Parastacus Brasiliensis Research Articles

Taxonomic review of the genus Parastacus Huxley, 1879 (Decapoda: Astacidea: Parastacidae) with description of five new species

The freshwater crayfish genus Parastacus Huxley, 1879 (Parastacidae) is reviewed. Seven species are redescribed: Parastacus brasiliensis (von Martens, 1869), P. defossus Faxon, 1898, P. laevigatus Buckup & Rossi, 1980, P. pilimanus (von Martens, 1869), P. pugnax (Poepigg, 1835), P. promatensis Fontoura & Conter, 2008, and P. varicosus Faxon, 1898. In addition, five new species are described: Parastacus bah, P. heterochaelis, P. manezinho, P. quasimodo and P. rudolphi. Descriptions, diagnoses, and synonyms of the genus and species are provided. In addition, information on the geographical distribution and an identification key is presented for all species.

Distributional patterns of the South American species of Parastacidae (Decapoda, Astacidea)

Abstract The distributional patterns of the species of the South American freshwater crayfishes of the family Parastacidae were analysed using panbiogeographical track analyses to identify targeted regions of crayfish biodiversity for understanding biogeographical patterns. Two generalized tracks were identified using the track analysis approach: (1) Uruguay and Brazil (Parastacus brasiliensis, P. brasiliensis promatensis, P. buckupi, P. caeruleodactylus, P. defossus, P. fluviatilis, P. gomesae, P. guapo, P. macanudo, P. pilimanus, P. pilicarpus, P. saffordi, P. tuerkayi, P. varicosus); and (2) Central-southern Chile (P. nicoleti, P. pugnax, Samastacus spinifrons, Virilastacus araucanius, V. jarai, V. retamali and V. rucapihuelensis). These areas were exclusive, with no overlap between them. The results indicate the presence of South American Parastacidae crayfish in Atlantic coastal sub-tropical and Pacific coastal temperate wet climate regions with biogeographic similarities to other South American inland water decapods.

The hole is deeper: description of two new species within the Parastacus brasiliensis (von Martens, 1869) species complex with an integrative taxonomy approach.

In this contribution, we describe two new species of burrowing crayfish species complex Parastacus brasiliensis from forestry areas in the central region of the state of Rio Grande do Sul, southern Brazil. We used an integrative taxonomy approach with morphology and the mitochondrial DNA 16S rRNA gene and also evaluated their conservation status according to the IUCN Red List Criteria. Parastacus guapo sp. nov. was collected near the municipality of Pantano Grande and it differs from all other congeneric species in having an epistome anterolateral section with a large conical projection ending in a big sharp spine on both sides. It also differs from P. brasiliensis sensu stricto in the shape of the rostral surface, sub-orbital angle, postorbital carina straight, sub-orbital angle > 90, postorbital carinae prominent in anterior and middle portions, carpal spine present, the internal surface of chelipeds palm with sparse tubercules, areola narrow and pleon short. Parastacus gomesae sp. nov. was collected in the municipality of So Jernimo, it differs from all analysed species for rostral spine absent, epistome anteromedian lobe heptagonal and mandible incisive process with seven teeth (the second tooth from the anterior margin is the largest). It is also distinguished of P. brasiliensis sensu stricto in the sub-orbital angle > 90, postorbital carinae prominent in anterior and middle portions, 34 rows of verrucose tubercles irregularly distributed on the palm dorsal surface of chelipeds, areola narrow and pleon short. Phylogenetic relationships confirmed the distinct position of these new species to the already described species. The extent of occurrence (EOO) / area of occurrence (AOO) of P. guapo sp. nov and P. gomesae sp. nov. were estimated at 937 km / 1,87 km, and 2.107 km / 23,9 km respectively. The main threats identified were continued decline in the quality of habitats, resulting from deforestation and forestry areas. However, as we know only one point of occurrence for each new species, we suggest that both be categorized as Data Deficient.

