Abstract The speciose genus Aegla Leach, 1820 is the only valid extant genus of the anomuran family Aeglidae, bearing 83 known species. This diversity may be even greater since there is some evidence for cryptic speciation. The genus is endemic to southern South America, occurring in freshwater habitats. We assessed the conservation status of 82 species of Aegla and found almost 70% of them under some level of threat, which represents a concerning proportion. Major threats to the group include freshwater pollution with urban, agricultural and industrial effluents, habitat modification and fragmentation, riparian forest removal, among others. Conservation measures are required to mitigate the major threats to freshwater ecosystems along rivers where the group occurs.

Parastacus defossus Faxon, 1898 is a fossorial crayfish species, which constructs its burrows in swampy areas in southeast Uruguay and in the state of Rio Grande do Sul, Brazil. The present field study was carried out in Lami, Porto Alegre, Rio Grande do Sul, Brazil, from May 2003 through August 2005. Environmental measurements (temperature, pH, dissolved oxygen, and water-table depth) of the water in the galleries were made monthly. Burrow morphology was analyzed by means of resin and gypsum casts. The spatial distribution and changes in the number and shape of the surface openings over time were observed in a 100 m² area. To estimate the spatial distribution of the openings, the observed distribution was compared with the expected distribution predicted by the Poisson and Negative Binomial frequency-distribution models. The adult population density was estimated by direct observation of burrows and counts in the study area. Inside the burrows of P. defossus, the water temperature ranged between 16.6°C (autumn 2004) and 23°C (spring 2003). The water was hypoxic and slightly acidic, and the dissolved oxygen content was very low (mean 1.43 mg/l) (18.2% saturation). The soil with burrows had higher percentages of coarse sand, fine sand, and silt. The spatial distribution of the openings showed a significant fit to the Negative Binomial distribution, indicating that the distribution of the openings is aggregated, as confirmed from the burrow morphology. The galleries are always formed by a central tunnel with multiple branchings that connect the underground water to the soil surface by one or more openings, which can be recognized by the chimneys. From knowledge of the burrow morphology, the population density was estimated to be about 120 individuals/100 m².

Analisou-se o crescimento de Aegla itacolomiensis Bond-Buckup & Buckup, 1994, em ambiente natural, a partir de amostragens mensais, realizadas entre junho de 2005 e maio de 2006, no arroio Solitária Alta, tributário da bacia hidrográfica do Rio dos Sinos, município de Igrejinha, RS, Brasil (29º33'10,2''S; 50º50'57''W). Os indivíduos foram coletados com o auxílio de um puçá, triados por sexo, medidos quanto ao comprimento do cefalotórax (CC) e devolvidos ao arroio no mesmo local de onde foram retirados. O crescimento em comprimento de machos e fêmeas de A. itacolomiensis foi avaliado pela análise das distribuições de frequências absolutas em intervalos de classe do CC. As modas dos histogramas de frequências do CC foram verificadas. O crescimento dos indivíduos foi estimado por meio da análise da progressão das modas calculadas, resultando nas curvas de crescimento para machos e fêmeas, respectivamente Ct= 23,21[1-e-0,0094 (t + 7,03)] e Ct respectivamente: Ct = 19,49 [1-e-0,0065 (t + 11,16)]. O recrutamento ocorreu na primavera e no verão. Os machos atingiram tamanhos maiores do que as fêmeas e apresentaram maior taxa de crescimento que estas. A longevidade estimada para os machos foi de 2,2 anos enquanto que para as fêmeas foi de 2,5 anos. O padrão de crescimento de A. itacolomiensis é semelhante ao de outras espécies de eglídeos anteriormente estudados.

To give more information about ecology and biology of Aegla itacolomiensis Bond-Buckup & Buckup, 1994 was analized its growth in the nature. Monthly samples were made from June 2005 to May 2006 in Solitária Alta stream, tributary of Rio dos Sinos basin, district of Igrejinha, RS, Brazil (29º33'10,2''S; 50º50'57''W). The specimens were collected by dip net, sexed and after the cephalotorax measured, the animals were brought back to the stream. The growth estimated by cephalotorax length for males and females of A.itacolomiensis was analized by absolut distributional size-classes frequency. The modal frequency of cephalotorax lenght was calculated. The growth was estimated trought the modal progression. The growth curves in cefalotorax length for males and females are described respectively by the equations: Ct = 23.21[1-e-0.0094 (t + 7.03)] e Ct= 19.49 [1-e-0.0065 (t + 11.16)]. Were found juveniles in the spring and summer. The males attained larger sizes and a higher growth rate than females. The estimated longevity was 2.2 years for males and 2.5 years for females.

