Libellula Quadrimaculata Research Articles

Ecological and distribution traits of the large white-faced darter Leucorrhinia pectoralis (Charpentier, 1825) in Slovakia

Abstract The dragonfly Leucorrhinia pectoralis was recorded in Slovakia at 38 sites in 112 findings and there were 707 imagoes. Reproduction was confirmed in seven sites by finding of 35 larvae and exuviae. The highest number of sites with the occurrence of L. pectoralis is located in the Záhorská nížina lowland; most sites in Slovakia are located at an altitude of 213–351 m. L. pectoralis was recorded together with 49 species of dragonflies, and the average number of L. pectoralis was 9.56 individuals per site. It occurs in the communities as a dominant species (9.5%) together with eudominants Coenagrion puella, C. hastulatum and Libellula quadrimaculata. By non-metric multidimensional scaling (NMDS), we found a coenotic correlation to peat species Libellula quadrimaculata, Leucorrhinia rubicunda, L. dubia and Sympetrum danae. By redundancy linear analysis (RDA), we found a Monte Carlo permutation test to make a non-random contribution to the explained variability of seven factors (p = 0.012–0.034). L. pectoralis statistically significantly prefers habitats in the forest landscape (r = 0.62, p = 0.0063), the presence of vegetation (r = 0.94, p = 0.0003) and peatbogs (r = 0.61, p = 0.0058). We did not confirm a significant correlation to altitude. Based on easy determination, territoriality (especially males) and bioindicative sensitivity of larvae, L. pectoralis is accepted as an umbrella species. L. pectoralis has a high dispersion potential and is suitable for creating the meta-population character of local populations, which is important for the conservation management of the species.

Comparative phylogeography uncovers evolutionary past of Holarctic dragonflies

Here, we investigate the evolutionary history of five northern dragonfly species to evaluate what role the last glaciation period may have played in their current distributions. We look at the population structure and estimate divergence times for populations of the following species: Aeshna juncea (Linnaeus), Aeshna subarctica Walker, Sympetrum danae (Sulzer), Libellula quadrimaculata Linnaeus and Somatochlora sahlbergi Trybom across their Holarctic range. Our results suggest a common phylogeographic pattern across all species except for S. sahlbergi. First, we find that North American and European populations are genetically distinct and have perhaps been separated for more than 400,000 years. Second, our data suggests that, based on genetics, populations from the Greater Beringian region (Beringia, Japan and China) have haplotypes that cluster with North America or Europe depending on the species rather than having a shared geographic affinity. This is perhaps a result of fluctuating sea levels and ice sheet coverage during the Quaternary period that influenced dispersal routes and refugia. Indeed, glacial Beringia may have been as much a transit zone as a refugia for dragonflies. Somatochlora sahlbergi shows no genetic variation across its range and therefore does not share the geographic patterns found in the other circumboreal dragonflies studied here. Lastly, we discuss the taxonomic status of Sympetrum danae, which our results indicate is a species complex comprising two species, one found in Eurasia through Beringia, and the other in North America east and south of Beringia. Through this study we present a shared history among different species from different families of dragonflies, which are influenced by the climatic fluctuations of the past.

Predation risk and habitat complexity modify intermediate predator feeding rates and energetic efficiencies in a tri‐trophic system

Abstract To understand the effects of environmental changes on ecosystems, it is important to determine the factors and mechanisms influencing the strength of species interactions in food webs. However, joint effects of predation risk and additional environmental factors on species interaction strengths in multitrophic systems remain largely unexplored, leaving a substantial gap in our understanding of the links between local environmental characteristics and food web properties. To fill this gap, we investigated the effects of habitat complexity and predation risk by top predatory dragonfly larvae (Aeshna cyanea) on feeding rates and energetic efficiency (i.e. the ratio of acquired and expended energy) of the larvae of three intermediate predatory odonate species (Libellula quadrimaculata, Sympetrum sanguineum, and Ischnura elegans) preying on cladocerans. We hypothesised that predation risk would decrease the feeding rate, especially in the structurally simple habitat, and increase the metabolic rate of all intermediate predators. We also expected higher feeding rates of intermediate predators using aquatic vegetation as a perching site (i.e. Sympetrum and Ischnura) in the structurally complex habitat. Finally, we expected to observe habitat‐ and predation risk‐dependent energetic efficiencies of the intermediate predators driven by changes in feeding and metabolic rates. The effect of predation risk on feeding rates was species specific and differed between the structurally simple and complex habitat. Habitat complexity increased feeding rates but only in the absence of predation risk. Moreover, predation risk signalled by chemical cues significantly increased Sympetrum vulgatum feeding rates but did not influence the feeding rates of the two other intermediate predators. Metabolic rates varied among the three intermediate predators but were not affected by predation risk. Estimated energetic efficiency decreased with intermediate predator body mass and depended, to a lesser extent, on the interactive effect of habitat complexity and predation risk. Our results imply that the effects of habitat complexity and predation risk on trophic interactions are likely to be determined by traits related to foraging and defence of the intermediate predators and their habitat domains, and that energetic efficiency is mainly determined by predator mass. Given that habitat complexity and predation risk can vary substantially across habitats, we conclude that it is important to consider habitat complexity and predation risk to better understand and predict the effects of environmentally driven variations on trophic interaction strength and metabolic rates that underlie the energetic efficiency of individual consumers. This has important implications for population and community dynamics as well as ecosystem functioning.

