Sand fiddler crab males, Uca pugilator (Brachyura: Ocypodidae), use their single enlarged claw as a weapon in fights for burrows and as a signal to attract females to burrows. Seventy-three males from a South Carolina marsh were in reared in the laboratory to determine if body size at the time of claw loss affects the morphology of the claw that subsequently regenerates. Thirty-six males were induced to autotomize claws and regenerated new ones. Thirty-seven males retained original claws. Across four molts, males regenerating claws gained more in claw length but less in body width and overall mass than males retaining original claws. The first molt accounted for these differences as males regenerating claws gained relatively little in body size but added much in claw length. Regenerated claws were more slender, having smaller dimensions of the manus relative to claw length. As the manus houses the claw closer muscle, regenerated claws are expected to be less powerful and appear more designed for signaling. Both regenerated and original claws became more slender with increasing length, suggesting that across a lifetime pressures arising from combat are reduced relative to those arising from mate attraction. Among regenerated claws, the height of the manus relative to claw length and the development of teeth and tubercles that facilitate pinching were greater when original claws were lost at smaller body sizes. Consequently, distinguishing original from regenerated claws can be difficult. An index, the score of tooth and tubercle development times the manus length divided by the product of carapace width and pollex length, discriminated claw types among reared crabs as well as sophisticated statistical techniques. Use of the index suggests that the frequency of regenerated claws increases with population density among neighboring natural populations. The relative size of regenerated claws was greater among males that had relatively large original claws prior to autotomy, suggesting that males may continue to signal their quality by regenerating a new claw that is relatively long.

The setae of gill-cleaning mechanisms and respiratory-water circulation system of ten species of ocypodid crabs are described. Epipodal setae are classified as of four types: anchor-, scale setule-, simple-, and digitate-scale-setule setae. A few short setae are found on the Milne Edwards aperture (MEA) in Ocypode, while long plumo-pappose setae were found on the MEA in Uca. The basal part of the epipod of third maxilliped (EpMp3) is armed with many pappose setae having digitate-scale setules in Uca. On the other hand, only a few setae are found on the basal part of the EpMp3 in Ocypode. The constricted setae were dominant on Müller's aperture. Setae on these structures were compared with those of previous studies.

Postlarvae and juveniles of pink shrimp were collected in the summers of 2005 and 2006 at three stations in northwestern Florida Bay, the main nursery ground of this species in South Florida. Collections were made at one- or two-hour intervals during three full moon nights and two new moon nights at depth intervals in the water column. Results of the five collections were consistent with the assumption that postlarvae use a flood-tide transport (FTT) to advance into the estuary by ascending in the water column during the dark-flood tide and resting near the bottom during the ebb tide. Evidence of a FTT were higher numbers of postlarvae per hour collected during the flood tide vs. ebb tide and the large number of postlarvae collected with highest velocity flood tide currents. ANOVA indicated significant differences in the number of postlarvae collected between tidal stages and moon phases, but not among depths. Postlarvae were more abundant during new moon than full moon. We also found different patterns of postlarval distribution between the new and full moon. During the new moon, a large peak of postlarvae occurred coincident with highest current speeds, whereas, with one exception, during the full moon postlarvae were more abundant in the second half of the flood period near the slack tide. In contrast, juveniles exhibited a behavior and migratory pattern opposite to that of postlarvae. ANOVA indicated significant differences between the number of juveniles captured between tidal stages and among depths, but not between moon phases. Juveniles were found almost exclusively near the surface on the ebb tide. Significantly larger juveniles were captured on the dark-ebb rather than on the dark-flood tide during both moon phases, suggesting that older juveniles were leaving the Bay on the ebb tide.