Molecular systematics reveals multiple lineages and cryptic speciation in the freshwater crayfish Parastacus brasiliensis (von Martens, 1869) (Crustacea : Decapoda : Parastacidae)

The characterisation of intraspecific genetic diversity in representatives of the South American crayfish genus Parastacus Huxley, 1879 is here carried out for the first time by comparing populations of Parastacus brasiliensis (von Martens, 1869) as currently defined. Phylogenetic reconstructions based on mitochondrial and nuclear markers indicate the existence of multiple lineages, of which only one can be considered as P. brasiliensis sensu stricto. In addition, there are seven other lineages, one of which is the subspecies Parastacus brasiliensis promatensis Fontoura & Conter, 2008, which is here elevated to species level. We thereby increase to 14 the number of recognised species within Parastacus in South America. Genetic distances among P. brasiliensis sensu stricto and the lineages ‘A’, ‘B’ and ‘C’ increase with geographical distances, suggesting isolation by distance as an important driver of diversification, and eventually speciation, in these burrowing crayfishes. Parastacus brasiliensis occurs mainly in the Guaíba Lake basin and studied populations show limited connectivity and gene flow, probably due to habitat fragmentation. On the basis of genetic and distribution data, the conservation status of P. brasiliensis sensu stricto is confirmed as Near Threatened (NT). These findings lead us to encourage the establishment of preservation areas for isolated populations. The importance of preserving the newly recognised distinct gene pools in order to maintain overall genetic diversity is emphasised.

Contest Duration and Dynamics are Affected by Body Size in a Potentially Subsocial Crayfish (Crustacea: Decapoda)

AbstractFighting is a costly behavior, consuming both time and energy. As a result, the benefits of acquiring resources must outweigh these costs. Resource value will thus influence willingness to invest in a contest through its objective (the intrinsic properties of the resource) and subjective value (context/state dependent). In burrowing crayfish, subjective resource value may vary with life stage: adults, subadults, and juveniles differ in their ability to obtain resources. As juveniles cannot dig their own burrows, we hypothesize that earlier life stages will exhibit lower aggression than later life stages. To test this, we evaluated contests between paired individuals according to their cephalothorax length (CL), encompassing different life stages of Parastacus brasiliensis. To quantify aggression levels, we recorded contest duration, the frequency of low and highly aggressive behaviors, the time to escalate to highly aggressive behaviors, the probability of initiating contests with highly aggressive behaviors, and the latency to initiate a contest. We examined the relationship between these dependent variables and CL (independent variable) using GLMs to test how aggressive behaviors develop. Contest duration increased with pair mean, winner's and loser's CL. Frequency of low aggressive behaviors increased with CL, whereas highly aggressive behaviors, latency, and time to reach highly aggressive behaviors were unrelated to CL. Smaller individuals had a higher probability of initiating contests with highly aggressive behaviors. Self‐assessment explains the contest dynamics of P. brasiliensis, with smaller individuals giving up sooner, probably due to lower energy and time budgets.

One step ahead of the enemy: investigating aggressive interactions between invasive and native crayfish before the contact in nature

Biological invasions are a major cause of biodiversity loss, and early action in these cases is more cost-effective than dealing with widespread invasions. Thus, understanding possible consequences of invasions is essential for control and management actions. Given the early stage of invasion of South America by Procambarus clarkii, a potentially harmful crayfish, we investigated aggressive interactions between this invasive crayfish and the native Parastacus brasiliensis to understand potential impacts of the invader on native species before they encounter each other in nature. We paired size-matched crayfish for two experiments: one with Pr. clarkii males and females against Pa. brasiliensis; and another with Pr. clarkii intraspecific interactions. We starved the crayfish then allowed to interact in the presence of food. In interspecific fights we compared the number of attacks, time with the resource, frequency of won interactions of each species and the first species to reach the resource. Regarding the interspecific fights, Pr. clarkii attacked more often, spent more time with the resource, won more interactions and reached the resource first more often than Pa. brasiliensis. Interspecific fights escalated faster than intraspecific fights. The invasive crayfish’s ability to win might be enhanced due to ownership effects, and its impact is likely to be severe because of its life-history traits. We conclude that Pr. clarkii is definitely a threat for native crayfish, requiring that immediate actions be taken, such as dam construction and manual removal of Pr. clarkii.

