Showing papers in "Journal of Crustacean Biology in 2015"
TL;DR: The taxonomic effort of amphipodologists was compared with the situation in Cumacea and Mysidacea and there is a strong geographical bias with 21 of the 30 taxonomists originating from Australia, Europe, North-America and Japan especially within the group of highest productivity.
Abstract: The term “taxonomic impediment” is widely used in the biodiversity literature. The taxonomic impediment consists of several problems: the incomplete knowledge of the largely unknown global biodiversity, the insufficient number of experts and their unbalanced distribution across the globe and the taxonomic infrastructures that are not meeting the demands yet. It is difficult to examine how severe the problem in the development of taxonomic knowledge is, because there might be big taxonomic gaps in knowledge in some groups, like many invertebrates, but small in some vertebrate taxa. As an example of an invertebrate taxon, the online WoRMS database was queried for amphipod crustaceans, and data for the cumulative increase of species numbers, species description rates and data from the taxonomic community were extracted. The increase of species numbers over time is strong and the species description rates are high since the 1960s. Within the group of 30 most productive amphipod taxonomists during the past 15 years, 9 are retired, 2 are on temporary contracts, 1 is a freelancer, 8 stopped working on amphipods leaving 9 out of 30 permanently employed. There is a strong geographical bias with 21 of the 30 taxonomists originating from Australia, Europe, North-America and Japan especially within the group of highest productivity. The taxonomic effort of amphipodologists was compared with the situation in Cumacea and Mysidacea.
60 citations
TL;DR: This work proposes a more accurate definition of the term anchialine as ‘a tidally-influenced subterranean estuary located within crevicular and cavernous karst and volcanic terrains that extends inland to the limit of seawater penetration.
Abstract: An improved understanding of the anchialine ecosystem and geology warrants a redefinition of the term ‘anchialine.’ Originating from subareal biological observations, the term anchialine now encompasses chemical, physical, geological and biological elements within the subterranean realm. We propose a more accurate definition of the term anchialine as ‘a tidally-influenced subterranean estuary located within crevicular and cavernous karst and volcanic terrains that extends inland to the limit of seawater penetration.’ This subterranean estuary is characterized by sharp physical and chemical stratification and merges with a marine system at the coast and a groundwater system inland. The anchialine ecosystem supports a relatively diverse biotic assemblage of stygobiotic species of marine origin dominated by members of Crustacea, both numerically and by species richness.
55 citations
TL;DR: The proposed period of fisheries closure (March to May) does not coincide with the main recruitment periods observed for X. kroyeri, and recruitment and abundances of reproductive females were highly correlated with the environmental factors such as higher water temperature and finer-grained bottom sediment.
Abstract: Population parameters of the shrimp Xiphopenaeus kroyeri (Heller, 1862) (sex ratio, length-frequency distributions (carapace length, CL), growth, lifespan, size of sexual maturity, spawning and recruitment) were analyzed in a long-term study from January 1998 through June 2003. The data on these parameters were collected and analyzed to test the hypothesis that the main period of juvenile recruitment in the bay coincides with the period of fishery closures currently designated by the Brazilian Institute of Environment and Renewable Natural Resources. Monthly collections were conducted along the southeastern Brazilian coast, using a shrimp fishing boat with “double-rig” nets sampling at stations up to 40 m depth. Sex ratios were female-biased only in zones with high reproductive activity such as in stations deeper than 15 m (χ2 test, p<0.05). The mean size of males and females was 15.3 ± 3.1 mm CL and 16.2 ± 4.7 mm CL, respectively, with size at sexual maturity estimates (CL50) of 14.8 mm for males and 15.5 mm for females. Mean growth curves provided estimates of CL∞ = 29.31 mm, k = 0.009/day, t0=−0.25 and CL∞ = 35.33 mm, k = 0.006/day, t0=−0.23 for males and females, respectively, and average lifespans of 1.35 for males and 2.12 years for females. Recruitment and abundances of reproductive females were highly correlated with the environmental factors such as higher water temperature and finer-grained bottom sediment (canonical correlation, r=0.63, p<0.001). The reproductive peaks in February-April 1998, March-May 1999 and February-May 2002 were followed by recruitment peaks in May-July 1998, July-September 1999 and April-June 2002, respectively. Thus, the proposed period of fisheries closure (March to May) does not coincide with the main recruitment periods observed for X. kroyeri.
