Freshwater ecosystems are characterized by a high spatial complexity. This heterogeneity affects the distribution of aquatic organisms in riverine landscapes. Morphological variation in natural populations is driven by evolutionary forces. In crustaceans, morphological variations have been observed between different basins, environments, or developmental sequences along their geographical distribution. In this study, we assessed the possible effects of spatial scale on the phenotype of Aegla plana Buckup and Rossi, 1977 using geometric morphometrics. We examined 110 adult specimens from three river basins in southern Brazil. We used 13 morphological landmarks for the dorsal view of the carapace; the coordinates were superimposed using a generalized Procrustean analysis. We used a multivariate analysis to test the morphological variation in crabs from different basins, and we employed the Mantel test to assess the relationship of spatial and environmental factors with the principal components matrix for the carapace shape. Populations from different river basins differed significantly in carapace centroid size. Carapace shapes also differed significantly among the river-basin populations, and the interaction between sex and populations was also significant. The environmental and geographical matrices were correlated with the carapace shape matrix. This morphological variation shows an association with the geographical distribution of microbasins, which suggests a biogeographical effect on the distribution of A. plana.

This study investigated the use of morphometric aspects of Aegla manuinflata Bond-Buckup and Santos, 2009 to determine the mean size of males and females at the onset of sexual maturity and to test for intraspecific sexual variations. The programs Mature I and Mature II were used to analyze relative growth. Relationships reflecting the onset of morphological sexual maturity were tested with the software REGRANS, as a means of comparing methodologies. The mean size at first maturity was estimated as 13.60 mm CL in males and 10.84 mm CL in females. The Principal Components Analysis showed that the dimensions of the chelipeds propodus length were primarily responsible for the total variance in the data for males and females. The Discriminant Function Analysis showed that there were no significant differences among juveniles; however, adult males and females were distinguished as two separate groups, indicating that sexual maturity in this species probably occurs after a single ecdysis. Aegla manuinflata shows heterochely, with the left cheliped being the larger in all categories. This seems to be a general pattern for members of Aeglidae.

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.

Aegla are endemic to southern South America and have been documented in Argentina, Bolivia, Brazil, Chile, Paraguay, and Uruguay. Documentation in Paraguay is sparse, with the last published encounter occurring in 1985; in 1999, the genus was proposed extinct within that country. Since then, a few individual aeglids have been found scattered throughout the Rio Tebicuary watershed. In 2009, aeglids were discovered within the Rio Jejuí watershed within eastern Paraguay; males and ovigerous females were successfully captured including a female carrying more than 20 juveniles beneath its pleon. All individuals from the 2010 field season were later identified morphologically as Aegla platensis Schmitt, 1942. This discovery comes after a two-decade gap in abundant aeglid collections within Paraguay and serves as the first recorded breeding population of aeglid crabs to be documented.

The morphology and morphotypes of the Hawaiian river shrimp, Macrobrachium grandimanus Randall, 1840 (Caridea: Palaemonidae), are examined in this study. This species has a dense aggregation of setae (termed “setal patch”) located on the major second cheliped and the function of this setal patch is unknown. Because previous research documented that this setal patch is not associated with grooming behaviors, a morphological study with detailed examination of the morphology of the second chelipeds was conducted using SEM and a dissecting microscope. Using morphometrics, three ontogenetic morphotypes within M. grandimanus were identified: females, small symmetrical males, and large asymmetrical males. There are morphometric differences and setation differences between small and large individuals as well as differences between the sexes. The setal patch is associated with large males, so while the function still remains unknown we present hypotheses about its function in behavioral and life history traits of these large males.

Among crayfish, primary burrowing species are the least understood ecologically. Many primary burrowing crayfish inhabit floodplains where forested landscapes have been fragmented by agricultural, industrial, or residential uses. In this study, site occupancy rates (ψ;) were modeled for two primary burrowing crayfish, Fallicambarus fodiens (Cottle, 1863) and Cambarus thomai Jezerinac, 1993, from Ohio and Kanawha river floodplains in West Virginia, U.S.A. Fallicambarus fodiens is one of West Virginia's rarest crayfish, while C. thomai is prevalent in most wetlands along both river floodplains. Occupancy rate modeling incorporated four environmental covariates (forest age, soil type, tree frequency, and land use). Based on presence/absence data, forests with tree ages > 100 years (ΔQAIC_c = 0) and sites with loam soils (ΔQAIC_c = 1.80) were most likely to harbor F. fodiens populations. For C. thomai, several models were supported owing to model selection uncertainty, but those with the land use covariate had more total model weight (total w_i = 0.54) than all other covariate models. Cambarus thomai rarely occupied industrial/agricultural sites, but were often present in forested and residential sites. Although the influence of covariates on site occupancy differed between species, both taxa readily utilized mature forested habitats when available. Conservation actions for F. fodiens and C. thomai should focus on preserving forested tracts along large river floodplains