Assessing the importance of burrows through behavioral observations of Parastacus brasiliensis, a Neotropical burrowing crayfish (Crustacea), in laboratory conditions

Abstract Background Crayfish from the Neotropical region comprise a unique group among crustaceans. Their burrowing habits have severe consequences for many ecological, morphological, and behavioral traits. Although they are all considered true burrowers, the degree of these adaptations and their relationships to the behavioral repertoires of these crustaceans have been discussed for a long time, although with no consensus. Results To address this situation, we performed behavioral observations of Parastacus brasiliensis in a laboratory environment. Animals (n = 7) were isolated and acclimated in experimental aquaria according to their size (two large and five smaller aquaria) and observed for seven days at four different times of the day (twice during the day and twice at night). Their behaviors were qualified and quantified. The time spent inside and outside the burrow was also observed and analyzed with a t test for paired samples. Their circadian activity was analyzed using Rayleigh's Z test. Animals spent 54.9% of the time hiding within the burrow and also remained longer in it during the day than at night. They spent more time active outside the burrow during the night. Conclusions These results suggest that these crayfish are nocturnal and are definitely not a part of the lotic species group. This species appears to be closely associated with its burrow but can exhibit considerable activity outside of it and can therefore be classified as a secondary burrower. Although this is a laboratory study, the results may stimulate further studies on the importance of burrows to these animals and provide basic background information for new studies on these cryptic crustaceans.

Aggressiveness and life underground: the case of burrowing crayfish

This study compared aggression in two morphologically similar neotropical burrowing crayfishes, Parastacus pilimanus, a primary burrower, and Parastacus brasiliensis, a secondary burrower. Intraspecific pairs were formed, with a maximum 15% difference in carapace and chelae length within each pair. Pairs were allowed to interact for 20 min, during which they were recorded, and the agonistic behaviour was then analyzed throughout these recordings. The species were compared with respect to mean bout duration, first bout duration, number of bouts, latency period, frequency of highly aggressive behaviours, frequency of low aggressive behaviours, as well as the number of approaches, antennal whips and chelae punches. The proportion of interactions that resulted in formation of a clear hierarchy was also compared. Parastacus brasiliensis was the more aggressive species, showing statistically higher values for all parameters except latency, as well as number of bouts and antennal whips (among winners); while P. pilimanus performed more chelae punches. In general terms, both species showed low aggression (due to the absence of clearly escalated fights and other behaviours), which differs from the pattern expected for crayfish. The formation of dominance relationships was more frequent in P. pilimanus than in P. brasiliensis. Due to possible pressure for co-existence and reduced competition for resources, the burrowing habit appears to influence aggression, with the more fossorial species being less aggressive. It is assumed that these differences are related to: (i) phylogenetic distance from the open water species; (ii) the burrowing habitat and the related morphological adaptations and (iii) a reduced need to acquire and defend resources other than their burrows.

Differences in oxygen consumption and diel activity as adaptations related to microhabitat in Neotropical freshwater decapods (Crustacea)

This study evaluated oxygen consumption (MO2) and diel activity in Aegla longirostri, Trichodactylus panoplus and Parastacus brasiliensis (three species of freshwater decapods that occur in sympatry), under two different conditions of O2 availability, limited and constant; and searched for the existence of a relationship between these two variables. The Kruskal–Wallis test showed that in all the species, MO2 was higher under constant O2 availability; T. panoplus and P. brasiliensis showed an oxygen-dependent pattern, while A. longirostri showed higher MO2 values and less variation in the values between the treatments, indicating a higher and more oxygen-independent metabolism. P. brasiliensis was more active in constant O2. A. longirostri was more active in limited O2 and did not show a clear diel activity in any case, showing behavioral changes when in unfavorable conditions. The Spearman's rank correlation analysis did not indicate any relationship between MO2 and activity. These results indicate a higher metabolism in A. longirostri. The less demanding metabolisms of P. brasiliensis and T. panoplus allow these species to occupy environments that are unavailable to A. longirostri due to differences in dissolved-oxygen concentrations.

Metabolic responses in two species of crayfish ( Parastacus defossus and Parastacus brasiliensis) to post-hypoxia recovery

The period of post-hypoxia recovery is essential for the rapid replenishment of energy reserves and for the removal of metabolic end products formed during hypoxia. Periods of post-hypoxia recovery were analyzed in two crayfish species, where Parastacus defossus is a fossorial species, and Parastacus brasiliensis lives in lotic environments with higher oxygen levels. After 4 h of hypoxia (2 mg O 2/L), groups of animals were placed in tanks with oxygenated water and were then removed at intervals of 1, 3, 6, and 9 h. Hemolymph and tissues (hepatopancreas, muscle, and anterior and posterior gills) were extracted for the determination of glucose, lactate, free glucose, glycogen, total proteins, total lipids, arginine phosphate, and arginine. As expected, lactate levels were restored more rapidly in P. defossus than in P. brasiliensis. P. defossus restored its glycogen reserves of the hepatopancreas and muscle tissue. Free glucose was quickly restored in all tissues of both species. In relation to arginine phosphate reserves, P. defossus showed a greater ability to restore this metabolite in the hepatopancreas. Both species recovered their arginine phosphate reserves, but they also used this metabolite in longer periods of recovery. Mainly in P. brasiliensis the reserves of total lipids seem to be an important source of energy during the recovery period. The animals developed various metabolic strategies to post-hypoxia recovery, mainly P. defossus which restored its reserves more completely and more rapidly than did P. brasiliensis.