Changes in hemolymph total CO2 content during the water-to-air respiratory transition of amphibiotic dragonflies.

Dragonflies (Odonata, Anisoptera) are amphibiotic; the nymph is aquatic and breathes water using a rectal gill before metamorphosing into the winged adult, which breathes air through spiracles. While the evolutionary and developmental transition from water breathing to air breathing is known to be associated with a dramatic rise in internal CO2 levels, the changes in blood-gas composition experienced by amphibiotic insects, which represent an ancestral air-to-water transition, are unknown. This study measured total CO2 (TCO2) in hemolymph collected from aquatic nymphs and air-breathing adults of Anax junius, Aeshna multicolor (Aeshnidae), Libellula quadrimaculata and Libellulaforensis (Libellulidae). Hemolymph PCO2 was also measured in vivo in both aeshnid nymphs and marbled crayfish (Procambarus fallax. f. virginalis) using a novel fiber-optic CO2 sensor. The hemolymph TCO2 of the pre- and early-final instar nymphs was found to be significantly lower than that of the air-breathing adults. However, the TCO2 of the late-final instar aeshnid nymphs was not significantly different from that of the air-breathing adults, despite the late-final nymphs still breathing water. TCO2 and PCO2 were also significantly higher in the hemolymph of early-final aeshnid nymphs compared with values for the water-breathing crayfish. Thus, while dragonfly nymphs show an increase in internal CO2 as they transition from water to air, from an evolutionary standpoint, the nymph's ability to breathe water is associated with a comparatively minor decrease in hemolymph TCO2 relative to that of the air-breathing adult.

FAUNA VILINIH KONJICA (ODONATA) PLANINE ZELENGORA I NACIONALNOG PARKA SUTJESKA

Visokoplaninska staništa u Bosni i Hercegovini (BiH) su često izolovana i teško pristupačna, zbog čegaje njihova fauna vilinih konjica sve do danas ostala gotovo potpuno neistražena. Cilj ovog rada bio jedati prvi pregled faune vilinih konjica Zelengore i Nacionalnog parka Sutjeska, jednog od odonatološkinajznačajnijih područja u zemlji.U fauni vilinih konjica Zelengore i NP Sutjeska registrovano je ukupno 35 vrsta, što predstavlja 55%faune ovog reda insekata u BiH. U rad su, uz podatke istraživanja provedenih u 2015. i 2016. godini,uključeni i neobjavljeni podaci autora prikupljeni između 2009. i 2014. godine, literaturni podaci tepodaci muzejskih kolekcija Zemaljskog muzeja BiH. Prikupljeno je ukupno 457 nalaza sa 53 lokaliteta,od čega je preko 76% novih podataka. Prema broju lokaliteta najzastupljenije vrste na istraživanomprostoru su: Cordulegaster bidentata Selys, 1843 (26), Cordulia aenea (Linnaeus, 1758) (23), Aeshnagrandis (Linnaeus, 1758) (15), Libellula quadrimaculata Linnaeus, 1758 (15) i Enallagma cyathigerum(Charpentier, 1840) (14), dok su lokaliteti sa najvećim brojem vrsta: Orlovačko jezero (22), Gornje Bare(20) i Donje Bare (19). Ova jezera su ujedno i lokaliteti sa najvećim brojem ugroženih i zaštićenih vrsta.Najznačajnije pronađene vrste su: Coenagrion scitulum (Rambur, 1842), Coenagrion hastulatum (Charpentier,1825), A. grandis, Aeshna juncea (Linnaeus, 1758), Somatochlora metallica (Vander Linden,1825), Cordulegaster heros Theischinger, 1979, C. bidentata i Sympetrum flaveolum (Linnaeus, 1758).Za reliktne vrste, C. hastulatum i S. metallica, planinska jezera Zelengore su jedino poznato stanište uBiH. Za vrste A. grandis i A. juncea ova jezera predstavljaju najznačajnija staništa u zemlji. Među registrovanimvrstama, 30 se nalazi na Crvenoj listi zaštićenih vrsta u Republici Srpskoj, a registrovane su i svetri vrste navedene na Crvenoj listi Federacije BiH. Cordulegaster heros je vrsta sa Dodatka II i IV Direktiveo staništima Evropske unije i ranjiva (VU) vrsta Mediterana.

