01529nas a2200157   4500008004100000245012800041210006900169260000800238300001000246490000800256520099900264100002001263700002101283700001801304856004901322       2004                        eng d00aMorphometric analysis of the larval branchial chamber in the dragonfly Aeshna cyanea Müller (Insecta, Odonata, Anisoptera)0 aMorphometric analysis of the larval branchial chamber in the dra  cJul  a81-910 v2613 aThe aquatic larvae of anisopteran dragonflies possess tracheal gills located in the rectum. Using stereological methods, we estimated the morphometric diffusing capacity for oxygen (D(MO2)) across the gill epithelium, i.e., from rectal water to the gill tracheoles, in the larvae of Aeshna cyanea. A 271-mg larva has a total branchial surface area of approximately 12 cm(2). Tracheoles make up 6% of the epithelial volume of the gills; the harmonic mean thickness of the water-tracheolar diffusion barrier is 0.27 microm and consists mainly of cuticle. The calculated D(MO2) is 23.0 microl min(-1) g(-1) kPa(-1), which, using published values for oxygen consumption in a similar species, would result in a mean driving pressure of 0.2 kPa at rest and 1.3 kPa during activity. Since these driving pressures are similar to those reported for other arthropods, we conclude that the D(MO2) of the gill is not rate-limiting for aerobic metabolism in Aeshna cyanea larvae. J Morphol. 261:81-91, 2004.1 aKohnert, Stefan1 aPerry, Steven, F1 aSchmitz, Anke  uhttps://worldodonata.myspecies.info/node/26102112nas a2200145   4500008004100000245009400041210006900135260000800204300001000212490000700222520163600229100003201865700002001897856004901917       2004                        eng d00aRelative sensitivity distribution of aquatic invertebrates to organic and metal compounds0 aRelative sensitivity distribution of aquatic invertebrates to or  cJan  a150-60 v233 aIn the field, a multitude of species can be exposed to numerous toxicants; thus, the sensitivity of individual species to particular toxicants must be known to predict effects and to analyze changes in species composition. For most species, no information about their toxicant sensitivity is available. To address this limitation, we have grouped the available information to assign sensitivities to aquatic invertebrate taxa relative to Daphnia magna. With respect to organic compounds, most taxa of the orders Anisoptera, Basommatophora, Coleoptera, Decapoda, Diptera, Ephemeroptera, Eulamellibranchiata, Heteroptera, Hirudinea, Isopoda, Oligochaeta, Prosobranchia, Trichoptera, Tricladida, and Zygoptera are less sensitive than D. magna. Some taxa of the Amphipoda, Plecoptera, and Cladocera (other than D. magna) are significantly more sensitive. For organic compounds, approximately 22% of the investigated taxa were more sensitive than D. magna. Most taxa of the orders Amphipoda, Basommatophora, Diptera, Ephemeroptera, Eulamellibranchiata, Heteroptera, Isopoda, Oligochaeta, and Tricladida are significantly less sensitive than D. magna to metal compounds. The taxa belonging to the Crustacea, with the exception of the order Isopoda, are much more sensitive. For metal compounds, approximately 30% of the investigated taxa were more sensitive than D. magna. Hence, D. magna is among the most sensitive taxa regarding both groups of toxicants. The sensitivities for several taxa are listed, and use of the relative sensitivity distribution to link toxicant effects in mesocosm studies and field investigations is discussed.1 avon der Ohe, Peter, Carsten1 aLiess, Matthias  uhttps://worldodonata.myspecies.info/node/26202350nas a2200181   4500008004100000245012600041210006900167260000800236300001200244490000700256520176700263100001602030700002002046700001902066700001502085700001902100856004902119       2004                        eng d00aMolecular and ecological evidence for small-scale isolation by distance in an endangered damselfly, Coenagrion mercuriale0 aMolecular and ecological evidence for smallscale isolation by di  cOct  a2931-450 v133 aCoenagrion mercuriale (Charpentier) (Odonata: Zygoptera) is one of Europe's most threatened damselflies and is listed in the European Habitats directive. We combined an intensive mark-release-recapture (MRR) study with a microsatellite-based genetic analysis for C. mercuriale