Aspects of the evolution of the branchiopod crustaceans are reviewed and discussed. Despite views to the contrary presented in recent textbooks, the monophyly of Branchiopoda is defended based on morphological characters. The crown group Branchiopoda is supported/diagnosed by a set of synapomorphies relating to limb morphology of both larvae and adults, including, among others, a similar naupliar swimming/feeding apparatus, a similar development of trunk limbs, and a similar morphology of adult trunk limbs with six endites (number reduced later) and an unsegmented endopod. Phyllopodous limbs are among the most well-known features of Branchiopoda, but it is uncertain whether the phyllopodous nature of the limbs in itself can be considered a synapomorphy for this group, because the limbs of other crustaceans, both recent and fossil, also can be characterised as at least partly phyllopodous. Homologies of branchiopod trunk limbs to those of other crustaceans are discussed; based on similarities to trunk limbs of certain ‘Orsten’ fossils, it is concluded that the large, undifferentiated ‘corm’ of the limb most likely is an enlarged basis. Within Branchiopoda, strong evidence for a monophyletic Phyllopoda sensu Preuss (all branchiopods except anostracans) is presented. A monophyletic Diplostraca is also preferred based on morphological information, and the supporting characters for this group are listed. A remarkable branchiopod crustacean from the Devonian has recently been described with morphological features combining those of Notostraca and ‘Conchostraca’; it has major significance for the understanding of early branchiopod evolution. The question of a marine versus freshwater origin of Branchiopoda is discussed.

The production of new articles in the flagellum of the second antennae of Asellus aquaticus was studied in both undamaged and regenerating antennae. Segmentation is an iterative process in two phases: 1) the first proximal flagellomere (the meristematic article) repeatedly gives off distally a new primary article; 2) each primary article divides into four secondary articles (a quartet). To a certain extent, production and development of different quartets are independent processes. Evidence is provided that the formation of new articles and their setae are partly decoupled. During regeneration from the preferred breakage point (the so-called ‘autotomy plane’), the flagellum is generated by the same mechanism of two-phase segmentation. The regenerated flagellum has a normal segmental composition, except for the tip (the apical complex), which has four flagellomeres rather than the normal five. The similar segmental pattern observed also in other malacostracan crustaceans and in insects, supports a close phylogenetic relationship among the two groups; if the latter proves not to hold, that similarity would provide an example of parallel evolution of developmental mechanism. The difference between ‘true’ articles and annulations, defined on the structure of the muscular system, is discussed on the basis of comparative developmental data. In general, annulations are produced more sequentially, compared with the almost simultaneous emergence of true articles.

The role of cheliped autotomy in the territorial behavior of the freshwater prawn Macrobrachium lar was analyzed to determine whether or not prawns modified their defended territory size based on cheliped autotomy. Territory size measurements were recorded for captive prawns interacting in artificial tank habitats and were logged according to the locations where agonistic encounters occurred and aggressive pressures were equal. All prawns used in this study were mid-intermolt males in the size class 9.0 ± 1.5 cm, with staged encounters occurring under three treatment conditions in which fully intact prawns were matched against animals possessing no chelipeds, one cheliped, or two chelipeds (fully intact). Separate experiments for each condition were completed with four prawns per tank per 14-day trial and were run a total of three times each. The defended territory size mean for the Control prawns (matched only against other intact animals) did not differ significantly from one quarter of the total tank area. The mean territory sizes for prawns within or between each treatment condition was significantly different. Prawns with one or two chelipeds autotomized each defended significantly smaller territories than other male prawns of equal size, but with both chelipeds intact. Our results show that the presence of chelipeds allowed the defense of larger territories compared with the territories defended by prawns with one or both chelipeds autotomized.

Many cave species exhibit k-selected life history characteristics, i.e., long life span, slow growth, and low reproductive effort, which can reduce their ability to survive rapid changes in environmental conditions and their potential for recovery from events that reduce their densities. In this study, we examined aspects of the life history, growth rate, and reproductive timing of the U.S. federally listed Illinois cave amphipod, Gammarus acherondytes, to assess its potential for recovery. Sampling between October 2003 to March 2005 with non-lethal techniques in Reverse Stream Cave, Illinois, U.S.A. showed that pre-juveniles and juveniles generally constituted > 50% of the population and thus strongly influenced fluctuations in population density. Except in September 2004, ovigerous females were collected every month, indicating that reproduction occurred year-round. Distinct peaks of pre-juveniles were observed from February to May and August to October. The seasonal recruitment of young appeared to be correlated with incubation time and flood events. Because it was difficult to track individual cohorts, the exact time to maturity or the life span could not be determined empirically. However, the minimum time to maturity was estimated at 14 to 16 months using a modeled growth curve. Our results suggest that G. acherondytes should recovery rapidly from perturbations if left undisturbed. A management strategy to aid recovery could be to reduce cave visitation during the major phases of recruitment. Additionally, our results indicate that establishing a laboratory population for use in future studies or to propagate individuals for reintroduction should require only one-and-a-half to two years. Our study shows how basic life history information obtained via non-lethal sampling can provide managers with vital information to develop conservation strategies for endangered species.

