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Two new species of Parastacus Huxley, 1879 are described from material collected in the state of Rio Grande do Sul, southern Brazil: Parastacus fluviatilis sp. nov. from highland streams and Parastacus caeruleodactylus sp. nov. from wetlands. Parastacus fluviatilis sp. nov. is distinguished mainly by large chelipeds with dense setae cover on the cutting edge of fingers, telson subtriangular with two lateral blunt spines and strongly concave ventral surface of lateral process of thoracic sternites 6 and 7. Parastacus caeruleodactylus sp. nov. is distinguished mainly by blue cheliped fingers and a large gap between them, reduced abdomen, dorsal and ventral margins of dactylus, propodus and carpus of second pair of pereiopods with tufts of long setae and mid-dorsal carina of exopod of uropods unarmed. According to IUCN Red List criteria both species are considered endangered. Habitat characterization and a method for defining the shape of second abdominal pleura are also provided.

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The aim of the present study was focused on and describes the gross morphological and scanning electron microscopical features of the gill of the red swamp freshwater crayfish. Our results noted that: all gills have the same general structure and appearance. The gill consists of axis with numerous finger-like filaments, having three morphological types; round, pointed and somewhat hooked shaped. There is a variation in the direction of filaments according to their position, in middle part were nearly perpendicular to gill axis while in the apex were nearly parallel to axis. There were characteristic system of gill spines on central axis, basal plate, setobranch and on the bilobed epipodal plate. There are four shape of spinated-like parts of setobranch seta, two pointed processes and two broad processes. The bilobed epipodal plate is devoid from any filaments and under SEM, its apical part has serrated free border and corrugated surface while the middle part has no serrated free border.

El objetivo del presente estudio fue describir las características morfológicas macroscópicas y mediante microscopio electrónico de barrido las branquias del cangrejo rojo de pantano de agua dulce. Nuestros resultados señalan que todas las branquias tienen la misma estructura y apariencia general. Las branquias se componen de ejes con numerosos filamentos similares a dedos, que tiene tres tipos morfológicos; redondo, punteado y con forma de gancho. Hay una variación en la dirección de los filamentos de acuerdo con su posición, en la parte media eran casi perpendicular al eje branquial, mientras que en el ápice fueron casi paralelas al eje. Hubo un sistema característico de espinas branquiales sobre el eje central, placa basal, espinas dorsales y sobre las placas epipodales bilobuladas. Se observaron cuatro formas de las ramas similares a espinas, dos procesos apuntados y dos procesos amplios. La placa epipodal bilobulada estaba desprovista de filamentos bajo microscopía electrónicas, su parte apical tiene una margen libre aserrado, con una superficie ondulada, mientras que la parte media no tiene margenes aserrados.

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Dwarf crayfish are a subfamily of freshwater decapods distributed along the southeastern coast of United States and the Central Plateau of México. Recent phylogenetic studies have found that diversity of dwarf crayfish in México could be currently underestimated, and suggested the existence of possible new species for a number of clades for which taxonomic identity was uncertain, including one from Zacapu, a small lake in the Trans-Mexican Volcanic Belt. Here, a congruence criterion between morphological and molecular evidence is used to test if this previously detected clade should be considered as a new species. A set of morphometric variables was taken to characterize variation from this population (including some newly proposed traits possibly valuable for species discrimination) and to compare it statistically to its closest relative, C. chapalanus. Also, additional individuals to those previously sequenced were included using a set of molecular characters, including 5 molecular markers (three mitochondrial and two nuclear fragments) and all extant species described to date from México. Principal Component Analysis, Mann-Whitney paired test and Discriminant Factor Analysis support morphological differentiation of the Zacapu population. Phylogenetic analyses are congruent with morphology and confirm that this population constitutes an exclusive monophyletic clade with high support values. Additionally, genetic Cytochrome Oxidase subunit I (cox1) distance between Zacapu and the closest related species is above the average between species distance in crayfish (ML=3.6%). Congruence between morphology and molecular evidence support the hypothesis that the population from lake Zacapu should be considered a new species, to which the name C. zacapuensis sp. nov. is given and its description provided. With respect to its closest relatives, C. zacapuensis sp. nov. is diagnosed according to the following set of morphological characters: a wider cephalotorax (5.10-5.70 vs. 4.40-4.70), wider abdomen (4.52-4.84 vs. 3.94-4.35) a more robust chela (2.12-2.48 vs. 1.72-1.96) and a shorter merus (3.04-4.20 vs. 4.26-4.71) and mesial process of first pleopod of the form I male reaching distally well beyond the other elements. This study emphasizes the utility of using an integrative framework for species recognition in crayfish.

