Species Of Aegla Research Articles

Sexual dimorphism in the cephalothorax of freshwater crabs of genus Aegla Leach from Chile (Decapoda, Anomura, Aeglidae): an interspecific approach based on distance variables

Some morphological studies based on the comparisons between two or three species of Aegla indicate that, as an expression of sexual dimorphism, the cephalothorax is longer in males and wider at the posterior end in females. To assess whether this is a general trend, we performed a series of covariational analyses relating the length and posterior width of cephalothorax in 1,242 specimens of both sexes from 17 of the 19 species of Aegla reported from Chile. By using a covariable homologous for all individuals, it was shown that the bias toward females in the posterior cephalothoracic width is greater than the bias toward males in the cephalothoracic length. Additionally, both variables show positive phylogenetic signal, both in each trait individually and their male–female relationship. For the entire Chilean clade of Aegla, both variables showed a narrow covariation pattern influenced by the sex of the individuals. Furthermore, the phylogenetic signal both in each variable individually and the female–male relationships derived from directional phylogenetic comparative analyses suggests that this relationship is inherited by shared common ancestry, restricting their adaptive potential to most probably directions of change. However, within certain limits, this variability has important reproductive and behavioral implications that are directly associated with the fitness of the taxon.

New species and records of the genus Aegla Leach, 1820 (Crustacea, Anomura, Aeglidae) from the West-Central region of Rio Grande do Sul, Brazil

Aeglidae are anomuran freshwater "crabs" found only in southern South America. In Brazil, the greatest species diversity occurs in hydrographic basins of the state of Rio Grande do Sul. Two new species, Aegla georginae and Aegla ludwigi, are described from the Ibicuí and Ijuí Rivers, respectively (Uruguay River Basin). The new taxa can be distinguished from other Aegla species based on both morphological and molecular characters. The two new species have a very restricted distribution and are categorized as endangered (A. georginae) and critically endangered (A. ludwigi) using IUCN Red List criteria. We also summarize and present new records of the Aegla species occurring in the Uruguay River Basin.

Distribution of cave-dwelling Aegla spp. (Decapoda: Anomura: Aeglidae) from the Alto Ribeira karstic area in southeastern Brazil based on geomorphological evidence

In this study, we assess the main ecological and evolutionary causes of the current distribution of cave dwelling species of Aegla from the Alto Ribeira karstic province, southeastern Brazil. Based on field surveys conducted over several years and on examination of scientific collections, we discuss herein how processes of colonization, dispersal, and vicariance could have resulted in the present pattern of distribution of these species. Given the extensive area of continuous limestone lenses interrupted by insoluble rocks, the distribution of aeglids from Alto Ribeira is limited by stratigraphic barriers, possibly due to difficulty in accessing other underground compartments and low vagility of juveniles. Sympatric speciation is unlikely, since molecular evidence does not support a strong sister-group relationship between extant troglophilic and troglobitic species with sympatric distribution in the study area. Under differing sources of evidence, we hypothesize that Pleistocene climatic fluctuations and drainage changes is the main cause of vicariance in the study area, while the fragmented nature of the limestone lenses probably hindered subsurface dispersion. Troglobites could be relicts of extinct epigean ancestrals, while the extant troglophiles did not achieve reproductive isolation after vicariance events, resulting in the present co-distribution with species less closely related.

Three new species of Aegla (Anomura) freshwater crabs from the upper Uruguay River hydrographic basin in Brazil

Surveys performed in streams from the sub-basins of the Canoas and Pelotas rivers, which jointly form the Uruguay River in southern Brazil, led to the discovering of three new species of Aeglidae: Aegla brevipalma, Aegla leachi, and A. oblata. Here we present their morphological descriptions coupled with phylogenetic analyses, to infer evolutionary relationships to other aeglids using DNA sequence data from the 16S rRNA and COII gene regions of the mitochondrial genome. The presence of these new species increases the importance of the Upper Uruguay ecoregion for biodiversity richness of freshwater fauna in the Neotropical South America.

