Species Of Aegla Research Articles

A new species of Aegla (Decapoda, Anomura, Aeglidae) from the Paranapanema watershed, southeastern Brazil

Abstract A new species of Aegla is described and illustrated from Alto Paranapanema (São Paulo State), a sub-basin of the Paranapanema watershed. The new species is compared to all seven species of Aegla currently known from the Paranapanema watershed using both morphological and mitochondrial genetic (COI) characters. Molecular sequence comparison analysis also suggested that several records from the Paranapanema watershed previously attributed to Aegla castro actually belong to different species. Opportunity is taken to provide a photograph of the holotype of A. castro (type locality Iapó River, State of Paraná, Tibagi sub-basin, Paranapanema watershed).

Hidden diversity of Aegla (Decapoda, Anomura) in a priority area for conservation

AbstractAegla is a genus of freshwater anomuran crabs encompassing 94 described species occurring in meridional South America. Brazil harbours the greatest diversity of species, mainly in its southern region, which becomes a priority area for Aegla conservation due to high species richness and phylogenetic diversity, elevated endemism and threats to the Atlantic Forest. Here, we assessed Aegla richness and distribution in this priority area and tested the hypothesis of crypticism in the region's species. Sampling sites were distributed inside and in the surroundings of five protected areas, covering the major distribution range of several species described for southern Brazil. We applied three species delimitation methods to COI mitochondrial gene data, coupled with phylogenetic and morphological analyses. By integrating species delimitation based on the COI data and traditional taxonomy, we uncovered a high proportion of hidden diversity among Aegla in our study area and identified ten known species besides impressive 17 new putative species. Of these, eight are possible new taxonomic units that do not conform to any known species, and nine are divided into three cryptic groups: Aegla jarai complex, Aegla franciscana complex and Aegla camargoi complex. Most of these species have a narrow spatial distribution, making them highly vulnerable to habitat degradation. Despite the real richness of the genus still being largely unknown, the high diversity revealed here makes our study area the richest known region regarding the number of Aegla species within its distribution, making this area even more worthy for conservation efforts.

Aegla lata Bond-Buckup & Buckup, 1994 (Decapoda: Anomura: Aeglidae): new occurrence and distribution map in the Paraná state, Brazil

Our study presents a new occurrence and distribution record for Aegla lata in the state of Paraná, Brazil, specifically in the municipality of Rolândia. This finding, documented in October 2020 during the collection of benthic macroinvertebrates, highlights the crucial need for continuous monitoring and conservation efforts, especially in the face of evolving habitat changes in the region. Eight male specimens of A. lata were captured in a stream in Rolândia, expanding the known distribution area and providing valuable insights into the species' biology. Morphological identification, following established protocols, revealed distinctive features, including carapace measurements, variations in chelae, and specific anatomical characteristics. Notably, visible differences in chelae morphology were observed, aligning with previous studies on allometric growth in Aegla species. Despite the current non-threatened classification, A. lata deserves special attention due to its endemism in the Paranapanema River basin in Paraná, Brazil. The region, characterized by agricultural activities and ongoing deforestation, poses a significant threat to Aegla species, emphasizing the urgency of conservation measures. This discovery expands the known distribution area of A. lata to Rolândia, providing critical information for establishing effective conservation policies.

Description of a new species of Aegla (Decapoda, Anomura) from the Paran 3 hydrographic basin, Brazil.

Freshwater crustaceans of the genus Aegla are endemic to southern South America, and present greater richness in the river basins of the state of Rio Grande do Sul, Brazil. However, recent studies have shown the enormous potential for discovering new species of Aegla in the state of Paran. In the last six year the number of species recorded has almost doubled, increasing from 9 to 16. In the present work, we expand the current knowledge about the diversity of Aegla in a set of poorly explored drainage basins in the western region of the state and describe a new species, Aegla urussanga n. sp., based on morphological and molecular evidence. A combination of morphological characters supports the new species: orbital spine absent, non-elevated epigastric prominences, robust protogastric lobes with scales, anterior dorsal margin of epimeron 2 armed and with pronounced concavity, sub-rectangular palmar crest of chelipeds, internal margin of the ventral face of the ischium of the cheliped with a proximal stout spine, a distal stout spine, and up to three tubercles with spiniform scales. The molecular data, based on partial COI sequences, also support the distinction of the new species from others that occur in adjacent river basins. The species with the smallest genetic distance from A. urussanga n. sp. is Aegla castro Schmitt, 1942 which occurs in the Iguau River basin. The new species occurs in distinct streams, probably interconnected in the past and currently isolated by the Itaipu reservoir and is the second species of Aegla described from the complex of drainage basins called Paran 3 basin.