The present study investigates the growth of Parastacus defossus Faxon, 1898, a fossorial species known only from Brazil (state of Rio Grande do Sul) and Uruguay. The estimated growth curve was calculated for animals from the wild and for juveniles cultivated in the laboratory. The specimens were collected monthly between January, 2003 to August, 2005, in Lami region, municipality of Porto Alegre, state of Rio Grande do Sul, Brazil. The VON BERTALANFFY (1938) growth model was used to estimate the growth curve . To calculate the modal values from the frequency distributions the software PeakFit 4.12© SeaSolve Inc., was employed. The growth curve for field animals is described by the equation: Lt = 30,98 [1 - e-0,0026 (t+44,86)] and for the juveniles cultivated in laboratory: Lt = 19,29 [1 - e-0,0048 (t+37,14)]. It was shown that, under laboratory conditions, the growth was slower than in the field. By comparing the data of P. defossus with those of P. brasiliensis (von Martens, 1869), it was possible to verify a slower growth, both in laboratory as under field conditions. The longevity of the studied species (1198.7 days or 40 months) also showed to be lower when compared to P. brasiliensis.

Este trabalho descreve a estrutura populacional e aspectos da biologia reprodutiva de Parastacus defossus Faxon, 1898, uma espécie com hábito fossorial que passa sua vida no interior de galerias subterrâneas. Aproximadamente 30 exemplares foram coletados mensalmente, de janeiro de 2003 a agosto de 2005 na região do Lami, Município de Porto Alegre, Rio Grande do Sul, Brasil. Registrou-se o comprimento mínimo, máximo e médio da carapaça de machos, fêmeas, juvenis e animais com ootestículo. Analisou-se a distribuição de freqüência por classes de tamanho, a proporção sexual, o recrutamento e o período reprodutivo. Foram amostrados um total de 766 exemplares, 315 machos (41,12%), 278 fêmeas (36,30%), 166 juvenis (21,67%) e sete animais com ootestículo (0,91%). Machos e fêmeas estiveram presentes durante todos os meses de amostragem e em todas as classes de tamanho, sendo que a maior freqüência de indivíduos foi registrada nas classes de tamanho ente 24 a 30 mm. A maior freqüência de juvenis foi observada na primavera/2003 e verão/2005. Diferenças significativas no tamanho de machos e fêmeas foram registradas apenas nas classes de tamanho entre 26-30 mm. A proporção sexual no período amostral foi de 1:0,88 (x² = 2,3; p > 0,05) e entre as classes de tamanho foram constatadas diferenças significativas nas classes de tamanho 26-28 mm (x² = 5,43; p < 0,05) e 28-30 mm (x² = 4,77; p < 0,05) de comprimento de carapaça, nas quais os machos foram mais freqüentes. Das 278 fêmeas coletadas, apenas 17 estavam ovígeras (6,11%), sendo a estação reprodutiva bem definida na primavera.

This study investigates the population structure and the reproductive biology of Parastacus defossus Faxon, 1898, a fossorial species that spends its life inside subterranean tunnels. Around 30 specimens were collected each month in the region of Lami, municipality of Porto Alegre, state of Rio Grande do Sul, Brazil, from January, 2003 to August, 2005. The minimum, the maximum, and the mean carapace length of males, females, juveniles and individuals with ootestis were recorded. The frequency distribution by size classes, the sexual proportion, the recruitment, and the reproductive period were analyzed. A total of 766 specimens were collected, from which 315 were males (41.12%), 278 were females (36.30%), 166 were juveniles (21.67%), and seven individuals had ootestis (0.91%). Males and females were present in all months and in all size classes. The highest frequency of individuals matched the size classes from 24 to 30 mm. The highest frequency of juveniles was recorded during the spring of 2003 and the summer 2005. Significant differences in the size of males and females were recorded in the size classes between 26 and 30 mm. The sex ratio between all males and females was 1:0.88 (x² = 2.3, p > 0.05). The proportion between males and females showed significant differences between the size classes 26-28 mm (x² = 5.43, p < 0.05) and 28-30 mm (x² = 4.77, p < 0.05) carapace length, were the number of males was highest. Of the 278 females, only 17 were ovigerous (6.11%) and the reproductive period was clearly restricted to the spring.