The reproductive biology of many species of anomuran crabs is only poorly known. Herein we studied the reproductive biology of two species of squat lobsters, Cervimunida johni Porter, 1903 and Pleuroncodes monodon (H. Milne Edwards, 1837), which are target of a trawl fishery operating on the continental margin along the Chilean coast. During the reproductive period (May–November) we maintained squat lobsters in the laboratory to examine whether mating is related to the reproductive molt of the female and to determine the interbrood interval between successive broods. In both species females mated during the intermolt period. Females became receptive shortly after having released larvae from a previous brood, when they formed pairs with males. The interbrood interval (from larval release until having a subsequent brood) lasted <72 hour in the majority of female C. johni, but was longer in P. monodon, where most females took 72–144 hours before producing a new brood. Despite longer interbrood intervals, copulatory mate-guarding was substantially shorter in P. monodon than in C. johni. These differences in reproductive behavior might be due to differences in the general biology of the two species, including mobility and intraspecific aggression. Mating during the intermolt period may have several advantages, namely reducing the risk of cannibalism and energy costs of molting during the reproductive season.

The crab Halicarcinus planatus (Fabricius, 1775) is the only member of Hymenosomatidae that inhabits the southern tip of South America, and it is the only decapod species that reproduces twice a year in the Beagle Channel. In this study, we analysed seasonal variations in development duration, body size, biomass (dry weight), and elemental composition (CHN) of larvae from a population living at the southernmost limit of the species' geographic range. Compared to offspring produced in December (early summer), larvae released in August (late winter) were on average larger and heavier, and they showed a higher carbon content (suggesting a larger lipid fraction). This pattern of intraspecific variation in larval size and biomass corresponds with minimum primary productivity in sub-Antarctic regions during winter, suggesting that large winter eggs may represent a reproductive adaptation to a regular pattern of variation in nutritional conditions, including food limitation in winter. As an additional or alternative explanation, also strong salinity fluctuations occurring in summer might reduce larval quality in the December cohort. In conclusion, seasonal variation in larval size and biomass may be related to variations in nutritional and/or physical factors.

Slipper lobsters (Decapoda: Scyllaridae) are rather rare in the fossil record. The exceptionally well-preserved scyllarid decapod described herein comes from the Late Cretaceous Hadjoula Lagerstätte, Lebanon. This new specimen represents the first fossil “postlarval” stage (nisto) described, and it is assigned with confidence to Arctidinae. Converging lines of evidence from the depositional environment and comparisons with modern analogues indicate that this nisto probably lived in small intra-shelf basins before migrating to shallow-water conditions during the adult stage.

Sphaerodromiidae is reported from the Paleocene of Texas with Dromilites? cardwelli (Armstrong, Nyborg, Bishop, Ossó-Morales, and Vega, 2009) new combination. The species is a sphaerodromiid but is too poorly preserved for confident generic placement. The morphology of the preserved sternum of D. ? cardwelli confirms placement in Sphaerodromiidae. Spaerodromiidae was previously known from the Cretaceous and Eocene; thus no range extension occurs.

Changes in metabolite levels in hemolymph and hepatopancreas were used as indicators of physiological status of juvenile wild and cultivated Farfantepenaeus duorarum (Burkenroad, 1939), during hyper-osmoregulatory conditions (salinity 22 ppt, 726 mOsm/kg). We analyzed the relationship between biochemical changes of wild and cultivated shrimp at different molt stages by measurement of osmotic capacity, hemocyanin, acylglycerides, cholesterol, glucose, glycogen and total protein. Biochemical analyses of hemolymph (blood) and hepatopancreas showed a decreasing trend in stages closer to molt and an increasing trend before intermolt. Osmotic capacity and blood proteins indicated a significant effect of the molt stage. Stages A, D1′ and D1′″ showed the greatest effect on the biochemical variables. Higher hemocyanin, cholesterol and glycogen concentrations were observed in wild shrimp than in cultivated shrimp. The effect of the molt cycle was associated with changes in cyclic ions and water balance that produced chemical changes in the hemolymph in both wild and cultivated.

