signature of individuals living in separated areas of the river. Methods We used stable isotope analyses (δ13C and δ15N) at three points of the river and ANOVA and Bayesian Ellipses analyses were performed. Results Our results showed that are a differential isotopic enrichment along the river course in 13C, providing important results on the environmental condition and anthropogenic impacts in the region. In addition, the food biology of P. brasiliana was characterized as a primary consumer corroborating with the detritivores feeding habit observed in previous studies of stomach content analysis. Conclusions Our research, limited to a single area along the northern coast of the state of São Paulo, uncovers intriguing findings that merit replication in other areas within the region. This is particularly crucial given the rising number of anthropogenic influences resulting from urban development, underscoring the need for improved monitoring of these areas.

Resumo Objetivo O objetivo deste estudo foi investigar a assinatura isotópica de P. brasiliana capturada em três diferentes pontos ao longo do fluxo fluvial em direção ao mar do rio Prumirim com a finalidade de testar a hipótese de similaridade entre a assinatura isotópica de indivíduos que vivem em areas diferentes do rio. Métodos Foram utilizadas análises de isótopos estáveis (δ13C e δ15N) em três pontos do rio e foram realizadas análises de Stable Isotope Mixing Models e Bayesian Ellipses. Resultados Nossos resultados mostraram que há um enriquecimento isotópico diferencial ao longo do curso do rio em 13C, fornecendo resultados importantes sobre as condições ambientais e os impactos antropogênicos na região. Além disso, a biologia alimentar de P. brasiliana foi caracterizada como um consumidor primário, corroborando com o hábito alimentar de detritívoros observado em estudos anteriores de análise de conteúdo estomacal. Conclusões Nossa pesquisa, limitada a uma única área ao longo da costa norte do estado de São Paulo, revela descobertas intrigantes que merecem ser replicadas em outras áreas dentro da região. Isso é especialmente crucial dada a crescente quantidade de influências antropogênicas resultantes do desenvolvimento urbano, ressaltando a necessidade de um monitoramento aprimorado dessas áreas.

Abstract We provide morphological and genetic evidence to establish the presence/occurrence of Alpheus angulosus, Alpheus buckupi, and Axianassa australis on the coast of Maranhão, Brazil. The specimens were collected in December 2019 by actively searching the estuaries and rocky shores of São Luís Island, northeast of Brazil. In addition to morphological analyses, two mitochondrial genes were obtained (Cytochrome C Oxidase I and 16S), and a phylogenetic analysis was conducted to verify the specimens’ identity. Accurate identification is an essential tool to obtain reliable information about the occurrence of the species and thus help assess biodiversity in a highly diverse region. These finding also serve to stimulate future studies in poorly studied areas as well as set a baseline for biodiversity conservation and preservation strategies.

Abstract Macrobrachium candango Mantelatto, Pileggi, Pantaleão, Magalhães, Villalobos and Álvarez, 2021 is an endemic shrimp species to the Brazilian Central-West region (Brasília, Federal District). The present study aims to analyze the relative growth, morphometry, morphological sexual maturity, and fecundity of this species. Specimens were collected from tributaries of the Paranoá Lake hydrographic basin, Brasília, during sporadic periods between 1983 and 2012. Relative growth was analyzed for different structures (carapace, abdomen, second abdominal pleura, merus, carpus, and propodus). The laterality and heterochely patterns were evaluated based on the dimensions of the propodus length. Fecundity was calculated as the average total number of eggs per female and egg size was measured to obtain the volume. There were differences in relative growth (p < 0.05) of the structures analyzed between juveniles and adults, and distinct allometric patterns were observed between the life stages, which could reflect the habit of these animals at each developmental stage. No pattern of laterality and heterochely was observed between the chelipeds of the animals analyzed (p > 0.05). The lack of laterality may indicate that this species directs energy to the smallest propodus when the largest propodus is injured. Egg volume ranged from 4.41 to 7.71 mm3, and fecundity ranged from 38 to 61 eggs, indicating a life cycle with abbreviated larval development. The characteristics presented herein are unprecedented for M. candango and present relevant information needed to assess the conservation status of this species, which is currently threatened.

