We studied spatial variation in the prevalence of the rhizocephalan barnacle Lernaeodiscus porcellanae on its porcelain crab host, Petrolisthes cabrilloi, at four southern California intertidal sites separated by only a few km. The prevalence of rhizocephalan externae varied significantly among sites in 2008-2009, with the southernmost site, White Point, consistently showing higher prevalence than the others. Externa prevalence was a good proxy of estimated true prevalence, i.e., the prevalence of rhizocephalans as a whole, not just those that had formed externae. We examined several hypotheses that might explain the observed spatial variation in prevalence. Host susceptibility to infection (indicated by the proxy of damage to host limbs, some of which are used to remove parasite infective stages), did not differ among sites. At all sites, prevalence was slightly higher in female crabs than in males, and the sex ratio at White Point was slightly female-biased while that at the other sites was male-biased; thus, among-site differences in sex ratio did contribute to observed variation in prevalence. However, most spatial variation in prevalence appeared to be due to the effect of host size. At all sites the probability of infection increased with increasing host size, and White Point crabs were on average much larger than crabs at other sites. Overall, the size-class distribution of host crabs explained 80.4% of the variation in prevalence of L. porcellanae. Larger P. cabrilloi have likely had greater opportunity to be infected by rhizocephalans, either because they are older, or because they have undergone more molts, during which they are especially vulnerable to infection. A deeper understanding of small-scale spatial variation in prevalence in L. porcellanae will require information on the causes of among-site variation in host population size structure.

The identification of nursery and spawning areas of coastal fish and shellfish populations represents fundamental information for stock assessment essential for giving advice for managers within the framework of Ecosystem Approach to Fisheries. This study investigates the bathymetric and spatial distribution of young-of-the-year and mature females of the deep-water rose shrimp, Parapenaeus longirostris, in the Strait of Sicily (Central Mediterranean Sea) in order to describe the species nursery and spawning areas. Data were obtained from trawl surveys carried out yearly in spring and autumn from 1994 to 2004, and nursery and spawning areas were inferred by means of GIS techniques. Species maximum abundance occurred between 100 and 300 m. We found that young-of-the-year concentrated on the outer shelf while mature females occurred mostly between the outer shelf and the upper slope. We detected four large areas of aggregation of young-of-the-year, and three areas of aggregation of mature females. High concentrations of young-of-the-year and mature females persistently occupied some of these areas, representing stable nursery and spawning areas. Young-of-the-year and mature females aggregate where retention and enrichment processes occur, linked to the semi-permanent patterns resulting from the meanders of the Atlantic Ionian Stream. We highlight the importance of studying the spatial distribution pattern of commercial species to identify habitats essential to those species' life cycle. We detected deep-water rose shrimp nursery and spawning areas in the Strait of Sicily and discuss their spatial pattern in relation to the hydrological characteristics of the area.

Our study details key parameters of the reproductive biology of the shrimp Palaemon longirostris, e.g., spatio-temporal variation of the sex-ratio, migration pattern, breeding period, fecundity, size at the onset of maturity, and egg volume. While P. longirostris population was very little studied in its distribution area, our fist aim was to complete that lack of knowledge and to provide a basis for understanding its population dynamic. Finally, our results were also compared with those reported from different studies on this species within Europe, in order to test the reported latitudinal cline of reproductive parameters in decapods. During a one-year survey, P. longirostris have been collected monthly across a large part of the Gironde estuary (France). Biometric measurements and determination of sex and maturation stages were carried out on preserved subsamples. Eggs were counted and measured for ovigerous females. In the Gironde, the breeding period was restricted from March to July, and related to water temperature. The size of the ovigerous females ranged between 7.1 and 14.6 mm cephalothorax length; according to their size, these females brought between 78 and 1391 eggs (547 on average). These results were compared with available data from the literature on French or foreign populations. For two reproductive parameters a latitudinal cline was noticed: e.g., an increase of the maximum females size and a restriction of the breeding period with latitude. Due to the weakness of available data on the reproductive biology of P. longirostris, it was very difficult to compare fecundity (number of eggs brought per female) and egg volume between localities. As expected fecundity could decrease with latitude, but this trend remains to be confirmed by more extensive studies on the species populations.

