Female Pleopods Research Articles

A new alternative technique for sterilising invasive crayfish: removing female pleopods did not alter courtship pheromone release in signal crayfish

A new alternative technique for sterilising invasive crayfish: removing female pleopods did not alter courtship pheromone release in signal crayfish

Reproductive behaviour of the branchial ectoparasite Bopyrus crangorum (Isopoda: Bopyridae) following ecdysis of the host Palaemon serrifer (Caridea: Palaemonidae)

Abstract The reproduction of bopyrid isopod parasites is thought to occur immediately following host ecdysis, but direct observations supporting this hypothesis are limited. The aim of this study was to describe the reproductive behaviour of the bopyrid isopod Bopyrus crangorum relative to host ecdysis based on video recordings. Several hours after host ecdysis, biphasic moulting of female parasites was observed. The cuticle of the posterior body was shed before that of the anterior body at an interval of 1 h. Two hours after female moulting, the male repeatedly moved from its initial position between the female pleopods and stopped at the anterior end of the fifth oostegite, immediately above the gonopore. To our knowledge, this repeated visiting behaviour by males has not been previously observed in bopyrid isopods. Oviposition through the female gonopore occurred 33 min later. The male-removal experiment showed that females with their males removed after visits to the gonopore oviposited eggs, whereas females with their males removed before visits did not. We propose that repeated visits by males to the gonopore are attempts to inseminate the female. We hypothesised that sperm are released onto the external surface of each gonopore and that the eggs are fertilised as they pass through the opening, which would explain the synchronous development of fertilised eggs inside the marsupium. The present study provides new information on the life history of bopyrid isopods, which allows for a better understanding of the host–parasite relationship.

Four new species of Heteromysis (Crustacea: Mysida) from public aquaria in Hawaii, Florida, and Western to Central Europe

Four new species of the subgenus Heteromysis (Olivemysis) were detected in material from (sub)-tropical aquaria in six public aquarium institutions around the globe. Modifications of pleopods by spines represent the strongest structural complex used for differentiation within this subgenus: male pleopods 1–4 modified in H. smithsoniana sp. nov., male pleopods 2–4 plus female pleopod 2 in H. hornimani sp. nov. and H. waikikensis sp. nov. Additional important diagnostic characters are provided by the antennulae, uropods, and telson. The male of H. sixi sp. nov. represents a very rare case within the genus Heteromysis by having only pleopod 2 modified by flagellate spines. The definition of the subgenus Olivemysis is modified in order to include H. sixi sp. nov. A summary of pleopod modifications in the genus Heteromysis and a key to the species of the subgenus Olivemysis are given. The here described new taxa more than double the number of Heteromysis species known from aquaria yet unknown in nature from three to seven.

A new species of the genus Eucalliaxiopsis Sakai, 2011 from the South China Sea (Decapoda, Axiidea, Eucalliacidae)

Abstract Eucalliaxiopsis liui sp. nov. is described from a specimen taken from the South China Sea. The new species differs from other species of Eucalliaxiopsis in the combination of a telson with a transverse posterior margin, without a transverse row of spiniform setae, and a hook on the upper margin of the carpus of the cheliped. Eucalliaxiopsis liui is unique in having a biramous female pleopod 2, its endopod slender, with finger-like appendix interna, and a slender segmented exopod.

Distribution, identification and range expansion of the common Asellidae in Northern Europe, featuring the first record of Proasellus meridianus in the Nordic countries

Two out of the three common Asellidae species in Northern Europe are increasing their ranges, aided by humanactivities. Here we report the discovery of Proasellus coxalis (Dollfuss 1892) in new areas in Norway and thediscovery of Proasellus meridianus (Racovitza 1919) for the first time in the Nordic countries, verified withDNA barcoding. A new, detailed photo-identification guide to Asellus aquaticus Linnaeus 1758, P. coxalis andP. meridianus is presented. In addition to head pattern, attention is drawn to the female pleopods as an easy way to differentiate between the two genera. Then detailed examination of male pleopods 1 and 2 can differentiate between P. coxalis and P. meridianus. The origins, competitive relationships and potential dispersal mechanisms of the two introduced species and the native A. aquaticus are explored. By examining the shipping activity at the small, freshwater port where P. meridianus was found, we highlight the great connectivity between many European brackish and freshwater ports and possible pathways for species transfer. The risk of trans-oceanic freshwater to freshwater (not just brackish and saltwater) species transfer through ballast water needs to be better communicated. Proasellus coxalis may have been introduced to the river system of Lake Stokkalandsvatnet together with fish transported in microaquaria used as live bait for fishing.