This paper describes the life cycle of the amphipod Jassa marmorata with data recorded over two years (from May 2002 to April 2004) in the Marine Protected Area of Portofino (Ligurian Sea, Italy). The population was sampled monthly at 5 m depth on artificial substrata. For each sample, the number of males, females, ovigerous females, and juveniles was recorded and related to water temperature. Two kinds of males, minor and major, were found, distinguishable by the presence of a thumb on the second gnathopod. The sex-ratio was significantly biased towards females (F:M = 5.6:1). The cycle revealed a female increase in mean body size during the cold season (late winter and early spring). This resulted in a peak in recruitment during the spring; females are fertile all through the year, but egg production is positively correlated with female size. During the summer of 2003, an anomalous increase in sea-water temperature was recorded. In this period the population completely disappeared, but the density during the next winter recovered again to usual values.

We investigated the value of microsatellite DNA markers to improve our knowledge of mating strategy with inference to sperm competition in particular, in the woodlouse Armadillidium vulgare. In terrestrial isopods, mature females develop a brood pouch or marsupium before egg laying, the pouch being formed by overlapping oöstegites during a special moult called parturial moult. Under laboratory conditions, we show that Armadillidium vulgare females are able to mate during parturial intermoults, even in the presence of a physical barrier such as that represented by the ventral marsupial plates. Our results reveal that the contribution of a second male mating with a female between two parturial moults could represent up to 50% of the paternal alleles in the brood (mean = 28% ± 15). This contrasts with data reported in the literature concerning closely related woodlice species, where males are suggested not to be able to mate with the female during the parturial intermoult period.

This study is intended to characterize the ovarian development and hemolymph vertebrate-type steroids concentration during the reproductive cycle of the freshwater prawn, Macrobrachium rosenbergii. A five-stage classification based on the external observation of the ovary's size and color as seen through the tegument was used. The results showed the existence of a direct correspondence between the ovarian stages and the gonadosomatic index, the oöcyte diameter, and the characteristics of ovarian histology. In each stage total bleeding of the prawns was conducted and the hemolymph concentrations of 17β-estradiol (E₂), testosterone (T) and 17α-hydroxyprogesterone (17-OHP; conjugated and unconjugated) were determined by solid-phase radioimmunoassay (RIA). High levels of unconjugated 17-OHP, relatively constant concentrations of unconjugated T, and null concentration of unconjugated E₂ were found throughout the five stages considered. Nonetheless, low levels of E₂ were determined in all stages, in conjugated (glucoronide) form. The highest levels were obtained in stage II and III (18.14 ± 14.52 pg/ml hemolymph) and progressively declined in the other stages (7.53 ± 6.76 pg/ml hemolymph). These results point out the possible involvement of vertebrate-type steroids in the endocrine regulation of the Macrobrachium rosenbergii's ovarian cycle. To our knowledge this is the first study concerning the vertebrate-like steroid levels throughout the ovarian cycle and is a step needed to characterize the hemolymph profile of these steroids in order to elucidate the possible role in the regulation of the reproductive crustacean cycle.

Rudolph and Crandall (2005) found a high percentage (81.3%) of intersex specimens with supernumerary gonopores in the Virilastacus rucapihuelensis type series. To determine the sexual system of this species, the sexual characters of 734 specimens collected from 5 populations of V. rucapihuelensis were examined. Six sexual forms were initially identified, on the basis of the presence or absence of gonopores in the coxae of the third and fifth pair of pereiopods. Subsequently, anatomical and histological analysis of gonads, gonoducts and androgenic gland, made it possible to distinguish three basic sexual types: male, female and intersex specimens; the latter comprise a male phase and two forms in female phase, which would originate from male phase intersexes. Ovigerous females and secondary sexual characters associated with eggs incubation were identified in adult females and in the intersexes in female phase. Evidence gathered suggests that V. rucapihuelensis is a partial protandric hermaphrodite species, with primary males and females. The possible neurohormonal mechanisms responsible for this type of sexual system are discussed, as are the external factors that could have a modifying effect on them.

