A kinetic characterization of (Na+, K+)-ATPase activity in the gills of the pelagic seabob shrimp Xiphopenaeus kroyeri (Decapoda, Penaeidae).

We characterize the kinetic properties of a gill (Na(+), K(+))-ATPase from the pelagic marine seabob Xiphopenaeus kroyeri. Sucrose density gradient centrifugation revealed membrane fractions distributed mainly into a heavy fraction showing considerable (Na(+), K(+))-ATPase activity, but also containing mitochondrial F0F1- and Na(+)- and V-ATPases. Western blot analysis identified a single immunoreactive band against the (Na(+), K(+))-ATPase α-subunit with an Mr of ≈ 110 kDa. The α-subunit was immunolocalized to the intralamellar septum of the gill lamellae. The (Na(+), K(+))-ATPase hydrolyzed ATP obeying Michaelis-Menten kinetics with VM = 109.5 ± 3.2 nmol Pi min(-1) mg(-1) and KM = 0.03 ± 0.003 mmol L(-1). Mg(2+) (VM = 109.8 ± 2.1 nmol Pi min(-1 )mg(-1), K0.5 = 0.60 ± 0.03 mmol L(-1)), Na(+) (VM = 117.6 ± 3.5 nmol Pi min(-1 ) mg(-1), K0.5 = 5.36 ± 0.14 mmol L(-1)), K(+) (VM = 112.9 ± 1.4 nmol Pi min(-1 )mg(-1), K0.5 = 1.32 ± 0.08 mmol L(-1)), and NH4 (+) (VM = 200.8 ± 7.1 nmol Pi min(-1 )mg(-1), K0.5 = 2.70 ± 0.04 mmol L(-1)) stimulated (Na(+), K(+))-ATPase activity following site-site interactions. K(+) plus NH4 (+) does not synergistically stimulate (Na(+), K(+))-ATPase activity, although each ion modulates affinity of the other. The enzyme exhibits a single site for K(+) binding that can be occupied by NH4 (+), stimulating the enzyme. Ouabain (KI = 84.0 ± 2.1 µmol L(-1)) and orthovanadate (KI = 0.157 ± 0.001 µmol L(-1)) inhibited total ATPase activity by ≈ 50 and ≈ 44 %, respectively. Ouabain inhibition increases ≈ 80 % in the presence of NH4 (+) with a threefold lower KI, suggesting that NH4 (+) is likely transported as a K(+) congener.

Molecular analysis validates of some informal morphological groups of Pagurus (Fabricius, 1775) (Anomura: Paguridae) from South America.

The systematics of the hermit crab genus Pagurus is complex, with a long history of taxonomic rearrangements. This group, with worldwide distribution, encompasses a large number of morphologically heterogeneous species. A total of 173 currently recognized species have been morphologically organized into 11 informal groups, in attempts to establish internal stability. This arrangement and the relationships among species of each informal group have remained obscure and have never been evaluated from a molecular phylogenetic viewpoint. Attempts to resolve these high-level classification problems have been restricted to morphological studies, with no satisfactory results because of the extensive overlap of the characters used. We evaluated the phylogenetic position of some of these informal groups of species of Pagurus occurring along the Pacific and Atlantic coasts of South America, using partial fragments of two molecular markers (16S mtDNA and Histone 3 nDNA). Our results indicated a clear polyphyletic arrangement of Pagurus; at the same time, the internal clades fit perfectly with pre-established informal morphological groups from South America, which may warrant a formal taxonomic subdivision of the genus. Additionally, the species belonging to the "provenzanoi group" clearly fit within a different taxon and should be reviewed. Also, the presence of the genus Propagurus in the ingroup could be interpreted by non-exclusive hypotheses: from one point of view, the genus Propagurus is nested within Pagurus, and therefore Pagurus is not valid as currently composed; or possibly, that more than one genus should be recognized among the South American species presently assigned to Pagurus. This latter perspective accords with the proposal to restrict Pagurus to only a few species.

The Influence of Natural Barriers on the Amphidromous Shrimp Potimirim brasiliana (Caridea, Atyidae) from Two Rivers in Southeastern Brazil.

