Precence of β-Carotene and Xantophylls in two species of the genus Niphargus (Crustacea: Amphipoda)

The presence of carotenoids in the Niphargus tatrensis Wrzesniowski and Niphargus aquilex schellenbergi Karaban has been investigated. In extracts separated by means of column and thin-layer chromatography, the following carotenoids were identified:

1. in Niphargus tatrensis: β-carotene, astaxanthin ester, rubixanthin, celaxanthin and astaxanthin.
2. in Niphargus aquilex schellenbergi: cantha-xanthin, astaxanthin ester, isozeaxanthin (only from Jeker), 4-keto-4′-hydroxy-β-carotene (only from Terzietebronbos), rubixanthin, celaxanthin and astaxanthin.

It was not possible to identifity the sexth fractions.     

Studies of the male reproductive system of the amphipod Orchestia platensis Kr?yer (Crustacea: Amphipoda)

Morphological details of the testis, seminal vesicles and vas deferens of Orchestia platensis are described. The follicular lumen of the mature testis contains spermatogonia, spermatocytes, spermatids and spermatozoa. The histochemical nature of the testis and the vas deferens is elucidated. The spermatozoa and vas deferens contain acid sulphated mucopolysaccharides and neutral mucopolysaccharides. In addition, they contain basic proteins, disulphide groups, lipids, phospholipids, RNA and DNA.     

The life history,production and food habits of Pontoporeia affinis Lindström (Crustacea: Amphipoda) in mesotrophic Lake Erken

The life history and feeding habits of Pontoporeia affinis Lindström were studied in mesotrophic Lake Erken during 1982 to 1983. The greatest densities and biomasses of P. affinis occurred at 12 m (662 ind./m² and 118.2 mg dw/m², respectively) with values decreasing at the shallower and deeper regions. The life cycle of Pontoporeia was one year, with recruitment occurring in April, at which time the majority of the population consisted of individuals <2 mm. Overall the gut content of Pontoporeia was predominantly composed of detritus (97.6%) with algae accounting for 2.3%. Annual production was highest at 12 m (386.2 mg dw/m²) and lowest at 16 m (8.1). The highest production occurred during September, coinciding with the autumn Bacillariophyceae bloom.     

The effect of salinity acclimation on the ultrastructure of the gills of Gammarus oceanicus (Segerstråle, 1947) (Crustacea: Amphipoda)

Summary Acclimation to low salinity induces changes in the ultrastructure of the gill cells of the marine euryhaline amphipod, Gammarus oceanicus. The gills are composed of a single cell type. In 100% artificial sea water, these cells contain moderate numbers of mitochondria which are randomly distributed in the cytoplasm. The plasma membrane is extensively invaginated at the apical, lateral, and basal surfaces. Acclimation to 20% artificial sea water induces a further invagination at the apical cell membrane to form an elaborate apical labyrinth. The extracellular spaces between the folds in the basal cell membrane dilate to 1500 Å or more. Mitochondria are more abundant and in many cells they undergo a change in conformation. The mitochondria are crowded into thin leaflets of cytoplasm between the dilated basal invaginations or into the narrow space between apical and basal cell membranes. Consequently, they lie in close contact with the plasma membrane over much of their surface.Supported in part by grants from the United States Public Health Service, 5 RO1 AM13455-03 and PHS FR-07085-04, and by a grant from the National Research Council of Canada administered by Dr. G. P. Morris.     

The functional role of Gammarus(Crustacea, Amphipoda): shredders, predators, or both?

Gammarus spp. are traditionally viewed under the functional feeding group (FFG) concept as herbivorous `shredders'. Although recent studies suggest that Gammarus should also be viewed as predators, this latter role remains contentious. Here, in a laboratory experiment, we objectively examine the balance between shredder and predator roles in a common freshwater species. Gammarus pulex preyed significantly on mayfly nymph, Baetis rhodani, in both the presence and absence of excess leaf material. There was no significant difference in predation where the alternative food, that is, leaf material, was present as compared to absent. Also, G. pulex shredded leaf material in the presence and absence of B. rhodani. However, shredding was significantly reduced where alternative food, that is, B. rhodani prey, was present as compared to absent. Further, G. pulex had a clear leaf species preference. Our results suggest that Gammarus function as both predators and shredders, with the balance of the two roles perhaps depending on food availability and quality. We discuss implications for the use of the FFG concept in assessing freshwater processes, and the role that Gammarus predation may play in structuring macroinvertebrate communities.     

Can heterochrony help explain the high morphological diversity within the genus Niphargus (Crustacea: Amphipoda)?