The ultrastructure of spermatozoa of two species of Aegla (A. parana and A. quilombola) (Crustacea, Decapoda) endemic to Brazil

The previously published ultrastructure of Aegla spermatozoa contributed to the phylogenetics of this unique taxon. The present study describes the spermatozoa of two additional aeglids, Aegla parana and A. quilombola. The spermatozoa consist of two hemispheres of the approximate same size and a bilayered acrosomal vesicle; both characteristics of the genus Aegla. The similarity of spermatozoa ultrastructure observed between A. parana and A. quilombola and the endemic Australian anomuran, Lomis hirta (Lomidae) reflects a sister group relationship, even though both are from different regions of the world and different environments today. Aeglid spermatozoa share the same organization with Lomis including the two equal size hemispheres separated by a membrane also two layers in the acrosomal vesicle with the external layer being surrounded by another membrane. The number of spermatozoa microtubular arms is unclear in Aegla, however, they are present in both the nucleus and cytoplasm. This observation does not agree with the presence of spermatozoa arms only in the nucleus, as an exclusive character for Aegla, as proposed previously. The presence of lipid-droplets and peroxisomes was observed only in the spermatozoa of A. quilombola. The greatly reduced number of spermatozoa observed in all specimens analyzed raises concerns about the conservation of several threatened species. In addition, the absence of any spermatophores seems to be a characteristic of the Aeglidae to date.

Cryptic diversity among populations of Aegla Leach, 1820 (Decapoda: Anomura: Aeglidae) from Tibagi River basin, Paraná state, Brazil, with descriptions of three new species

ABSTRACT Freshwater crustaceans of the genus Aegla are endemic to southern South America. In Brazil, the greatest diversity of aeglid species occurs in river basins in the Rio Grande do Sul state. Nevertheless, recent studies have shown that the potential for discovering new species of Aegla in the Paraná state is huge. In recent years, for example, seven new species have been described for the state of Paraná. Furthermore, there is a need to solve problems related to cryptic species and refine taxonomic information about the group. Here we expand our current knowledge of the freshwater biodiversity of Aegla in the region by describing three new species. Aegla nanopedis sp. nov., Aegla abrupta sp. nov., and Aegla santosi sp. nov. were discriminated based on morphological and molecular evidence. Particular morphological characters of the carapace, chelipeds, epimeron and uropods distinguished the new taxa. Molecular results also support the separation of the new species from the closely related species A. jacutinga, A. castro and A. lata. The new species have limited distribution and are categorised as endangered (Aegla nanopedis sp. nov.) and vulnerable (Aegla abrupta sp. nov. and Aegla santosi sp. nov.) according to International Union for Conservation of Nature Red List Categories and Criteria.

Aegla buenoi n. sp. (Decapoda: Anomura): first record of aeglid crab from Cinzas River basin, Brazil.

A new species of freshwater anomuran crab, Aegla buenoi n. sp., is described. The new taxon was collected from two streams within the Cinzas River basin, Paran state, Brazil. We used morphological and molecular data (COI mtDNA) to distinguish the new species from its congeners. Aegla buenoi n. sp. is differentiated by morphological diagnostic features of the cephalothorax, chelipeds, second abdominal epimeron, and uropods. Molecular results confirm the separation of A. buenoi n. sp. from closely related species (A. castro Schmitt, 1942, A. lata Bond-Buckup Buckup, 1994, and A. jacutinga Marl Teixeira, 2020). Hence, our study increases the known diversity of aeglids and reports the first species of Aegla from the Cinzas River basin.

Natural diet of the endemic freshwater crab Aegla castro Schmitt, 1942 (Decapoda: Anomura: Aeglidae)

Abstract We characterized the natural diet and feeding dynamics of Aegla castroSchmitt, 1942 (Aeglidae), an endemic freshwater crab. Research was undertaken on the trophic spectrum of the species by analyzing the stomach contents of individuals collected in a stream in southeastern Brazil, and evaluating the diet through the index of relative importance (IRI). Seasonal and circadian variations in diet composition were analyzed, and the feeding dynamics investigated through repletion index (RI) analysis. We analyzed a total of 240 stomachs and identified 20 main food categories of the diet, which were studied throughout the seasons. Aegla castro maintained a constant RI throughout the year, with a peak of food activity between midnight (00) and 0600. The species was characterized as an omnivorous generalist and opportunist. The high overlay in the diet composition of adults of both sexes and juveniles indicates that they share the same food resources, even though they seem to exploit them in different quantities and frequencies. Future research should focus on the species of Aegla whose diets have not yet been described, and use available data to inform trophic network analyses and models.