Fecundity and brood loss during incubation were investigated in the crangonid shrimp Crangon uritai. Changes in egg length, volume and dry weight were also studied. During embryonic development, egg length and egg volume increased by 43.5% and 69.3%, respectively, whereas egg dry weight decreased by 23.2%. Crangon uritai ovigerous females (5.61-14.11 mm CL) carried 412 to 13,824 eggs per brood, depending on their body size in both early and late stages of egg development. The reproductive output of C. uritai averaged 0.24, based on dry weight in early eggs. Brood loss through embryonic development was independent of female size and estimated to be a 5.56% loss in the number of eggs and an 8.44% loss in brood dry weight. Possible reasons for brood loss include the burrowing behavior of shrimp and increasing egg size, which results in reduced area for eggs to attach.

Aspect of reproductive ecology of Caridina typus and Caridina sakishimensis were studied in six headwater streams in Kikai-jima Island, Southern Japan. Monthly surveys were conducted from June 2005 to June 2008. Shrimp specimens were collected with a hand scoop net. The population size of C. typus was lowest during high precipitation periods but showed immediate recovery attributed to successful recruitment and increased following the major spawning activities, while that of C. sakishimensis remained stable throughout the study period. The breeding season of C. sakishimensis was estimated to extend from March to November, with a main breeding season lasting from June to September, while that of C. typus lasted from March to December. Overall ovigerous females comprised 50% to 80% of mature females of C. sakishimensis during the main spawning season, which indicated that this species remained and spawned mainly in the headwaters. Both C. sakishimesis and C. typus carried a large number of small sized eggs. This study revealed that the spawning season, egg size, and brood size are similar in both species; usage of headwater streams was different between C. sakishimensis and C. typus. Caridina sakishimensis employed these water bodies as spawning ground while C. typus used them as nursery ground.

Crayfish are a highly diverse group of freshwater crustaceans with great ecological and economic importance. Many species construct terrestrial burrows within which they reproduce, overwinter, and/or avoid desiccation. Basic life-history and environmental tolerance information is still lacking for many species, particularly in regards to terrestrial portion(s) of their life cycle. In this paper we present and evaluate a design for a crayfish burrowing chamber that allows for experimental control of burrowing conditions, including substrate, groundwater height and flow, as well as direct observation of burrow construction and measurement of groundwater quality. Results of evaluation assays with Cambarus striatus, a widespread secondary burrower native to the southeastern United States show that chambers are amenable to studies examining burrowing behavior, survivorship, growth and water quality. Water table height was easily manipulated in chambers. Seepage rates were strongly affected by substrate type: burrows in coarse substrate filled rapidly but collapsed quickly whereas burrows in fine substrates filled very slowly and did not collapse. Cambarus striatus burrowed readily in fine substrate, produced complex burrows with chimneys, and exhibited high survivorship and positive growth over a 4 week period. Ammonia levels were higher in burrows than in the groundwater flowing through the chambers, but did not significantly affect growth or survivorship of C. striatus. Maximum burrow depth was significantly affected by substrate type, but not presence/absence of chelipeds. Suggested improvements include larger chamber size and the use of mesh barriers to keep crayfish from burrowing against the inner chamber walls.

Burrow architecture of the ghost crab, Ocypode ceratophthalmus was studied at Sai Kaew beach (a pristine sandy habitat) in southern Thailand. The burrows of 131 individuals were cast with molten wax and carefully excavated. Only complete burrow casts with crab-occupant (n  =  67) were used in the data analyses. Burrows were grouped into categories according to their shapes: J, U or Y-burrows; and further classified into those excavated by juvenile and young adult crabs based on carapace width: juvenile, Juv, (CW < 20 mm; n  =  53) and young adults, YgA (CW ≥ 20 mm; n  =  14). All J, U and Y-burrows have an ascending arm that opens on the surface of the substrate ( =  Open Arm, OA). The other ascending arm of U and Y-burrows terminates a short distance from the surface of the shore ( =  Blind-ending Arm, BeA). Y-burrows were predominant (66%) as compared to J and U-burrows (13% and 21% respectively). Juvenile Y-burrows had a steeper angle of descent of the OA which may provide better protection from predators through rapid retreat to deeper depths. Smaller β_Juv (cf. α_Juv) indicates a gentler gradient that may facilitate escape. β_Juv is also not significantly different from β_YgA suggesting an optimal gradient for crabs to push through the last cm or so of sand above the BeA to escape from predators. The larger θ in YgA burrows could improve maneuverability down the shaft as YgA have larger body volumes than Juv. α_Juv and α_YgA of J, U and Y-burrows and β of U and Y-burrows were not significantly different. The arm depths of juvenile J, U and Y-burrows were also similar. Comparison of the relationship between arm depth and shaft depth against the total depth in Juv and YgA Y-burrows indicates that the deepening of Y-burrows occurs mainly by the lengthening of the shafts. Results from this study provide evidence that the J and U-shaped burrows could be the precursors of Y-shaped burrows in the excavation process.