Amylases from the midgut gland of wild Farfantepenaeus subtilis (Pérez-Farfante, 1967) and Litopenaeus schmitti (Burkenroad, 1936), and farmed Litopenaeus vannamei (Boone, 1931) were characterized through studies on the effect of inhibitor and metallic ions, optimal pH and temperature, thermal stability and zymograms. The substrate zymogram revealed nine, eight, ten and seven amylolytic bands from F. subtilis, L. schmitti, adults and juveniles L. vannamei, respectively. Total amylolytic activity in the farmed shrimp was three times as high as that of the wild specimens. Amylases from all species exhibited residual activity above 85% at alkaline pH (7.0–8.0), with optimal temperature between 40 and 50°C. None of the enzymes from the species were thermally stable at temperatures above 55°C. Alpha-amylase activity in F. subtilis and L. schmitti was totally inhibited by Type I inhibitor at 50 and 100 µg.mL^-1, while enzymes from adult and juvenile L. vannamei retained 43.5 ± 1.98 and 22.5 ± 0.65% of their activity, respectively, at these same concentrations. Ca² increased amylase activity in all species only at a concentration of 1 mM, inhibiting activity at 5 and 10 mM. All other ions employed (Cd² , Zn² , Hg² , Cu² and Al³ ) strongly inhibited amylase activity, regardless of the concentration used.

The diversity of large branchiopods in Australia has not be reviewed since 1983 for fairy and brine shrimps (Anostraca), 2005 for clam shrimps (Laevicaudata, Spinicaudata, Cyclestherida), and 1955 for shield shrimps (Notostraca). Presently five genera and 59 species of anostracans are known to occur in Australia (up from three genera and 29 species in 1983), with 35 described species plus five known undescribed species of Branchinella, 18 described plus one known undescribed species of Parartemia, two described species of Streptocephalus, two species of Australobranchipus, and two Artemia. Of these Branchinella clandestina and Streptocephalus queenslandicus could be junior synonyms and hence invalid. A few species are widespread (B. australiensis, B. occidentalis, B. affinis), but the majority are restricted to a state or two and many are localised. All species of Parartemia and a few Branchinella are halobionts, while the remainder live in strictly fresh waters. Debate rages on whether one of the two international species of Artemia are native or introduced. The degree of congeneric occurrences varies between genera and across the continent. The clam shrimp fauna is less well known with at least two species of Lynceus, two of Eocyzicus, six of Caenestheria, two of Caenestheriella, an enigmatic species supposedly belonging to Cyzicus, seven of Limnadia, two of Eulimnadia, eight of Limnadopsis, one of Eoleptestheria, and one of Cyclestheria. Two further species of Lynceus, four of Limandia and four of Limnadopsis are being described. This makes 42 species, up from 26, but descriptive and molecular work in progress suggest many more at least in the four genera being studied (Lynceus, Eocyzicus, Caenestheriella, Limnadia). Eocyzicus parooensis and an undescribed species of Limnadia are halophilic. For the Notostraca, the supposedly widespread Triops australiensis and Lepidurus apus viridis may represent many species separable molecularly.