Entangled Aeglidae (Decapoda, Anomura): Additional evidence for cryptic species

AbstractCryptic species are a major challenge for morphologically based species identification. Molecular approaches to species delimitation can be a valuable tool to provide preliminary taxonomic hypotheses and significantly complements morphological taxonomy. In South America, the freshwater crabs of the genus Aegla have sparked much interest as they are key species in the often‐endangered freshwater ecosystems and themselves are often considered endangered species. Morphological similarity among Aegla species is not always positively correlated with genetic relatedness and growing evidence suggests that several putative single taxa are actually assemblages of cryptic species. We coupled broad geographically sampling (Argentina, Brazil and Uruguay) with multilocus (COI, 16S and ANT) phylogenies to investigate the diversity of Aegla uruguayana. Our species delimitation analyses suggested that 19 aeglid populations form a well‐supported clade, although individuals from 10 populations possibly represent a complex of cryptic species. The significant amount of cryptic diversity found in aeglids seem to rely on several factors, including habitat fragmentation, life history features, morphological stasis, convergent evolution and recent divergence. The search for new diagnostic characters and the description of the cryptic species that remain unnamed will probably be the next challenge for this unique group of crustaceans.

Population structure and habitat occupation in two sympatric Aegla species (Decapoda, Anomura, Aeglidae) in Atlantic Forest, Brazil

Abstract This study deals with population structure and habitat sharing of two sympatric aeglid species, Aegla jarai Bond-Buckup and Buckup, 1994 and Aegla muelleri Bond-Buckup and Buckup, 2010 at Espingarda Creek, Serra do Itajai National Park, Rio Itajai-Acu basin, Santa Catarina, Brazil. Individuals of A. jarai (n = 190) and A. muelleri (n = 131) were captured from June/2001 to May/2002 in monthly collection. A total of 89 males and 101 females (2 ovigerous) of A. jarai were collected with a sex ratio of 1:1, and 56 males and 75 females (2 ovigerous) of A. muelleri, with a predominance of females. Aegla jarai was larger than A. muelleri and the reproductive period of A. jarai was in the winter and spring, while that of A. muelleri was in the spring. Three cohorts were observed throughout the year, and both species have a recruiting period in the spring and summer. Both species perform their entire life cycle in the Espingarda Creek and their coexistence is attributed to space partitioning: the larger A. jarai lives in the large spaces formed between boulders, while the smaller A. muelleri shelters in the small spaces between pebbles.

Aegla nebeccana n. sp. (Crustacea, Aeglidae) from Ivaí Basin, Paraná, Brazil.

A new species of freshwater anomuran, Aegla nebeccana n. sp. (Decapoda: Aeglidae), is described from the Ivaí River sub-basin, a tributary of the Paraná River Basin, in Paraná state, southern Brazil. The species is illustrated in detail with drawings and photographs. It can be distinguished from its congeners based on both morphological and molecular evidence. Morphologically, the new species resembles Aegla meloi Bond-Buckup Santos, 2015 by the general shape of the carapace and chelipeds, but differs by having a developed protograstic lobe and by the cheliped ischium ornamentation. Aegla nebeccana n. sp. has pronounced protogastric lobes, similar to Aegla castro Schmitt, 1942 and Aegla schimitti Bond-Buckup Buckup, 1994 but differs clearly from these in relation to the morphology of the cheliped palmar crest. Based on molecular analysis, A. nebeccana is sister species of Aegla parva Bond-Buckup Buckup 1994.