47 citations
TL;DR: Recent observations and continued warming in the northwest Atlantic may signal a permanent poleward expansion of C. sapidus into the Gulf of Maine, and if so, then a key goal for ecologists and managers will be to understand the effect of the blue crab on GoM food-webs and fisheries.
Abstract: Worldwide, climate-change is shifting species distributions poleward. Here I present recent (2012-2014) observations of the blue crab, Callinectes sapidus Rathbun, 1896, in the Gulf of Maine (GoM), north of its historical range of Cape Cod, Massachusetts. To test the hypothesis of a climate-driven range expansion, I examined near-surface ocean temperatures. On average, ocean temperatures in the GoM in summer 2012 and 2013 were up to 1.3°C higher than the average of the previous decade, suggesting that warmer waters may have promoted the recruitment of C. sapidus to the GoM. Previous ephemeral populations of C. sapidus in the Gulf of Maine have been reported since the 1860s. Recent observations and continued warming in the northwest Atlantic may signal a permanent poleward expansion of C. sapidus into the GoM. If so, then a key goal for ecologists and managers will be to understand the effect of C. sapidus on GoM food-webs and fisheries.
47 citations
TL;DR: It is concluded that attempts to integrate modern and extinct representatives of the spinicaudatans in a holistic approach result in many of the fossil families becoming paraphyletic or polyphyletic, highlighting the persistent rift between biological and palaeontological studies of the group.
Abstract: In order to understand relationships between living and fossil groups of spinicaudatan clam shrimp, it is important to review historical and contemporary attempts at evaluating the evolutionary history of the group. A comprehensive review of previous phylogenetic and paleontological work is presented here and considered in an evolutionary context in an attempt to bridge the gap between neontological and fossil works and to present a foundation upon which future studies may contribute to the understanding of spinicaudatan evolutionary history. This study is broken into three discrete sections dealing with various aspects of spinicaudatan neontology and paleontology. First, a brief review of the current state of branchiopod systematics is presented. Second, we offer reviews of contemporary efforts in the paleontological study of fossil Spinicaudata with familial and super-familial descriptions of major fossil groups. Finally, an effort to establish biologically sound hypotheses of relatedness between fossil and living lineages of ‘clam shrimp’ is presented. We conclude that attempts to integrate modern and extinct representatives of the spinicaudatans in a holistic approach result in many of the fossil families becoming paraphyletic or polyphyletic, highlighting the persistent rift between biological and palaeontological studies of the group. It is our hope that the hypotheses presented here will aid in a more synthetic studies of Spinicaudata and also allow biological patterns to be investigated across the groups over geologic time.
45 citations
TL;DR: The early morphological decapod studies are summarized, common problems that are causing a lack of consensus in molecular studies are addressed, a means of evaluating molecular trees is presented, and suggestions for good phylogenetic practice are offered.
Abstract: Since the late 1800s, several infraordinal relationships have been proposed for Decapoda; however, reaching a consensus among higher-level relationships is proving difficult. Molecular methods were first applied to higher-level decapod phylogenetics in the 1990s and have significantly contributed to our understanding of the group: sampling is becoming more thorough, a greater number of phylogenetically informative characters are being sequenced, and analysis procedures are becoming more consistent between studies. However, relationships among the deep lineages of Decapoda remain unclear. Several phylogenetic hypotheses have been suggested, and while there is some agreement among studies, an ultimate consensus among higher-level relationships has yet to be reached. This is largely the result of differences in sampling effort, marker selection, data-recycling, and analysis. Because most studies have generated conflicting phylogenetic hypotheses, the foundation on which the trees were built (data and analysis procedures) must be considered and evaluated. In this review, we summarize the early morphological decapod studies, address common problems that are causing a lack of consensus in molecular studies, present a means of evaluating molecular trees, offer suggestions for good phylogenetic practice, review the previous molecular studies of infraordinal decapod phylogeny, and discuss the future directions of the field, with special attention paid to next-generation sequencing (NGS) techniques.
42 citations
TL;DR: The data are consistent with the hypothesis of survival in situ and suggest that gene flow within A. cornigerais limited, hinting at possible speciation processes acting independently on the Antarctic continental shelf and the peri-Antarctic islands.