Postembryonic development of nine species of Niphargus (Crustacea: Amphipoda) was studied, with spine development and shifts in allometric growth being combined in developmental sequences that were compared across species. The developmental sequences show high diversity with respect to the position of individual events in the sequence, as well as a high frequency of events being inapplicable in some species. Within Niphargus, the highest degree of independence between events occurs mainly in early mid-aged instars, where the shifts in position are both the largest in magnitude and also the most frequent in occurrence. Constructive troglomorphic features of subterranean species were inferred to develop more because of accelerated growth rather than a delayed offset of growth. Shifts in both relative timing and growth rate appeared to have played a role in the evolution of sexually dimorphic elongated appendages. Growth patterns differed greatly between species for individual sexually dimorphic and troglomorphic traits, hinting at their possible independent origin. The independence between developmental events that was generally apparent might indicate the existence of an important genetic basis for the extreme intrageneric morphological variation arising from numerous highly variable body parts being combined in a ‘mosaic’ manner. Moreover, we suggest that the overall diversity of the genus might actually be underestimated in light of possible convergent features accompanied by ‘cryptic’ speciation. We conclude that both sequential and growth heterochrony appear to have played a key role in the evolution of Niphargus, the most diverse genus of freshwater amphipods. A preliminary list of heterochronic characters is provided.     

The juxtaposed compound eye and organ of Bellonci in Haploops tubicola (Crustacea: Amphipoda) — The fine structure of the organ of Bellonci

Summary The amphipod species Haploops tubicola has an unusual compound eye that is divided into three separate parts, each with one common cuticular lens. The dorso-frontal eyepair has, in addition to the lens, a so-called vitreous body, which is constructed like a dioptric lens and is inserted in the ray-path. The vitreous body is actually — and for which evidence is presented — a secretory product formed in the intercellular spaces of the organ of Bellonci. Histochemical analysis has shown that the secretion is strongly PAS-positive and lacks glycogen.     

Classification of amphipod compound eyes — The fine structure of the ommatidial units (Crustacea,Amphipoda)

Summary The ultrastructure of the compound eyes of 13 amphipod species has been investigated. An amphipod type of compound eye can be characterized by the constellation and consistency of a number of morphological features, most of which are also found in other compound eyes. The amphipod eye falls into four sub-categories (types). The ampeliscid type has a tripartite aberrant lens eye; the lysianassid type has a reduced or no dioptric apparatus and a hypertrophied rhabdom; the hyperid type possesses a large number of ommatidial units with long crystalline cones and dark instead of reflecting accessory pigment; and finally, the gammarid type can be interpreted as a generalized amphipod type. The lysianassid type is adapted to low light intensities and demonstrates convergent development with the compound eyes of other deep-sea crustaceans. The ampeliscid type is more similar to the gammarid type. The type characterization of the amphipod compound eye might well serve as a basis and incentive for functional studies also revealing adaptational mechanisms.This paper is dedicated to Professor Erik Dahl on his 65th birthday and retirement from the Chair of Structural Zoology, Department of Zoology, University of LundThe investigation has been supported by grants from the Swedish Natural Science Research Council (Grants 2760-009 and 009-43). Our thanks are due to the staffs of the marine biological stations in Espegrend (Norway) and Kristineberg (Sweden) and of the research vessel Jean Charcot, Brest, France. The skilled technical assistance of Mrs. Rita Wallén and Miss Maria Walles is gratefully acknowledged     

The association between the caprellid Pariambus typicus Krøyer (Crustacea,Amphipoda) and ophiuroids

The work of Kazutsugu Hirayama over the past 25 yearspromoted the wide use of the marine rotifer Brachionusplicatilis as an experimental model in zooplanktonecology. His reports about the nature of geneticvariation in the B. plicatilis complex stimulated usto investigate how mate recognition maintains speciesboundaries. For the past several years, we haveexamined chemical communication between female andmale B. plicatilis. Here we report on the comparativebinding of polyclonal antibody against the materecognition pheromone (MRP) to three B. plicatilisstrains and three B. rotundiformis strains.Quantification of anti-MRP binding permitsinvestigation of how the female mating signal differsamong closely related Brachionus species and strains.Antibody binding reflects differentiation independentof the male receptor which has been describedelsewhere. Anti-MRP bound to females of all sixstrains and was localized in the corona. Antibodybinding greatly reduced mating in all three B. plicatilis strains. However, antibody bindingsignificantly reduced mating in only one of the B. rotundiformis strains. The MRP of both species has asimilar molecular weight, but the differential bindingsuggests that the mate recognition pheromone onfemales has differentiated in B. plicatilis and B. rotundiformis.     