Biological and ecological notes about the snapping shrimp Alpheus formosus Gibbes, 1850 from two continental islands in São Paulo State - Brazil

Abstract While previous studies on Alpheus formosus Gibbes, 1850 focused on taxonomic and phylogenetic issues, the present study provides information on the biology and ecology of this snapping shrimp, a representative coral reef species widely distributed in the Atlantic Ocean. We studied A. formosus between 2015 and 2016 on two islands in Sao Paulo state, Brazil: Laje de Santos and Vitoria Island. We analyzed 47 specimens from Laje de Santos and 44 from Vitoria Island. Individuals ranged in size from 2.0 mm to 13.99 mm CL. The mean number of embryos attached to the pleopods of females was 211.28 ± 312.8 in Laje de Santos and 125.2 ± 177.8 in Vitoria Island. This species should be included in monitoring programs of coral ecosystems they inhabit as A. formosus represents a key element in trophic dynamics of these ecosystems.

Effect of Habitat Diversity on Population Development of the Amazon River Prawn

ABSTRACT The aim of this study was to determine if the Amazon river prawn [Macrobrachium amazonicum (Heller, 1862)] population structure is affected by habitat heterogeneity. An experiment was conducted in mesocosms to emulate conditions from a natural aquatic environment. Twelve rectangular earthen ponds of ∼100 m2 each were used as mesocosms. Each mesocosm was stocked with 22 juveniles/m2 of Amazon river prawn in three different treatments: GB: mesocosm with substrate made of geotextile blanket, BB: mesocosm with substrate made from bamboo, and WS: mesocosm without substrate. The prawns were sampled monthly for 5 mo to analyze the male morphotypes, incidence of eggs in female pleopods, ovarian stage, body mass, and sex ratio. Both geotextile blanket (GB) and bamboo (BB) substrates increased frequency of the Cinnamon Claw morphotype, accelerated the appearance of Green Claw 1 and 2 morphotypes, and decreased the frequency of the Translucent Claw morphotype at the 5th mo. The substrates also increased the...

Male influence on the ovarian development of the crustacean parasite Bopyrina abbreviata (Isopoda, Bopyridae)

The presence of a male in a population of terrestrial isopods can accelerate the onset of female reproduction, a feature that has been suggested also to occur in bopyrid isopods. This paper aims to estimate the influence of the male presence on the ovarian maturation of Bopyrina abbreviata. Females of B. abbreviata of different sizes were collected at Términos lagoon, Campeche, Mexico. The organisms were morphometrically classified as immature or mature, the male presence or absence at female's marsupium was recorded, and the degree of ovarian development was determined histologically. The internal organization of B. abbreviata agrees with that described for bopyrids and isopods in general. The ovarian cells originate from a dorsal lamina germinal layer that extends horizontally. The ovarian development of lone and paired immature females was classified as incipient and medium, respectively. In mature females it was classified as advanced, in the paired females and in the one lone mature female studied. The lone mature female differed from paired mature females only in the presence of reabsorption process in some oocytes located closer to the ventral wall of the ovary. Morphology variations between lone and paired females suggests that the presence of a cryptoniscus larva or a male between the female's pleopods stimulates the onset of reproduction and accelerates the ovarian development of B. abbreviata.