Export of biomass and metals from aquatic to terrestrial ecosystems via the emergence of dragonflies (Insecta: Odonata)

Long-term monitoring of the abundance and spatial distribution of 18 widespread species of Odonata has made it possible to assess their contribution to the export of aquatic productivity that entered the Barabinsk forest-steppe ecosystem. The annual emergence of Odonata varies from 0.8 to 4.9 g/m2 of the land area and from 2.3 to 13.3 g/m2 of the water area, which is 4–5 times larger than that in Diptera. The total flux of organic matter from water to terrestrial ecosystems remains relatively stable (sixfold interannual variability) irrespective of large interannual variations in the abundance of separate species (e.g., 42-fold interannual variability in Libellula quadrimaculata). The metal content was determined in nine Odonata species. Export of metals by dragonflies decreases in the series K > Na > Mg > Ca > Fe > Zn > Cu > Mn > Pb > Ni > Cr > Cd. Therefore, odonates appear to be quantitatively and qualitatively important providers of aquatic resources to the forest-steppe landscape of Western Siberia.

Identification of diverse circular single-stranded DNA viruses in adult dragonflies and damselflies (Insecta: Odonata) of Arizona and Oklahoma, USA

Next generation sequencing and metagenomic approaches are commonly used for the identification of circular replication associated protein (Rep)-encoding single stranded (CRESS) DNA viruses circulating in various environments. These approaches have enabled the discovery of some CRESS DNA viruses associated with insects. In this study we identified and recovered 31 viral genomes which represent 24 distinct CRESS DNA viruses from seven dragonfly species (Rhionaeschna multicolor, Erythemis simplicicollis, Erythrodiplax fusca, Libellula quadrimaculata, Libellula saturata, Pachydiplax longipennis, and Pantala hymenaea) and two damselfly species (Ischnura posita, Ischnura ramburii) sampled in various locations in the states of Arizona and Oklahoma of the United States of America (USA). We also identified Sclerotinia sclerotiorum hypovirulence-associated DNA virus-1 (SsHADV-1) in P. hymenaea, E. simplicicollis and I. ramburii sampled in Oklahoma, which is the first report of SsHADV-1 in the New World. The genome architectures of the CRESS DNA viruses recovered vary, but they all have at least two major open reading frames (ORFs) that have either a bidirectional or unidirectional arrangement. Four of the viral genomes recovered, in addition to the three isolates of SsHADV-1, show similarities to viruses of the proposed gemycircularvirus group. Analysis of the Rep encoded by the remaining 24 viral genomes reveals that these are highly diverse and allude to the fact that they represent novel CRESS DNA viruses.

Slow-motion analysis of female refusal behaviour in dragonflies

By means of slow-motion film analysis we found new female refusal behaviour patterns against male harassment in a variety of Odonata species. Often, females could escape simply by flying faster than males. Due to the morphological preconditions, there were differences in the two suborders. In Anisoptera, several behavioural specialities were analysed: (a) females of Aeshna cyanea, which oviposit solitarily and endophytically, clung to the substrate with great force when being pulled away by attacking males. (b) Anax imperator females showed a very fast, characteristic bending of the abdomen causing sudden U-turns for escape. (c) Solitary Libellula quadrimaculata females flew loops to escape pursuing males or to shake them off. They either used the impact of the crashing male for the turning moment or they generated it themselves by an abrupt change of the wing beat direction. In Zygoptera we investigated different Calopteryx species, which all oviposit alone. Fleeing was most common but wing clapping, not...

