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A new barnacle species, Chthamalus neglectusYan and Chan, 2004, was described from Hong Kong. It belongs to the “challengeri” group of Chthamalidae. The larvae of Chthamalus neglectus differ from C. challengeri, C. antennatus, C. montagui, and C. dalli (challengeri group) in the teeth of the labrum, shape of cephalic shield, setation formula, and cephalic shield sculpturing under both light and scanning electron microscopes. This further confirms it is a new Chthamalus species.
This study refers to the ecology of Lamproglena clariae. Specimens were collected from the Vaal Dam and Vaal River Barrage in the Gauteng Province, South Africa, for a two-year period. Data were analysed statistically. There was a positive correlation between the host's physical dimensions and the size of the parasite. Larger fish had larger parasites than smaller ones. Parasites from both sites preferred the fourth gill and the median part of the gill arch for attachment. There was no significant host gender preference by parasites. A similar seasonal pattern was observed in the prevalence, abundance, and mean intensity at both localities. This study shows that some aspects of the ecology of the parasite are influenced by the host to which it attaches. Its attachment-site preference was also determined by the position of the gill on the gill chamber. The parasite abundance and prevalence were neither dependent on the size of the host nor influenced by the water quality.
Based on a comparison of the internal musculature of the fifth and sixth limbs of the cypridinid ostracode Isocypridina quatuorsetae, it is tentatively concluded that the sixth limbs of members of the Cypridinidae are biramous, each bearing an exopod represented by a cluster of small bristles (setae) and an endopod with two podomeres. The protopod contains a coxa with two endites and a basis with one endite.
We used DNA sequences from 18S rDNA (808 bp) and COI mtDNA (599 bp) to infer evolutionary history of northern groups of the deep-sea mysid genus Pseudomma. The V4–V7 regions of 18S show an average of 1.31% sequence divergence between species. A secondary structure model is constructed and used in phylogenetic analyses to allow for different evolutionary rates in paired and unpaired nucleotide partitions. COI is observed as highly variable with uncorrected p-distance averaging 33%. Phylogenies for these sequences were estimated by maximum-likelihood, Bayesian, and maximum-parsimony analyses. More or less similar tree topologies were obtained for each gene with these methods. Pseudomma longisquamosum was placed in a basal clade, using Parapseudomma and Amblyops as outgroups, but the exact relationship of other basal taxa is less clear when results from the two genes are compared. An ancient presence of Pseudomma in the Tethys Sea is suggested by phylogenetic structure, molecular clock considerations, and present distributions. A well-supported Atlantic clade may have diverged from Indo-Pacific groups in the Miocene because of the closure of the Gibraltar Strait. More recent speciation events are proposed in the Norwegian Sea, and an Arctic intrusion from the North Pacific across the Bering Strait is suggested for the circumpolar species Pseudomma truncatum.
The distribution and population structure of the neustonic isopod Idotea metallica were studied from samples collected on two consecutive plankton cruises performed in spring off the Catalan coast (western Mediterranean). On both cruises, high densities were observed along the oceanic side of the shelf-seas front, generally with lower numbers on each side of the front. High densities of the isopod were associated with samples with high quantities of flotsam. Size-frequency distributions were dominated by juvenile individuals, and no significant differences were found in size structure between the population on the oceanic side of the front and that on the coastal side. Temporal variability in the observed distribution patterns is attributed to the mesoscale variations in the inshore-offshore position of the shelf-slope front, which appears to act as a semipermeable barrier concentrating I. metallica, associated with other oceanic neustonic organisms, on its oceanic side.
A new genus, Pseudohalmyrapseudes, and species, P. aquadulcis, of apseudomorphan tanaidacean from a freshwater spring in the Northern Territory, Australia, is described and illustrated. The new genus is placed in the family Parapseudidae and is closely related to Halmyrapseudes but differs by possessing: 1) a four- or five-articulated inner antennular flagellum; 2) a male cheliped lacking carpal lobes and with a defined tooth on the dactylus; 3) setae on the dorsal margins of the basis of the pereopods 2–4; 4) the ventral margin of merus and carpus of pereopod 6 bearing simple setae. Pseudohalmyrapseudes is suggested to occupy a phylogenetic position between Halmyrapseudes and Longiflagrum. Apseudes mussauensis conforms to the diagnosis of Pseudohalmyrapseudes and is transferred to this genus.