Allometric growth, sexual maturity, and life cycle of Aegla lata (Decapoda, Anomura), a critically endangered species

AbstractAegla lata Bond-Buckup & Buckup, 1994 is a critically endangered species, extinct in its type-locality. Its currently known geographical distribution is restricted to small streams of the lower Tibagi River Basin (Paraná state, southern Brazil), where it is vulnerable to the environmental degradation that takes place in these watersheds. Scientific knowledge on the species is limited to the original description and a few occurrence records. No information about its biology is available. Aiming to fill this gap, we investigated the relative growth, sexual maturity, sexual dimorphism, and the reproductive and recruitment periods of A. lata. Monthly sampling occurred from May 2014 through June 2015 in the Bule stream in the southern limit of Mata dos Godoy State Park, Londrina, Paraná state, Brazil (23°27ʹ20.86″S, 51°16ʹ32.44″W). The analysis of allometric growth was used to differentiate juveniles and adults. According to the development stage of the chelae, two sequential groups of adult males were recognized (morphotypes I and II). The estimated average cephalothorax length (CL) at the onset of morphometric maturity of males and females are similar, suggesting puberty molt takes place at nearly the same size in both sexes. Males and females are heterochelous, with a clear predominance of the left chela as the most developed of the pair. Both chelae are larger in adult males than in adult females of similar CL. The reproductive period is markedly seasonal, extending from the austral autumn to winter (May to August), as well as those recorded in other species of Aegla from similar latitudes. A single annual recruitment pulse was detected from October 2014 to February 2015.

Selecting and ranking areas for conservation ofAegla(Crustacea: Decapoda: Anomura) in southern South America integrating biogeography, phylogeny and assessments of extinction risk

AbstractThe rapid degradation of freshwater habitats in southern South America may cause the extinction of the endemic species ofAegla, as well as other freshwater species and components of riverside environments related to them. Information on the distribution of species and their conservation status is essential for developing conservation strategies.The updated distribution ofAeglain its southernmost distribution was analysed in order to prioritize freshwater ecoregions, applying biogeographical, phylogenetic and conservation status and complementarity approaches.The distributions of the species ofAeglawere delineated on maps and plotted against freshwater ecoregions. A data matrix of areas versus species was constructed and a taxon–area cladogram was created. Ecoregions were ranked, based on their species richness and using a complementarity criterion, to create a list of those considered important for conservation. The conservation status ofAeglaspecies was assessed on the basis of the categories and criteria of the International Union for Conservation of Nature (IUCN) to produce a decreasing order of the risk of species extinction. These assessments were combined to define a consensus ranking of the priority areas for conservation.The areas of maximum species richness and endemicity, and consequently highest priority of conservation, were the Lower Parana and Patagonia ecoregions. The Cuyan Desaguadero and Mar Chiquita Salinas Grandes ecoregions were the areas of second priority, and the Chaco and Lower Uruguay ecoregions were the areas with the third priority for conservation. Ten out of the 20 species analysed fall within the threat categories of the IUCN. Sixty per cent of the species ofAeglaanalysed have at least one population contained in protected areas.The results obtained may be used to design strategies for implementing conservation policies on freshwater species, generate biogeographical atlases and contribute to selecting Ramsar sites.

Genetic diversity of three Aegla species (Decapoda, Anomura) revealed by AFLP and mtDNA markers

Abstract Representatives of the genus Aegla present a conserved morphology; thus, the increased use of molecular markers has raised many taxonomic issues. We used AFLP and mtDNA to investigate the genetic differentiation and phylogenetic relationships of morphologically similar species with overlapping distribution areas in southern Brazil: A. georginae, A. ludwigi, and A. platensis. While A. platensis is widely distributed, the critically endangered A. georginae and A. ludwigi have limited distributions. Although both markers showed populations with low levels of genetic variability, they differed markedly in revealing relationships between populations; according to AFLP, the genetic distances between A. platensis populations were as high as those between distinct species, a result not observed when considering mtDNA data. We emphasize that the use of multiple lines of evidence is necessary for defining correct levels of genetic diversity and a good species-level taxonomic resolution. Such features are essential for the management and conservation of Aegla species.

A new species of Aegla Leach, 1820 (Crustacea, Anomura) from the Iguaçu River basin, Brazil.

A new species of aeglid crab, Aegla okora n. sp., is described. This species was found in the Iguaçu River basin in Paraná state, southern Brazil. Aegla okora n. sp. was discriminated based on morphological and molecular data (mitochondrial COI). Morphologically, the new species differs from congeners of the same river basin by the presence of a trapezoidal areola and the ventromesial border of the ischium having three tubercles, besides other exclusive additional morphological characteristics. Molecular results demonstrated that there is no overlap between the intraspecific distances of Aegla okora n. sp. and the interspecific distance of other species of Aegla added to the analysis, confirming the separation of species and increasing the known diversity of the Iguaçu River basin.