Habitat selection by small (≤ 15.0 mm carapace length (CL)) and large (> 15.0 mm CL) individuals of the crayfish, Orconectes marchandi, O. ozarkae, O. punctimanus, and Cambarus hubbsi was examined at 4 sites in 2 streams in the Spring River watershed. Replicate quadrat samples were collected from riffle, run, pool, emergent vegetation, stream margin, and backwater habitats during the summers of 1998 and 1999. A 3-factor ANOVA was used to determine effects of habitat, species, and year on crayfish density for each site and stream. Habitat selection by crayfish was determined by comparing habitat used to habitat available for each species and size class. There were significant temporal differences in habitat used by some species-size classes of crayfish, but significant species by habitat interactions were detected at all sites for both crayfish size classes. Small O. ozarkae and O. punctimanus used mainly vegetated habitat, whereas both size classes of C. hubbsi used mainly riffles and runs. Large individuals of Orconectes spp. and small O. marchandi were more broadly distributed across pools, backwaters, stream margins, and vegetated habitats. Selection indices showed that individuals of all small Orconectes species and large O. ozarkae and O. punctimanus strongly selected vegetated, backwater and stream margin habitats at all sites and times on both streams, even though these habitat types comprised only ∼15% of the available habitat. Both size classes of C. hubbsi selected mainly riffle habitats. Redundancy analyses showed a significant positive relationship between crayfish densities and percent emergent vegetation and a negative relationship with current velocity and depth. Backwater, stream margin, and vegetated habitats can contain extremely high densities of crayfish and may act as important habitats, especially for Orconectes species.

Growth at moult (for both the prepubertal and terminal moults), and moulting seasonality in the spider crab Maja brachydactyla in the Ría de A Coruña (NW Spain) was quantified within a mark-recapture experiment. Crabs 70-130 mm carapace length (CL) underwent a mean increase at moult of 32.4% from their pre-moult size, with no significant differences between sexes or moult types. Generalised Linear Models (GLMs) were used to construct growth models, employing a combination of information from the mark-recapture study and previous studies performed in laboratory and extensive culture to characterize driving factors. The first model revealed that study method growth did not differ between males and females. However, the effects of the study method (mark-recapture, laboratory, and extensive culture), the pre-moult CL and the interaction between them were significant. The smallest-sized crabs underwent a greater increase in size in the laboratory and culture studies, while the largest individuals underwent greater growth in the field. In the second model, the significant effects were pre-moult CL, moult type, and the interaction between the two variables, indicating that larger crabs showed higher growth rates in prepubertal moults. Mean intermoult period estimated for prepubertal moults in the field ranged 50-86 days, which was slightly lower than the 84.7 days observed in the laboratory. Prepubertal moults occurred primarily in spring and autumn in the field, while under culture conditions, the crabs moulted mainly in the spring. The intermoult period for terminal moults was estimated to be 90 days, slightly lower than the 104 days from the laboratory. The terminal moult took place generally in summer (June-September) both at sea as well as in culture. The intermoult period of juveniles at sea was highly variable, and some of the specimens did not moult for more than 5 months.

The land crab Johngarthia planatus is an eastern tropical Pacific species with a known distribution from Mexico to Colombia. Complete larval development of the species is fully described and illustrated from laboratory-reared material. The five zoeal stages and the megalopa are compared with those of Gecarcinus lateralis lateralis from the Atlantic coast. Main differences for zoeal stages are observed in the carapace and telson lateral spines while minor differences are observed in the mouthparts setation. For the megalopa stage a difference in size of the third maxilliped exopod supports the separation of Johngarthia from Gecarcinus. A brief comparison of all known zoea I and megalopa stages of species of the Gecarcinidae is made, taking into account recent new descriptions.

The brachyuran genus Titanocarcinus A. Milne-Edwards, 1864, is rediagnosed and restricted to six species. It is referred to the Tumidocarcinidae Schweitzer, 2005, based upon characters of the sternum, male pleon, and dorsal carapace, along with the closely related Lobonotus A. Milne-Edwards, 1864. Several species that had been referred to Titanocarcinus are herein referred to other genera, including two new ones, Nitotacarcinus and Lathahypossia, or to other families in indeterminate genera. One new species is described from the lowermost Eocene of Spain, Titanocarcinus decor. Titanocarcinus as currently defined ranged from the Cretaceous to Eocene in northern and central Europe. Lobonotus is known only from the Eocene of North and Central America.