Abstract: The diversity and distribution of Antarctic life has been strongly influenced by climatic events, in particular by large scale extension of ice sheets onto the continental shelf during repeated glacial cycles. It has been suggested that populations of benthic marine biota in the Antarctic were limited to very few refugia because the Antarctic shelf was covered with ice. Using the broadly-distributed pycnogonid Austropallene cornigeraas a model, in this study we tested different hypotheses for possible locations of glacial refugia ( ex situon the peri-Antarctic islands or in situon the Antarctic shelf). We sampled 64 individuals of A. cornigerafrom peri-Antarctic islands, the Weddell Sea and East Antarctica. The phylogeographic structure was analysed using partial sequences of the nuclear ribolomal genes 18S and 28S and the mitochondrial cytochrome coxidase subunit I gene (COI). The 18S and 28S sequences were highly conserved. Sequences of the COI were variable and revealed highest haplotype diversity for populations on the Antarctic shelf and lowest for the population from the remote island of Bouvetoya. In addition, the data showed clear genetic distances between the island and shelf populations. Our data are consistent with the hypothesis of survival in situ. The results also suggest that gene flow within A. cornigerais limited, hinting at possible speciation processes acting independently on the Antarctic continental shelf and the peri-Antarctic islands.
39 citations
TL;DR: The conceptual model presented provides a simple framework for future research in anostracan biogeography and drives speciation and reverses competitive dominance patterns, leading to selection mediated priority events.
Abstract: A conceptual model for anostracan biogeography based on the “Monopolisation Hypothesis” and the “Theory of Island Biogeography” is discussed and presented. In this model anostracan species evolve allopatrically (in geographically isolated, unoccupied insular habitats), cladogenically (in small, genetically isolated founder populations via strong priority effects), or anagenically through local adaptation to changing environmental conditions. The Monopolization Hypothesis drives speciation and reverses competitive dominance patterns, leading to selection mediated priority events. Conversely, the spatial distribution of anostracan habitats (basins) drive island biogeographical patterns depending upon the relative isolation and size of any one given pool. The conceptual model presented provides a simple framework for future research in anostracan biogeography.
31 citations
TL;DR: Patterns of habitat preference of broad groups of decapod crustaceans suggest that the limits of distribution are controlled by the Bauplan of each group rather than by extrinsic factors.
Abstract: Patterns of diversity and faunal turnover of major groups of decapod crustaceans throughout the Phanerozoic are analyzed based upon data from all known fossil species reported to date. Age, range, and habitat preference data were compiled for 3637 species arrayed in 1035 genera and 173 families. Grouped at the infraordinal level, Anomura, Gebiidea, and Axiidea consistently occupied specific, preferred environments throughout their geologic history. Achelata are known from a variety of siliciclastic environments until the Holocene when they are found in coral and other carbonate environments. Habitat preferences of dendrobranch and pleocyemate shrimp, with a low preservation potential, are difficult to evaluate because they are found almost exclusively in low energy siliciclastics and lithographic limestones, whose mode of origin is not clear. Clawed lobsters, the so-called podotreme or primitive crabs, and heterotreme crabs have historically occupied a wide range of habitats. However, the temporal pattern of diversity of these groups is one of faunal turnover on a scale of tens of millions of years. Clawed lobsters were the first of these groups to be most diverse, followed in the Late Jurassic and Cretaceous by the podotreme or primitive crabs. Heterotreme crabs appeared in the Early Cretaceous and dominate numerically in the Cenozoic. These patterns of habitat preference of broad groups of decapods suggest that the limits of distribution are controlled by the Bauplan of each group rather than by extrinsic factors.
29 citations
TL;DR: The early stages of the life cycle are more tolerant to starvation than other decapods previously studied, which indicates a great potential of this species for aquaculture.
Abstract: Fil: Pantaleao, Joao Alberto Farinelli. Universidade Estadual Paulista Julio de Mesquita Filho; Brasil
28 citations
TL;DR: Four growth bands were visible in European lobster hatched in a Norwegian hatchery and maintained alive for four years before prior processing, and band counts in the other three species were identical to size-at-age interpretation determined from length-frequency analysis.