Tolerance, optimum ranges, and ecological requirements of freshwater Ostracoda (Crustacea) in Lake Aladağ (Bolu, Turkey)

During monthly sampling from Lake Alada (Bolu, Turkey) between April 2003 and June 2004, nine ostracod taxa (Candona candida, Cypridopsis vidua, Darwinula stevensoni, Eucypris virens, Eucypris sp., Heterocypris sp., Limnocythere inopinata, Physocypria kraepelini, and Tonnacypris lutaria) were recorded from seven stations. Physocypria kraepelini was commonly found in the lake while the others were recorded in particular months. UPGMA analyses clustered three groups based on their occurrence. Accordingly, the occurrence of species (C. candida, E. virens, and T. lutaria) was positive and significantly related to each other. Two species, P. kraepelini and D. stevensoni, showed a significant positive relationship with electrical conductivity. A significant negative correlation was found between the occurrence of P. kraepelini and dissolved oxygen, while there was a significant positive correlation between the occurrence of P. kraepelini and turbidity. About 76% of the relationship between species and environmental factors was explained by the first two axes of canonical correspondence analyses (CCA). Temperature and dissolved oxygen were the two most important influences on the species assemblages. All species showed different but high optima and tolerance ranges, corresponding with their cosmopolitan characteristics. These responses may be related to unstable ecological characteristics of Lake Alada, which is often subjected to human activity.     

Neurogenesis in the developing visual system of the branchiopod crustacean Triops longicaudatus (LeConte, 1846): corresponding patterns of compound-eye formation in Crustacea and Insecta?

In the discussion on arthropod phylogeny, the structural evolution of compound eyes and optic ganglia in Crustacea and Insecta is an important topic. On the one hand, many morphological features as well as developmental aspects of the visual system in Insecta and Crustacea correspond in so much detail that eye design in these two groups is likely to have a common euarthropodan ancestor. On the other hand, however, some authors advocate a convergent evolution of the crustacean and insect visual system founding their arguments on differences in the arrangement of the visual neuropils and the fibre connections between Malacostraca and Entomostraca (the "entomostracan enigma"). Therefore, information about cellular aspects of visual system formation in entomostracan Crustacea is likely to enliven this debate, but is not yet available. To fill this gap, we examined the proliferation of neuronal stem cells in the developing visual system of the tadpole shrimp Triops longicaudatus (LeConte, 1846) (Entomostraca, Branchiopoda, Phyllopoda, Calmanostraca, Notostraca) by in vivo incorporation of the proliferation marker bromodeoxyuridine and subsequent immunohistochemical detection. Our results indicate that in the developing visual system of T. longicaudatus, three band-shaped zones containing neuronal stem cells are present corresponding to the proliferation zones found in Malacostraca. We therefore conclude that the ontogenetic mechanisms of visual-system formation are evolutionarily conserved (homologous) in Branchiopoda, Malacostraca, and Insecta.     

The development of the nervous system in Laevicaudata (Crustacea, Branchiopoda): insights into the evolution and homologies of branchiopod limbs and ‘frontal organs’

We investigated the development of the external morphology and of the nervous system in Lynceus biformis and Lynceus brachyurus (Laevicaudata, Branchiopoda), by using immunohistochemical methods in combination with a confocal laser scanning analysis. In both Lynceus species, a free-swimming nauplius larva, equipped with three appendages, hatches from resting eggs. Despite their close phylogenetic relationship to each other, considerable differences are present in their external morphology. Hatching L. brachyurus larvae are equipped with a large and flattened labrum, where in contrast, the L. biformis larvae possess a smaller labrum with four conspicuous posteriorly directed spines at its margin. Despite these differences, the development of the nervous system is quite similar in both species. The hatching larvae are equipped with a naupliar nervous system, and only in the more advanced stages, the development of the ventral nerve cord starts. Furthermore, our investigation into the nervous system provided insights into architecture and evolution of protocerebral sensory organs, the dorsal setae field and the dorsal frontal organ, only present in Laevicaudata. The identification of frontal filaments with an associated frontal filament organ in Lynceus revealed—after a comprehensive comparison with other branchiopods—that these organs exist throughout Branchiopoda and are comparable to those in other crustaceans. Additionally, our results of the peripheral nervous system analysis showed that the innervation pattern of the naupliar appendages (antenna and mandible) and the trunk appendages could be serially homologized, despite much difference in gross morphology of these. Based on the innervation pattern of limbs, we suggest that the larval uniramous mandibular palp, found in the larvae of all ‘large’ branchiopods, is largely exopodal of nature (contrary to most earlier statements) and that the endopodite of the trunk limbs consists of only one distal endite-like segment (confirming some earlier statements) and not of three as proposed by others.     