Parastacus brasiliensis (von Martens, 1869) é um lagostim de água doce endêmico da região meridional brasileira, ocorrendo nas bacias que formam o estuário do Guaíba, na depressão central do Estado do Rio Grande do Sul. O objetivo deste estudo é descrever e ilustrar a morfologia externa e a distribuição dos diferentes tipos de setas nos apêndices de exemplares adultos de P. brasiliensis. Em laboratório, os exemplares foram dissecados e detalhes da organização morfológica foram descritos e ilustrados com auxílio de câmara clara adaptada ao estereomicroscópio. Microscopia eletrônica de varredura foi utilizada para um melhor detalhamento no estudo das setas. Os resultados obtidos foram comparados com outras espécies de lagostins e com estágios juvenis de P. brasiliensis. Os tipos de setas e o padrão de distribuição observados são similares ao encontrado em Austropotamobius pallipes (Lereboullet, 1858). Diferenças foram encontradas no basipodito e no coxopodito do primeiro maxilípodo e na primeira maxila de P. brasiliensis, onde setas serradas são substituídas por formas plumodenticuladas e multidenticuladas.

Parastacus brasiliensis (von Martens, 1869) is an endemic South Brazilian freshwater crayfish that occurs in the river systems belonging to the Guaíba estuary, in the central lowlands of the state of Rio Grande do Sul. The aim of this study is to describe and illustrate the external morphology and the distribution of the different types of setae on the appendages of adult P. brasiliensis. In laboratory, the specimens were dissected and the details of the morphological organization described and drawn with a camara lucida adapted to a stereomicroscope. A scanning electron microscope was utilized for a more detailed study of the setae. The results were compared with other crayfish species and also with the juvenile stages of P. brasiliensis. The types and the distributional pattern of the setae observed are similar to Austropotamobius pallipes (Lereboullet, 1858). Differences were found in the basipodite and the coxopodite of the first maxilliped and in the first maxilla of P. brasiliensis, where the serrate setae are replaced by the plumodenticulate and multidenticulate forms.

Os macro-invertebrados bentônicos que ocorrem em quatro rios, três pertencentes à bacia do Rio Pelotas (Rios Divisa, Marco e Silveira nas cabeceiras do Rio Uruguai) e um ao sistema Taquari-Antas (Rio Antas), tributário da bacia do Guaíba, no Estado do Rio Grande do Sul, foram identificados. Duas amostras foram coletadas no verão, outono e primavera, com uma réplica em cada rio. Foram coletados 28961 espécimes de macro-invertebrados compreendendo Platyhelminthes, Annelida, Acarina, Insecta, Crustacea e Mollusca. Na comparação entre os rios, Silveira e Marco mostraram diferenças significativas nos índices de Shannon-Weaver (H’), no Recíproco de Simpson (1/D), de Margalef (DMg) e na Equitabilidade (E). O rio Silveira possui os maiores índices médios de diversidade e de EPT (Ephemeroptera, Plecoptera, Trichoptera). Os valores de EPT caracterizaram o rio Divisa com a maior abundância (73%), seguido pelo Marco (71%), Antas (48%) e Silveira (36%), Estes resultados sugerem que o rio Silveira sofre um moderado stress ambiental, de origem antrópica, embora mostre uma maior diversidade da macrofauna bentônica.