Abstract: The age information of commercially important species is crucial in fisheries management. Age of various fish and molluscan species has routinely been determined by counting annual growth bands deposited within the hard structures. In crustaceans such structures were previously believed to be lost and replaced due to molting. However, a technique was recently developed to use growth bands deposited in hard structure retained through molting as an age indicator. In the present study, the applicability of the novel technique is investigated for four crustacean species collected from Northern Atlantic for the first time: European lobster, Homarus gammarus (Linnaeus, 1758); Norway lobster, Nephrops norvegicus (Linnaeus, 1758); Atlantic rock crab, Cancer irroratus Say, 1817; and northern shrimp, Pandalus borealis (Kroyer, 1838). The gastric mill ossicles in the first three species were processed to show the growth bands while the eyestalk was used in the shrimp species. Four growth bands were visible in European lobster hatched in a Norwegian hatchery and maintained alive for four years before prior processing. Band counts in the other three species were identical to size-at-age interpretation determined from length-frequency analysis. Validation of the periodicity of annual deposition of growth bands is essential before applying the technique on a wider scale.
TL;DR: Although northwestern Morocco can still be considered a hotspot for large branchiopods, conservation measures should be taken to prevent further loss of biodiversity.
Abstract: An extensive field survey was conducted between 2012 and 2014 to update the knowledge on the diversity and distribution of large branchiopods in northwestern Morocco. Historical data were available from the 1980s to allow comparison with our current survey, but most exact locations of previously sampled large branchiopod populations were unknown. Fifteen (of the known 17) Moroccan large branchiopod species (9 Anostraca, 3 Notostraca, and 3 Spinicaudata) were recovered during our survey, including two endemic species for Morocco (Linderiella africana and Tanymastigites brteki). When comparing our results with historical data, a general decline in habitat numbers and species richness per habitat over the last 30 years becomes apparent. Although northwestern Morocco can still be considered a hotspot for large branchiopods, conservation measures should be taken to prevent further loss of biodiversity.
TL;DR: Although confirmed colonized areas are all located in the state of Sao Paulo, the invasive risk analysis showed that P. clarkii is a potential highly invasive species for Brazil, underlining the urgency to understand the invasion process in Brazil and develop efficient management techniques.
Abstract: This study reports new records of Procambarus clarkii Girard, 1852 in Southeastern Brazil and investigates its possible pathways of introduction. The Brazilian crayfish pet trade was surveyed with regard to species’ availability and price, reporting its persistence, even though illegal. An invasion risk analysis was performed by applying a protocol developed specifically to invasive freshwater invertebrates (FI-ISK). Procambarus clarkii has confirmed occurrences from urban and non-urban areas in the state of Sao Paulo, including the Jaragua State Park, an Atlantic Forest conservation area. The pet trade is an important introduction vector but some subsequent translocation can also be due to the release of live bait by anglers. Besides passive dispersal, these newly discovered populations, especially those located in non-urban areas, are likely to naturally disperse further through active spread and river drift of juveniles. Although confirmed colonized areas are all located in the state of Sao Paulo, the invasive risk analysis showed that P. clarkii is a potential highly invasive species for Brazil. These introductions have unknown consequences; however, many impacts are associated with this species establishment around the world, underlining the urgency to understand the invasion process in Brazil and develop efficient management techniques.
TL;DR: A review of the taxa from the Indian subcontinent (Bangladesh, India, Nepal, Pakistan, and Sri Lanka) taking a strongly conservative approach to assessing the reported species is provided.
Abstract: The large branchiopod crustaceans (fairy shrimp, tadpole shrimp, and clam shrimp) of India have been examined with varying degrees of scientific rigour since the late 1800s. Although 86 nominal species have been reported for India, the validity of many is in question – particularly for the clam shrimp. Most Indian endemic taxa are poorly described; some lack type material or the type material has been lost. Most recent revisions of key groups have made no attempt to validate identifications using existing type material, or even to procure topotype material. Worse, recent reviews treat old synonyms as valid names without any analysis or explanation. We provide a review of the taxa from the Indian subcontinent (Bangladesh, India, Nepal, Pakistan, and Sri Lanka) taking a strongly conservative approach to assessing the reported species. We recognize only 42 species: 16 anostracans, 2 notostracans, 3 laevicaudatans, 21 spinicaudatans (with reservations), and a single species of cyclestherid. This should establish a base point for future work on the branchiopods of the subcontinent.
TL;DR: In this paper, a multi-laminar calcium-phosphate-chitin composite was found to be the dominant body component of Spinicaudata preserved in their 380 million year fossil record.