The South American shrimp Palaemonetes argentinus inhabits inland freshwater habitats such as lakes, rivers and streams, but also coastal brackish marshes and lagoons. Hence, this so-called “freshwater” shrimp is expected to be able to reproduce in a wide range of salinities. Here we examined effects of three salinities (1, 15, 25 ppt) on survival and reproductive cycle of females originating from two separate populations in Argentina: 1) Lake Chascomús (LC), a shallow inland lake with low and stable ionic concentrations; and 2) Vivoratá Creek (VC), a lotic stream draining into the adjacent brackish lagoon Mar Chiquita, where salinity is tide-dependent. After an observation period of four months, survival was generally high, without showing significant differences between salinities or populations. Ovarian maturation was measured on a scale ranging from “empty” ovaries ( =  females with newly laid eggs) to fully developed ovaries ( =  females ready to spawn). Most LC shrimps (> 80%) developed their ovaries again after an initial egg extrusion (beginning of the experiment) and produced new eggs at all tested salinities. In VC shrimps, ovarian maturation and egg deposition were successful in both the lowest and the highest salinity (1, 25 ppt), but developed ovaries were resorbed in most individuals at the intermediate salinity (15 ppt). Ovarian resorption was never observed at the highest salinity treatment, thus this phenomenon may have been provoked by unknown factors other than ionic concentration. At 15 and 25 ppt, the beginning of vitellogenesis started later and the total time to ovary maturation was longer than at 1 ppt, lengthening in both populations the time between consecutive spawning of eggs by nearly 10 days. Irrespective of the origin of a population, female P. argentinus survived and completed all reproductive events under a wide range of salinities, which supports the hypothesis that this species is in an early stage of evolutionary invasion of freshwater habitats.

Sand bubbler crabs Scopimera inflata are central place foragers that spend long periods feeding on nutritionally poor surface sediment adjacent to their burrows. Individuals make series of excursions from their burrows usually moving progressively in clockwise or anticlockwise directions so that they feed on areas of “virgin” sediment on successive forages. However, they foraged further from the burrow than was predicted by a model of central place foraging. Foraging crabs were under intense predation pressure from the red-capped plovers Charadrius ruficapillus in the study area. Success rates of plovers in capturing crabs were high. Crabs can escape attacks by retreating back into their burrows but normally waited for less than a minute before recommencing to forage. This may be sufficient to escape a second plover attack because plover waiting times at burrows were only about 10 s in duration.

Portunus pelagicus (blue swimmer crab) is widely distributed and fished throughout the indo-west Pacific, but little is known of its biology and ecology in southeast Australia. In this study, the reproductive biology of P. pelagicus inhabiting Wallis Lake, a large coastal lake that supports the largest regional commercial fishery for the species was investigated. Males and females with mature gonads occur throughout the fishing season (November to July), however, ovigerous females are most prevalent in November and December. The mean size at which 50% of females reached maturity is estimated at 46 mm carapace length (CL). Fecundity increased linearly with CL and females are capable of producing up to 3 broods of eggs within the observed spawning season, with crabs of 60-69 mm CL producing approximately 76% of the estimated total egg production. Increasing the current minimum carapace length above 60 mm CL would potentially provide greater protection to mature females and increase total egg production, but this would reduce total retained catches in the fisheries.