Fecundity of the giant freshwater prawn <i>Macrobrachium rosenbergii</i> (Decapoda: Palaemonidae) in conditions of aquaculture

Giant freshwater prawn Macrobrahium rosenbergii is one of the most prospective species of Decapoda for artificial reproduction. It is cultivated mostly in the areas with subtropical and moderate climate, but rare is grown to the maximal size. Investigations for improvement the biotechnological process of this species cultivation were conducted in Crimea in 2010-2013, in particular for the stage of early ontogenesis. In total, 245 individuals were used in the experiments. The embryonic development was divided into 5 stages. The eggs were taken from pleopods of vital females and observed by microscope with measurements by ocular micrometer and weighting. Initial realized fecundity (IRF) and finite realized fecundity (FRF) were determined by the weight method. IRF for the females with length 7.7-14.3 cm and weight 5.2-38.4 g was 3071-54692 eggs in one clutch; FRF for the females with length 7.5-14.2 cm and weight 5.3-38.1 g was 678-39925 eggs in one clutch. Both IRF and FRF increased with the length and weight of females increasing. During embryonic development, the eggs grew in 1.5 times in size and 2.1 times in weight. The volume of the eggs ovulated and just laid to pleopods was 0.08 mm 3 under the temperature 24 о C and 0.06 mm 3 under the temperature 28 о C.

Population structure, morphometric analysis and reproductive biology of Portunus sanguinolentus (Herbst, 1783) (Decapoda: Brachyura: Portunidae) in Honghai Bay, South China Sea

Portunus sanguinolentus (Herbst, 1783) is commercially important in China, but its yields have declined in recent years. Here, the morphometric characteristics and organ indices are analysed to obtain baseline information about the population structure, sexual maturity, and fecundity of this species. Specimens were collected monthly from the waters of Honghai Bay, off the South China Sea. A 1.26:1 male:female sex ratio was recorded. Male crabs reached sexual maturity at a carapace width (CW) of 74-87 mm, while this CW range was 76-92 mm for females. Fifty percent of males and females were mature at a CW of 76.4 and 82.2 mm, respectively. Spawning peaked in February (53.4%), while the smallest and largest berried female crabs were 77.1 mm CW and 139.6 mm CW, respectively. A total of 58,600 to 565,000 eggs was attached to the pleopods of berried females, with female fecundity being significantly correlated to CW. The assimilated information is expected to help improve the sustainability of this crab fishery in China.

Review of the fish parasitic genus Ceratothoa Dana, 1852 (Crustacea, Isopoda, Cymothoidae) from South Africa, including the description of two new species.

The genus Ceratothoa Dana, 1852 is revised for South African waters and re-diagnosed. Ceratothoa retusa (Schioedte & Meinert, 1883) is recorded from the eastern coast, and Ceratothoa africanae sp. n. and C. famosa sp. n. are described; C. imbricata (Fabricius, 1775) and C. trigonocephala (Leach, 1818), are redescribed, revised and excluded from the South African fauna. Ceratothoa africanae sp. n. can be distinguished by the stout body shape of the female; triangular cephalon with a pointed rostrum; short uropods which do not extend past the pleotelson; large carinae on the pereopod basis; a broad pleon; and large medial lobes on female pleopods. Ceratothoa famosa sp. n. is characterised by the long rectangular body shape; pereonite 1 with a raised medial protrusion; narrow antenna with antennule article 1 expanded; uropods which reach the posterior margin of the pleotelson; narrow rami on uropods; and no appendix masculina on pleopod 2 of the male specimens.

First record of Janinella nom. nov. (Crustacea: Isopoda: Microparasellidae) in the South Atlantic: revision of the genus and description of a new Brazilian species

The family Microparasellidae (Crustacea: Isopoda) is reported for the first time from South America. The genus Janinella nom. nov. is proposed as the replacement name for Paracharon Coineau 1970. It is new for the Atlantic Ocean. A new species of Janinella from the interstitial Brazilian infralittoral is described. Janinella brasiliensis sp. nov. is distinguished from the New Caledonian congener Janinella renaudae by the tiny antennal scale, the number of teeth of the mandibular incisor and the shape of the maxilliped epipod. These species differ also by the morphology of the male and female pleopods, and the length of the uropodal exopod. Based on the re-examination of J. renaudae and the characters of J. brasiliensis sp. nov., a revised diagnosis of the genus Janinella is provided. Habitat preferences are described: Janinella species live in well-sorted coarse-grained sands affected by high hydrodynamics. The chemical composition of the grains is of low relevance.http://zoobank.org/urn:lsid:zoobank.org:pub:8594F887-1183-44CB-BB31-E59A0F7E2167

Ontogenetic shifts in resource allocation: colour change and allometric growth of defensive and reproductive structures in the Caribbean spiny lobsterPanulirus argus