Distributional patterns of endemic southern South American freshwater aeglids (Crustacea: Decapoda: Anomura: Aeglidae)

The biogeographical and phylogenetic patterns of Aegla Leach, 1820 were analysed integrating track and cladistic biogeographic methods. We obtained 73 individual tracks, 10 generalised tracks and three nodes. Two taxon-area cladograms were constructed based on previous phylogenetic trees published for Aegla and Brooks Parsimony Analysis (BPA) was applied to the presence-absence matrices of generalised tracks (rows) vs components (columns). Four and three equally most parsimonious trees were obtained and two strict consensus cladograms, respectively. The consensus cladogram shown here has a basal separation among three areas: Argentinean-Chilean Patagonian areas, Cuyan ecoregion in central-western Argentina, and the remaining areas in Argentina, Uruguay, Bolivia and Brazil. Within the latter, north-western Argentina, south-western Bolivian and Uruguay ecoregions were nested within several southern Brazilian areas. Our results support a close relationship between the Parana dominion of the Neotropical region and the Subantarctic subregion of the Andean region, which might be related to a temperate climate prevailing in southern South America before being disrupted by cooling and aridification conditions and to geo-climatic events that occurred since the Mesozoic. The Yungas biogeographic province was also supported by the distribution of Aegla. Nodes were all located in southern Brazil, coinciding with the hydrological processes of headwaters and drainages that occurred due to the Serra do Mar uplift. Some species of Aegla previously classified as a single species might constitute species complexes.

Does the landscape surrounding streams affect the occurrence of freshwater crabs? A case study of the genus Aegla (Crustacea: Decapoda: Anomura) in subtropical basins

ABSTRACT Changes in the landscape where watersheds are located may affect the stream biota in different ways. In order to explore this idea, we collected freshwater crabs of the genus Aegla Leach, 1820 in subtropical region of southern Brazil. We also measured a number of landscape features and physico-chemical variables in the collection streams and surroundings in order to ascertain which factors affect the occurrence of these crustaceans. A total of 167 individuals of Aegla were collected in 21 streams. The collection was comprised of three species: A. odebrechtii, A. platensis, and A. singularis. The occurrence of A. platensis was influenced by physico-chemical variables (total carbon and total organic carbon) and stream morphometry factors (level curves sum). The occurrence of A. singularis was influenced by land use (pasture and exposed soil and agriculture) and the stream morphometry (level curves sum). Only a small number of A. odebrechtii were collected and their occurrence was influenced by land use (pasture and exposed soil and agriculture). The topography of the area studied limits the types of land use and areas that are less favorable for agriculture (more hilly areas) are have more riparian vegetation (or less anthropic stress). As a result, these areas are less subject to changes in water quality, which is reflected in the distribution of Aegla species.

Diversity and conservation status of Aegla spp. (Anomura, Aeglidae): an update

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.

Field evaluation of oxygen consumption by two freshwater decapod morphotypes (Trichodactylidae and Aeglidae); the effect of different times of the day, body weight and sex

We report an analysis of the effect of two different times of day (noon and dusk), body weight and sex on the oxygen consumption rate (OCR) of the freshwater crabs Trichodactylus kensleyi (Trichodactylidae), Aegla singularis and A. platensis (Aeglidae) in their natural environment. Both families are sympatric in the studied locations, with a co-occurrence found between T. kensleyi and A. singularis or T. kensleyi and A. platensis. The mean OCR was highest in A. singularis and lowest in A. platensis. The OCR was higher in Aegla species at noon, and Trichodactylus consumed more oxygen at dusk. In aeglids, there was no difference in oxygen consumption between noon and dusk. T. kensleyi exhibited statistically significant differences in the OCR between noon and dusk. The oxygen uptake of all three species analysed was not influenced by the sex of the individual but varied according to the animals’ weight. The families evaluated share some biological and ecological characteristics, such as diet and habitats, but the strategies used in the regulation of gas exchange at different times of the day were different. Environmental factors may be influencing the oxygen consumption of each morphotype differently.

Three new species of Aeglidae ( AeglaLeach, 1820) from Paraná State, Brazil

This study describes three new aeglid species, Aegla meloi , Aegla loyolai and Aegla lancinhas , all of them recorded from Parana State, Brazil. Along with the description, we also present an analysis of their phylogenetic relationships to other species of Aegla . The conservation status using the IUCN Red List criteria was assessed for each new species. The new species have restricted distributions and can be found in altitudes higher than 700 m. The new species are phylogenetically close to other species present in Parana State and Ribeira do Iguape River basin, yet clearly differ morphologically and genetically from other known species of Aegla .