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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.(AU)

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.(AU)

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Quick, reliable and non destructive methods are necessary to estimate size structure on commercial land crabs, in order to acquire relevant information concerning the health of their populations. Cardisoma guanhumi and Ucides cordatus are two land crabs that are exploited at a high scale and also in an artisan way in the Caribbean area and in the coasts of Brazil, which populations are endangered due to uncontrolled exploitation. The purpose of this work is to provide various methods to estimate indirectly crab body size. Sampling was carried out in Carenero (C. guanhumi) and Cumaná (U. cordatus) (Venezuela). For each species, three methods were used to measure burrow diameter (Vernier, internal spring caliper and photograph), and these were correlated with real body size of the crabs. Model II linear regression analyzes, i.e. Ordinary Least Squares and Mayor Axis, were used to build and test the performance of forecasting models. Cardisoma guanhumi showed a high bivariate data dispersion using Vernier and photo measuring methods, increasing these towards larger animals. Less dispersion was achieved with the spring caliper method; this resulted in the most accurate measurements of indirectly estimated body size in C. guanhumi (r²= 0.61), whereas Vernier measurements were the least precise. On the other hand, all three methods gave reliable estimates for U. cordatus, being the Vernier method the most accurate (r²= 0.71). However, in both species, all forecasting equations overestimated the size of smaller crabs (those below the mean) but underestimated the size of larger crabs. Nevertheless, all three methods were statistically significant for each of the species, and looking at the above mentioned underand overestimations, they can serve as reliable and fast non-destructive tools to be used by resource managers and field biologists to acquire size structure information concerning these two species. Vernier and internal spring caliper ...

Para la estimación de la estructura de tamaños en cangrejos terrestres comerciales y la obtención de información relevante para su manejo, es necesario utilizar métodos rápidos, confiables y no destructivos. Cardisoma guanhumi y Ucides cordatus son dos cangrejos terrestres que son explotados comercialmente en el Caribe y en Brasil. El propósito de este trabajo es suministrar métodos indirectos para la estimación del tamaño del caparazón de los cangrejos y por consiguiente, de la estructura de tallas. Los muestreos se llevaron a cabo en Carenero (C. guanhumi) y en Cumaná (U. cordatus) (Venezuela). Se utilizaron tres métodos para estimar el diámetro de sus madrigueras: Vernier, compás y fotografía. Estos se correlacionaron con el tamaño real del cangrejo. Se aplicó el análisis de regresión Ordinary Least Squares Model II y la capacidad de predicción se probó utilizando el modelo II Mayor Axis para las regresiones. Cardisoma guanhumi mostró una fuerte dispersión de sus datos en los métodos de Vernier y fotografía. Menos dispersión se obtuvo con el método del compás y fue el más preciso (r²= 0.61). Para U. cordatus las medidas con Vernier fueron la más adecuadas (r²= 0.71). Sin embargo los tres métodos fueron confiables. Los diferentes métodos mostraron ventajas y desventajas y dependerá del que aplique los métodos, decidir cuál será el más adecuado para sus propósitos.

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Determinamos el momento del desarrollo postembrionario en que se produce la diferenciación sexual primaria en la langosta Cherax quadricarinatus. Esta es evidenciada por la presencia de las gónadas y sus respectivos conductos. También determinamos la diferenciación sexual definida por la aparición de los caracteres sexualessecundarios. Se observaron 797 machos, 506 hembras y 456 individuos intersexos de 0.02 a 89.96 g (de criadero y laboratorio). Disecamos una submuestra de 106 machos, 69 hembras y 59 individuos intersexos para la caracterización macroscópica de la estructura gonadal. La diferenciación de los gonoporos se inicia aproximadamente a los 0.10 g, en sincronía con la diferenciación del sistema reproductor en machos, hembras e intersexos. La adquisición de la forma definitiva de ovario, oviducto, testículo y vaso deferente son posteriores. El appendix masculina iniciasu diferenciación a los 0.12-0.2 g y adquiere los rasgos característicos del appendix de los adultos a partir de 1-2 g.La diferenciación de la mancha roja (red patch) ocurre a partir de los 2.3 g.