Abstract: Spinicaudata (colloquially ‘the clam shrimp’) are freshwater branchiopod crustaceans that occur worldwide in lakes and temporary pools. The spinicaudatans are easily recognizable by their bivalved carapace which is unusual among arthropods in that it is subject to only partial molting. During ecdysis (molting), the outer surface of the carapace is not shed, resulting in the retention of the ontogenetic record of an individual through distinct growth-rings representing each molt. When this unusual feature is considered alongside the interesting chemical properties of the carapace, “clam shrimp” present an interesting biological material not seen anywhere else: a multi-laminar calcium-phosphate-chitin composite. In addition, the carapace survives numerous destructive taphonomic processes (including transport, decay, compaction, and desiccation) to become the dominant body component of Spinicaudata preserved in their 380 million year fossil record. Understanding the mechanical properties and chemical composition of this structure may not only aid in a better understanding of the evolutionary history of this group but also facilitate efforts to develop novel materials that retain functional material properties even in harsh aquatic conditions. Therefore, this study aims to provide quantitative information about the composition and mechanics of this unique and interesting biological material and help predict possible biases in the fossilization of different species of Spinicaudata to aid future palaeontological research.
TL;DR: The effect of water temperature on the growth of juvenile snow crabs Chionoecetes opilio (Fabricius, 1788) was investigated in laboratory culture experiments and size- and temperature-dependent growth models were developed for snow crab juveniles.
Abstract: The effect of water temperature on the growth of juvenile snow crabs Chionoecetes opilio (Fabricius, 1788) was investigated in laboratory culture experiments. Laboratory-born juveniles were cultured from instar I to VIII at four temperatures (approximately 1, 3, 5 and 8°C). The growth indices (size increments at moulting in mm and in % of premoult carapace width) were significantly higher in crabs reared at 5°C than in those reared at other temperatures. The relationship between the mean temperature (T) and intermoult period (D) of each instar was described by the heat summation theory equation: D=K∕(T−α). The thermal constant K is the summation of the effective temperature for development (above the threshold temperature, α) up to a selected biological end point. The thermal constant tended to increase and the threshold temperature tended to decrease with increasing mean premoult carapace width of each instar, reaching asymptotes of 1573 day-degrees and −4.7°C, respectively. Size- and temperature-dependent growth models were developed for snow crab juveniles.
TL;DR: In this paper, the authors provided information on the population structure, growth, mortality, maximum recruitment yield, and longevity for pink shrimp Farfantepenaeus subtilis on the coast of Pernambuco state, northeastern Brazil.
Abstract: This study provides information on the population structure, growth, mortality, maximum recruitment yield, and longevity for pink shrimp Farfantepenaeus subtilis (Perez-Farfante, 1967) on the coast of Pernambuco state, northeastern Brazil. A total of 1246 specimens (545 males and 701 females) were monthly collected from August 2011 to July 2012. Mean total length of females was higher (11.42 ± 1.61 cm) than males (10.5 ± 1.62 cm) and dominated in the largest length classes. Estimation of von Bertalanffy growth parameters for total length resulted in L∞ of 19.74 cm and k of 1.06 year −1 for males, while females’ L∞ was 21.64 cm and k was 1.10 year −1 . Mortality of females was higher than males resulting higher value in the exploitation rates. The exploitation rate for maximum recruitment yield was similar between males and females with a value of 0.67, which was above the exploitation rates (0.50-0.64).
TL;DR: The data suggest that small mating groups on some hosts and high mortality on all hosts contribute to the evolutionary origin and persistence of dwarf males.
Abstract: Androdioecy is a sexual system characterized by the coexistence of hermaphrodites and males. It has evolved several times independently in ancestrally hermaphroditic barnacles. Life history and sex allocation theory suggest that dwarf males can occur in hermaphroditic populations with very small mating groups, low growth rates and high mortality rates. We tested these predictions in the androdioecious barnacle Chelonibia testudinaria (Linnaeus, 1758), an epibiont on loggerhead sea turtles, blue crabs, and horseshoe crabs. The potential number of mates is indeed very small on invertebrate hosts but larger on sea turtles. Growth rates are host-specific but comparable to those of other purely hermaphroditic barnacle species. The maximum age of hermaphrodites was less than three years, which is lower than in most purely hermaphroditic species. Our data suggest that small mating groups on some hosts and high mortality on all hosts contribute to the evolutionary origin and persistence of dwarf males.