The population dynamics and secondary production of the fiddler crab Uca rapax Smith, 1870 in the Itaipu Lagoon (Southeast Brazil) were studied. Samples were taken monthly over a period of 12 months, in order to test latitudinal gradient predictions about secondary production and P/B ratio. Males and females showed the same growth rates (K = 2.083) and reached the same asymptotic size (15.57 mm). However, females showed higher total (Z = 3.20) and annual mortality (A = 0.96 ind·year⁻¹) than males (Z = 1.89; A = 0.85 ind·year⁻¹). Recruitment occurred in all months, except in June, 2007. Secondary production was estimated in 113.4 g AFDW·m⁻²·year⁻¹ and the production to biomass ratio (P/B) was 15.09. The production and P/B ratio estimated in the present study did not agree with the latitudinal gradient literature predictions.

The first meiotic prophase was analyzed in both genders of Pacific white shrimp Litopenaeus vannamei. Progression through meiosis, from the formation of the synaptonemal complex to diplotene is described during molting stages. Most of the meiotic cells in both genders were observed at pachytene, recognized by complete synapsis of bivalents. In both genders, the zygotene, pachytene, and diplotene stages occurred at inter-molt, pre-molt, and post-molt stages in all individuals, which suggests that there is no relationship between molting and the first meiotic prophase. Sperm counts from the vas deferens and spermatophores support a continuous production of male gametes. The nature of the synaptonemal complex in gonad cells shows that each pair of homologous chromosomes synapses end to end, revealing a high chromatin density and a complex tangled arrangement in the nucleus. Both genders have 44 bivalents, of which around 40 have an o-ring configuration, and the rest have a v-shape, meaning that most bivalents present chiasmata at both ends, each representing two crossing-over events per bivalent per meiosis.

Wild-caught larvae, attributed to the lobster shrimp Axius serratus, consisting of two zoeal stages and a decapodid (megalopa), are described in detail. Parentage of larvae was ascertained based on geographic distribution of axiideans and gebiideans ( =  former thalassinideans) within the study area and close morphological resemblance to other congeneric larval stages. Larvae of A. serratus represent the first described ‘thalassinidean’ larvae from Canadian Atlantic waters and the first for Axiidae within the northwest Atlantic. Among axiidean larvae, those of A. serratus most closely resemble larvae of A. stirhynchus from the eastern Atlantic. Distinct features include the spination of the pleon that set A. serratus zoeae apart from those of most other ‘thalassinideans’ but that, in combination with a telson very similar to Homarus americanus, contributes to the general resemblance of A. serratus larvae to those of the American lobster. The primary distinction between these taxa is the presence of a chela on the third pereiopod in the latter that is not present in the former. In view of these appendages being prone to loss or damage, other characters that separate these taxa are listed and discussed. Given the uncertain status of some taxa within Axiidae and limited detailed information of larvae with certain parentage, difficulties in delineating the family based on larvae persist, as they do for cladistic analyses using adult morphology and molecular approaches.