from the Itchen Valley, UK, as part of an effort to understand the dispersal characteristics of this protected species. MRR data indicate that adult damselflies are highly sedentary, with only a low frequency of interpatch movement that is predominantly to neighbouring sites. This restricted dispersal leads to significant genetic differentiation throughout most of the Itchen Valley, except between areas of continuous habitat, and isolation by distance (IBD), even though the core populations are separated by less than 10 km. An urban area separating some sites had a strong effect on the spatial genetic structure. Average pairwise relatedness between individual damselflies is positive at short distances, reflecting fine-scale genetic clustering and IBD both within- and between-habitat patches. Damselflies from a fragmented habitat have higher average kinship than those from a large continuous population, probably because of poorer dispersal and localized breeding in the former. Although indirect estimates of gene flow must be interpreted with caution, it is encouraging that our results indicate that the spatial pattern of genetic variation matches closely with that expected from direct observations of movement. These data are further discussed with respect to possible barriers to dispersal within the study site and the ecology and conservation of C. mercuriale. To our knowledge, this is the first report of fine-scale genetic structuring in any zygopteran species.1 aWatts, P, C1 aRouquette, J, R1 aSaccheri, I, J1 aKemp, S, J1 aThompson, D, J  uhttps://worldodonata.myspecies.info/node/25601935nas a2200181   4500008004100000245009600041210006900137260000800206300001200214490000800226520137800234100002301612700001801635700001601653700001701669700001801686856004901704       2004                        eng d00aMechanisms and significance of reduced activity and responsiveness in resting frog tadpoles0 aMechanisms and significance of reduced activity and responsivene  cMar  a1113-250 v2073 aHatchling Xenopus laevis tadpoles spend most of their time attached to objects or the water surface by mucus secreted by a gland on the head. While attached, swimming activity and responsiveness to swim-initiating stimuli are reduced over long periods of time. We have investigated the mechanisms and significance of this apparent long-term inhibition. In behavioural experiments we show, firstly, that innervation of the cement gland and GABA(A)-mediated inhibition are necessary for attachment to reduce responsiveness, and secondly, that denervation of the cement gland increases tadpole activity and increases their predation by damselfly nymphs (Zygoptera). To investigate the neuronal pathway from the cement gland to GABA(A) inhibition, we have devised an immobilized, inverted tadpole preparation where a weight attached to the mucus simulates the force as it hangs. Simulated attachment reduces responsiveness and spontaneous fictive swimming activity. We have recorded the activity and responses of trigeminal neurons innervating the cement gland. They are spontaneously active and simulating attachment results in a sustained increase in this activity. We propose that hanging from a mucus strand increases firing in cement gland afferents. This leads to tonic GABA inhibition that reduces tadpole activity and responses, and leads to fewer attacks by predators.1 aLambert, Thomas, D1 aHoward, Jenny1 aPlant, Andy1 aSoffe, Steve1 aRoberts, Alan  uhttps://worldodonata.myspecies.info/node/25701258nas a2200145   4500008004100000245014300041210006900184260000800253300001100261490000700272520074000279100002301019700002101042856004901063       2004                        eng d00aA phylogenetic perspective on larval spine morphology in Leucorrhinia (Odonata: Libellulidae) based on ITS1, 5.8S, and ITS2 rDNA sequences0 aphylogenetic perspective on larval spine morphology in Leucorrhi  cMar  a653-620 v303 aLeucorrhinia (Odonata, Anisoptera, Libellulidae) consists of 14-15 species with a holarctic distribution. We have combined the morphological characters of a previous study with sequence data from the ITS1, 5.8S rDNA, and ITS2 regions of the nuclear ribosomal repeat. Cloning was used to investigate the intra-individual variation and such variation was found in all