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The female of Haplostoma banyulensis (Brément, 1909) is redescribed on the basis of specimens parasitizing the compound ascidian Trididemnum tenerum (Verrill) at Strangford Lough, Northern Ireland. It is shown to have a mandible, which was not reported in the original description or in succeeding studies. This species can be distinguished from its 10 congeners of subgroup 1 of Haplostoma by the following characteristics: labrum with six distinct processes subequally spaced; legs 1–4 exopods with armature formula 5,4,5,5; leg 4 with longest exopod; copulatory organs including two copulatory pores and two seminal receptacles; and subcylindrical caudal ramus with three spinal elements on terminal margin.
The female of an ascidicolous copepod, Haplostoma eruca (Norman, 1869), is redescribed on the basis of specimens living in the intestine of Ciona intestinalis (Linnaeus) from the Clyde Estuary, Scotland. The redescription resolves some taxonomic problems involving H. eruca in the original and succeeding works. Detailed morphological features of H. eruca reported in this paper make it easy to distinguish this species from its 10 congeners of subgroup 1 of Haplostoma. The following features are thought to be species-specific: rostrum with two small ventral tubercles in addition to hairlike sensilla; antennule with conspicuously truncated distal margin; integument around single copulatory pore with many minute tubercle-like elements; and conical caudal ramus with two unequal armature elements on medial margin near apex.
Both sexes of a new genus and species, Lobopleura ambiducti (Copepoda, Harpacticoida), are described from a sandy beach on the Isle of Iona, Scotland. Within the family Ancorabolidae, the new genus is characterised by the following autapomorphies: paired genital system in both sexes; male P3 endopod-2 not secondarily subdivided; P4 endopod with only one apical seta and P5 baseoendopodal armature reduced to one vestigial seta. Lobopleura ambiducti is unique within the subfamily Laophontodinae in exhibiting the most plesiomorphic armature pattern on P1 endopod-2. Aspects of pre-copulatory mate guarding behaviour are discussed. Despite the absence of type material for direct comparison, Laophontodes expansusSars, 1908, is transferred to Lobopleura based on the following combination of characters: dorsoventrally depressed body shape; somites with laterally produced lobate processes; wide bell-shaped cephalothorax; rostral shape and detailed morphology of antennule, antenna, mouthparts and first to fifth thoracopods. Material previously identified as Laophontodes sp. from County Dublin, Ireland, and Laophontodes expansus from Gullmarfjord, Sweden, proved upon re-examination to be conspecific with L. ambiducti, new genus, new species. An updated generic diagnosis is provided for ProbosciphontodesFiers, 1988, resulting from the re-examination of type material of Probosciphontes stellataFiers, 1988, and P. ptenoposticaFiers, 1988. The presence of a minute antennary exopod bearing a single (reduced) seta is confirmed in all material of Lobopleura and Probosciphontodes examined. The strong support for a sistergroup relationship between Lobopleura and Probosciphontodes is discussed.
Re-examination of the type material of Ismardis spartacus Leigh-Sharpe, 1936 (Copepoda, Harpacticoida), discovered in the gonad and mantle cavity of Patella caerulea L. (Mollusca), revealed that the species should be allocated to the genus Harpacticus Milne-Edwards, 1840, and not to the Thalestridae as previously suggested. The genus Ismardis and the family Ismardiidae are relegated to junior synonyms of Harpacticus and Harpacticidae, respectively. Harpacticus spartacus, new combination, is conspecific with the “schwächeren” form of the Mediterranean H. nicaeensisClaus, 1866. The taxonomic confusion surrounding H. gracilisClaus, 1866 is reviewed, and the species is regarded as unrecognizable, rendering all subsequent records unconfirmed, doubtful, or erroneous. At least some material previously identified with this species proved to be conspecific with H. longiantennataApostolov and Petkovski, 1980 (Banyuls-sur-Mer) or based on an amalgamate of H. obscurus T. Scott, 1895, and H. giesbrechtiKlie, 1927 (Norway). Several species formerly relegated to junior synonyms of H. gracilis are reinstated as speciesinquirendae: H. elongatus Boeck, 1865; H. dentatusKrichagin, 1873; and H. fucicolusT. Scott, 1912. The only European record of H. pulvinatus Brady, 1910, being otherwise endemic to the Southern Hemisphere, is based on a misidentification, being attributable to H. nicaeensis. Other records of the latter from outside the Ponto-Mediterranean basin are unverifiable and probably false, including the Angolese material of H. nicaeensis, which is regarded as speciesinquirenda in Harpacticus.