Dolichopodidae (Diptera) of a Nymphaeid‐Dominated system in the Netherlands: Species composition,diversity, spatial and temporal distribution

The composition of the Dolichopodid fauna was studied at various sites within nymphaeid stands during one growth season in an oxbow lake with the aid of adhesive traps; additional observations were made by means of hand-net collecting at various localities within nymphaeid stands. The first method gave the best results.

With this method the species composition, diversity, spatial and temporal distribution of the Dolichopodid fauna within nymphaeid stands could be described.

Nine species appeared to be common, viz. )in order of decreasing numbers( Hydrophorus praecox )Lehm.(, Dolichopus latilimbatus Mcq.¹(, Campsicnemus picticornis )Zett.(, Rhaphium antennatum )Carl.(, Dolichopus nubilus Mg., Hydrophorus litoreus Fall., Campsicnemus pectinulatus Lw., Campsicnemus lumbatus Lw. and Rhaphium elegantulum )Mg.(. With respect to the spatial distribution within the nymphaeid zone both Hydrophorus species were found in large numbers on sites bordering on the open water, while the largest numbers of all other species mentioned above were caught on sites near the helophyte zone. A distinct succession of Dolichopodid species with respect to their numbers could be observed during the growth season on the floating leaves in the sequence Hydrophorus, Campsicnemus, Rhaphium and Dolichopus spp.

The reasons for these distribution patterns are discussed on the basis of what is known of the ecology and behaviour of the various species.     

Spatial analyses of the phylogenetic diversity of Minaria (Apocynaceae): assessing priority areas for conservation in the Espinhaço Range,Brazil

The protection of areas that shelter high evolutionary diversity represented by geographically and phylogenetically isolated lineages is becoming an important conservation strategy. Nevertheless, the spatial distribution of this component of biodiversity is still unknown for most groups, which limits its application for selecting priority areas to conserve. In the present study, we reconstructed the phylogeny of Minaria (Apocynaceae) based on plastid (trnH-psbA, rps16, trnS-trnG and trnD-trnT) and nuclear (ITS and ETS) DNA markers and 34 morphological characters, and analysed the geographic distribution of the phylogenetic diversity (PD) and endemism (PE) in this genus. Minaria includes 21 species that are highly concentrated in the Espinhaço Range, in eastern Brazil, most of which (～75%) are narrowly distributed. The spatial analyses of PD and PE of Minaria indicate four evolutionary relevant areas in this region. The Serra do Cipó and the Diamantina Plateau contain 10 endemic species and present the highest levels of PD. However, the two other areas also deserve special attention. Rio de Contas has high levels of PE, because of two endemic sister species that represent a phylogenetically isolated lineage and the Southern Espinhaço Range houses the most critically endangered species of the genus. Most endemic species of Minaria occur in vegetation islands on rocky outcrops (campos rupestres). These low-fuel areas are less susceptible to fire, suggesting that the Espinhaço Range has served as a historical refuge for fire-sensitive lineages. Our results suggest that conservation units in the Espinhaço Range cover a great proportion of the evolutionary diversity of Minaria and that fire management is probably an important strategy to preserve this endemic biodiversity.     

Taxonomic and ecological remarks on boring sponges (Clionidae) from the Straits of Gibraltar (southern Spain): tentative bioindicators?

An important programme of biomonitoring along the coast of Algeciras Bay (Straits of Gibraltar) has allowed us tentatively to consider six species of boring sponges of the genus Cliona as biological indicators: Cliona celata, C. viridis, C. rhodensis, C. vermifera, C. schmidti and C. vastifica. The taxonomy and distribution of these species have been considered in this paper. Ecological observations have permitted us to identify some important characteristics of their habitat on the basis of local environmental parameters. Cliona viridis and C. celata withstand sedimentation higher than 7 gr/m² and a solid suspension of 38 mg/1. Cliona vermifera and C. schmidti did not tolerate sedimentation higher than 1 gr/m². One of these, C. vermifera Hancock, is recorded for the first time in the Iberian Peninsula.     