The parasitic metanauplius larva of an undescribed species of Caribeopsyllus, the second thaumatopsyllid species to be reported from the Caribbean, was discovered in Ophiothrix angulata in Belize. In addition, metanauplii of Caribeopsyllus chawayi, whose free-living stages were previously known, were found to parasitize Ophiactis savignyi. Their ophiuroid hosts usually contained a single larva that caused them no discernable physical damage. Caribeopsyllus chawayi, which was initially described from Mexico, is here reported from Belize and is suggested to occur in Brazil. It might occur in the Pacific Ocean, as its host is circumtropical. Larvae of the Belizean thaumatopsyllids are exceptional among copepod nauplii for their large size, four pairs of appendages, true chelate mandibles, elaborate tripartite eyes, accessory photoreceptive structures (Gicklhorn's organ), sexual dimorphism, and endozoic parasitism. Thaumatopsyllus paradoxus and Caribeopsyllus amphiodiae, the only other thaumatopsyllids with known metanauplii, have the same suite of specializations. However, metanauplii of the latter two species crawl, whereas the Belizean metanauplii swim. Both Belizean species have an antennal arthrite used for feeding and well-developed mandibular setae used for locomotion, which are lacking in C. amphiodiae. They leave the host as non-feeding positively phototactic copepodids. Morphological features distinguishing the metanauplii of Belizean species from that of C. amphiodiae indicate that the latter should be referred to a new genus if the systematic significance of its unique morphology is corroborated. Similarities between thaumatopsyllids and siphonostomatoids in the ontogenesis of their caudal rami suggest that Thaumatopsyllidae may belong to the Siphonostomatoida, or be closely allied.

Arthropods exhibit a vast variety of morphological forms. Developmental studies on diverse arthropod groups will help clarify how these forms evolved during arthropod evolution. The terrestrial isopod Porcellio scaber is a suitable novel animal model for developmental studies; it is well adapted to terrestrial habitats and these adaptations make the species interesting from the evolutionary perspective. Porcellio scaber is already extensively used in ecotoxicological and physiological studies and its biology is well known, but a comprehensive description of its ontogenetic development is still missing. Here, a staging system of P. scaber embryos and marsupial mancas based on morphological observations with light microscopy techniques is presented. An important adaptation of oniscids to terrestrial lifestyle is formation of specific structures in the digestive system, which enable effective water retention and good digestion of cellulose-rich plant material. Differentiation of the digestive system during P. scaber embryogenesis is described and the results show that digestive system is well developed already in late-stage embryos. The presented staging system should provide a useful basis for the expanding field of gene expression studies during arthropod embryogenesis and enable comparative developmental studies between arthropod groups.

The hydrothermal vent crab Gandalfus yunohana is found along the Izu-Ogasawara Arc in the north-western Pacific at depths from 420 to 1400 m. To study the larval developmental characteristics of this vent endemic species, we collected adult crabs from a depth of 445 m in May 2005 from the Kaikata Seamount (26°42.607′N, 141°04.457′E). These individuals were maintained at atmospheric pressure and temperature (15 and 18°C) for several months, until two females spawned and released larvae. Larvae were maintained at atmospheric pressure and at five different temperatures ranging from ∼18 to 30°C and fed Artemia sp. At ∼18°C, no larvae survived until the second zoeal stage. Some larvae reached the second or third zoeal stages when reared at ∼21°C. At 24-30°C, six individuals metamorphosed into the megalopal stage following a fifth or sixth zoeal stage 34-60 d after hatching. Megalopae swam actively, but they eventually died 58-104 d after hatching and showed no signs of moulting into the juvenile crab stage. Newly hatched first stage zoeae were phototactic, and we observed relatively high temperature requirements for larval survival and development. These facts suggest that zoeae may be distributed relatively high in the water column in warmer near-surface waters during their planktotrophic development. This is the first report of successful larval rearing of any species of bythograeid crabs. Our study establishes the conditions under which the megalopae moult to the first crab stage, laying the groundwork for future experiments.

Eocarcinus praecursor, the putative earliest member of Infraorder Brachyura of Early Jurassic age in Great Britain, cannot be accommodated within that infraorder. Numerous characters are inconsistent with placement within Brachyura, including: a lack of fusion of the epistome with the dorsal carapace; chelipeds on the first and putatively second pereiopods; lack of true orbits; development of large, strong antennae; notches in the carapace to accommodate the antennae; articulating rings on the pleomeres; development of prominent epimeres; and orientation of the chelipeds. Rather, E. praecursor must be referred to its own superfamily and family within Infraorder Anomura.