Metabolic responses of Parastacus defossus and Parastacus brasiliensis (Crustacea, Decapoda, Parastacidae) to hypoxia

The metabolic responses of two crayfish species living in different habitats, Parastacus defossus and Parastacus brasiliensis, were analyzed after different periods of hypoxia (2.0mg O2/L of oxygen). In the laboratory, groups of animals were subjected to hypoxia for 1, 2, 4, and 8h. The hemolymph, hepatopancreas, muscle, and anterior and posterior gills were removed for determination of glucose, free glucose, glycogen, lactate, total proteins, total lipids, total cholesterol, arginine, and arginine phosphate. In both species, glucose and lactate increased significantly after 4h of hypoxia, but decreased after 8h (p>0.05) from the beginning of the experiment. Reductions of glycogen, lipids, and cholesterol were recorded in hepatopancreas and muscle tissue, especially of P. defossus, after 4h of hypoxia. Free glucose levels decreased in all tissues of P. brasiliensis, mainly in the hepatopancreas and muscle (p<0.05), while P. defossus showed smaller reductions of these reserves. All reserves in the anterior and posterior gills, with exception of the glycogen reserves, behaved similarly in both species. Both crayfishes stored and used arginine phosphate, mainly P. defossus, which also showed higher concentrations of all metabolites than did P. brasiliensis. Both species showed metabolic adaptations to hypoxia, but, as expected, P. defossus appeared to be better adapted.

Seasonal variation of the effect of high-carbohydrate and high-protein diets on the intermediate metabolism of Parastacus brasiliensis (Crustacea, Decapoda, Parastacidae) maintained in the laboratory

The goal of this study was to evaluate the effect of a high-carbohydrate diet (HC) and a high-protein diet (HP) on the metabolism of the crayfish Parastacus brasiliensis (Von Martens, 1869), collected in different seasons and maintained in the laboratory for 15 days. Crayfish were collected monthly from January 2002 to January 2004 at São Francisco de Paula, Southern Brazil, in Guarapirá stream. In the laboratory, the animals were kept submerged in aquariums under controlled conditions. They were fed ad libitum, for 15 days with either a HC or HP diet. At the end of this period, haemolymph samples were collected, as were hepatopancreas, gills, and abdominal muscle that were removed for determination of glycogen, free glucose, lipids, and triglycerides. The haemolymph samples were used for determination of glucose, proteins, lipids, and triglycerides. Statistical analysis (ANOVA) revealed significant seasonal differences in biochemical composition in crayfish maintained on HC or HP diets. Independent of the diets offered to the animals and the controlled conditions for 15 days, the indications of seasonality were unchanged. The observed changes seemed to be related to the reproductive period. Moreover, the HC diet increased all energy reserves in adult parastacids, which may aid in reproduction.

Seasonal variations in the intermediate metabolism of the crayfish Parastacus brasiliensis (Crustacea, Decapoda, Parastacidae) in the natural environment and experimental culture

The goal of this study was to evaluate the effects of seasonal variations on energy metabolism in different tissues of the freshwater crayfish Parastacus brasiliensis (von Martens, 1869). Crayfish were collected monthly from January 2001 to January 2003 in São Francisco de Paula, Rio Grande do Sul, Brazil, in a stream and in a culture tank. Haemolymph samples were collected from each crayfish in the field with a syringe, by puncturing the membrane at the base of the chelipeds. Hepatopancreas, gills, and abdominal muscle were removed for determination of free glucose, glycogen, total lipids, and triglycerides. The haemolymph samples were used for determination of glucose, total proteins, total lipids, and triglycerides. Statistical analysis revealed significant differences in biochemical composition in crayfish collected in the stream compared to the experimental tank during the year, principally in glucose and triglycerides in haemolymph, glycogen and total lipids in all tissues study, and triglycerides only in abdominal muscle. The regular food intake partially modified these seasonal variations of the metabolic pattern. Environmental conditions (e.g., food availability and water temperature) and reproductive period appeared to be the main factors influencing the seasonal patterns of variation in energy metabolism.