Localization of monoaminergic neurons in the central nervous system of Astacus astacus Linné (Crustacea)

Summary The cellular localization of biogenic monoamines in crustaceans was studied by means of a highly specific and sensitive fluorescence method devised by Falck and Hillarp. It was found that neurons displaying specific fluorescence in the central nervous system were confined to the protocerebrum, the medulla externa and interna and the ventral nerve cord. The method allows a distinction between the fluorophores of 5-hydroxytryptamine (and 5-hydroxytryptophan), which emit the yellow light, and the fluorophores deriving from the catecholamines (and DOPA), which emit the green light. Green-fluorescent neurons occurred abundantly in the aforementioned parts of the central nervous system while yellow-fluorescent neurons were sparsely present in the same parts.The present work has been carried out at the departments of Histology and Zoology at the University of Lund. The authors take great pleasure in expressing their warmest thanks for laboratory facilities, provided by Professors Erik Dahl (Zoological Institute) and Bengt Falck (Histological Institute).The research reported in this document has been sponsored by the Air Force Office of Scientific Research under Grant AF EOAR 66-14 through the European Office of Aerospace Research (OAR), United States Air Force and by a grant from the Swedish Natural Science Research Council 99-32 (nr 5995).     

Distribution and diversity of desmosomatid and nannoniscid isopods (Crustacea) on the Greenland–Iceland–Faeroe Ridge

The distribution and diversity of isopods (Crustacea, Isopoda; families Desmosomatidae Sars, 1897 and Nannoniscidae Hansen, 1916) was examined in Icelandic waters where a diversity of water masses (temperature range −0.9 to 12°C) occurs and the topography is characterized by the large and shallow Greenland–Iceland–Faeroe (GIF) Ridge extending across the North Atlantic in an east-west direction. Both families were species rich in the area, in total occurring with 34 species in 20 genera. Most of the species were restricted either to the north (10) or to the south (14) of the GIF Ridge, occurring either in cold (−0.8 to 2.8°C) or warm (>2°C) water masses. Five species were found on both sides of the Ridge, occurring at a wide range of temperatures (−0.9 to >4°C), while another five species extend across the GIF Ridge. Most species occurred in two and more water masses and the species north of the Ridge occurred usually within narrower temperature range than the species living south of the Ridge. The water masses in association with the Ridge seem to limit distribution of most species. Despite similar number of species occurring in the areas north and south of the Ridge, the areas differ considerably in diversity pattern with depth.     

Das Schwimmen der Talitridae (Crustacea,Amphipoda): Funktionsmorphologie,Phänomenologie und Energetik

The Talitridae, well-known for their jumping behaviour, swim with help of the tail-flip. This movement of the abdomen is also known from other amphipods like the Gammaridae which are normally not able to move by jerks outside the water. The suspected homology between the tail-flip when swimming and the jerky movement of the abdomen when jumping gave rise to this investigation, mainly based on high frequency film recordings, on the swimming ofHyale nilssonii, Orchestia cavimana, andTalitrus saltator (family Talitridae) as well as three related species of the families Gammaridae and Corophiidae. Comparative morphometrical and SEM-studies on the habitus of the species and the build of the involved limbs reveal the rather uniform construction of the Gammaridea; functional adaptation to the environment and to the way of living become apparent in minor alterations. The joints of the pleopods and uropods show a clear structural adaptation to the mechanical strain during swimming. The pleopods are moved metachronally in all examined species; angular velocity and rate of beating indicate the efficiency of the swimming movement. In the Talitridae, the metachronal beat of the pleopods is nearly always coupled with the tail-flip while in the Gammaridae and Corophiidae the tail-flip, in addition to the beat of the pleopods, is mostly used for a start from the subsoil or for a change in swimming direction.H. nilssonii, Gammarus locusta, andCorophium volutator, all inhabitants of the tidal zone in the North Sea shallows, turned out to be the best swimmers while the (semi-) terrestrially living species,O. cavimana andT. saltator, proved to be rather poor swimmers. This clearly indicates the ecological significance of swimming for the different species. Furthermore, the tailflip is found to be of rather subordinate importance. It contributes to a higher velocity if used moderately but is rather obstructive if a large angle is covered while extending and flexing the abdomen. The efficiency of swimming is inversely proportional to the efficiency of jumping in the three talitridean species. Thus, better adaptation to terrestrial life is accompanied by loss of swimming efficiency. Examined under the aspect of locomotional homology, it is concluded that the tail-flip used while swimming is homologous to the jerky movement of the abdomen used for jumping. The comparison of the swimming performance of the examined species with other crustaceans and some fishes illustrates the over-all good results of the Gammaridea.