Benthic macroinvertebrate in four rivers, three in the Pelotas River basin (Divisa, Marco and Silveira rivers, in the headwaters of the Uruguai River) and one in the Taquari-Antas system (Antas River), a tributary in the Guaíba basin, in the state of Rio Grande do Sul, were identified. Two samples were collected in summer, autumn and spring, with one replicate in each river. The total of 28,961 specimens included members of Platyhelminthes, Annelida, Acarina, Insecta, Crustacea and Mollusca. The Silveira and Marco rivers showed significant differences in the indices of Shannon-Weaver (H’), Simpson’s Reciprocal (1/D), Margalef (DMg) and Equitability (E). The Silveira River showed the highest means of diversity and the EPT index (Ephemeroptera, Plecoptera, Trichoptera). Comparison among the diversity indices, considered individually, were insufficient to show differences in community structure, for the purpose of ecological characterization of the rivers. The EPT values characterized the Divisa River as having the highest abundance (73%), followed by the Marco (71%), Antas (48%) and Silveira (36%). These results suggest that the Silveira River is subject to moderate environmental stress, from human impact, although it showed the highest diversity of the major macrobenthic groups.

Uma maneira de estimar o desenvolvimento gonadal ao longo do ciclo reprodutivo é observar o crescimento das gônadas em relação aos órgãos utilizados para o estoque de energia. O objetivo desse estudo foi acompanhar os índices gonadossomático e hepatossomático durante o ciclo reprodutivo de Aegla platensis Schmitt, 1942. Animais adultos foram coletados em Taquara, Rio Grande do Sul, Brasil (29°46'S, 50°53'W). Machos e fêmeas foram pesados e dissecados, gônadas e hepatopâncreas (HP) foram retirados e pesados para obtenção dos índices gonadossomático (IG) e hepatossomático (IH). Nas fêmeas, os índices também foram comparados com o grau de desenvolvimento dos ovários. Nos machos o IG mostrou um pico de desenvolvimento gonadal no outono (p < 0,05), quando os valores do IH diminuíram (p < 0,05). Fêmeas mostraram um aumento do IG no final do verão e início do outono (p < 0,05) e os valores do IG aumentaram à medida que o ovário tornava-se maduro. Em A. platensis, tanto nos machos como nas fêmeas, os valores do IH nunca mostraram valores mais baixos que o IG, o que pode indicar que esses aeglídeos apresentam um padrão de utilização de energia diferente dos outros decápodos, onde à medida que o desenvolvimento gonadal aumenta os valores do IH diminuem marcadamente.

One way to estimate gonadal development through the reproductive cycle is to observe the growth of the gonads related to the organs used to store energy. The aim of this study was to follow the gonadosomatic and hepatosomatic indexes during annual cycle of Aegla platensis Schmitt, 1942. Adult animals were collected in Taquara, Rio Grande do Sul, Brazil (29°46'S, 50°53'W). Males and females were initially weighed and dissected and had their gonads and hepatopancreas (HP) removed and weighed in order to estimate the Gonadosomatic (GI) and hepatosomatic (HI) indexes. In females, the indexes were also compared to the degree of development of the ovaries. In males the GI showed a peak of gonadal development in the autumn (p < 0.05), just when the HI showed a decrease (p < 0.05). Females showed a rise in the GI at the end of summer and beginning of autumn (p < 0.05). In females, GI values increased as the ovary matured. In A. platensis, for both males and females, the HI never showed values lower than the GI, which may indicate that these aeglids show a different pattern of energy utilization from other decapods, where as gonadal development peaks the HI decreases markedly.

O crescimento de Aegla jarai foi analisado com objetivo de contribuir com informações referentes ao perfil bio-ecológico do caranguejo. As coletas foram realizadas de julho de 2001 a setembro de 2002 no Ribeirão Espíngarda, localizado no Parque Nacional da Serra do Itajaí, Santa Catarina, Brasil. Os espécimes foram separados por sexo e medidos quanto ao comprimento do cefalotórax e, após a biometria, devolvidos ao ribeirão. O modelo de von Bertalanffy foi utilizado para estimar o crescimento em tamanho através da progressão das modas resultando nas curvas de crescimento Ct = 25,11 [1- e - 0,0082 (t + 29,02)] (para os machos e Ct = 23,33 [1- e - 0,0048 (t + 46,45)] (para as fêmeas). As curvas baseadas nas médias também foram obtidas: Ct = 23,56 [1- e - 0,0101 (t + 19] (para os machos) e Ct = 22,69 [1- e - 0,0052 (t + 40,95)] (para as fêmeas). O recrutamento estendeu -se durante a primavera (outubro, novembro e dezembro) e no início do verão (janeiro). Na população de A. jarai, os machos atingiram tamanhos superiores e apresentaram uma taxa de crescimento maior do que as fêmeas. A longevidade, para ambos os sexos, foi estimada em dois anos.