A new species, Thaumatocypris rudjakovi, from near Madagascar is described and illustrated. The specimens studied previously had been referred to T. echinataMüller, 1906 by Rudjakov (1993). The description includes the analysis of appendage muscles. The species T. echinata is discussed, and a key is presented to genera of the Thaumatocyprididae.
In adult females of the halocyprid ostracod Conchoecia imbricata, paired saclike ovaries lie separately at the both sides of the alimentary canal in the posterior region of the trunk. The ovarian wall consists of a thin layer of the ovarian epithelium, making itself into many folds. Oogonia, very early previtellogenic oocytes, and young somatic interstitial cells are gathered in a nipple-shaped germarium in each terminal of the ovaries. In the germarium, oogonia are concentrated in the most terminal region, and very early previtellogenic oocytes are located in the remainder, arranged in order of their sizes, the larger ones nearer to the ovarian lumen. These oocytes grow and leave the germarium, not to enter the ovarian lumen, but to ride on the outer surface of the ovarian wall, sandwiched between the ovarian epithelium and its basement membrane. They grow further to mature, supported by a few tall ovarian epithelial cells and raising the basement membrane of the ovarian epithelium. The larger oocytes lie farther from the germarium on the ovarian wall. Both the basic ovarian structure and the arrangement of the early female germ cells in the germarium of C. imbricata are common to those of the podocopid ostracods, many other crustaceans, and other mandibulate arthropods, but the further growth of the oocytes on the outer surface of the ovarian wall is similar to the pattern seen in the myodocopid ostracods, the branchiurans, the pentastomids, and the chelicerate arthropods. Such an intermediate oogenetic mode in C. imbricata is unique, not only among the ostracods and other crustaceans, but also among other mandibulates and the chelicerates.
Two-weeks starvation caused 45% decrease in the metabolism of the Antarctic amphipod Abyssorchomene plebs. Glutamic acid (Glu) in the concentration of 10 mM increased reactions of starved animals three times, but did not change reactions of the fed ones. Two-hours exposure of both starved and fed amphipods in the kynurenic acid (Kyn) solution in the concentration of 0.1 mM blocked the reactions of the latter group for glutamic acid (Glu). The reactions of invertebrates for glutamic acid (Glu) and kynurenic acid (Kyn) are similar to the well-known antagonistic reactions in the brains of vertebrates.
A new cumacean species from the shallow waters of South of Chennai, India, is described. Austrocuma kornfieldi, new species, is the second Austrocuma known to science. This genus is characterized, among other features, by the presence of a reduced number of pleopods. Even though extensively used, pleopod number does not seem to be a good character for family-level diagnoses within the Cumacea, because the number of pleopods has undergone reductions in several of the lineages. The position of the genus Coricuma within the Cumacea has been debated, and the present description of A. kornfieldi, together with an analysis of pleopod number in cumaceans, reinforces the placement of Coricuma within the Family Bodotriidae.
Reproduction, growth, population structure, and size at sexual maturity of the shiba shrimp, Metapenaeus joyneri were investigated in the western coast of Korea, Yellow Sea, from April 1994 to November 1995. The spawning season was June–August with peaks in July. Inseminated shrimp appeared from June to August, and the recruitment to the fished population took place in August. This shrimp shows a one-year life cycle with a single spawning season. Size at 50% sexual maturity (CL50), determined from both mature females and inseminated females, was 19.6 mm and 20.4 mm CL, respectively. The smallest mature female found was 19 mm CL. Fecundity was directly proportional to the size of the female, with clutch sizes varying from 73,185 ova in the smallest female to 206,131 ova in the largest. Diameters of ova ranged from 220 μm to 340 μm. Size distribution of the population was similar in both years of the study. Shrimps were not caught within the studied area during winter (December–March), indicating that the shrimp migrated outside the range of the fishery or were not catchable at this time. Growth was estimated by the modified von Bertalanffy growth function incorporating seasonal variation in growth. In both years, females (K = 1.22 year−1 and L∞ = 34.7 mm CL) grew faster and reached a larger size at the same age than males (K = 1.02 year−1 and L∞ = 29.0 mm CL). The result is supported by differences in growth performance indices (ϕ′) between females and males.