The oldest confirmed brachyurans, referable to the Homolodromioidea and Glaessneropsoidea, are Early to Middle Jurassic in age. Geographically, all of the occurrences are in Europe, with one exception, in Tanzania.

The biochemistry of fatty acids (FA) can be affected by a number of factors, including environmental temperature, which may affect the way FAs are physiologically metabolized. In this study, we investigated FAs in Pachygrapsus crassipes, in relation to environmental temperatures in southern California. Although there was a trend toward differences in FA abundances in the hepatopancreas of females compared with those found in the hepatopancreas of males, these differences were not significant through most of the year. The sampling month influenced changes in the abundances of both individual FAs (identities) and FA saturation categories (saturated  =  SAFA, monounsaturated  =  MUFA, polyunsaturated  =  PUFA). The abundances of palmitoleic acid, palmitic acid, and docosahexaenoic acid were found to fluctuate significantly over time, although this fluctuation did not appear to be directly influenced by temperature since an increase in FA abundance between February and April preceded an increase in temperature. In all months except for June, PUFAs dominated the FA profile. Changes in FAs may be an acclimatory mechanism used by P. crassipes to take advantage of specific biochemical properties of FAs. We conclude that, while temperature may affect FA abundance and composition, other underlying factors, such as changes in day length, food availability, molting, mating and reproduction, may also influence FA abundances in P. crassipes from southern California.

Darwin recognized the coral inhabiting barnacles as congeneric belonging to Pyrgoma. Ross and Newman (1973) assigned those with fused shell and elongated scuta to the genus Savignium. Later those with tooth like articular projection on tergum were assigned to Trevathana dentata. We sequenced and analyzed the divergence of three mithochondrial genes (12S rDNA, 16S rDNA, COI) of Savignium crenatum from two host coral, of Neotrevathana elongata from Echinopra and of T. dentata from five host corals genera, Leptastrea, Platygyra, Favia, Favites, and Cyphastrea. Based on the molecular analysis of these genes we show that members of populations of the nominal species T. dentata occupying different host corals display clear genetic differences, suggesting that the barnacles from these five different coral genera represent five distinct biological species. These species display host specificity at the generic level. Barnacles colleted from the same host genus but different geographical regions, clustered in the same clades. We described morphological characters of the shell, opercular valves, and limb characteristics, trophi and cirri, of barnacles from these host coral. We concluded that the material extracted from Leptastrea conform with Darwin's type and the specific epithet of Trevathana from Leptastrea should continue to be dentata, specimens from the four other host corals are four new species of Trevathana; namely T. mizrachae n. sp. from Platygyra, T. margaretae n. sp. from Favia, T. jensi n. sp. from Favites, and T. sarae n. sp. from Cyphastrea. The morphological data confirm the results of the molecular analysis that species of coral inhabiting barnacles are highly genus-level host-specific.

An analysis of museum specimens reveals that reports of the chelonophilic barnacle Cylindrolepas darwiniana are misidentifications of the similar turtle barnacle Platylepas decorata. As a result, contemporary collections from loggerhead and hawksbill sea turtles represent the first report of this turtle barnacle since its description nearly a century ago. Novel morphological characters that clearly distinguish C. darwiniana from other turtle barnacles have been ascertained from the recent specimens and are reported.

Two species in the new genus Watlingia are described from the Chatham Rise, east of New Zealand, from depths of 350-530 m. The subadult female and male are described and figured for W. cassis, and the subadult female is described and figured for W. chathamensis. The new genus is characterized by the maxillule palp with a single seta, well-developed accessory flagellum of the antennule, and biarticulate uropod endopod.

We report on allozyme and mitochondrial DNA variation in 13 populations of the supralittoral amphipod Orchestia cavimana. The species colonizes fresh and brackish shores of Northern Africa, Near East and throughout Europe. Populations were sampled across a large part of the species range (Cyprus, Turkey, northern and southern Italy, United Kingdom and Germany), including the type locality (Cyprus). Both sets of molecular markers agree in identifying two divergent lineages. A first lineage includes populations from Cyprus and Turkey. A second genetically homogeneous lineage groups Italian, English and German populations. Genetic divergence between the two lineages is high (D_Nei  =  0.720 ± 0.06 for allozymes and K2P  =  0.191 ± 0.001 for mitochondrial DNA) and comparable to that among morphologically distinct congeneric species reported for the same set of molecular markers.