A phylogenetic analysis of a fragment of the mitochondrial gene 16S was used to test the monophyletic status of Potimirim. Existing doubts on the taxonomic status of Potimirim brasiliana (once P. glabra) and P. potimirim (once P. mexicana) were clarified. Potimirim mexicana and P. potimirim are distinct species according to molecular data and appendix masculina morphology. A new species (Potimirim sp. 1) from Puerto Rico was revealed with molecular data, and it is evolutionarily related to P. potimirim and P. mexicana according to our analysis. We found out three distinct species under the name P. glabra. Then, we recommend the application of the name P. glabra for the populations of the Pacific slope of Central America and revalidation of P. brasiliana for the Brazilian ones. The need for a new name to those “P. glabra” of the Caribbean is highlighted, and it was provisionally referred as Potimirim sp. 2. The ontogenetic (juveniles to adults) development of the appendix masculina of P. brasiliana was observed and compared to the other species of Potimirim (adults). In the light of our phylogenetic hypothesis, we postulate a pattern of character addition for the evolution of the appendix masculina of Potimirim. This hypothesis is plausible for two key reasons. First, Potimirim is a monophyletic group according to our hypothesis. Second, the shape of appendix masculina found in adults of P. americana is similar and comparable to those found in the earliest juvenile stages of P. brasiliana, a derived species according to our phylogeny (P. americana, ((P. mexicana, Potimirim sp. 1, P. potimirim), (P. glabra, (P. brasiliana, Potimirim sp. 2)))). As so, the basal P. americana retain the ancestral morphological state of the appendix masculina when compared to the other species of Potimirim. In our interpretation the ontogeny of the appendix masculina recapitulated the proposed phylogeny, giving further support to it.

Herein, we report a new species of leptostracan, Nebalia koreana (Malacostraca) collected from the southern and eastern coasts of the Korean peninsula. All the specimens of this species were collected by means of light traps from harbors where the bottoms are sandy and with algal mats. The new species differs from all other known Nebalia in the following characters: the carapace is relatively small, and covers the lateral sides of pleonite 2 and partially the lateral sides of pleonite 3; the fourth article of the antennule has up to five short distal spines; pleonites 3 to 7 have rounded denticles along the posterior dorsal borders; the epipod of thoracopod 7 bears 5 to 6 plumose setae along the posterior margin, which are lacking on the remaining thoracopods; and the protopod of pleopod 4 lacks serration along the posterior border. Only two species of Nebalia have been reported from the tropical or subtropical seas of Asia. Therefore, the new species is the first species of Nebalia found in the temperate zone of Asia. Additionally, type localities and world distribution of the genus Nebalia are provided in this paper.

We describe the first species of Parabathynellidae discovered in Germany and assign the new species to Parabathynella due to its five-segmented antenna, the structure of the male thoracopod VIII, and the uropodal endopod bearing one basal plumose seta and a terminal spine. This new species, P. badenwuerttembergensis, differs largely from its congeners in its large body size, the rich number of ornaments on appendages (antennules, antenna, mouthparts, thoracopods I–VII, uropod), and of segments of appendages (exopod of thoracopod I–VII); these suggest a basal position of a new species within the genus. A two-segmented female thoracopod VIII with three apical setae, the feature of the male thoracopod VIII, and the possession of setae along both the inner and the outer margin of the uropodal exopod lead us to discuss the possible inclusion of Montanabathynella salish Camacho et al., 2009, into Parabathynella. Based on its own apomorphic characters Montanabathynella is maintained as a separate genus having a close relationship to Parabathynella.

Cancer is one of the “oldest” names in carcinology, but like many old and familiar things it has fallen into use as a catch-all category, especially by non-taxonomists. Much taxonomic revision has occurred in Brachyura: Cancridae [Cancer] in recent years, and unfortunately, much of it has passed completely under the radar of biologists. A summary of that revisionary work is provided along with a list of currently accepted names for the living species of Cancridae. We offer this contribution in an effort to cut off the use of old, and in many cases invalid, binomina, and to encourage the use of a modern, up-to-date classification of cancrid crabs.

The second gnathopods of caprellid male amphipods are larger than the ones observed in females. The second gnathopods are armed with a propodus or tooth that is associated with a poison producing gland, by which male-male contests lead to fatal outcomes. Here we observed the ultrastructure of the second gnathopods by scanning electron microscopy and compared the relationship between the number of pores in the poison tooth and body length among the males of four caprellid species: Caprella acanthogaster, C. bispinosa, C. scaura, and C. penantis. All species possess pores on the poison tooth, and the number of pores increased with body size. The number of pores also differed among specimens of the four species. Furthermore, in males of three caprellid species, except for C. penantis, we found additional pores at the tip of the dactylus of second gnathopods. The number of pores on the tip of the dactylus did not increase with body length, and the average number of them differed among the three species. Although it is not known if venom is released from the pores of both structures, larger individuals that possess more pores on the second gnathopods could have a competitive advantage in male-male competition.