AbstractThe migratory behavior of freshwater shrimps may be affected by natural barriers in limnetic environments. This study evaluated the river areas separated by natural barriers, such as waterfalls, which affect the amphidromous shrimps' (Potimirim brasiliana) population features and reproductive aspects. Results indicate that in the Félix and Prumirim Rivers from southeastern Brazil shrimps show few differences in sampling areas, and these differences may not be causally related to the waterfalls. This is demonstrated by the absence of a pattern in the size and sex ratio in each area and the absence of a significant difference in most reproductive aspects. The presence of juveniles and reproductive individuals in all sampling areas strongly indicates a constant migration along them in both rivers, indicating that all individuals evaluated correspond to one single patchy population structure for each river. This migration conducted by P. brasiliana, such as its crawling behavior, demonstrated that it would be important to maintain the minimum number of individuals flowing between the different river sampling areas in this shrimp group. Thus, based on a helpful model observed in P. brasiliana, the results help us understand how natural barriers may affect the populations of amphidromous shrimp and how the migration behavior up- and downstream can help sustain the population. This premise can help future construction decisions and impacts of unnatural barriers, such as dams.

Comparative spermatozoal ultrastructure and molecular analysis in dromiid crabs and their phylogenetic implications for Dromiidae and Podotremata (Decapoda: Brachyura).

We described the spermatozoal ultrastructure and conducted a molecular analysis of Dromiidae Hypoconcha parasitica, Hypoconcha arcuata, Moreiradromia antillensis and Dromia erythropus. To elucidate the relationship between the different species of this brachyuran group, we also compared the spermatozoal morphologies and phylogenetic positioning among species of Dromiidae, Dromioidea and Podotremata. Specimens were collected from the northern coast of São Paulo, Brazil and were fixed and processed followed by transmission electron microscopy and molecular analysis routines. The Dromiidae spermatozoa studied are characterized by a discoidal acrosome, with three or four concentric zones, which are centrally separated by a bilaterally capitate perforatorial chamber, with a "mushroom"-shaped apex in the Hypoconchinae and a "T-shape" in Dromiinae. Above the perforatorial chamber, there is an apical protuberance, continuous with the subopercular region and the operculum, which forms a low, centrally perforated dome. Under differential interference contrast microscopy, the spermatozoa show 3 to 4 radial arms. The spermatozoal characters in Hypoconchinae and Dromiinae do not separate these subfamilies from the Dromiidae and Dromioidea. Ultrastructural differentiation was only found between representative Dromioidea and other Podotremata. Thus, the spermiotaxonomy of these Hypoconcha, Moreiradromia and Dromia species corroborated previous morphological and molecular studies, supporting the monophyly of Dromiidae and Dynomenidae in relation to Homolidae and Latreilliidae.

Redescription of the freshwater shrimp Macrobrachium jelskii (Miers, 1877) (Caridea, Palaemonidae).

Macrobrachium jelskii is a freshwater shrimp endemic to South America, occurring in all major Brazilian basins. It is used in various activities, such as fishing, fishkeeping and even as food for humans and animals, and therefore its distribution is affected by anthropic influence. Misidentification of M. jelskii is recurrent because of its morphological similarity to some sympatric species such as M. amazonicum and M. acanthurus. Thus, the aim of this study is to redescribe M. jelskii, proposing some characteristics that allow for a clearer differentiation of this species when compared to other similar congeneric species that occur in South America. The informative characters were the size and the shape of the rostrum, the ratio of the carpus and chela, the ratio of the chela and carapace length and the shape of the carpus of the second pereiopod, as well as the ratio between the length of the internal pair of posterior spine of telson and median apex of the posterior margin of telson. Although the intraspecific variability is high, the combination of the characters mentioned herein, including a morphological key, is very useful and makes it easier to differentiate between these three species.

Early larval development of the rock shrimps Sicyonia dorsalis Kingsley, 1878 and S. typica (Boeck, 1864) (Dendrobranchiata) with remarks of larval morphology of Sicyoniidae Ortmann, 1898 / Desenvolvimento larval inicial dos camarões-pedra Sicyonia dorsalis Kingsley, 1878 e S. typica (Boeck, 1864) (Dendrobranchiata) com observações sobre a morfologia larval de Sicyoniidae Ortmann, 1898

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.