On the Scotian Shelf (SS), Chionoecetes opilio (snow crab) larval releases are spread out over at least a 12-week period in the spring. This large spread in the timing of snow crab larval release may be caused by the large variability in the timing of the spring phytoplankton bloom found on the SS, or complex oceanographic factors. It has been reported that C. opilio release their larvae in response to post bloom senescent algae exposure, and that the release may also be timed with the high spring tide. Objectives of this study include exploring the possibility of tidal, current, and senescent algae induced larval release in ovigerous C. opilio from the SS population; temperature influences were also examined. Another objective was to determine if the female or the embryos themselves control the hatching process. The average duration of hatching was 9.6 d for the warmer treatment and 12.3 d for the cooler treatment. A mixed-effects model using a logistic regression indicated no significant influence of senescent algae upon the larval release patterns (P > 0.5); and a statistically significant temperature influence upon larval release patterns (P < 0.0001). Detached embryos still hatched 14 days post removal, and throughout the duration of hatching were relatively synchronous with those still attached to the female (two-sided KS, D  =  0.308, P > 0.5). Larval release did coincide with local high tide and the associated higher current speeds. The results of this study indicate that C. opilio embryos are not receiving chemical cues from the female or senescent algae, but rather, are under endogenous control. Whether they rely on internal pressure, some type of internal biochemical cue or external physical factor such as hydrostatic pressure from high tides or increased current speed warrants further study.

Declines in abundance of the commercially important blue crab Callinectes sapidus have led fishery managers to search for new management strategies. Assessing year-class strength at megalopal or early juvenile stages may contribute to this effort, but separation from co-occurring species is difficult in many areas because morphological characteristics vary with season and published descriptions do not adequately distinguish C. sapidus from C. similis and other related species. Callinectes sapidus and C. similis megalopae were collected monthly and cultured in the laboratory to a size at which positive identification could be made. Measurements on intact megalopae and early crab exuviae of both species revealed seasonal differences, with spring megalopae having larger carapaces, longer rostral spines and antennae and more setae on some mouth parts than fall megalopae. This seasonal pattern of morphological variability was verified through examination of samples collected from MS (1976–1979) and NC (2005) coastal waters. Rostrum length, total carapace length and rostrum length as a percent of total carapace length of NC megalopae were negatively correlated with water temperature 2–4 weeks prior to collection.

Callinectes sapidus and C. similis megalopae can be rapidly separated within locations and seasons by: 1) the shape of the antero-lateral carapace margin, 2) rostral length as a percent of total carapace length, and 3) the combined length of the distal eight segments of the antenna. Such rapid separation is essential for fisheries studies requiring identification of large numbers of individuals. Molecular analyses or more detailed morphological analyses remain necessary for definitive separation regardless of season. Keys to common coastal portunid megalopae and first crab stages were compiled to aid investigators in separating C. sapidus megalopae and early juvenile stages from co-occurring portunids.

This study provides a systematic and phylogenetic overview of the extinct reptant decapod family Mecochiridae. Mecochiridae are distinguished from both their traditional out-groups, Glypheidae and Erymidae, using cladistic and geometric morphometric techniques. Cladistic analysis of 12 species using 21 traditional and new characters verifies the in-group genera Mecochirus and Pseudoglyphea. Glyphea emerges as a sister group to Pseudoglyphea, suggesting a re-assignment of the genus to Glypheidae. The genus Meyeria is recovered as paraphyletic, suggesting the establishment of a new taxonomic group for species of Meyeria that exhibit a posterior tuberculated ridge, a well-developed hepatic bulge or ridge, and unornamented pleura. Both relative warp and Eigenshape analysis of the carapace and groove patterns that have long been used as descriptive morphological features succeeded in highlighting modes of shape change that when subjected to a discriminant analysis proved useful in distinguishing members of Mecochiridae. This study shows that landmark geometric morphometric methods and eigenshape analysis can be used to investigate the fidelity of existing taxonomic groupings based on other methods, and that an integrated cladistic and morphometric methodology has the potential to aid in resolving relationships among other unknown or problematic fossil taxa.