The complete larval development of Crangon uritai Hayashi and Kim is described from laboratory-reared material. This species has five zoeal stages and one postlarva. Detailed morphological descriptions and illustrations of each stage are provided. The larvae of C. uritai present two remarkable differences compared with those of other congeneric species, C. affinis and C. hakodatei: the number of zoeal stages, and in possessing one submarginal seta of antennal scale in zoeal stages. One outstanding simple seta on the rostrum is the only remarkable difference in the postlarval stage.
Embryos and larvae of the european lobster H. gammarus, reared under laboratory conditions, were investigated in order to determine the nature and metabolism of carotenoproteins during embryogenesis. Extracts of embryonic as well as larval stages were analysed, using DEAE-Cellulose filtration, electrophoresis, and thin layer chromatography. Ovoverdin is the main carotenoprotein of the yolk; two fractions, having different molecular weight (No1: 700 kDa and No2: 600 kDa) were observed. Larval extracts were found to contain three coloured carotenoproteins: blue (Lm1a), red (Lm1b), and yellow (Lm1c). Yolk carotenoids were identified as free astaxanthin and unesterified phoenicoxanthin, whereas esterified astaxanthin was found to occur in the forming tissues. Astaxanthin diester is the main carotenoid of the embryo; in larval tissues, this carotenoid is associated to the red carotenoprotein. The increase in esterified astaxanthin suggests enzymatic mechanisms leading to acylation reactions occurring at an early stage of embryonic development.
The distribution of the rusty crayfish, Orconectes rusticus, has been purported to include large portions of Iowa and Minnesota among many other states, whereas the golden crayfish, O. luteus, has been reported from Kansas, Arkansas, Missouri, and Illinois. Recent collections made in several river basins in Iowa and southern Minnesota and examination of museum specimens collected in Iowa revealed that many records attributed to O. rusticus are in fact O. luteus. We provide a suite of quantitative and qualitative characteristics, both morphological and genetic, that distinguish O. luteus and O. rusticus and also demonstrate that female O. luteus exhibit form alternation. Comparisons of mitochondrial 16S rRNA haplotypes among populations of O. luteus, O. rusticus, O. cf. rusticus, O. placidus, and O. virilis revealed relatively high levels of sequence divergence among taxa as well as within some taxa. We conclude that O. luteus is a native species in Iowa and southern Minnesota with introduced populations of O. rusticus occurring in both states. A more thorough survey of these states, particularly Iowa, is needed to assess the distributions of O. rusticus and O. luteus. If O. rusticus has a relatively restricted distribution in Iowa, efforts to control its anthropogenic and natural dispersal may be more effective if implemented in the near future. Our study indicates the need for more research in taxonomy, even in regions where the fauna is thought to be known well, in order for the conservation of native species and detection and management of nonindigenous species to be successful.
The relationships between mean intensity and prevalence of infestation of Pseudione humboldtensis and the size and sex of the hosts, the squat lobsters Cervimunidia johni and Pleuroncodes monodon, from three fishing grounds in northern Chile are described. The prevalences were 13.6% and 6.8% for C. johni in Coquimbo and Huasco, respectively, while in P. monodon they were 18.2% and 0.6% in Coquimbo and Caldera, respectively. Between fishing grounds, no significant differences were found in the prevalence of infestation between male and female C. johni, but in Coquimbo, the prevalence of infestation in P. monodon was significantly higher in females. The sizes of infested squat lobsters were significantly lower than those of uninfested hosts. Males and females parasitized by P. monodon showed significantly lower body weights than uninfested hosts. Parasitized males of C. johni showed lower body weight than uninfested males. Only 0.6% of ovigerous females of C. johni and none of P. monodon were infested. The near absence of infested ovigerous females suggests castration process in females. A nonlinear relationship was detected between host size and parasite size for both females and males. Multiple infestations of P. humboldtensis were found in both host species, but they were more common in P. monodon. Given the high prevalence of multiple infestations (50%) and the significantly lower body weights of infested P. monodon, we suggest that this host is more vulnerable to P. humboldtensis than is C. johni.