TL;DR: The present study determines whether three penaeid species could use bioflocs as food sources and suggests mechanical functions of the third maxilliped to collect bioFlocs in a water column and proposes a filter feeding habit of L. vannamei and a cannibalistic habit of F. chinensis and M. japonicus.
Abstract: Bioflocs contribute to the nutrition and growth of some penaeid shrimp, such as L. vannamei, by providing an additional food source in intensive, limited exchange production systems. However, it remains unclear whether other penaeids could use bioflocs as food sources. Furthermore, little is known concerning the feeding mechanism of shrimp for harvesting and consuming bioflocs. This study determines whether three penaeid species could use bioflocs as food sources and suggests mechanical functions of the third maxilliped to collect bioflocs in a water column. The postlarvae of L. vannamei, F. chinensis, and M. japonicus were assessed in 14-day culture trials with four treatments: biofloc water with feeding (BF-f), natural seawater with feeding (SW-f), biofloc water without feeding (BF-nf), and natural seawater without feeding (SW-nf). Litopenaeus vannamei exhibited a significantly higher specific growth rate (SGR) in the BF-f treatment than in the SW-f treatment, whereas the other two species did not demonstrate any differences in their SGR and survival rate between BF-f and SW-f treatments, suggesting that bioflocs might contribute to the growth of L. vannamei postlarvae but do not affect the survival and growth of F. chinensis or M. japonicus. The results obtained from the non-feeding experiments implied a filter feeding habit of L. vannamei and a cannibalistic habit of F. chinensis. Differences in the third maxillipeds are relevant in this regard. The feeding mechanism of M. japonicus with intermediate features of setae requires further study. The present study may contribute to understanding the different feeding abilities of bioflocs as food source in currently farmed penaeid shrimp in the Far East Asian countries.
TL;DR: The results suggest that changes in whole-body immune parameters of juvenile prawns are effective to characterize overall prawn health and environmental conditions.
Abstract: The effects of acute ammonia exposure on juvenile Macrobrachium nipponense (De Haan, 1849) were evaluated. The LC50 values and 95% confident intervals for total ammonia nitrogen (TAN) after 24, 48, 72 and 96 hours’ exposure were 139.78 (108.77-179.63), 84.17 (50.40-127.87), 64.07 (44.78-91.66) and 40.42 (30.46-53.62) mg/l. Then a 96-hour acute toxicity experiment was conducted in five concentrations of TAN (0, 5, 10, 15 and 20 mg/l). The whole-body activities of alkaline phosphatase (AKP), acid phosphatase (ACP), superoxide dismutase (SOD), catalase (CAT), and the concentration of malonaldehyde (MDA) were measured. The results demonstrate that the concentrations used in this study induce the immune response and that damage may be accompanied by a depression of the antioxidant defense system and the accumulation of malonaldehyde (MDA). These results suggest that changes in whole-body immune parameters of juvenile prawns are effective to characterize overall prawn health and environmental conditions.
TL;DR: The conservative approach suggests 55 species occurring within central and eastern Australia, which raises the number to about 70 species Australia wide: one third of the known global spinicaudatan diversity.
Abstract: Multispecies spinicaudatan assemblages, where several species co-occur simultaneously within the same water body, are relatively rarely observed. In part, this can be due to taxonomic impediments and the presence of cryptic species. Several recent studies on Australian Spinicaudata revealed much higher species diversities than previously known for this continent. Herein we summarize the results of three years of extensive sampling within eastern and central Australia, including 232 sampling events from 205 water bodies, and present new genetic data on Eulimnadia and Paralimnadia. Species were delimited following an evolutionary systematics framework using mitochondrial and nuclear markers to identify reproductively isolated species (biological species). Our conservative approach suggests 55 species occurring within central and eastern Australia, which raises the number to about 70 species Australia wide: one third of the known global spinicaudatan diversity. The central Paroo River catchment exhibited the largest spinicaudatan diversity ever observed on a regional scale with 31 species recorded on just approximately 60 km2. Diversities within water bodies are exceptionally high: half of the water bodies feature two or more species, with up to seven species and up to four congeners co-occurring simultaneously. Such diversities within water bodies have never been observed before for Spinicaudata. When a water body was sampled multiple times or when sediment samples were artificially incubated, the total species count was further increased (up to eight species). Nevertheless, most species are mutually exclusive, suggesting competition and/or restrictive habitat requirements are responsible for shaping spinicaudatan communities.