We determined the earliest stage of postembryonic development at which primary and secondary sexual differentiations occur in the freshwater (“red claw”) crayfish Cherax quadricarinatus. For this purpose,797 males, 506 females and 456 intersex specimens within a weight range of 0.02-89.96 g were observed under stereoscopic microscope to determine the presence of the genital openings at the basis of the third (females) or fifth (males) pair of pereiopods. Animals presenting both pairs of genital openings were considered as intersex. A subsample of 106 males, 69 females and 59 intersex were dissected for the macroscopic characterization of gonad morphology. The development of the genital openings began approximately at 0.10 g, simultaneously with the differentiation of the reproductive system in females, males and intersex. Although the differentiation of the reproductive system started very early in the postembryonic development, the definitive form and colour of ovaries, oviducts, testes and vasa deferentia was acquired later. The differentiation of the appendix masculina began at 0.12-0.2 g and acquired the elongated shape of the adult at 1-2 g. The soft red patch characteristic of adult males started at 2.3 g of body weight in both chelipeds.

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Cherax quadricarinatus is a large freshwater crayfish species Parastacidae) native of north-west Queensland and the Northern Territory of Australia. The species typically exhibits a gonochoristic sexual system, although in cultured populations various types of intersex individuals have been described as functional males. In the present study, the macroscopic morphology and the gonadal histology of one type of intersex are described and discussed. All intersexes having both pairs of genital openings (female and male openings) and lacking both appendix masculinae and red patches were functional females with normal ovaries and oviducts. From a histological point of view, they did not differ from normal females having previtellogenic and/or vitellogenic ovaries according to size.

Cherax quadricarinatus, es un astácido dulceacuícola de gran tamaño de la (familia Parastacidae) originario delnoroeste de Queensland y del norte de Australia. Presenta un sistema sexual gonocórico, aunque en poblaciones decultivo se han descrito varios tipos de individuos intersexos como machos funcionales. En el presente estudio se describe y discute la morfología macroscópica y la histología gonadal de un tipo de intersexos. Todos los intersexos que presentan ambos pares de aberturas genitales (femeninas y masculinas) y carecen de ambos apéndices masculinos y de la mancha roja, fueron hembras funcionales con ovarios y oviductos normales. Desde el punto de vista histológico no difieren de las hembras normales, presentando ovarios previtelogénicos y/o vitelogénicos de acuerdo a su tamaño.

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This work describes the morphology and histology of the P. argentinus digestive tract. The foregut comprises the mouth, oesophagus, and stomach and is lined by a simple cylindrical epithelium overlain by cuticle. There are tegumental glands in the oral region and in the first portion of the oesophagus and of the hindgut. The cardiac stomach is an oval dorsal sac in the cephalothorax and has no calcified structures. The pyloric stomach comprises an upper chamber and a lower gland filter. The filter consists of an outer row of elongated setae and an inner row of dorsally curved setae forming longitudinal channels 16-18 microm wide. The midgut runs from the dorsal chamber of the pyloric stomach to the sixth abdominal somite without caeca. The hindgut runs from the sixth abdominal somite to the ventral anus. The mid-gut epithelium comprises dominant cylindrical cells and small undifferentiated cells in the first portion. The hindgut wall presents longitudinal folds, conspicuous muscular bundles, and a folded cuticle. The digestive tract of P. argentinus is basically similar to that of most of decapods. The absence of calcified structures in the stomach and the width of the longitudinal channels in the filter are related to the predominantly detritivorous diet.