We collected postlarvae (PL) and early juveniles of Farfantepenaeus aztecus and F. duorarum < 7.0 mm CL from the Gulf of Mexico and verified their species identity using a multiplex Polymerase Chain Reaction (PCR) assay, which targeted the 16S rRNA mitochondrial gene. We examined young with ≥ 5 dorsal teeth (DT) for differences in morphology and used a General Discriminant Analysis approach and ‘best’ subsets model-building technique to help identify the ‘best’ characters to discriminate taxa and predict species membership. Farfantepenaeus duorarum with ≥ 5 DT and F. aztecus with ≥ 7 DT have spinules on the epigastric and first DT, a character not previously reported for these two species. Differences in antennal scale shape and sixth pleomere length discriminate > 95% of Farfantepenaeus sp. with < 7 – 8 2 rostral teeth. Farfantepenaeus duorarum has an antennal scale with an acutely rounded margin about twice the height of the adjacent lateral spine, and has a sixth pleomere length measurement < 2.5 mm. In F. aztecus, the antennal scale has a more broadly rounded margin with a lateral spine that approaches or exceeds the tip of the scale, and has a sixth pleomere length measurement > 2.5 mm. Species discrimination of Farfantepenaeus sp. with ≥ 7 – 8 2 rostral teeth requires body measurements. Classification models accurately discriminate > 90% of Farfantepenaeus sp. from the western Gulf and increase the reliability of discrimination by > 20% over characters that have been used for species discrimination, some of which are unreliable. The unsatisfactory performance of the models in discriminating Farfantepenaeus sp. from the eastern Gulf is consistent with the possibility of different ecological populations in the eastern and western Gulf that may warrant further study. Integration of molecular taxonomy and comparative morphology, as we did here, can provide insight into the patterns of diversity and ecological and evolutionary principles that encompass fisheries management.

We report 15 polymorphic microsatellite loci isolated from the river prawn Macrobrachium nipponense. Their genetic characteristics were evaluated in 40 individuals from two Korean populations. The number of alleles ranged from 4 to 16, and the observed and expected heterozygosities ranged between 0.35 and 1.00 and 0.41 and 0.90, respectively. We assessed the cross-species amplification of each locus in five species of palaemonid prawn and two species of atyid prawn.

The marine interstitial Microloxoconcha dimorpha n. sp. has two morphotypes in the male, “L type” and “S type”; they occur sympatrically and can be distinguished by the size of their carapaces and the morphology of the male copulatory organs. Conversely, the genetic relationships based on the partial mitochondrial COI gene did not demonstrate an independent clade as belonging to only one type. The L and S types are therefore not reproductively isolated from each other, and they express an intra-sexual dimorphism. We also argue that the morphological features of the male copulatory organ could have changed prior to the establishment of reproductive isolation.

The mitochondrial gene cytochrome-c oxidase subunit 1 (COI) and the nuclear ribosomal DNA region known as Internal Transcribed Spacer 1 (ITS1) are used in a phylogenetic analysis of Ridgewayia from the Galapagos Islands and of a new species, Ridgewayia tortuga, from the Florida Keys. In addition, the phylogeny of Calanoida is reconstructed based on the 18S ribosomal RNA gene. The following characters exclude R. tortuga from the three recognized species groups of Ridgewayia: the presence of only 7 setae on the terminal endopod segment of leg 2; a 20-segmented male right antennule with two geniculations, the first between segments 9 and 10 and the second between segments 16 and 17; and details of the male fifth leg, in particular the elongate, unarmed, right endopod with a bifurcated tip. The molecular analysis shows that the first half of the COI gene not only fails to differentiate the various species of Ridgewayia, but it also fails to differentiate between the families Ridgewayiidae and Pseudocyclopidae. The second half of this gene and the ITS1 region are species specific. Molecular and morphological evidence suggest that the Galapagos ridgewayiids are the result of one colonization event and that the current phylogeography of these animals can be explained by a combination of vicariance and active migration models. The 18S ribosomal RNA gene proves successful in the reconstruction of the phylogeny of Calanoida with the following main conclusions: 1) Centropagoidea is the sister branch to all other Calanoida; 2) Ridgewayiidae and Pseudocyclopidae likely share a common ancestor with Augaptiloidea; 3) Ridgewayiidae and Pseudocyclopidae should be included in the same superfamily, the Pseudocyclopoidea; and 4) Spinocalanoidea likely needs to be included in Clausocalanoidea to recover the monophyly of the latter superfamily.