The growth of Aegla jarai was examined aiming to contribute with information about the bioecological profile of the species. The sampling was carried out at the Espíngarda River system situated at the Parque Nacional da Serra do Itajaí, Santa Catarina State, Brazil from July 2001 to September 2002. The sex and the length of cephalothorax (mm) were recorded and the specimens were brought back to the stream. The von Bertalanffy's model was used to estimate growth based on the modal progression of the size, which resulted in the growth curves described by Lt = 25.11 [1- e - 0.0082 (t + 29.02)] (for the males) and Lt = 23.33 [1- e - 0.0048 (t + 46.45)] (for the females). The curves based on the means were also obtained which were Lt = 23.56 [1- e - 0.0101 (t + 19] (for the males) and Lt = 22.69 [1- e - 0.0052 (t + 40.95)] (for the females). The recruitment period extended throughout spring (October, November and December) and early summer (January). In the population of A. jarai the males attained larger sizes and a higher growth rate than females. The estimated longevity was two years for both sexes.

A familia Parastacidae compreende os crustáceos límnicos popularmente conhecidos como lagostins da água doce. Parastacus Huxley, 1879 é o único gênero que ocorre no Brasil, e inclui, no estado do Rio Grande do Sul, a espécie endêmica, Parastacus brasiliensis (von Martens, 1869). Os espécimes foram coletados com armadilhas em um arroio nas cabeceiras da bacia do Rio Gravataí, município de Taquara, Rio Grande do Sul, Brasil. Os animais capturados foram transportados até o Laboratório de Crustáceos Universidade Federal do Rio Grande do Sul e criados em aquários até atingirem o estado adulto. Os espécimes foram dissecados e suas estruturas examinadas por microscopia óptica e desenhados em câmara clara. O material foi ainda preparado para fotografia sob exame com microscópio eletrônico de varredura. Procedeu-se à análise e classificação de todos tipos de setas encontradas nas formas adultas de P. brasilieinsis.

The family Parastacidae comprises the limnic crustaceans popularly known as crayfishes or crawfishes. Parastacus Huxley, 1879 is the only genus occurring in Brazil and has an endemic species, Parastacus brasiliensis (von Martens,1869), in Rio Grande do Sul State. The individuals were collected with traps from a brook in the springs of Gravataí basin, Taquara, Rio Grande do Sul State, Brazil. The captured animals were taken to the Universidade Federal do Rio Grande do Sul Carcinology Laboratory and raised to full growth in aquaria. The specimens were dissected, and the setae analysed under optical microscopy and drawn with the aid of a camera lucida. Material was prepared for photography under scanning electron microscope. The analysis and classification of all types of setae in the adult forms of P. brasilieinsis was performed.

The growth study, in length and weight, of Aegla leptodactyla Buckup & Rossi, 1977, was developed based on biometric data of 2,435 specimens collected from Rio da Divisa, a tributary of the Rio Silveira, district of São José dos Ausentes, Rio Grande do Sul State, Brazil. The samplings were realized from April/2000 to July/2001. The captured specimens had recorded the Sex and the length and width of cephalothorax. The specimens from June/2000, November and May/2001 were weighted, and those from June and July/2001 had recorded their length and width of the chelipeds. For the description of the growth the von Bertalanffy's model was utilized. The growth curves in length (mm), for data obtained through the modal progression, are described by the equations: Ct = 19.83 [1- e - 0,0023 (t +55,5)] for males and Ct = 18.096 [1- e - 0,0024 (t +48,6)] for females. For data obtained through the progression of age group means, the equations for males and females are, respectively, Ct = 18.15 [1- e - 0,0027 (t +52)] and Ct = 20.7 [1- e - 0,002 (t +63,4)]. For the growth description in weight (g), for data obtained through modal progression, the equations are: Pt = 3.88 [1- e - 0,0023 (t +55,5)]3,073 for males and Pt = 2.78 [1- e - 0,0024 (t +48,6)]3,1046 for females, and for data obtained from progression of age group means: Pt = 2.96 [1- e - 0,0027 (t +52)]3,073 (males) e Pt = 3.65 [1- e - 0,002 (t +63,4)]3,1046 (females). The analysis of covariance did not record significant differences between the length of right and left chelae, of males and females.