The identification of subterranean species at risk and the development of management strategies face a host of challenges such as inaccessible habitat, a lack of basic ecological information, and, in the case of aquatic species termed stygobionts, groundwater contamination and withdrawal. In light of these challenges, genetic data may inform management and conservation decisions. We present here results from an analysis of population structure of the stygobiont, Antrolana lira, from nine geographic locations spanning two-thirds of the species' entire range in the Shenandoah Valley of Virginia and West Virginia. A 658 bp fragment of DNA coding for the cytochrome oxidase c subunit I (COI) gene was sequenced from 70 individuals, yielding 14 haplotypes. Phylogenetic analysis of the 14 haplotypes showed the presence of three distinct clades which corresponded to three geographic groups. Divergence levels among sequences within sites and among sites within clades was low (uncorrected “p”  =  0.00 to 0.42%), but were much higher among sequences between clades (uncorrected “p”  =  9.53 to 11.24%). AMOVA corroborated these findings, partitioning over 99% of the sequence variation to differences among clades. The genetic structure of A. lira clades seemed to largely mirror the geologic structure of the area, with potential subterranean hydrologic barriers separating the clades. Geographic populations within each clade likely constituted only one or two demes. We suggest that these clades remain at risk from anthropogenic disturbances such as urban development, and propose that each of the clades be considered a distinct management unit in order to preserve the total genetic diversity for the species.

The vigorous burrowing activities of many thalassinidean shrimp have such dramatic effects on their habitats of soft sediment that these animals are often considered ecosystem engineers. Because they strongly interact in these communities, basic information about their life histories and population dynamics is needed to effectively manage the habitats in which they live. These data can only be obtained if the shrimp can be accurately identified. On the west coast of the United States, two species of burrowing intertidal shrimp in the genus Neotrypaea, N. californiensis and N. gigas, often co-occur and are not easily differentiated morphologically except as adult males by characters of the major claw (which is often lost in collection). Here we describe and validate (using mtDNA data from the cytochrome b gene) an allozyme marker (LDH) that can be scored rapidly and inexpensively for the identification of these species. We used this marker to generate a large sample of molecularly-identified specimens that we then used to evaluate a variety of morphological characters in an effort to differentiate the two species. With the exception of characters associated with the male major claw, most of the morphological characters examined here were not useful in distinguishing members of the two species. The exceptions were two simple and robust characters associated with the eyestalks—length, and shape of the distal outer edges. These could be used to reliably differentiate between the two species regardless of sex, and over a wide range of sizes. We hope that these characters will facilitate future studies of the distribution, habitat preference, and comparative biology of these two often co-occurring species.

The karyotype of Atyaephyra desmarestii, the European freshwater shrimp, from Louros River (NW Greece) was studied through the examination of metaphase chromosome spreads from the first zoeal stage larval tissues. A total of 42 mitotic metaphases were examined and the diploid chromosome number was determined to 2n  =  32. The karyotype consisted of 22 metacentric and 10 submetacentric chromosomes. Atyaephyra desmarestii karyotype is reported here for the first time providing a basis for further cytogenetic comparative study of the species populations.

In this study we determined the rate of growth of juvenile Florida stone crabs (Menippe mercenaria Say, 1818) reared in the laboratory. We monitored carapace width and intermolt duration through the first 12 juvenile molts. Because all experimental crabs had been reared from eggs in the laboratory, we knew the exact age and molt dates for each individual. Mean carapace width of 1st stage juveniles was 2.0 ± 0.2 mm. Juveniles reached the 13th juvenile stage (15.9 ± 2.1 mm) in a mean of 297.6 ± 32.7 d. The rate of growth in carapace width fit a linear model and was similar in pattern to that reported for juveniles of other brachyuran species.