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This work describes the morphology and histology of the P. Argentinus digestive tract. The foregut comprises the mouth, oesophagus, and stomach and is lined by a simple cylindrical epithelium overlain by cuticle. There are tegumental glands in the oral region and in the first portion of the oesophagus and of the hindgut. The cardiac stomach is an oval dorsal sac in the cephalothorax and has no calcified structures. The pyloric stomach comprises an upper chamber and a lower gland filter. The filter consists of an outer row of elongated setae and an inner row of dorsally curved setae forming longitudinal channels 16-18 microm wide. The midgut runs from the dorsal chamber of the pyloric stomach to the sixth abdominal somite without caeca. The hindgut runs from the sixth abdominal somite to the ventral anus. The mid-g ut epithelium comprises dominant cylindrical cells and small undifferentiated cells in the first portion. The hindgut wall presents longitudinal folds, conspicuous muscular bundles, and a folded cuticle. The digestive tract of P. argentinus is basically similar to that of most of decapods. The absence of calcified structures in the stomach and the width of the longitudinal channels in the filter are related to the predominantly detritivorous diet.(AU)

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This work describes the morphology and histology of the P. Argentinus digestive tract. The foregut comprises the mouth, oesophagus, and stomach and is lined by a simple cylindrical epithelium overlain by cuticle. There are tegumental glands in the oral region and in the first portion of the oesophagus and of the hindgut. The cardiac stomach is an oval dorsal sac in the cephalothorax and has no calcified structures. The pyloric stomach comprises an upper chamber and a lower gland filter. The filter consists of an outer row of elongated setae and an inner row of dorsally curved setae forming longitudinal channels 16-18 microm wide. The midgut runs from the dorsal chamber of the pyloric stomach to the sixth abdominal somite without caeca. The hindgut runs from the sixth abdominal somite to the ventral anus. The mid-g ut epithelium comprises dominant cylindrical cells and small undifferentiated cells in the first portion. The hindgut wall presents longitudinal folds, conspicuous muscular bundles, and a folded cuticle. The digestive tract of P. argentinus is basically similar to that of most of decapods. The absence of calcified structures in the stomach and the width of the longitudinal channels in the filter are related to the predominantly detritivorous diet.

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A conglomerate of 8-12 neurons in the medulla externa of the crayfish eyestalk was explored in their reaction to a polyclonal antibody against the tyrosinated octapeptide Red Pigment Concentrating Hormone (Tyr-RPCH). These are large neurons with diameters within a range of 33-43 microns and they were all positively stained with neutral red. By intracellular staining with lucifer yellow, the neurons were found to branch extensively within the medulla externa and the lamina ganglionaris of the eyestalk. Each neurite bifurcates at about 40 microns from the soma. Both branches run to the medial edge of the eyestalk; one proceeds distally to the lamina ganglionaris, while the other runs proximally to the medulla interna. Both end freely in multiple arborizations, covering from the medial to the lateral edges of the eyestalk. No branches were found to the sinus gland, the main neurohaemal organ of the eyestalk. A group of 4 neurons in the conglomerate consistently rendered positive reaction to the anti-Tyr-RPCH antibody (A-RPCH). They are superficially located in the cluster, and at the electron microscope, they showed the usual features of a secretory cell, i.e., clear and dense granules, an active and well-developed Golgi apparatus, and rough endoplasmic reticulum. The dense granules were larger (mean diameter: 101.5 nm) than the clear granules (mean diameter: 90.3 nm). The immunopositive reaction at the electron microscope was found to be largely confined to the dense-cored granules.

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Similar to intact crayfish, animals with an isolated protocerebrum-eyestalk complex, exhibit competent circadian rhythms in the electroretinogram (ERG). The ERG rhythms of the two eyes remain in phase after isolation of the protocerebrum but can be desynchronized after surgical bisection of the protocerebrum. The desynchrony of the two ERG rhythms reveals the existence of at least two circadian pacemakers in the eyestalk-protocerebrum complex. In addition, the fact that desynchrony of the ERG rhythms only occurs in bisected preparations suggests that pathways between the protocerebral lobes normally couple the two pacemakers.