Reproductive Biology in Females of Aegla strinatii (Decapoda: Anomura: Aeglidae)

Females of Aegla strinatii (n 5 466) were sampled monthly (September 2003 to September 2005) by means of sieves and traps from Rio das Ostras (24u38916.20S; 48u24905.20W), at Jacupiranga State Park, South of Sao Paulo State, Brazil. The reproductive period was markedly seasonal (from May to September) encompassing the Austral late autumn through late winter. This is in accordance to the pattern of reproductive period variations in relation to the latitudinal climate variability verified in species of Aegla. The proportion of adult females exhibiting the ovigerous condition was higher in young/small specimens as compared to old/large ones, and suggests the occurrence of senescence in the latter group. Average size at the onset of functional maturity in females was estimated as 16.66 mm of carapace length (rostrum excluded). The number of eggs per ovigerous females ranged from 1 to 325. Eggs are slightly elliptical and average size varied according to embryonic stage. Mean (6 standard deviation) carapace length of juveniles (n 5 118) was 1.50 6 0.05mm (range: 1.40-1.65mm).

Type and non-type specimens of Aegla (Decapoda: Anomura: Aeglidae) housed in the Museo de La Plata, Argentina

The present contribution deals with the type and non-type material of the species of Aegla (Decapoda: Anomura: Aeglidae) deposited in the Invertebrate Collection of Museo de La Plata, Argentina. One hundred and thirty-four lots are included, of which 10 lots are type specimens. The material examined includes 11 of the 13 species known from Argentina. Among the studied lots, those examined by Ringuelet (1948, 1960) and by Bond-Buckup & Buckup (1994) stand out. Also, several lots from different regions of Argentina were identified. Type specimens examined were compared with the original descriptions; photographs of the specimens are given in the present report. For each lot the following information is provided: georeferenced locality of collection, collector and collecting date, bibliographical references, category, number of collection according to the rules of the Museo de La Plata, label data (precise transcription), remarks and map of the locations.

Conservation Assessment of Southern South American Freshwater Ecoregions on the Basis of the Distribution and Genetic Diversity of Crabs from the Genus Aegla

We assessed the conservation priority of 18 freshwater ecoregions in southern South America on the basis of Aegla (genus of freshwater crabs) genetic diversity and distribution. Geographical distributions for 66 Aegla species were taken from the literature and plotted against ecoregions and main river basins of southern South America. Species richness and number of threatened and endemic species were calculated for each area. To assess taxonomic and phylogenetic diversity, we generated a molecular phylogeny based on DNA sequences for one nuclear (28S) and 4 mitochondrial (12S, 16S, COI, and COII) genes. All species richness and phylogenetic methods agreed, to a large extent, in their rankings of the importance of conservation areas, as indicated by the Spearman's rank correlation coefficient (p < 0.01); nonetheless, some of the lowest correlations were observed between taxonomic and phylogenetic diversity indices. The 5 ecoregions of the Laguna dos Patos Basin (Eastern Brazil), Central Chile, South Brazilian Coast, Chilean Lakes, and Subtropical Potamic Axis (northern Argentina and southern Uruguay and Paraguay) had the highest biodiversity scores. Conservation of these regions will preserve the largest number of species and the greatest amount of genetic diversity within the South American freshwater Aegla fauna. Biodiversity across rivers and within areas was heterogeneously distributed in the ecoregions of Upper Paraná, Ribeira do Iguape, Upper Uruguay, and South Brazilian Coast (i.e., one river showed significantly more biodiversity than any other river from the same ecoregion), but homogeneously distributed in the other ecoregions. Hence, conservation plans in the former regions will potentially require less effort than plans in the latter regions.

Molecular Systematics and Biogeography of the Southern South American Freshwater “Crabs” Aegla (Decapoda: Anomura: Aeglidae) Using Multiple Heuristic Tree Search Approaches

Recently new heuristic genetic algorithms such as Treefinder and MetaGA have been developed to search for optimal trees in a maximum likelihood (ML) framework. In this study we combined these methods with other standard heuristic approaches such as ML and maximum parsimony hill-climbing searches and Bayesian inference coupled with Markov chain Monte Carlo techniques under homogeneous and mixed models of evolution to conduct an extensive phylogenetic analysis of the most abundant and widely distributed southern South American freshwater"crab,"the Aegla(Anomura: Aeglidae). A total of 167 samples representing 64 Aegla species and subspecies were sequenced for one nuclear (28S rDNA) and four mitochondrial (12S and 16S rDNA, COI, and COII) genes (5352 bp total). Additionally, six other anomuran species from the genera Munida,Pachycheles, and Uroptychus(Galatheoidea), Lithodes(Paguroidea), and Lomis(Lomisoidea) and the nuclear 18S rDNA gene (1964 bp) were included in preliminary analyses for rooting the Aegla tree. Nonsignificantly different phylogenetic hypotheses resulted from all the different heuristic methods used here, although the best scored topologies found under the ML hill-climbing, Bayesian, and MetaGA approaches showed considerably better likelihood scores (Delta> 54) than those found under the MP and Treefinder approaches. Our trees provided strong support for most of the recognized Aegla species except for A. cholchol,A. jarai,A. parana,A. marginata, A. platensis, and A. franciscana, which may actually represent multiple species. Geographically, the Aegla group was divided into a basal western clade (21 species and subspecies) composed of two subclades with overlapping distributions, and a more recent central-eastern clade (43 species) composed of three subclades with fairly well-recognized distributions. This result supports the Pacific-Origin Hypothesis postulated for the group; alternative hypotheses of Atlantic or multiple origins were significantly rejected by our analyses. Finally, we combined our phylogenetic results with previous hypotheses of South American paleodrainages since the Jurassic to propose a biogeographical framework of the Aegla radiation.