This study focuses on the ovarian maturation stages in Farfantepenaeus paulensis, which are reported for each stage with histologic, stereological, and morphometric analyses, as well as the specific female protein profile. Unilateral eyestalk-ablated females were dissected and the middle lobes of each ovary were rinsed in cold 100 mM phosphate buffered saline containing 0.001 PMSF, for light microscopic and biochemical analyses. Fragments of ovary were fixed in Bouin's solution, cut into 7 μm sections and stained for morphometric and stereological analyses. Immunohistochemistry was used for the detection of vitellin immunoreactivity. The ovarian protein profile was determined using ELISA, SDS-PAGE and Western blot assays. Five ovarian maturation stages were classified by histological analysis: immature, early maturing, late maturing, mature, and spent. Germ cell diameter varied from 48 μm (± 8) for oögonia in the immature stage to 224 μm (± 43) for vitellogenic oöcytes in the mature stage. Protein profiles in ovarian stages showed the presence of seven bands and in Western blot analysis two bands immunoreactive to vitellin antiserum were detected with molecular weights of 105 kDa and 75 kDa. In the ELISA assay vitellin was detected in the five maturation stages and a gradual increase of this protein was observed from the immature stage to mature stages.

Premolt and vitellogenesis are mutually exclusive events in the wild population of the brachyuran crab, Metopograpsus messor; active vitellogenesis occurs only in intermolt females, at a relatively low ecdysteroid profile, judged from radioimmunoassay. Bilateral eyestalk ablation, however, has resulted in simultaneous precipitation of premolt and ovarian growth in the same crab, thus severing the normal antagonistic programming of these two high-energy demanding processes. This result argues for the necessity of eyestalk principles in maintaining the normal (antagonistic) programming of growth and reproduction in the species. Ovaries of the eyestalk ablated crabs precociously accumulate yolk and the oöcytes could attain the size of a fully grown egg within 10 days post-ablation. The eyestalk ablated females have also shown dramatic rise in haemolymph ecdysteroid levels, even surpassing the levels (P < 0.05) of the normal premolt individuals, revealing that ovarian growth can occur under a high ecdysteroid titre in M. messor. It remains to be seen whether the precociously grown ovaries were influenced by the elevated ecdysteroid titer.

A new genus and species of Laophontidae, Spiniferaphonte ornata n. gen., n. sp., is described from the coast of Kenya. The new genus is closely related to Laophontina and Wellsiphontina as shown by the following synapomorphies: a denticulate operculum, a sexually dimorphic P4 exopod (reduced chaetotaxy of the ultimate segment in the male), and the absence of sexual dimorphism in the P2 and P3 endopods. The two-segmented exopod of P1 and the presence of a seta on the endopodal part of the male P5 are plesiomorphies indicating that the new genus represents a separate lineage within this group. The proposal of the new genus Spiniferaphonte is supported by the following autapomorphies: three smooth setae on the female P5 exopod and a robust, dorsally bent, and strongly sclerotised caudal seta V. Within the Laophontidae, it is striking that the presence of distinct, thorn-like processes on the caudal rami is limited to interstitial genera. Distinct processes on the proximal segments of the antennule and a proximally thickened caudal seta V also appear to be associated with this interstitiality. These structures may play a role in the movement and the anchoring of the animals in their interstitial habitat.

Two species of the poecilostomatoid copepods, Allopodion ryukyuensis n. sp. and Xenomolgus varius Humes and Stock, are recorded from galls and crypts on the scleractinian corals Montipora informis and Porites sp.(p), respectively, in Okinawa, Japan. Allopodion ryukyuensis is distinguished from its sole congener, A. mirum Humes, by having shorter caudal rami and abdominal somites, rounded lateral margins of the female genital double-somite, and a greater number of setal elements on the third exopodal segment of legs 2-4. The morphological features of the galls and crypts on the scleractinian hosts inhabited by A. ryukyuensis and X. varius are described, and it is proposed that certain other scleractinian-associated copepods likely also make use of similar habitations.