Parasitism of Odonata by Arrenurus (Acari: Hydrachnidia) larvae in the Lake Świdwie, nature reserve (NW Poland)

Larvae of a vast majority of water mite species are parasites of aquatic insects. Owing to this, they migrate to new localities, and are able to survive unfavourable environmental conditions. This also concerns species from subgenus Arrenurus s. str., parasites of dragonflies. The detailed analysis of this phenomenon, however, has only been possible in the last several years, since the key to the identification of larvae from genus Arrenurus Dug. was published. In 2010, the parasitism of Arrenurus s. str. larvae on dragonflies in the Lake Świdwie reserve (NW Poland) was analysed. Larvae of 9 species of water mites were recorded on 107 imagines of dragonflies from 8 species. The following were identified as hosts of water mites for the first time: Anax imperator, Libellula quadrimaculata, and Leucorrhinia caudalis. The highest prevalence occurred in the case of: Erythromma najas and Lestes dryas (100%), Coenagrion pulchellum (96.5%), and C. puella (80.0%). Coenagrion pulchellum was infested by 9 species of parasites, C. puella by 6, and Erythromma najas and Lestes dryas by three species. The highest number of host species occurred in the case of Arrenurus maculator (5); followed by A. cuspidator, A. batillifer cf., A. bicuspidator, and A. tetracyphus (3 each); A. papillator, A. tricuspidator, and A. bruzelii (2 each), and A. claviger (1). Differentiation of preferences of particular parasites towards various parts of the host body was observed, probably related to the coevolution of parasites and hosts, and competition between the host species. The body sizes of the parasites suggest that approximately 50% of body size growth of water mites from subgenus Arrenurus s. str. occurs at the stage of parasitic larva.

Spatial displacement of Odonata in south-west Siberia

A brief account is presented of mass dragonfly migrations observed previously in Russia and West Siberia in particular. A mass migration in Libellula quadrimaculata is described in detail. It occurred on 1 July 1981 in the south-western part of the West Siberian Plain in the valley of the Ishym River. From 1968 to 2008 we studied population dynamics, spatial distribution and displacement in dragonflies in the West Siberian forest-steppe. Detailed research was conducted at the biological station of the Russian Academy of Sciences near the Chany Lake. Mass migrations in L. quadrimaculata and some Leucorrhinia spp. followed situations with an extremely high population density and local mass aggregations and occurred with a period of c.10 years, correlated with fluctuation of water level in the region, mainly in the south. It is suggested that dragonfly migration not only optimizes their population size but increases the rate of transport of chemical elements and organic matter to dry land from eutrophic wate...

Dragonflies (Odonata) Emerging from Brackish Pools in Saltmarshes of Gaspé, Quebec

Enallagma hageni, Lestes disjunctus, Sympetrum costiferum, Sympetrum danae, Sympetrum internum, and Sympetrum obtrusum were observed emerging from brackish pools with an overall salinity range of 6.0-17.3 ppt in three saltmarshes in Gaspé, Quebec. Lestes congener, Libellula quadrimaculata, and species of Sympetrum were prominent among the larvae in these pools.

Use of Saltmarsh by Dragonflies (Odonata) in the Baie des Chaleurs Region of Quebec and New Brunswick in Late Summer and Autumn

During late summer and autumn, in the Baie des Chaleurs region of Quebec, 18 species of adult dragonflies were recorded during one or more visits of at least 2 hours each to 14 saltmarshes. Three species, Aeshna canadensis, Sympetrum danae and S. internum, were present in more than half of the sites. The most abundant species was S. internum with over 100 seen at some locations. Adults of several species, including Aeshna canadensis, A. umbrosa, Enallagma civile, E. hageni, Ischnura verticalis, Lestes disjunctus, Libellula quadrimaculata, Sympetrum danae, S. internum and S. obtrusum, occurred in relatively high frequencies in both Baie des Chaleurs saltmarshes and in those elsewhere in Acadia. Within Baie des Chaleurs observations of emergence and/or presence of larvae, as well as regional abundance, were recorded for Aeshna canadensis, A. umbrosa, Ischnura verticalis, Sympetrum costiferum, S. internum and S. vicinum. Oviposition in saltmarsh pools was recorded for Aeshna canadensis, Enallagma civile, E, hageni, Ischnura verticalis, Lestes congener and Sympetrum danae. The saltmarsh dragonfly fauna of Baie des Chaleurs is significantly different from that of the rest of Acadia based on frequencies predicted from the latter region. To a large extent this difference is a result of significantly increased use of saltmarsh habitat by adults of six species including Lestes congener, Sympetrum danae, Aeshna canadensis, Sympetrum costiferum, Lestes disjunctus, and Sympetrum internum (in order of decreasing significance) in Baie des Chaleurs in comparison with saltmarshes elsewhere in Acadia. Local amelioration of salty conditions in certain saltmarshes, superimposed on regional amelioration as a result of protection from storms and saltwater dilution in the Baie des Chaleurs estuary, may contribute to an environment where adaptation can occur or where already tolerant species can exist. Dragonflies use saltmarsh habitat on the northeast coast of North America more extensively than is currently documented.