We describe the current distributions and relative abundances of southeastern Pennsylvania's crayfish; changes in the region's crayfish fauna over the last century; and, where pertinent, the relationship of the current fauna to site-specific characteristics, basin-wide attributes, and exotic crayfish. The crayfish fauna currently inhabiting the region bears little resemblance to the historical assemblage. Whereas historical surveys yielded Orconectes limosus and Cambarus bartonii, both native species, recent collections produced eight species including five exotics. Many areas occupied by exotic Orconectes no longer support O. limosus. Cambarus bartonii was found in a number of invaded systems, but was typically a minor component of the crayfish community and may not be able to persist in those systems indefinitely. The distribution of Cambarus (Puncticambarus) sp., an undescribed member of the Cambarus acuminatus complex, was extremely limited, with populations only found in four streams, all of which are threatened by urbanization and exotic crayfish. Exotic species collections include the first published records for Procambarus clarkii in Pennsylvania and extend the ranges of Orconectes virilis and Orconectes obscurus in the state by > 150 km. These results indicate the need for conservation and management initiatives aimed at preserving the native crayfish that remain in southeastern Pennsylvania.

The distributions of freshwater fauna in the La Plata Basin, including decapods, are dynamic; their actual distributions depend on not only their movements but also on environmental fluctuations. The La Plata system has a diverse range of environments, which are colonized by crustaceans with complex evolutionary histories. Our aim was to elucidate the distribution patterns and relationships of current freshwater decapod fauna in terms of the different geo-climatic processes at work in the La Plata system. We recognized 13 zones based on their unique environmental characteristics. Species lists were assembled through field samples, examination of museum collections, and literature analysis. Faunistic similarity was evaluated using the Jaccard index and cluster analysis. A parsimony analysis of endemicity (PAE) was applied to determine the most parsimonious of all possible tree topologies. There were 69 species freshwater decapods analyzed in the La Plata Basin. The Mata Atlántica (MA), Paraná Superior (PS), and Uruguay Superior (US) zones are distinguished by their high species richness values, whereas the western and southern basin regions exhibit the lowest species richness values. The Paraguay-Pantanal (PP) and Paraguay-Pilcomayo-Bermejo (PPB) zones share some prawn taxa with the Amazon Basin. The eastern zones of the La Plata Basin were grouped by the presence of several species of the genera Parastacus, Aegla, and Trichodactylus. The northern, central, and western zones were characterized by species of the genera Dilocarcinus, Sylviocarcinus, and Zilchiopsis. According to the PAE analysis, two major zones were recognized in relation to the presence of freshwater decapods (eastern and western-central zones). In the western-central zones, three sub-areas were identified; one shares species with the Amazon basin the others have a relationship with the eastern and northern regions and represents a region that is strongly influenced by a temperate climate and therefore possesses diminished species richness values.

Diastylis sexpectinata, a new species of cumacean that extends from São Paulo State (Brazil) to northern Patagonia (Argentina), is herein fully described and illustrated. This species can be easily distinguished from the other members of the genus by the following combination of characters: 1) carapace with a pair of anterolateral horns and six longitudinal rows of conical teeth (middle and uppermost rows poorly developed or absent in the adult male), 2) third and fourth pereiopods of the female without rudimentary exopods, and 3) uropod endopod consisting of two articles, the proximal one in the female with 3-4 teeth on outer margin. The description of the female of Diastylis hammoniae is completed and the adult male described for the first time based on its type material and additional specimens herein reported. The type species of Leptostylis (?) mancoides was also re-examined and its synonymy with Diastylis hammoniae is proposed. The synonymy of D. hammoniae with Diastylis manca is also strongly suspected, but until additional specimens become available D. manca should be treated as “species inquirenda.” An identification key to the species of the genus Diastylis from Argentina and Uruguay is given.