Resource allocation theory predicts a disproportionately large allocation of resources to defensive structures during early ontogeny in organisms that are subject to more intense predation at smaller than at larger body sizes. We tested this prediction on the Caribbean spiny lobster Panulirus argus, which exhibits a negative relationship between predation risk and body size with a high natural mortality of smaller individuals. Independent allometric growth analyses demonstrated that numerous defensive structures (e.g. orbital horns, segments supporting the antenna, the tail fan) display negative allometric growth throughout ontogeny. We interpret these findings as lobsters investing disproportionately more resources to defensive structures when small to improve survivorship. Similarly, we observed an ontogenetic shift in lobster colour pattern; small individuals (< 23 mm carapace length) that inhabit nursery grounds (preferably among red algae) displayed a disruptive pattern (camouflage), whereas larger juveniles displayed a bicolour pigmentation typical of adult lobsters. This shift in colour pattern further suggests that small lobsters employ cryptic coloration throughout their asocial algal stage. However, this cryptic coloration offers no advantage when lobsters grow larger and start dwelling in crevices. Other structures linked to reproduction (e.g. female pleopods and male pereopods) experienced either isometric or positive allometric growth throughout ontogeny. Our results support one of the main predictions of resource allocation theory and demonstrate ontogenetic shifts in defensive structures and coloration concomitantly with changes in lobster mortality risk mediated by size-dependent predation risk. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●●, ●●–●●.

Brasileirinidae, a new isopod family (Crustacea: Isopoda) from the cave in Bahia (Brazil) with a discussion on its taxonomic position

The aquatic troglobiont Brasileirinho cavaticus (Crustacea: Isopoda: Calabozoidea), new genus and species is described from the karst cave of the State of Bahia, Brazil. Based on its unique pleonal features i.e. the total absence of female pleopods I–II, uniramous male pleopods I–II, minute, uniramous respiratory pleopods III–V in both sexes and pleotelson not exceeding 45% of the pleon length, a new family, Brasileirinidae, is created. Some biological, ecological and behavioral data for the species are provided together with the nature conservation issues. Additionally, an assignment of the new species to the suborder Calabozoidea is discussed through comparison with the other two calabozoid species, Calabozoa pellucida and Pongycarcinia xiphidiourus. For the latter species, some previously missing morphological details, as well as a new locality record, are provided. According to the updated morphological evidence, the previously assumed relationships of Calabozoidea are discussed and, consequently, the diagnostic characters of some taxa emended.

Description of a new genus of Cryptochiridae (Decapoda: Brachyura) associated with &lt;i&gt;Siderastrea&lt;/i&gt; (Anthozoa: Scleractinia), with notes on feeding habits

Members of the Cryptochiridae are small gall-crabs that live as obligate symbionts of scleractinian corals. Only two species have so far been recorded in the western Atlantic Ocean. Herein a new Cryptochiridae genus and species is described, and new information is added on the life history of cryptochirids. The new genus is characterized by having the carapace with the lowest deflection angle among the genera, and also shows the following features: thoracic sternite 4 with setules and constriction smaller than half of the width of the basis, anterior margin curved with apical row of granules; third maxilliped with subcircular exopod reaching medially the lateral margin of the ischium; pereiopod 2 with prominent distomesial and anterolateral expansion on the merus, propodus almost twice larger than dactylus; thoracic sternite 7 with complete medial suture, female pleopod 3 uniramous with longitudinal opening. Male first pleopod straight with subdistal curvature of approximately 90°. Individuals belonging to the new genus are found in galls in massive corals although this structure is cited as being characteristic of ramified corals. The long plumose setae of the maxilliped 3 suggest a filter-feeding function, but the toothless chelae suggest that they are used to gather mucus.

Direct evidence of parasitism by Copidognathus stevcici (Acari, Halacaridae) in crabs Maja squinado and M. brachydactyla (Brachyura, Majidae) in the laboratory

Marine mites belonging to the family Halacaridae were found associated with adult females of the spider crabs Maja brachydactyla Balss, 1922 and M. squinado (Herbst, 1788) held under laboratory conditions. Morphological study of collected samples identified the mites as Copidognathus stevcici Bartsch, 1976. C. stevcici was found on pleopods of ovigerous and post-ovigerous females in both crab species, with an intensity ranging from 10 to 326 mites per host. Mites were observed alive on their host for extended periods and direct evidence of feeding on crab's eggs is provided. The COI mtDNA sequence of these mites is reported as an addendum to the species description.