Resumo O objetivo deste estudo foi descrever e ilustrar os estágios larvais iniciais, ou seja, o desenvolvimento naupliar completo e a primeira protozoea (PZI) de Sicyonia dorsalis e S. typica obtidos em laboratório. Também fornecemos observações a partir de uma análise comparativa da morfologia desses estágios entre representantes do gênero e as características morfológicas para distingui-los de outros Penaeoidea no plâncton. Nossos resultados indicam que o desenvolvimento naupliar de Sicyonia é composto por cinco estágios (NI a NV). Não foram encontradas diferenças na morfologia dos estágios naupliares e PZI das duas espécies estudadas, apesar de serem consideradas filogeneticamente distantes dentro do gênero. Nossa hipótese é que as diferenças morfológicas surgem mais tarde durante o desenvolvimento ontogenético. As comparações com as descrições larvais de congêneres revelaram que os estágios naupliares e PZI são muito semelhantes, no entanto, algumas diferenças morfológicas foram observadas. Conforme ilustrado aqui, há uma clara necessidade de novas descrições do grupo estudado e generalizações e conclusões de padrões na morfologia larval neste momento precisam ser feitas com cautela, pois dados de um número ainda insuficiente de espécies estão disponíveis.

Abstract The aim of this study was to describe and illustrate the early larval stages, i.e., the complete naupliar development and the first protozoea (PZI) of Sicyonia dorsalis and S. typica obtained under laboratory conditions. We also provide remarks from a comparative analysis of the morphology of these stages among representatives of the genus and furnish morphological characteristics to distinguish them from another penaeoidean in the plankton. Our results indicate that the naupliar development of Sicyonia is composed of five stages (NI to NV). No differences were found in the morphology of the naupliar and PZI stages of the two studied species, even though they are considered phylogenetically distant into the genus. We suspect that morphological differences arise later during ontogenetic development. The comparisons with larval descriptions of congeners revealed that naupliar stages and PZI were very similar, nevertheless, some morphological differences were observed. As illustrated here, there is a clear need of new descriptions of the studied group and generalizations and conclusions of larval morphology patterns at this point need to be made with caution, because data of a still insufficient number of species is available.

Abstract Marine shrimps of the genus Thor Kingsley, 1878 are distributed in the eastern and western Atlantic, eastern Pacific, and Indo-West Pacific. Thor manningi Chace, 1972 was originally described from Antigua and since then has been recorded from other Atlantic localities, including the Caribbean Sea, Bermuda, USA, Brazil, and Ascension Island. Specimens previously identified as T. manningi from Panama and Brazil were analyzed using a combination of morphological and molecular approaches. The analyses yielded a new species from the Atlantic coast of Panama, herein described as Thor paulae sp. nov. Moreover, we provide additional morphological observations on T. manningi, mainly regarding mouthparts and pereopods. The new species is morphologically similar to the Pacific Thor cocoensis Wicksten and Vargas, 2001 and Thor marguitae Bruce, 1978. However, it can be separated from them by the carpus of the second pereopod, rostral dorsal dentition, and chela of the first pereopod, respectively. The two species studied here can be easily distinguished by the supraorbital prominence in T. manningi (versus absent in the new species), and the pterygostomial margin rounded and unarmed in T. manningi (versus angular, with tooth in the new species). Thor manningi is morphologically closer to the western Atlantic Thor dobkini Chace, 1972 and Thor floridanus Kingsley, 1878, but can be separated from both by the merus of the first pereopod (T. dobkini) and dactylus of fourth and fifth pereopods (T. floridanus, but with the possibility of overlap). We provide a comparative table with morphological characters of all 17 valid species of Thor, as well as a worldwide identification key to the genus.

Abstract The morphology of the first zoeal stage of Pilumnus vinaceus is described and compared with the zoea I of Pilumnus all species in the literature. Two ovigerous females of P. vinaceus were maintained in the aquarium facilities until the larvae hatch. The larvae of each ovigerous female were dissected using a stereoscopic microscope. The zoea I of P. vinaceus has common characteristics among the Pilumnidae as: [1] antenna of type 2; [2] maxilliped 1 with 2+2+3+3 setae on the basis and with 3,2,1,2,5 setae in the endopod; [3] maxilliped 2 with 1+1+1+1 setae on the basis and 1,1,6 setae on the endopod; [4] telson with furcal rami armed with dorsal and lateral spines. Considering the species of Pilumnus that occur in the western Atlantic, it becomes possible to identify P. vinaceus zoea I by means of the verification of the following characteristics: [1] pleonites with mediolateral processes; [2] number of setae on the antennule. It is however, important to consider that there is still a great deficit in the knowledge about the morphology of the larval forms of the species assigned to Pilumnus and we argue in favor of new descriptions to build a more robust dataset on zoeal morphology characters and use it in a phylogenetic context on the genus.