TL;DR: A novel preparation method was used for observing growth increments within these calcified structures of Nephrops norvegicus and Cancer pagurus and it was found that clear and readable growth increments were observed.
Abstract: It has recently been confirmed that some species of decapod crustacean retain their gastric mill and calcified region of the eyestalks throughout their moults. It had previously been assumed that crustacea lost all growth structures that could potentially record age information, such as the bones and otoliths in fish, through moulting. In this study, a novel preparation method was used for observing growth increments within these calcified structures of Nephrops norvegicusand Cancer pagurus(Linnaeus, 1758). This method involved: boiling, drying, resin embedding, sectioning, and polishing the gastric mill and eyestalks. Clear and readable growth increments were observed in longitudinal sections of the mesocardiac ossicle of the gastric mill for N. norvegicus, and longitudinal sections of the zygocardiac ossicle of the gastric mill for C. pagurus. Growth increments were also observed in longitudinal sections of the calcified region of the eyestalk for N. norvegicus. Validation is needed to confirm the periodicity of these growth increments.
TL;DR: In this paper, three new aeglid species, Aegla meloi, Aegla loyolai and Aegla linha, were described from Parana State, Brazil.
Abstract: This study describes three new aeglid species, Aegla meloi , Aegla loyolai and Aegla lancinhas , all of them recorded from Parana State, Brazil Along with the description, we also present an analysis of their phylogenetic relationships to other species of Aegla The conservation status using the IUCN Red List criteria was assessed for each new species The new species have restricted distributions and can be found in altitudes higher than 700 m The new species are phylogenetically close to other species present in Parana State and Ribeira do Iguape River basin, yet clearly differ morphologically and genetically from other known species of Aegla
TL;DR: Correlation analysis revealed strong positive relationships between both carapace length and stomach volume, and the size of the gastric mill, which is thought to facilitate an increase in size and range of prey species.
Abstract: Nephrops norvegicus (Linnaeus, 1758) is a decapod crustacean of high economic importance found across the northeast Atlantic. Little is currently known about the variation in stomach morphology with body size. In this study, a novel two-stage endocasting technique was used to determine stomach volume in relation to carapace length. Scanning electron microscope images of the teeth of the gastric mill were analysed to determine the changes in gastric mill size and structure with growth. Correlation analysis revealed strong positive relationships between both carapace length and stomach volume, and the size of the gastric mill. These changes are thought to facilitate an increase in size and range of prey species.
TL;DR: The new species is genetically and morphologically similar to Cherax holthuisi, however, both species can be easily distinguished by certain morphological characteristics or by using sequence divergence, which is substantial, for considering C. subterigneus n.
Abstract: Cherax ( Cherax ) subterigneus n. sp., is a crayfish endemic to the Aitinjo Lake of West Papua, Indonesia. This species is one of the field-captured species from this region that are exploited for ornamental purposes. Its commonly used commercial name in the pet trade is “Black Orange Tip Crayfish,” “Orange Tip Crayfish,” or “Red Tip Crayfish.” The new species is genetically and morphologically similar to Cherax holthuisi , however, both species can be easily distinguished by certain morphological characteristics or by using sequence divergence, which is substantial, for considering C. subterigneus n. sp. as a valid species. We have also added a note about the probable incorrect subgeneric assignment of the Cherax peknyi and mandatory change of incorrect original spelling of recently described C. gherardii as C. gherardiae .
TL;DR: This paper presents an overview of the known associations between amphipods and other crustaceans, and focuses on groups 2-4, which are quite common and widely distributed among the different amphipod clades.
Abstract: This paper presents an overview of the known associations between amphipods and other crustaceans. Such associations are quite common and widely distributed among the different amphipod clades, and in most cases show a high degree of host specialisation. They can roughly be divided into 5 groups: 1) living among the epifauna of large Crustacea, 2) living directly on the surface or appendages of their crustacean hosts, 3) living among the eggs of their crustacean hosts, 4) living in the permanent burrows of infaunal crustaceans, and 5) living on or in gastropod shells tenanted by hermit crabs. This survey concentrates on groups 2-4.