A new genus and new species of hermit crab (Crustacea: Anomura: Paguroidea: Diogenidae) from the eastern tropical Pacific

Tetralobistes gen. nov., a presently monotypic genus of hermit crab of the family Diogenidae, is described to accommodate a new species, Tetralobistes bicentenarius sp. nov. In many characters, Tetralobistes gen. nov. is similar to Areopaguristes Rahayu &amp; McLaughlin, 2010, Paguristes Dana, 1851, and Pseudopaguristes Mclaughlin, 2002. However, it differs most significantly in the morphology of the male first pleopods and lacks male second and female first pleopods. The most conspicuous character separating Tetralobistes gen. nov. from the other three genera is the shape of the telson, with a typical subdivided (four-lobes) posterior margin.

Fecundity of Nephrops norvegicus from the Irish Sea

Potential fecundity, number of oocytes in the mature ovary, and realized fecundity, number of eggs extruded and attached to the pleopods of female Nephrops, caught at the start of the incubation period were estimated for females from the eastern and western Irish Sea grounds. Potential fecundity was found to differ significantly between eastern and western Irish Sea stocks, while realized fecundity did not differ between areas. Inter-year comparison of realized fecundity, and effective fecundity (the number of mature eggs on the pleopods of females at the end of the incubation period) in the western Irish Sea stocks revealed no significant variation over time. Egg loss during the transition from oocytes in the ovary to mature eggs increased with female size, ranging from 40% at 25 mm carapace length (CL) to 65% at 40 mm CL. No relationship was found between egg diameter or volume and female size.

Microcope gen. nov.—a new deep-sea genus of Munnopsidae (Crustacea, Isopoda,Asellota), with description of two new species from the Southern Hemisphere

A new genus of Munnopsidae Lilljeborg, Microcope gen. nov., is described including Eurycope ovata Birstein, 1970 from the northwestern Pacific, and two new species, collected in the Cape Basin, and Atlantic Sector of the Southern Ocean. The new genus combines characters common for some genera of Eurycopinae Hansen and Betamorphinae Kussakin, but cannot be related to any known genus of the existing subfamilies and, thus, still remains incertae sedis. Microcope gen. nov. is characterized by minute eurycopine-like broad oval body with fused pereonites 5–7 on the one hand, and betamorpha-like face, pereopods 2–4 and uropods, with extended distomedial projection of the protopod on the other hand. The following combination of characters distinguishes the new genus: short head hidden under the anterior flange of pereonite 1, absence of rostrum, slender male pleopods 2, flattened female pleopod 2, and distinct shape and armament of pereopods 5–7 and pleopod 3. The descriptions of Microcope gen. nov., as well as the two new species, M. denticulate sp. nov., and M. levissima sp. nov., are presented.

Evolutionary significance of prenuptial molting in female Pagurus hermit crabs

Molting and breeding entail major energetic costs for female crustaceans. However, females of some hermit crabs perform a molt immediately prior to copulation (prenuptial molt). The evolutionary significance of the prenuptial molt was examined in Pagurus hermit crabs, and two hypotheses were tested: (1) prenuptial molt might enhance the success of the present clutch by cleaning the pleopods of females and thereby preventing eggs from being dislodged from the pleopods, and (2) prenuptial molt might function for growth and increase future fecundity at the cost of energetic expenditure on the present brood. Although these hypotheses are not mutually exclusive, our results rejected the former hypothesis and supported the latter hypothesis. All four Pagurus species examined showed significant negative relationships between prenuptial molting and continuity of breeding; i.e., they showed high molting frequency after they had a long rest period from breeding. Females of P. minutus increased their size through the prenuptial molt, and showed a decreased clutch size due to the molt. The number of dislodged eggs increased if females molted in P. minutus. These results suggest that hermit crabs undergoing a prenuptial molt might not gain any clear immediate advantage of enhanced survival of eggs in the present clutch, and that the prenuptial molt would mainly contribute to growth.