The crustaeeans of Aeglidae family oeeur in South America's fresh water enviranments, featuring as important links in the food chains. The present article has the intention to give an acount of the results from investigations made from April/2000 to July/2001 on the biological and ecological features of Aegla leptodactyla Buckup & Rossi, 1977, an endemic species from the headwaters of the Rio Pelotas Basin in Rio Grande do Sul State, Brazil. The sampling was performed at the Rio da Divisa, tributary of Rio Pelotas, municipal district of São José dos Ausentes, Rio Grande do Sul. The animais were collected with a hand net (puçá) at four different sites of the river. High contents of dissolved oxygen was verified, with a medium value of 108% and alow conductivity (avarage of 13.7mS/cm). The water mean temperature was 16ºC and the pH remained neutral, average of 7.5. The velocity of the water current varied from 0.54 to 0.78m/s. A total of 1,323 males and 1,112 females of A. leptodactyla was sampled. Ovigerous females were observed from April through September and the smallest egg bearing female measured 14.09 mm cephalothorax length. The recruitment took place in November and December. The sex-ratio of the population was 1.19 males for 1 female.

The validity of Aegla rosanae Campos Jr., 1998 as a new species was analysed. On the basis of comparisons with Aegla paulensis Schmitt, A. rosanae was considered its junior synonym.

The crustaceans of the genus Aegla Leach, 1820 are found in streams, rivers and lakes from Franca, São Paulo, Brazil (20º60'S, 47º40'W), to Ilha Madre de Dios, Chile (50º01'10"S, 75º18'45"W) in South America. The growth and cheliped asymmetry of Aegla platensis Schmitt, 1942 were analyzed. The animals were collected from July 1997 to September 1998 at Arroio do Mineiro, Taquara, Rio Grande do Sul, Brazil (29º46'S, 50º53"W). The sex, length, width of the carapace and the total weight of the crab were registered. And after that, the animals were returned to the stream. In the statistical analysis von Bertalanffy's model was used. The growth curves in length (mm) of males and females are described, respectively, by the following equations: L1 = 17.39 [1 - e -0041(t + 3913)] and L1 = 19.12 [1 - e -0.0033 (t + 50.38)]. The equations that describe the growth in weight (g) of males and females, respectively, are: Wt = 2.48 [1 - e -0.0041(t + 3913)]3.04 and Wt - 3.38 [1 - e - 0033(t + 50.38)]3.05 Among 36,5% males had larger left chelae and 52% of females had chelae of the same size.

The absence of morphological external characteristics that allow the recognition of the sex as well as the presence of both male and female gonopores in the same animal [except in some sexual forms of Parastacus nicoleti (Philippi, 1882)] gives rise to the hypothetical existence of some form of hermaphroditism in crayfishes belonging to the genus Parastacus Huxley, 1879. Specimens of Parastacus brasiliensis (von Martens, 1869) were collected in a rivulet at Mariana Pimentel municipality, Rio Grande do Sul, Brazil. In the laboratory they were reared and dissected. The results suggest that P. brasiliensis may be a sequential hermaphroditic species, but male and female gonadal tissues were not simultaneously present in the analized samples. In testes and ovaries two pairs of genital ducts are present; that connect, respectively, to the gonopores on the coxae of the fifth and the third pairs of pereiopods. In the females only the apertures and anterior ducts seem to be functional, while in the males only the apertures and posterior ducts may be functional. The existence of different degrees of obstruction in the female genital apertures and different degrees of projection in the male genital apertures was observed. The aspect of the gonopores were used to recognize, externally, the sex of animais.