The pink shrimp (Farfantepenaeus duorarum) is an ecologically and economically important penaeid species in the southeastern United States. The biological and economic importance of this species prompted us to conduct a molecular genetic assessment of pink shrimp genetic diversity and population genetic structure. We sequenced a 558-base portion of the mitochondrial DNA (mtDNA) control region from pink shrimp collected at five locations ranging from North Carolina to south Texas. Haplotype and nucleotide diversity values in pink shrimp are among the highest yet reported for decapods. In our samples, all haplotypes were unique, and the average nucleotide diversity was approximately 2%. Nucleotide divergence between haplotypes ranged 0.2–3.9%. A mismatch analysis produced a unimodal distribution of pairwise differences between haplotypes that is consistent with a historic rapid population expansion. A population expansion, high mutation rate in the control region, and large population size all probably contributed to the development of high genetic diversity. This level of genetic diversity suggests that the mtDNA control region might be useful as a genetic marker in peneaid shrimp used for aquaculture. We detected no population differentiation, suggesting that long-term dispersal and gene flow are high enough to maintain a genetically homogeneous population structure over the geographic distances used in this analysis. The continuous distribution and high numbers of pink shrimp around south Florida likely have contributed to the genetic homogeneity observed in pink shrimp inhabiting the Atlantic Ocean and Gulf of Mexico. These data provide a baseline from which the genetic diversity and population structure of pink shrimp, which are highly exploited and vulnerable to the varied impacts of regional shrimp aquaculture, can be appraised in the future.
Zoeal stages of Conchodytes nipponensis, not previously known from Korea, are described from laboratory-reared material. This is the first account of the larval development of a species from the genus Conchodytes and the first larval description of a pontoniid species from Asian waters. The Gnathophyllidae had been considered as a synonym with the Pontoniinae by Bruce, whereas others regard both groups as distinct. Morphological comparisons between the first zoea of C. nipponensis and that of Gnathophyllum americanum indicate that the Gnathophyllidae have great affinity with the Pontoniinae. According to the viewpoint of some authors, similar larvae do not necessarily signify related adults. Therefore, the Pontoniinae and the Gnathophyllidae may be distinct.
Breeding and recruitment patterns were described and analyzed in a population of Palaemon gravieri inhabiting warm-temperate waters of southern Korea. Breeding period was seasonal, beginning in March, peaking (89% ovigerous females) in May, and then ending by August. Females with embryos near hatching had ovaries filled with vitellogenic oocytes ready for new spawning, indicating successive spawning. Laboratory observations on females incubating embryos confirmed that they spawn again after incubated embryos hatch; the female then underwent a post-hatching molt and then never had further ovarian development and spawning, indicating that the female has just two broods per year. Breeding period was constrained by temperature, and release of larvae coincided with a plankton bloom in the sampling area. Females reached sexual maturity and produced a brood in their first year, overwintered, and produced a brood again the following summer. Reproductive output (effort) of the female was rather high. No significant relationship was found between female size and embryo size. Embryo volume was relatively small, indicative of small amount of energy allocation to each embryo. Embryo loss during incubation was not high. Recruitment of juveniles was closely linked to the breeding period, beginning in July and ending in September. Reproductive life history traits for P. gravieri seem to be closer to stochastic (bet-hedging) models in which adults live in stable environments but in which juvenile (= larval) mortality is variable.