This paper deals primarily with a full redescription of the mature female of Ascidicola rosea Thorell, 1859, and a young female is described mainly in regard to the urosome. The two species of solitary ascidians containing this copepod, which lacks an eye, were collected at different localities: Microcosmus sabatieri Roule at Banyuls-sur-Mer, and Ascidia mentula Müller at Strangford Lough. Many systematists have studied this long-known, elongated, pinkish copepod (Ascidicolidae: Ascidicolinae). However, the major articulation between the metasome and urosome has been interpreted differently by authors, and morphological details have not always been consistently described. The intent of the present paper is to resolve such problems. It shows that the ventral transverse spinose pad posterior to the penultimate (second abdominal) segment of the urosome of the mature female is homologous to much of the ventral part of the penultimate (third abdominal) segment of the urosome of the young female.

The calanoid copepod family Ridgewayiidae, containing demersal and cave-dwelling forms, has representatives worldwide, but most have been known from the Northwestern Tropical Atlantic. Eight valid genera were hitherto known, most of them were described recently (Ridgewayia Thompson and Scott, Exumella Fosshagen, Brattstromia Fosshagen and Iliffe, Placocalanus Ohtsuka, Fosshagen and Soh, Exumellina Fosshagen and Iliffe, Normancavia Fosshagen and Iliffe, Robpalmeria Fosshagen and Iliffe, Stargatia Fosshagen and Iliffe). Biological collections in cave environments in an island off the Caribbean coastline of Honduras, Central America, showed the presence of ridgewayiid copepods. These specimens were found to belong to an undescribed genus of the family. The new genus Hondurella is distinguished from the other eight known ridgewayiid genera by a combination of characters that include a simple rostrum with no filaments, maxilliped with modified setae, first leg with a modified exopod and a reduced endopodal armature, and most importantly, a female fifth leg with a slightly modified exopod and a 1-segmented endopod, plus a reduced right exopod of the male fifth leg, and the presence of spines on the middle segments of the male right antennule. As all other ridgewayiids, the new genus retains several plesiomorphic characters, thus confirming the primitive profile of this family. The distribution of Ridgewayiidae in the Caribbean region remains largely unknown, but it is suggested that distributional patterns and a relatively high degree of endemism are related to the geological origin and dynamics of the area. Aside the modified maxillipedal setae, mouthparts in the new genus,are normally developed; this, together with our observations of the gut contents, suggest that this ridgewayiid is more a particle-feeder than a carnivorous form.

Freshwater decapods like the palaemonid river shrimp have received little attention in the Baja California Peninsula, México. From the first formal report in 1878 to now, only three Macrobrachium species have been reported (M. americanum, M. digueti, and M. tenellum) from the peninsula in only three basins. We made a taxonomic study of freshwater shrimp, which included an extensive field survey at 81 sites distributed on both the Pacific and the Gulf of California slopes and a revision of material from the area that had been deposited in scientific collections. We report six species of Macrobrachium by adding M. hobbsi, M. michoacanus, and M. olfersii. We also discuss some aspects of the diversity and conservation of these species in the peninsula and provide an identification key for the Macrobrachium shrimp of northwestern México.

A new genus and species Bathione magnafolia of bopyrid infesting the deep-water galatheid crab Munidopsis depressa is described on the basis of material collected in the southern Gulf of California, in depths between 835 and 870 m and extreme hypoxic conditions (0.007 and 0.29 ml O₂/L). Females and males of the new species were compared with females and males of 21 closely related pseudionine genera. Infestation rates by these bopyrids of M. depressa were estimated from 1.2% to 2.5%. Pseudione humboldtensis Pardo, Guisado & Acuña, 1998, shares many characters with the new species and is transferred to the new genus.

The elevation of the six subgenera of Penaeus s. lat. to generic level has proven controversial, some accepted the change while others rejected it out of hand. Such a taxonomic reassignment lends itself to testing by the use of molecular techniques. Data are available from studies of cytochrome oxidase subunit I, and 12S and 16S rRNA. However, analyses of these data sets alone, or in combinations, still have not provided a useable taxonomy of Penaeus s. lat. Ideally we should have a taxonomy where both the morphological and molecular data are in agreement. This is especially critical because of the economic importance of penaeid fisheries around the world. Solving many of these taxonomic problems may await the development of new techniques, but in the meantime specific issues using existing data or techniques should be explored. 1) How widely separated molecularly are Farfantepenaeus and Melicertus? since if these two subgenera are indeed close perhaps they should merge into a single genus Melicertus that contains all the grooved shrimp. 2) Penaeus monodon is usually regarded as being closest to the ancestral line; its affinities to other Penaeus s.str. and to Fenneropenaeus, need further research.