Hermit crabs were collected over 13 years from different habitats in the coastal lagoons of Términos, Alvarado, Tamiahua, and Madre in the southwestern Gulf of Mexico. The distribution, habitat, relative abundance, shield-length data, and zoogeographical affinities of each of the ten species are presented. A zoogeographical analysis assigned the species to four distribution patterns: Eurytopic (Clibanarius vittatus, Petrochirus diogenes, Paguristes tortugae, Pagurus criniticornis); Endemic to the Gulf of Mexico (Paguristes hernancortezi); Warm-Temperate Caribbean (P. hummi, Pagurus maclaughlinae); and Warm-Temperate (P. annulipes, P. longicarpus, P. pollicaris). Five species extend their previously recorded distribution southward, and eight species are now recorded further south within the Gulf of Mexico.
Ovigerous crabs of the xanthid Palapedia integra were collected in South Korean waters, and their larvae were reared in the laboratory. Four zoeal stages are described and illustrated. The durations of zoeal stages I–IV were 4, 4, 4, and 6 days, respectively. Morphological characteristics of the first zoeal stage are compared with those of Palapedia valentini in the Kraussiinae and to other brachyuran species. The first zoea of P. integra is significantly different from that of P. valentini in having 3 4 setae on the endopod of the maxilla. Based on zoeal morphology, it is suggested that P. integra may not belong in the genus Palapedia.
A greater understanding of population dynamics is essential in the management of any species. The Western Gulf stone crab, Menippe adina, is taken as incidental by-catch in the blue crab, Callinectes sapidus, fishery in Mississippi. However, there is a lack of information on the ecology of M. adina in estuaries of the northern Gulf of Mexico. We know that M. adina is associated with hard-bottom habitats such as rock-rubble jetties and oyster reefs and that this habitat is sparse in Mississippi Sound, which mainly consists of soft-bottom habitat. Many studies have demonstrated that habitat complexity is important to several benthic crustaceans because it provides a matrix of different sized refuges that organisms can use to escape from predation. The importance and availability of refugia varies throughout the life history of organisms because of the increase in size of an organism as it grows. Refuge limitation acting on a specific size class may create a demographic bottleneck thereby limiting the production of a population through mortality, migration, or stunting of the affected size class. We tested this refuge limitation bottleneck hypothesis in juvenile stone crabs by supplementing an existing oyster reef with four different sizes of polyvinyl chloride (PVC) pipe. We found that lack of refuge affected both population size structure and density of large juvenile stone crabs on the reef. We also found that competition for available refuges may occur among M. adina and two other xanthid crab species, Eurypanopeus depressus and Panopeus simpsoni. We examined the diet of oyster toadfish, Opsanus beta, in Mississippi Sound and found that the three xanthid crabs comprised a significantly large portion of oyster toadfish diet. Predation by O. beta emphasized the importance of the availability of suitable refugia for the xanthids.
The complete embryonic development of the mangrove crabs Goniopsis pulchra and Aratus pisonii is described based on morphological features observable in live eggs. Periods of development are defined in steps of 48 hours each and in relation to the time of embryonic development. Eight periods were described and illustrated for Aratus pisonii and nine for Goniopsis pulchra. Embryo development from recently spawned eggs to hatching lasted 14 days for Aratus pisonii and 15 for Goniopsis pulchra at 26–28°C. The embryonic development of the two species was very similar; growth was synchronous, appendages were formed during the same periods, complexity of abdominal and ocular processes were chronologically comparable. Goniopsis pulchra eggs were slightly larger, while in Aratus pisonii the digestive gland was easier to observe in later periods and the telson grew larger. Cromatophores were more evident in Aratus pisonii embryos, especially those of the telson.
During the mating season, males of the fiddler crab Uca lactea build semidomes of mud at the entrances of their burrows to which they attract females for mating in the upper intertidal zone. Related species build similar structures which either reduce aggression between neighboring males or attract sexually receptive females. Male U. lactea did not build disproportionately more semidomes as density increased, suggesting that these structures do not modulate aggression. Larger males built higher and wider semidomes as would be expected if the semidomes are a courtship signal. When the high tides were too low to cover their habitat and the sediment dried, males were unable to build new or repair existing semidomes. Towards the end of the mating season more small males built semidomes perhaps because large males prevented them from courting earlier when most females mated. We made two experimental enclosures, added males to one and males and females to the other, and monitored semidome building. Males built significantly more semidomes in the enclosure with females. Overall, our observations support the hypothesis that the semidomes of U. lactea are a sexual signal.