To investigate the extent of protandric simultaneous hermaphroditism (PSH) in the genus Lysmata, observations were made on the sexual system of L. californica, a species from the warm-temperate eastern Pacific. Observations on a large number of female-phase individuals (FPs) from a museum collection indicated that FPs with broods containing advanced embryos spawn again (successively) soon after brood hatching. Female-phase individuals maintained in pairs went through successive cycles of embryo brooding concomitant with gonadal vitellogenesis, hatching, molting, and spawning. Time-lapse video observations confirmed that FPs are able to copulate as males and inseminate postmolt, prespawning FPs. Prespawning FPs maintained alone did not produce successful broods of embryos. Thus, FPs of L. californica are outcrossing simultaneous hermaphrodites. Size-frequency distributions of sexual phases showed that individuals develop first in the male phase (MP) and then change to the female phase. Individuals apparently change from MP to FP in a single molt, as shown by (a) “transitional” individuals that were fully MP externally but whose ovotestes were full of vitellogenic oocytes and (b) a distinct change in the presence/absence and growth of pleopod characters from MP to FP. Female-phase individuals retain male gonopores from the MP phase, and relative growth of male ejaculatory ducts is similar in MPs and FPs. Pleopod flanges related to embryo attachment and incubation are somewhat masculinized in FPs of L. californica. The sexual system of L. californica is similar to that of L. wurdemanni from the Gulf of Mexico and L. amboinensis from the Indo-West Pacific. Protandric simultaneous hermaphroditism is probably widespread if not ubiquitous in the genus Lysmata.
During a three-month rearing period we compared the (1) survival rate, (2) growth at moult, (3) number of moults, and (4) overall growth of the young of the year (YOY) of two crayfish species, the indigenous Austropotamobius pallipes and the nonindigenous Procambarus clarkii. One hundred twenty YOY of each species were reared in different test conditions, i.e., three temperatures (16°, 20°, and 24°C) combined with two different dietary regimes (either animal or detritus food items). The two species showed a number of similarities in their survival rate and growth format. First, in both species, animal proteins appeared fundamental for the YOY growth, because an exclusively vegetal diet significantly slowed growth rate. Thus, the YOY seemed to behave as obligate carnivores, and detritus appeared ineffective in sustaining growth. Then, an exclusively animal diet showed some deficiencies: exoskeleton appeared pale in its colour when the diet was composed of animal items only, possibly because carotenoids were lacking. Third, an increase in the temperature caused a decrease in both survival and growth rate, because it determined a reduction of the moult increment in both species. Differences between the two species were that the nonindigenous crayfish showed a significantly higher tolerance of elevated temperatures, and growth was significantly faster in P. clarkii than A. pallipes, being approximately double when the crayfish were reared with an animal diet. Together with other behavioural and ecological properties, these features make P. clarkii more competitive than A. pallipes in disturbed habitats and areas which are subject to man-induced modifications.
The galatheid genus RaymunidaMacpherson and Machordom, 2000, is reported for the first time from Taiwan, and the species collected is also new to science. The new species is most closely related to R. confundensMacpherson and Machordom, 2001, but differs in having a more robust cheliped and walking legs covered with distinct squammae. The coloration of the new species is probably unique in the genus by both the carapace and abdomen being uniform in color. Analysis of the mitochondrial cytochrome oxidase I gene sequences also supports the specific status of this Taiwanese form.
Boninpagurus acanthocheles, a new genus and new species of hermit crab (Decapoda: Anomura: Paguridae) from shallow waters of the Ogasawara (Bonin) Islands, Japan, is described and illustrated. The new genus is characterized by the following characters: in males, the coxa of the right fifth pereopod has a straight or slightly curved, elongate sexual tube that is about 2–3 times the coxal length, directed laterally or posterolaterally, the proximal portion of the tube being stout and opaque and the distal portion transparent; the coxa of the left fifth pereopod has a short protrusion of vas deferens; females have paired gonopores and lack first pleopods. The new genus is similar to Anapagrides in several diagnostic features, from which it is distinguished by morphology of the male sexual tubes, the fourth pereopods, and female gonopores.