investigated species. Parsimony jackknifing was used to identify supported groups. The effect of sequence alignment and gap coding was explored by a modified sensitivity analysis. Loss of spines in Leucorrhinia larvae has occurred twice: once in Europe and once in North America. The role of spines as a defence against predation is discussed in a phylogenetic context.1 aHovmöller, Rasmus1 aJohansson, Frank  uhttps://worldodonata.myspecies.info/node/25801780nas a2200157   4500008004100000245013100041210006900172260000800241300001200249490000800261520125300269100001501522700001801537700001801555856004901573       2004                        eng d00aRemarkable iridescence in the hindwings of the damselfly Neurobasis chinensis chinensis (Linnaeus) (Zygoptera: Calopterygidae)0 aRemarkable iridescence in the hindwings of the damselfly Neuroba  cMar  a595-6010 v2713 aThe bright green dorsal iridescence of the hindwings of Neurobasis chinensis chinensis males, very rare in Odonata, is known to play a significant role in their courtship behaviour. The mechanism responsible for such high contrast and spectrally pure colour has been investigated and found to be optical interference, producing structural colour from distinct laminations in the wing membrane cuticle. The ventral sides of these iridescent wings are dark brown in colour. In a single continuous membrane of wing cuticle, this is an effect that requires a specialized structure. It is accomplished through the presence of high optical absorption (kappa = 0.13) within two thick layers near the ventral surface of the wing, which leads to superior dorsal colour characteristics. By simultaneously fitting five sets of optical reflectivity and transmissivity spectra to theory, we were able to extract very accurate values of the complex refractive index for all three layer types present in the wing. The real parts of these are n = 1.47, 1.68 and 1.74. Although there is often similarly significant dorsal and ventral colour contrast in other structurally coloured natural systems, very few system designs comprise only a single continuous membrane.1 aVukusic, P1 aWootton, R, J1 aSambles, J, R  uhttps://worldodonata.myspecies.info/node/25902121nas a2200169   4500008004100000245009700041210006900138260000800207300001000215490000800225520159000233100001801823700002301841700001901864700001901883856004901902       2004                        eng d00aIntraguild predation and interference competition on the endangered dragonfly Aeshna viridis0 aIntraguild predation and interference competition on the endange  cJun  a135-90 v1403 aWe examined the effects of intraguild predation (IGP) and interference competition on an endangered dragonfly, Aeshna viridis Eversm. (Odonata: Anisoptera). A. viridis is rare in Europe due to the decrease in suitable habitats harboring the macrophyte Stratiotes aloides L. Stratiotes plants are the principal oviposition substrate for A. viridis females and protect the larvae of A. viridis from fish predation. In our study lakes A. viridis larvae are sympatric with larvae of Aeshna grandis and Aeshna juncea. The susceptibility of A. viridis larvae to IGP by similar-sized larvae of A. grandis and A. juncea was tested in a laboratory predation experiment. Microhabitat use of A. viridis and A. grandis was studied in the laboratory to determine the possible effects of interference competition on the spatial distribution of A. viridis larvae. Our results show that at least in laboratory conditions, A. viridis is susceptible to IGP and interference competition. In competition, A. grandis larvae dominated the middle and outer portion of S. aloides rosettes whereas A. viridis stayed in the inner parts. When A. grandis larvae were absent, A. viridis colonized the middle and outer parts of the rosettes. We conclude that asymmetric predation between odonate larvae of equal size can be intense, and that both IGP and interference competition affect A. viridis. Although natural habitat complexity diminishes their impact, these interactions may nevertheless influence the distribution of A. viridis in S. aloides waters and restrict its microhabitat use in S. aloides rosettes.1 aSuutari, Erna1 aRantala, Markus, J1 aSalmela, Jukka1 aSuhonen, Jukka  uhttps://worldodonata.myspecies.info/node/260