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.

Taxonomic and Biogeographical Status of Three Species of the Spider Crabs of the Genus Acanthonyx Latreille, 1828 (Majoidea: Epialtidae) as Determined by DNA Barcoding and Morphological Analyses Along the Western Atlantic.

Ana Francisca Tamburus and Fernando Luis Mantelatto (2016) The genus Acanthonyx Latreille, 1828 contains 17 valid species, including A. dissimulatus Coelho, 1993, A. petiverii H. Milne Edwards, 1834 and A. scutiformis (Dana, 1851), which occur along the Brazilian coast. The high degree of intraspecific variation in the angle of hepatic region, size of the tubercles of the carapace and length of setae on the carapace and pereopods has resulted in difficulties with the taxonomy of this genus. Analysis of more consistent morphological and molecular characters are required to clarify the status of the three species that occurs in Brazil. For the molecular data, we used the barcode region of the mitochondrial gene COI as a marker, and we correlated this with morphological characters of adults and juveniles. The three species of Acanthonyx were morphologically similar and the matrix of genetic distances and maximum likelihood trees showed that A. dissimulatus and A. scutiformis belonged to the same group with A. petiverii. They could not be separated using the diagnosing characters proposed in the original description or genetically (present study), thus indicating that the taxonomic status of the first two species is questionable. The division into two distinct groups corresponding to A (Caribbean, Brazil, Venezuela) and B (USA, Mexico) was well supported and indicated that there are genetic differences between these populations. Present study suggests the existence of a single species in Brazil and Caribbean, assigned to A. petiverii (type locality in Antilles). The existence of a new species restricted to North America confirms the cryptic diversity within Acanthonyx.

Molecular and morphological differentiation between two Miocene-divergent lineages of Amazonian shrimps, with the description of a new species (Decapoda, Palaemonidae, Palaemon).

Palaemoncarteri (Gordon, 1935) and Palaemonivonicus (Holthuis, 1950) are morphologically similar species of South American freshwater shrimps. Past studies have questioned the taxonomic status of both species, which are supposed to have partially sympatric geographic distributions in the Amazon basin. We analyzed a 550 bp fragment of the mitochondrial 16S rRNA gene from these Amazonian Palaemon species as well as from 11 palaemonids as the outgroup. Additionally, we checked diagnostic characters of the genus and family as well as other morphological characters that have been little explored before. Palaemoncarteri and Palaemonivonicus are allocated in two sister lineages, with wide genetic divergence and little morphological differentiation. The divergence time between these lineages was estimated as approximately 10 million years ago. Both molecular and morphological data support the taxonomic validity of both Palaemoncarteri and Palaemonivonicus, refuting the hypothesis of synonymy. In addition, a new species, Palaemonyuna sp. n., closely related to Palaemonivonicus, is described. Our findings indicate that these species can be differentiated using the projection of the anterolateral margin and anterolateral spine of the first antennular segment, shape of the rostrum, and relative size of the appendix masculina.

Influence of environmental factors on the bathymetric distribution of the flecked box crab Hepatus pudibundus (Herbst, 1785) (Crustacea: Aethroidea) in the Southeastern Brazilian coast / Influência de fatores ambientais na distribuição batimétrica do caranguejo de baú Hepatus pudibundus (Herbst, 1785) (Crustacea: Aethroidea) na costa sudeste do Brasil

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.

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.

Molecular analysis of the freshwater prawn Macrobrachium olfersii (Decapoda, Palaemonidae) supports the existence of a single species throughout its distribution.