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El presente trabajo es una revisión breve sobre los detalles ultraestructurales de las fibras nerviosas gigantes y su posible correlación con hallazgos fisiológicos hechos en el axón gigante del calamar. Tanto en secciones finas, como en réplicas obtenidas por crío-fractura, el aspecto más llamativo ha sido la gran cantidad de membranas apareadas que llenan la capa de Schwann. Estas membranas limitan hendiduras intercelulares permeables que conectan la superficie axónica con el espacio extracelular del endoneuro, dejando, así, al axolema como la única barrera continua interpuesta entre el axoplasma y el exterior de la neurona. Se ha observado, tanto en las secciones como en las réplicas, zonas de adosamiento íntimo del axón y de su célula de Schwann a nivel d elos llamados complejos estructurales, en los cuales aparecen involucradas las membranas plasmáticas de ambas células adyacentes. Estas zonas podrían constituir la expresión morfológica del acoplamiento funcional dado a conocer en la misma preparación. Además, la célula de Shwann parece ser muy activa a juzgar por la cantidad de perfiles de exo-endocitosis observados en todas sus superficies de fractura. Finalmente, las células del endoneuro aparecen diferentes en los varios tipos de fibras gigantes estudiados: en el calamar, ellas se muestran como células esponjosas, mientras que en la langosta, ellas exhiben una cantidad extraordinaria de imágenes de exo-endocitosis entremezcladas con algunas uniones epiteliales de baja resistencia y con uniones estrechas incompletas. Por último, en el camarón de río, la célula endoneurales muestran el mismo aspecto que el de la glía adaxónica (AU)

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El presente trabajo es una revisión breve sobre los detalles ultraestructurales de las fibras nerviosas gigantes y su posible correlación con hallazgos fisiológicos hechos en el axón gigante del calamar. Tanto en secciones finas, como en réplicas obtenidas por crío-fractura, el aspecto más llamativo ha sido la gran cantidad de membranas apareadas que llenan la capa de Schwann. Estas membranas limitan hendiduras intercelulares permeables que conectan la superficie axónica con el espacio extracelular del endoneuro, dejando, así, al axolema como la única barrera continua interpuesta entre el axoplasma y el exterior de la neurona. Se ha observado, tanto en las secciones como en las réplicas, zonas de adosamiento íntimo del axón y de su célula de Schwann a nivel d elos llamados complejos estructurales, en los cuales aparecen involucradas las membranas plasmáticas de ambas células adyacentes. Estas zonas podrían constituir la expresión morfológica del acoplamiento funcional dado a conocer en la misma preparación. Además, la célula de Shwann parece ser muy activa a juzgar por la cantidad de perfiles de exo-endocitosis observados en todas sus superficies de fractura. Finalmente, las células del endoneuro aparecen diferentes en los varios tipos de fibras gigantes estudiados: en el calamar, ellas se muestran como células esponjosas, mientras que en la langosta, ellas exhiben una cantidad extraordinaria de imágenes de exo-endocitosis entremezcladas con algunas uniones epiteliales de baja resistencia y con uniones estrechas incompletas. Por último, en el camarón de río, la célula endoneurales muestran el mismo aspecto que el de la glía adaxónica

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The present paper is a brief review on the ultrastructural details of giant nerve fibers and their possible correlation to some physiological findings which have been reported in the squid giant axon. In both, thin sections and freeze-fracture replicas, the most striking feature is the exceeding amount of paired membranes populating the Schwann cell layer. These membranes represent permeable intercellular clefts connecting the axon surface to the endoneurial extracellular space, thus leaving the axolemma as the only continuous barrier between the axoplasm and the neuron exterior. Close apposition of the axon and Schwann cell at the level of structural complexes involving both cells plasma membranes are observed in sections and replicas. These zones could represent the morphologic expression of the functional coupling reported in the same preparation. Besides, the Schwann cell appears to be very active according to the amount of exo-endocytotic profiles seen in all its fracture faces. Finally, the endoneurial cells are different in the various giant fibers studied: in the squid they appear as spongy cells, whereas in the lobster they exhibit an extraordinary amount of exo-endocytosis mixed with some gap and a few incomplete tight junctions, and in the crayfish they present the same features as the adaxonal glia.

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