Phylogeography of a facultatively migratory dragonfly, Libellula quadrimaculata (Odonata: Anisoptera)

The biogeography of a widely distributed dragonfly (Libellula quadrimaculata) was examined via a phylogenetic analysis of 416 bp of the mitochondrial cytochrome oxidase I subunit (COI). Phylogenetic analyses under parsimony and minimum evolution produced trees with similar topologies, and revealed strong support for three clades corresponding to populations in Asia, Europe and North America. However, resolution was poor within clades, and genetic distances between populations within continents was quite low (1–2%). Several populations of this species are known to engage in periodic mass migrations, and it is possible that introgression from gene flow due to the mobility of this species has obscured phylogenetic patterns within continents. I was unable to test for phylogenetic patterns coincident with historical glacial refugia given the lack of phylogenetic patterns within continents. However, given that some sequence divergence was observed between populations within continents, it is possible that phylogenetic patterns exist, and subsequent studies should make use of larger data sets, and molecular data from faster evolving genes. Despite the propensity for periodic, short distance migrations in L. quadrimaculata, gene flow appears to be limited and does not influence the phylogenetic relationships of populations between continents.

The dragonfly Libellula quadrimaculata (Odonata: Libellulidae) makes optimal use of the dorsal fovea of the compound eyes during perching

We studied visual orientation and perching behaviour of a territorial libellulid dragonfly species, Libellula quadrimaculata. The studies were performed during sunny, cloudless conditions at a pond in southern Styria, Austria, from May to July of 2001 and 2002. Individual males were observed for periods of 3 to 4 weeks.We measured dragonfly's horizontal orientation relative to the solar azimuth, and vertical orientation relative to the solar altitude. The measurements indicated that the males had a favourable view of the sky during perching. In addition, the relative amounts of ultraviolet (UV) and blue-violet radiation in scattered light (not direct sunlight) were calculated for the whole sky and for the section of the sky viewed by the fovea. Our results show that the dorsal fovea is directed preferentially toward a section of the sky away from the sun, with less radiation but a higher UV and blue-violet saturation.The present findings fit in well with the hypothesis, based on optical and physiological data, that the fovea, which is sensitive only to blue and UV radiation, is optimally suited to the detection of small, rapidly flying insects against the blue sky. The findings supply the first behavioural correlates of this foveal specialisation.

Effects of Fish Predators and Abiotic Factors on Dragonfly Community Structure

ABSTRACT We compared the community structure of odonates (Odonata) in 13 waters in northern Sweden, which differed with respect to fish presence and abiotic factors. Richness and abundance of odonates were estimated by collecting exuviae during the whole emergence season of 1999. Redundancy analysis revealed that fish presence influenced the community composition of the odonate larvae. While species richness per sample was not affected by the presence of fish, total abundance of odonates was higher in waters without fish. In waters with fish, Aeschna juncea and Leucorrhinia dubia showed lower abundances, whereas Erythromma najas and Cordulia aenea showed higher abundances. The abundances of Coenagrion hastulatum, Libellula quadrimaculata, and Leucorrhinia rubicunda did not differ between waters with and without fish. Of the six abiotic factors analyzed only water acidity was associated with odonate community structure.