Resumo: Foi realizada uma descrição completa e detalhada da primeira zoea de Ogyrides occidentalis. As larvas foram obtidas em laboratório a partir de uma fêmea com embriões coletada em Ubatuba, estado de São Paulo, Brasil. Os caracteres morfológicos são comparados com a descrição anterior da espécie proximamente relacionada O. alphaerostris. Apesar de algumas semelhanças (número de apêndices, somitos abdominais e cerdas na maioria dos apêndices) foram encontradas diferenças substanciais entre as duas espécies, como o tamanho das larvas e do rostro, e segmentação de algumas estruturas (exopodito da antena e entre coxa e base do primeiro maxilípede). No entanto, essas diferenças devem ser interpretadas com cuidado porque a descrição larval de O. alphaerostris foi realizada antes da padronização proposta para as descrições da morfologia larval de decápodes. A presente descrição larval forneceu informações adicionais para corroborar a recente ressurreição de O. occidentalis e será útil para futuros estudos ecológicos e comparativos.

Abstract: A complete and detailed description of the first zoeal stage of Ogyrides occidentalis is provided. Larvae were obtained in the laboratory from a female with embryos collected in Ubatuba, State of São Paulo, Brazil. The morphological characters are compared with previous description of the close related O. alphaerostris. Despite of some similarities (number of appendages, pleonites, and setae on the majority of appendages) substantial differences were found between the two species, as the size of larvae and rostrum and segmentation of some structures (antenna exopod, first maxilliped coxa and basis). However, these differences must be interpreted carefully because larval description of O. alphaerostris was conducted before the proposed standardization for decapod larval morphology descriptions. The present larval description furnished additional information to corroborate the recent resurrection of O. occidentalis and will be useful for future comparative and ecological research.

Abstract Atya gabonensis Giebel, 1875 and Atya scabra (Leach, 1816) are amphidromous shrimps. In some areas, these species populations are vulnerable due to the anthropogenic impact on their habitats and commercial exploitation. However, basic morphometric data is still lacking. This study provides morphometric data on both species in the Fluvial Island Domain of Paraíba do Sul River basin, Brazil. Sampling was performed bimonthly from January 2013 to March 2014. Individuals were analysed according to sex, weight, carapace length and width, abdomen length, second abdominal pleura height and width, length of third pereopod articles, and length and width of the male appendix interna. We sampled 42 individuals of A. gabonensis and 16 individuals of A. scabra. In both species, females showed abdomen and second abdominal pleura larger than males, while males showed third pereopod articles larger than females, both related to sexual dimorphism. We detected differences in the carapace length × carapace width relationship and in the growth pattern of the male appendix interna between species, with A. gabonensis presenting the carapace and the male appendix interna wider than A. scabra. Morphometric aspects of both species are unpublished for this region, and this data is valuable for A. gabonensis in the western Atlantic and for A. scabra from Rio de Janeiro state. Such information is essential for future systematic assessment and establishment of conservation management policies.

Abstract The present study provided information extending the known geographical distribution of the calappid crab Cryptosoma balguerii (Desbonne in Desbonne and Schramm, 1867). We provide new data that extends the range of this species in the western Atlantic farther to the south in the Brazilian region, State of São Paulo and check its identification by molecular tools within Cryptosoma and other calappid crabs. New records of marine species provide a baseline for a better understanding of the biodiversity of ecological provinces. This work is an example of the importance of an exhaustive and continuous investigation on the biodiversity of subtidal rocky bottoms.

Resumo: Este estudo avaliou as relações dos fatores ambientais e a distribuição espaço-temporal de H. pudibundus, com a hipótese de ocupação diferencial em uma região do litoral sudeste do Brasil. As amostragens ocorreram mensalmente no período de janeiro a dezembro de 2000, ao longo de nove transectos de 2 a 40 m de profundidade, na região de Ubatuba, litoral norte de São Paulo. Foram coletados 1808 indivíduos de H. pudibundus. A maior abundância foi registrada no inverno nos transectos 10 a 25 m de profundidade. A abundância foi positivamente correlacionada com o teor de matéria orgânica e a textura do sedimento (valores de phi). Durante o outono e inverno com a retração da ACAS ocorre o revolvimento do sedimento e a supensão da macrofauna detritívora e filtradora, aumentando a disponibilidade de alimento. Locais caracterizados por sedimentos mais finos oferecem maior disponibilidade de alimentos, além de facilitar o comportamento de H. pudibundus se enterrar. Devido ao comportamento predatório oportunista, esta espécie se alimenta de uma grande variedade de organismos, incluindo moluscos, anelídeos e foraminíferos, que são as presas mais abundantes nas áreas estudadas, principalmente em locais com grãos menores.