Macrobrachium olfersii is an amphidromous freshwater prawn, widespread along the eastern coasts of the Americas. This species shows great morphological modifications during ontogenesis, and several studies have verified the existence of a wide intraspecific variation. Because of this condition, the species is often misidentified, and several synonyms have been documented. To elucidate these aspects, individuals of M. olfersii from different populations along its range of distribution were investigated. The taxonomic limit was established, and the degree of genetic variability of this species was described. We extracted DNA from 53 specimens of M. olfersii, M. americanum, M. digueti and M. faustinum, which resulted in 84 new sequences (22 of 16S mtDNA, 45 of Cythocrome Oxidase I (COI) mtDNA, and 17 of Histone (H3) nDNA). Sequences of three genes (single and concatenated) from these species were used in the Maximum Likelihood and Bayesian Inference phylogenetic analyses and COI sequences from M. olfersii were used in population analysis. The genetic variation was evaluated through the alignment of 554 bp from the 16S, 638 bp from the COI, and 338 bp from the H3. The rates of genetic divergence among populations were lower at the intraspecific level. This was confirmed by the haplotype net, which showed a continuous gene flow among populations. Although a wide distribution and high morphological intraspecific variation often suggest the existence of more than one species, genetic similarity of Caribbean and Brazilian populations of M. olfersii supported them as a single species.

Male reproductive apparatus and spermatophore morphology of the hermit crabs Pagurus brevidactylus and P. criniticornis (Anomura, Paguridae).

Spermatozoa of most crustacean species are nonmotile and are packed into spermatophores. In Decapoda, spermatophores are highly variable in morphology and can be useful in the solving of taxonomic and systematic questions, especially among the Anomura. In this study, the morphology and morphometry of the spermatophores of the western Atlantic hermit crabs Pagurus brevidactylus and P. criniticornis are described. The abdomen of fresh male specimens was dissected to expose the reproductive system and to extract the spermatophores, which were analyzed by stereoscopic, light, and scanning electron microscopy. The vas deferens can be divided macroscopically in three regions, all of them containing spermatophores. Tripartite spermatophores are composed of an elongated cylindrical main ampulla, a triangular accessory ampulla, a narrow cylindrical peduncle, and a round pedestal. Dimensions of the spermatophore components are positively correlated to the size of the crab. Morphological patterns observed in this study resemble those of other pagurid hermit crabs investigated to date. The morphological character distribution confirms classifications based on adult morphology and molecular analysis.

Population and reproductive features of the freshwater shrimp Macrobrachium jelskii (Miers, 1877) from São Paulo State, Brazil / Aspectos populacionais e reprodutivos do camarão de água doce Macrobrachium jelskii (Miers, 1877) do Estado de São Paulo, Brasil

The aim of this study was to describe the population structure and reproduction of Macrobrachium jelskii from a stream in the central region of São Paulo State. A total of 1,215 specimens was collected monthly during one year (February 2008 to January 2009), being 535 males, 578 females and 102 juveniles. The overall sex-ratio was not significantly different from the expected 1:1, but has significantly differed in some months. A total of 136 ovigerous females were collected and the reproductive period was continuous with peak of occurrence on the hottest months. An increase in juveniles following the highest frequency of ovigerous females was observed and characterized the recruitment period. The fecundity was low and varied from 1 to 56 eggs per female. The biological profile observed here matched, in general aspects, with the pattern developed by tropical and subtropical inland populations, with some particularities related with environmental characteristics.

O objetivo deste estudo foi descrever a estrutura populacional e a reprodução de Macrobrachium jelskii de um ribeirão na região central do Estado de São Paulo. Um total de 1215 espécimes foi coletado mensalmente durante o período de um ano (fevereiro de 2008 a janeiro de 2009), sendo 535 machos, 578 fêmeas e 102 juvenis. A razão sexual total não foi significantemente diferente da esperada 1:1, mas diferiu significativamente em alguns dos meses coletados. Um total de 136 fêmeas ovígeras foi coletado e o período reprodutivo foi considerado contínuo com pico de ocorrência nos meses mais quentes. Um aumento no número de juvenis foi identificado após a mais alta frequência de fêmeas ovígeras e caracterizou o período de recrutamento. A fecundidade foi baixa e variou de 1 a 56 ovos por fêmea. O perfil biológico observado aqui correspondeu, em aspectos gerais, com o padrão desenvolvido por populações continentais tropicais e subtropicais, com algumas particularidades relacionadas com as características do ambiente.