TL;DR: Variation observed in the size and composition of ejaculates produced by similarly-sized males indicates that not all males invest equally in reproduction, and larger males may invest disproportionately more in the sperm plug (acellular component), possibly as paternal assurance.
Abstract: Variation in the quality of ejaculate produced by male American lobsters, Homarus americanusMilne Edwards, 1837, has been previously described, but never quantified. This study examined the size and composition of ejaculates produced by 111 males ranging from 60 to 108 mm in carapace length (CL). Ejaculates were obtained via electrical stimulation, photographed and then processed for histology. Half of the males produced an ejaculate from each gonopore, 29% produced only one ejaculate, and the remainder (21%) produced none. Males as small as 64 mm CL produced an ejaculate containing sperm. Ejaculate weight increased with male size, but there was a negative relationship between ejaculate weight and the percent of the ejaculate that was composed of sperm mass. Variation observed in the size and composition of ejaculates produced by similarly-sized males indicates that not all males invest equally in reproduction. Additionally, larger males may invest disproportionately more in the sperm plug (acellular component), possibly as paternal assurance.
TL;DR: It was inferred that haplotype clades of C. brevimanus diverged during or near the interglacial period when sea levels were relatively higher, and their population expansion and remixing occurred through the glacial periods in the late Pleistocene.
Abstract: We evaluated the genetic diversity and demographic history of the terrestrial hermit crabs Birgus latro and Coenobita brevimanus using mtDNA COI sequence data (573 bp). Tissue samples from 163 individuals of B. latro and 63 individuals of C. brevimanus were collected at 11 and four localities in the North-Western Pacific Region, respectively. Haplotype diversity was high and similar in B. latro (0.8809) and C. brevimanus (0.9222). Nucleotide diversity was higher in C. brevimanus (0.01088) than in B. latro (0.00404). No genealogical structure was observed in haplotypes of B. latro whereas four haplotype clades were found in C. brevimanus . Weak but significant genetic population structure with the isolation by distance was detected in B. latro , but no genetic population structure was observed in C. brevimanus , likely because of the small number of sampling localities for the latter. Demographic history analyses suggested that B. latro and C. brevimanus had different histories of population expansion. Birgus latro experienced population expansion once during the glacial period when sea levels were relatively lower in the late Pleistocene. Conversely, it was inferred that haplotype clades of C. brevimanus diverged during or near the interglacial period when sea levels were relatively higher, and their population expansion and remixing occurred through the glacial periods in the late Pleistocene.
TL;DR: Two new species of Hyalella are described from the eastern United States and Canada, based on morphological characters but informed by genetic analyses, and an updated key to the described species in North America and the Caribbean is provided.
Abstract: Since the 1990s, it has been presumed that different populations/size classes of the freshwater amphipod Hyalella azteca (Saussure, 1858) were different species, and a multitude of genetic evidence was later produced to confirm that it is in fact a cryptic species complex However, no new species of Hyalella have been described from the eastern United States or Canada since then Herein we describe two new species, Hyalella ( Hyalella ) spinicauda and Hyalella ( Hyalella ) wellborni , collected from Illinois, Indiana, Michigan, Wisconsin, and Texas, USA, and Ontario, Canada, based on morphological characters but informed by genetic analyses In addition, we provide an updated key to the described species of Hyalella in North America and the Caribbean
TL;DR: The red swamp crayfish Procambarus clarkiiability to survive in high salinity levels was highlighted by carrying out laboratory experiments and histomorphological observations on its antennal glands, which highlighted its salinity tolerance.
Abstract: The brackish habitat colonization by the red swamp crayfish Procambarus clarkii(Girard, 1852) has aroused lively interest among many biologists. Here, we focused on its salinity tolerance by carrying out laboratory experiments and histomorphological observations on its antennal glands. Adult crayfish of similar size were subject to increasing salinity levels up to 35‰ in a recirculating system. Only one male molted, and no specimens died during the experiment (only 3 females and 1 male). The antennal gland tissue organization (mainly regarding labyrinth and nephridial tubules) in the treated crayfish showed alterations if compared with the control specimens. We never found sexual differences in both laboratory experiments and histological observations. Our data highlighted the P. clarkiiability to survive in high salinity levels. This tolerance ought to be investigated in order to improve our understanding of mechanisms driving the coastal brackish area colonization by P. clarkii.