Abstract: This study evaluated the relationships between environmental factors and the spatio-temporal distribution of H. pudibundus, with the hypothesis of differential occupation in coastal areas of southeastern Brazil. The samplings took place monthly in January-December 2000 period, along nine transects from 2 to 40 m of depth, in Ubatuba region, northern coast of São Paulo. We collected 1808 individuals of H. pudibundus. The highest abundance was recorded in winter in the transects 10-25 m deep. Abundance was positively correlated with organic matter content and texture sediment (phi values). With the retreat of the South Atlantic Central Water (SACW) in autumn and winter, the sediment swirls, suspending the detritivore and filter-feeding macrofauna, increasing the food availability. Sites characterized by finer sediment offer higher food availability, besides facilitating H. pudibundus burying behavior. Due to its opportunistic predatory behavior, this species feeds on a variety of organisms, including mollusks, annelids and foraminifera, which are preys more abundant in the studied area and in sediments of finer grain size.

Abstract Apart from traditional characters, other data have been used for taxonomy, like color patterns. Based on the different colors (green and orange) observed for some Calcinus tibicen (Herbst, 1761) specimens, we evaluated the genetic distance for cytochrome oxidase subunit I mitochondrial gene of individuals collected in Pernambuco (northern Brazil) and in São Paulo (southeast Brazil). We found low genetic variation (0.2-1.1%), and no evidence of isolation on our molecular tree based on genetic distance. We suggest high levels of gene flow between specimens with different color patterns, which are polymorphisms and might be related to the kind of nutrition as well different ecological and evolutionary predation characteristics.

Differences on reproductive performance between two sampling points of the porcelain crab Pachycheles monilifer from Ubatuba (São Paulo, Brazil), one from Itaguá Beach (living on Schizoporella errata) and the other from Grande Beach (living on Phragmatopoma caudata) has been previously observed. Therefore could be expected a specific behavior in substrate preference to optimize the best biogenic habitat. Considering this premise, our goal was to test the substrate preference of this species when both substrates were simultaneously available. In total, 185 individuals were collected in these same localities and they were submitted to substrate selection experiments. The trials were conducted on containers with quiet seawater at 28 ± 1°C and under dark photoperiod. Specimens were exposed to substrates by 30 min. Trials started with the release of one animal per treatment in the middle of the opposite side to the substrate inside the containers. After the established time, the substrate preference of each porcelain crab was verified. As result, no preference pattern was found and the choices in the experiment were not significantly different from the expected. This lack of preferences may be an indication that porcelain crabs are generalists in habitat use regardless of sex of individuals and potential benefit in fitness. Therefore, the differences on the reproductive aspects of the P. monilifer probably are associated with environment factors not simulated in this study and may indicate the occurrence of plasticity in habitat selection behavior.

During the last decades, knowledge on biodiversity of freshwater decapods has increased considerably; however, information about ecology of these crustaceans is scarce. Currently, the freshwater decapod fauna of Costa Rica is comprised by representatives of three families (Caridea: Palaemonidae and Atyidae; Brachyura: Pseudothelphusidae). The present study aims to describe the species diversity and distribution of freshwater crabs inhabiting the basin of the Rio Grande de Térraba, Pacific slope of Costa Rica, where the Instituto Costarricense de Electricidad (ICE) plans to implement one of the largest damming projects in the region. Samples were collected in 39 locations at an altitude ranging from 20 to 1,225 m. Sampling was carried out during several months in 2007, 2009 and 2010. We collected a total of 661 crabs, comprising eight species of Pseudothelphusidae of three genera, representing 53% of the 15 pseudothelphusid crab species currently recorded from Costa Rica. The most common species was Ptychophallus paraxanthusi followed by P. tristani. Freshwater crabs were more frequently encountered in the middle-low region of the basin (between 311 and 600 m) and less frequently in the medium-high basin (between 601 and 1,225 m). Ptychophallus paraxanthusi showed the widest distribution and was collected in altitudes ranging from 20 to 700 m. The Rio Grande de Térraba region can be considered as a relatively small, but highly diverse system. Therefore, any alteration of the basin of Rio Grande de Térraba, and especially the possible construction of a hydroelectric power plant, needs to be carefully analyzed to mitigate the damaging effects of this project on the freshwater crabs. More ecological information about freshwater crabs from Costa Rica and the Central American region are needed to reach a first reasonable overview on the ecological role of these decapods in freshwater systems.