PHYLOGENETIC RELATIONSHIPS AMONG THE SPECIES OF AEGLA (ANOMURA: AEGLIDAE) FRESHWATER CRABS FROM CHILE

Nineteen species and subspecies of freshwater crabs from the anomuran family Aeglidae are represented in Chile, 16 of which are endemic to this country. We sequenced ∼2,600 nucleotides of the 12S, 16S, COI, and COII genes from mitochondrial DNA to estimate phylogenetic relationships among the Chilean aeglids. We sampled 16 putative Chilean species and subspecies and one morphologically unrecognized taxon according to the most recent Aeglidae classification. In addition to the Chilean aeglids, one sample of Aegla riolimayana and two samples of Aegla affinis were collected from Argentina to check previous hypotheses about the origin of the group. Two other anomurans, one galatheid (Munida subrugosa) and one porcellanid (Pachycheles haigae), were sequenced to serve as outgroups in our phylogenetic analysis. Our results show the clear separation of Aegla papudo from the other Aegla species, as has been suggested previously based on morphology. Its basal position in the Aeglidae trees also supports a Pacific origin for the Aeglidae. Our phylogenies provide strong monophyletic support for the currently recognized species, with the exception of Aegla laevis and Aegla cholchol samples, which form nonmonophyletic groups.

Phylogenetic Relationships among the Species of Aegla (Anomura: Aeglidae) Freshwater Crabs from Chile

Phylogenetic Relationships among the Species of Aegla (Anomura: Aeglidae) Freshwater Crabs from Chile

HIGHLY REPETITIVE DNA SEQUENCES UNIQUE TO AEGLIDAE (ANOMURA)

Highly repetitive DNA sequences were investigated in order to shed light on evolutionary relationships in groups of Decapoda. The investigation emphasized the relationships AeglidaeAnomura and between different species of Aegla. Analyses of molecular restriction and hybridization patterns (RP and HP, respectively) were used as experimental approaches. Highly repetitive restriction fragments obtained from species of Brachyura, Anomura, and Aeglidae were isolated and employed as molecular probes. Our results suggest that some highly repetitive DNA sequences are evolutionarily conserved among Caridea, Brachyura, and Anomura. Moreover, a 400-bp band appears to be conserved among Aeglidae, since it was exhibited by all species studied. Relative quantification of the 400-bp band showed that it is highly conserved in these species. The Aeglidae is a monotypic family that is restricted to South American temperate and subtropical fresh waters (Argentina, Uruguay, Chile, Bolivia, Brazil, and Paraguay), a unique phenomenon among anomurans. The only known fossil record is that of the marine species Haummuriaegla glaessneri Feldmann from New Zealand

A família Aeglidae (Crustacea, Decapoda, Anomura)