A year's monitoring of a population of Maja squinado in Galicia, NW Spain, revealed the seasonal formation of pods. From September to November 1994, we analysed samples from five pods located in two areas near the coast, Mexilloeira and O Carreiro, as well as specimens living in isolation in the same area. These pods were made up mainly of juveniles, except for the aggregation detected in September in O Carreiro, where 72% of the animals were adults. The sex ratio was around 1:1 in juveniles, with a predominance of females in the adult population. No differences were found in the proportion of juveniles vs. adults, sex ratio, size range, or intermoult stage between animals in pods and isolated specimens. The arrangement of the animals in the pod as well as the large number of specimens in the premoult or postmoult stage would suggest that these pods serve as a form of protection.
Tidal, diel, and spatial variations in numbers, sex, size, and colour morphology of shore crabs Carcinus maenas caught in baited drop nets during tidal periods, at neap tide and spring tide, were studied in the strongly tidal Looe Estuary, Cornwall, Southwest England. Depth, salinity, temperature, pH, and oxygen tensions were measured simultaneously. High numbers of both genders were caught in the estuary. In total, 61% of adult crabs caught were females. However, the sex ratio (males over females) in the catches significantly increased (P < 0.05) from approximately 0.2 at the station nearest to the mouth of the estuary to approximately 4 at the innermost station. Due to the well-established relationship between carapace colouration and intermoult duration, catches were analysed with regard to red and green colour forms, besides for sex and size. Green crabs were caught throughout the estuary and constituted 79% of total catches. Green males dominated the shallow stations, whereas green females dominated the deep stations. The catch per unit effort (CPUE) was related to tidal and diel phases, with most adult crabs being caught during high tide and only few during low tide. Also, more adult crabs were caught during night time than during day time. The CPUE increased with increasing depth, and crabs were never caught at salinities below 15‰ and rarely at salinities below 20‰. Oxygen tension, temperature, and pH exerted no effect on the distribution of shore crabs. Even though conclusions based on these data depend on whether catch-data analysis reflects true population abundances, sex ratios, and colour morphology compositions, the data suggest that the small size, strong current, and high salinity characteristics of the Looe Estuary allow both genders and colour forms to migrate into the estuary during high tide and to return to the shore before low tide, thereby exploiting a marginal feeding habitat.
The first stage zoea and megalopa of the hydrothermal vent crab Xenograpsus testudinatusNg, Huang, and Ho, 2000, are described, figured, and compared with a typical varunid, Brachynotus sexdentatus (Risso, 1827). Further comparisons are made between the first stage zoea of X. testudinatus and those representing the remaining current families of the Grapsoidea, namely Gecarcinidae, Glytograpsidae, Grapsidae, Plagusiidae, and Sesarmidae. A number of zoeal characters, including (1) the absence of the antennal exopod, (2) the setal formula [0,4] for the maxillular endopod, (3) the presence of a spine on both the distal coxal and proximal basal lobes of the maxilla, and (4) the presence of a minute spine on the lateral margin of the telson fork, appear to distinguish X. testudinatus first stage zoea from all the other grapsoids examined for this study. The zoeal evidence suggests that Xenograpsus is significantly different from known grapsoid larvae and the genus should eventually be removed from the Varunidae. Although Xenograpsus has similarities with known Scopimera (Ocypoidea) first stage zoea descriptions, including two of the above characters (1,2) and the setation of the maxillary endopod [2,3], these are not considered significant. A new family may need to be established to accommodate Xenograpsus within the Grapsoidea.
The reproductive performance of two Varunidae crabs, Cyrtograpsus angulatus and C. altimanus from Jabalí Island (40°32′S, 62°15′W), Argentina, were compared. The following reproductive variables were measured in the laboratory for fixed females of each species: realized fecundity (number of eggs/female); EW: egg dry weight (egg dry weight/number of eggs); RO: reproductive output (egg dry weight/female dry weight); RF: relative fecundity (number of eggs by female/female dry weight); and RSOM (relative size at the onset of maturity). Cyrtograpsus angulatus showed a greater realized fecundity than C. altimanus, in accordance with the greater size of the former (20.88 ± 0.66 mm and 8.52 ± 0.12 mm carapace widths, respectively). The EW, RO, and RF presented similar values for both species, whereas C. altimanus had a greater RSOM than C. angulatus.