Morfologia externa de Parastacus brasiliensis (Decapoda, Parastacidae)

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.

Morfologia setal de Parastacus brasiliensis (von Martens) (Crustacea, Decapoda, Parastacidae)

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.

A new species of Stratiodrilus (Polychaeta, Histriobdellidae) from freshwater crayfishes of southern Brazil

A new species of polychaete, Stratiodrilus vilae, epizoic on Parastacus brasiliensis (von Martens, 1869) and P. defossus Faxon, 1898, is described from the State of Rio Grande do Sul, southern Brazil. The new species has one pair of long, anal, conical ventral lobes, one on each side of the anus, claspers in the males, and one pair of tubercles in each of the posterior locomotor appendages; and the jaw apparatus not reaching the limit between the head and the first segment.

OCCURRENCE OF PROTANDRIC HERMAPHRODITISM IN A POPULATION OF THE NEOTROPICAL FRESHWATER CRAYFISH PARASTACUS BRASILIENSIS (PARASTACIDAE)

Preliminary studies have shown that males and females of the freshwater crayfish Parastacus brasiliensis (von Martens, 1869) have an intersexed internal genitalia characterized by the existence of genital ducts of both sexes that connect to a gonad with male or female components, according to the sex. To determine the type of sexuality of this species, specimens (n = 92) from 11.7 to 40.0 mm carapace length were collected at Mariana Pimentel municipality, Rio Grande do Sul, Brazil (30°20′39″S, 51°22′39″W). Anatomical and histological analysis of the gonads disclosed the existence of three sexual forms: (1) intersexed males (n = 36), (2) transitionals between male and female sex (n = 8), and (3) intersexed females (n = 48). The transitionals present the following common morphological features: both genital apertures are present, but the female apertures are closed, as is usual in males; coexistence of oocytes and testicular acini in the same gonad (ootestis); and a longitudinal collecting tubule, large in diameter in the testicular region. The ovarian component of the gonad includes previtellogenic and primary vitellogenic oocytes. Of the 44 individuals classified as males by the analysis of the aspect of the genital apertures, 18.2% were transitionals, suggesting the existence of primary males that never change sex and a sexual system that is known as partial protandry. The existence of small females suggests that some females never go through a male phase. The histology of the gonads and genital ducts is described, and the germ cells are identified in each sex. The possible reasons for the existence of hermaphroditism in the studied population are discussed based on theoretical models.

Occurrence of Protandric Hermaphroditism in a Population of the Neotropical Freshwater Crayfish Parastacus Brasiliensis (Parastacidae)

Preliminary studies have shown that males and females of the freshwater crayfish Parastacus brasiliensis (von Martens, 1869) have an intersexed internal genitalia characterized by the existence of genital ducts of both sexes that connect to a gonad with male or female components, according to the sex. To determine the type of sexuality of this species, specimens (n = 92) from 11.7 to 40.0 mm carapace length were collected at Mariana Pimentel municipality, Rio Grande do Sul, Brazil (30°20′39″S, 51°22′39″W). Anatomical and histological analysis of the gonads disclosed the existence of three sexual forms: (1) intersexed males (n = 36), (2) transitionals between male and female sex (n = 8), and (3) intersexed females (n = 48). The transitionals present the following common morphological features: both genital apertures are present, but the female apertures are closed, as is usual in males; coexistence of oocytes and testicular acini in the same gonad (ootestis); and a longitudinal collecting tubule, large in diameter in the testicular region. The ovarian component of the gonad includes previtellogenic and primary vitellogenic oocytes. Of the 44 individuals classified as males by the analysis of the aspect of the genital apertures, 18.2% were transitionals, suggesting the existence of primary males that never change sex and a sexual system that is known as partial protandry. The existence of small females suggests that some females never go through a male phase. The histology of the gonads and genital ducts is described, and the germ cells are identified in each sex. The possible reasons for the existence of hermaphroditism in the studied population are discussed based on theoretical models.

Aspectos anatômicos e funcionais do aparelho reprodutor de Parastacus brasiliensis (von Martens) (Crustacea, Decapoda, Parastacidae)

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.