The family Aeglidae comprises the genus Aegla with recent species and the genus Haumuriaegla with the fossil species H. glaessneri Feldmann, 1984. The results from the revision of the family Aeglidae, mainly from the study of the genus Aegla Leach, 1820, based on material collected in the southern and the south-eastern States of Brazil and on the examination of several collections from Brazilian and foreign institutions, are presented. Two diagnostic keys for the identification of the species of Aegla are included, one for the Brazilian, Uruguayan and north-eastern Argentinean representatives and another for the species from Chile and the remaining areas of Argentina. The results of the revision of 59 species of Aegla are presented, under the following headings: list of synonymies, type-material, diagnosis, description, size, examined material, geographic distribution and discussion. Illustrations of each species and of morphological details and maps recording known places of occurrence, with exception of A. intermedia Girard, 1855, a doubtful, never found again, species, with missing type-material, are included. The raw data from all measurements taken on samples and the results of statistical analysis are enclosed Four species are synonymized: A. neuquensis affinis Ringue let, 1948, A. montana Ringue let, 1960 and A. maulensis Bahamonde e López, 1963 are treated as junior synonyms of A. affinis Schmitt, 1942. A. lenitica Buckup & Rossi, 1977 is considered a junior synonym of A. prado Schmitt, 1942. Two subspecies have their status changed into species-level: A. paulensis Schmitt and A. affinis Schmitt. The knowledge about the areas of occurrence of nineteen species is extended. Twenty new species are described and illustrated: A. intercalata sp. n., A. ringueleti sp. n., A. septentrionalis sp. n. A. rossiana sp. n., A violacea sp. n., A. itacolomiensis sp. n., A. inconspicua sp. n., A ligulata sp. n., A marginata sp. n., A inermissp. n., A. spinosa sp. n., A. lata sp. n., A. jarais sp.. n., A. obstipa sp. n., A. spinipalma sp. n., A. grisella sp. n., A. longirostri sp. n., A. parva sp. n., A. leptochelas sp. n. and A. microphthalma sp. n. Lectotype and Paralectotype designations for A. scamosa Ringuelet,1948 are done. The results of the investigations support the hypothesis that the majority of the species of Aegla may not have very large areas of occurrence, living only in one basin or often in adjacent drainage basins.

AEGLA BAHAMONDEI, NEW SPECIES (CRUSTACEA: DECAPODA: ANOMURA) FROM THE COASTAL MOUNTAIN RANGE OF NAHUELBUTA, CHILE

Aegla bahamondei, new species (Crustacea, Anomura, Aeglidae) is described from the Tucapel River on the western slope of Cordillera de Nahuelbuta, Chile. Morphologically it closely resembles A. rostrata Jara from preandean lakes of the Valdivia and Tolten river basins. A. bahamondei differs from A. rostrata in its acute median tubercle on the fourth thoracic sternum, less prominent overall spinulation, and nonstilettolike rostrum. The morphological similarity between A. bahamondei and A. rostrata is interpreted as indication of recent common ancestry. It is hypothesized that A. bahamondei represents the plesiomorphic and A. rostrata the apomorphic species. The Chilean coastal mountain range of Nahuelbuta, stretching between 37? and 39?, is a region of faunistic individuality compared with the remaining southern Chilean territory. This view is supported by the existence of at least two genera of Plecoptera (Insecta) and one species of Anura restricted to this region (Illies, 1969; Formas, 1979); these authors presume that the Cordillera de Nahuelbuta served as a refuge for the preglacial Tertiary fauna. Arenas (1976) has suggested that in postglacial times some freshwater fishes and amphibians could have extended their geographic range from this coastal refuge to the Andes. Four species of crayfishes (Parastacidae) and three species of Aeglidae (Bahamonde and L6pez, 1963; Jara, 1977) are known from freshwaters in the Chilean region between Concepci6n and Valdivia provinces. However, none of the Aegla species have been recorded from the Cordillera de Nahuelbuta itself or from its immediate surroundings. This paper describes as a new species a form of Aegla Leach found in a small river on the western slope of the Cordillera de Nahuelbuta.

Aegla rostrata n. sp., (Decapoda, Aeglidae), nuevo crustáceo dulceacuícola del Sur de Chile

Summary Aegla rostrata n. sp. (Decapoda, Aeglidae), a new freshwater crustacean from Southern Chile The description of Aegla rostrata n. sp. a new species of Aegla from lakes and rivers of the Valdivia basin (Provincia de Valdivia, Chile) is given. Its characteristics being: rostrum long, narrow, styli‐form and quitinous tipped, exceeding by 2 to 21/2 times the length of the corneas. Protogastric prominences squamous and well marked. Posterior branchial margin expanded and recurved. Palmar crest wide, subrectangular and broadly serrated. Externally A. rostrata resembles A. denticulata Nicolet, 1849, but differs from the last because it lacks the longitudinal carina along the dorsum of the carapace and the median tubercule on the fourth toracic sternum. A. rostrata has been found in the lakes Rinihue, Panguipulli and Calafquen, as well as in rivers Calle Calle and Huanahue. In the lake Rinihue A. rostrata has been collected from the litoral to depths of 320 m. This distribution makes it the second species ...

The species of Aegla, endemic South American fresh-water crustaceans

The species of Aegla, endemic South American fresh-water crustaceans