El conocimiento de la biodiversidad de decápodos de agua dulce ha aumentado considerablemente durante las últimas décadas. Sin embargo, información sobre la ecología de estos crustáceos es limitada. Actualmente, la fauna de los decápodos de agua dulce está compuesta por representantes de tres familias (Caridea: Palaemonidae y Atyidae; Brachyura: Pseudothelphusidae). El presente estudio describe la diversidad de especies y la distribución de cangrejos de agua dulce de la cuenca del Río Grande de Térraba, vertiente Pacífica de Costa Rica, donde el Instituto Costarricense de Electricidad (ICE) está planeando construir una de las plantas hidroeléctricas más grandes de la región. Las muestras fueron recolectadas en 39 localidades a una altitud entre 20 y 1.225 m. El muestreo se efectuó durante varios meses de los años 2007, 2009 y 2010. Se colectó un total de 661 cangrejos de ocho especies de Pseudothelphusidae de tres géneros, lo que representa un 53% de las 15 especies de Pseudothelphusidae actualmente reportado para Costa Rica. La especie más frecuentes fue Ptychophallus paraxanthusi, seguida por P. tristani. Los cangrejos de agua dulce fueron más frecuentes en la región medio-baja de la Cuenca (entre 311 y 600 m) y menos frecuentes en la región medio-alta (entre 601 y 1.225 m). Ptychophallus paraxanthusi demostró la distribución más amplia y fue colectado en altitudes entre 20 y 700 m. Se puede considerar el Río Grande de Térraba un sistema pequeño, pero altamente diverso. Por lo tanto, cualquier alteración de la Cuenca del Rio Grande de Térraba, y especialmente la posible construcción de la planta hidroeléctrica, requiere un análisis cuidadoso para mitigar efectos dañinos de este proyecto sobre los cangrejos de agua dulce. Se requiere más información ecológica sobre los cangrejos de agua dulce de Costa Rica y la región de Centro América para obtener una primera visión razonable del rol ecológico de estos decápodos en los sistemas dulceacuícolas.

Species of the family Pinnotheridae constitute an ideal group for morphometric studies due to their complex morphological adaptations. These adaptations respond to the selective pressure of a symbiotic life style. This study describes the relative growth and morphometric features of the symbiotic pea crab Austinixa aidae (associated with the ghost shrimp Callichirus major), from the sandy beaches in the southwest Atlantic, Brazil. Significant differences were detected in the biometric proportions, particularly the chelar propodus length and carapace width, of each sex. These dimensions were also related to the size at which the individuals reached morphological sexual maturity (5.1 mm of carapace width for both sexes). Males and females were 2.4 times wider than long, which corresponds to the principal adaptation developed by Austinixa species to live in cryptic environments. Moreover, juveniles were proportionally more rounded. The changes in the biometric proportions of carapace length and width of A. aidae were more pronounced in males and females, adaptations that facilitate roaming within the galleries of their hosts.

Las especies de la familia Pinnotheridae constituyen un grupo ideal para la realización de estudios morfométricos, debido a sus complejas adaptaciones morfológicas. Estas adaptaciones son respuesta a la presión de selección debida a su vida simbionte. En este estudio se describió el crecimiento relativo y las características morfométricas del cangrejo simbionte Austinixa aidae (asociado con el camarón fantasma Callichirus major), de una playa de arena del Atlántico suroeste de Brasil. Se determinaron diferencias significativas en las proporciones biométricas de cada sexo, entre la longitud del propodio y ancho del caparazón. Estas dimensiones estuvieron relacionadas también con la talla en que los individuos muestran cambios morfológicos en su madurez sexual (5.1 mm de ancho del caparazón en ambos sexos). Los machos y hembras fueron 2,4 veces más anchos que largos, lo que corresponde a la adaptación principal que las especies del género Austinixa, han desarrollado para vivir en ambientes crípticos. Además, los juveniles fueron proporcionalmente más redondeados. Los cambios en las proporciones biométricas de longitud y ancho del caparazón de A. aidae, fueron más pronunciados en machos y hembras, adaptaciones que facilitan el desplazamiento al interior de las galerías construidas por sus hospederos.