Mechanical Properties of Demembranated Flight Muscle Fibres from a Dragonfly

The mechanical properties of demembranated muscle fibres of synchronous flight muscle from a dragonfly Libellula quadrimaculata, asynchronous flight muscle from the giant waterbug Lethocerus indicus and synchronous psoas muscle from rabbit were compared in relaxed, active and rigor conditions. The properties were compared to the known structure and protein compositions of these muscles. We found that active tension of L. indicus flight muscles was stretch-activated (tension was low and was significantly increased following a rapid stretch of 1 % of muscle length), whereas both dragonfly flight muscle and rabbit psoas muscle were not (active tension was high and did not significantly increase following a rapid stretch of 1%). Three different properties have been suggested to give rise to stretch activation in asynchronous muscles: (1) a matching of the helix periodicities of actin target sites to myosin crossbridge heads, (2) a special form of troponin subunit called troponin-H, and (3) the high resting stiffness of these muscles inducing strain in the thick filaments. Rabbit psoas muscle has none of these properties. Dragonfly flight muscles do not have the helix matching, but they do have a form of troponin-H and a high resting stiffness. It seems most likely that dragonfly flight muscles are not stretch-activated because they do not have the helix matching. Note: Present address: Department of Biophysics, King's College London, 26–29 Drury Lane, London, WC2B 5RL, UK.

On the Cytology and Fine Structure of the Neogregarine Syncystis aeshnae Tuzet and Manier, 1953 (Apicomplexa, Syncystidae)

The neogregarine Syncystis aeshnae Tuzet and Manier, 1953, was obtained from two species of dragonfly larvae, Aeshna grandis and Libellula quadrimaculata, collected in southern Sweden. Merogony, gamogony, and sporogony were observed in the adipose tissue, which was destroyed, and the haemocoele. Merozoites had a traditional apical complex. Gamonts associated in pairs did not unite conoid‐to‐conoid, and the border between gamonts was not found to break down. Each association produced 32 spores in bilobed gametocysts. Spores were elongate, oval, 4.0–5.8 × 8.0–10.0 μm in fixed and stained condition, each with 4+4 terminal and four equatorial thread‐like projections. The thick‐walled spore is considered the sporocyst. Species identification, ultrastructural cytology, and problems associated with using the terms “oocyst” and “sporocyst” are discussed.

Influences On the Choice Between Territorial and Satellite Behaviour in Male Libellula Quadrimaculata Linn. (Odonata: Libellulidae)

AbstractTerritorial behaviour of male Libellula quadrimaculata Linn. was investigated at Wicken Fen, Cambridgeshire, in 1986. Males were intensely territorial, expelling any other males that flew into their territory. Territories were defended for the mating opportunities that they provided. As local population density increased a number of males adopted satellite behaviour, although most continued to behave territorially. Wingspan and hindwing length were significantly larger in satellites than in territorial males. The likelihood of satellite behaviour was not related to male age. There was also no difference in age between satellite-host pairs in which both individuals were of known age. Satellite males were not observed to mate successfully, though they did not suffer the costs associated with territorial defence. A series of removal experiments demonstrated that the satellites could take over a territory and behave aggressively to other males. Scaling factors may have an important function in forcing larger males to adopt the less successful satellite role. Notably, flight muscle content was lower than expected in larger individuals, which should result in lower power output per unit body weight, and thus lower maximum acceleration and manoeuverability.

Fluid Secretion By the Malpighian Tubules of the Dragonfly Libellula Quadrimaculata

ABSTRACT Fluid secretion by the Malpighian tubules of Libellula quadrimaculata is unusual in that it is dependent on sodium and entirely independent of potassium in the external medium. It is suggested that this is due to the primitive, sodium-rich haemolymph of the Odonata. Similarities between these tubules and those of the millipede Glomeris marginata, which has a similar sodium-based haemolymph, support this view. Fluid secretion by the tubules is also dependent on the osmotic pressure of the external medium, declining considerably at higher osmotic pressures. However, there is no difference in the secretory rates of tubules isolated from larvae adapted to tap water, de-ionized water or salt water, even though there are large differences in the haemolymph osmotic pressure under these different conditions. This suggests some form of adaptation of the tubules in larvae from these different conditions. A factor which causes a five-to six-fold increase in the rate of secretion was present in the thoracic ganglia, and a slightly lower increase in secretion rate was recorded in larvae that had been feeding.

Die Libellenfauna der westlichen und nördlichen Mongolei und einige Phänomene ihrer intrakontinentalen Isolation

The Dragonfly Fauna of the Western and Northern Parts of Mongolia and Some Phenomena of Their Intracontinental IsolationBased on 2100 specimens, mostly collected during the II. Mongol‐German Biological Expedition of 1964, a brief survey of the dragonfly fauna of Mongolia is given, including special remarks on those species the author met with in the western and northern districts of the country. 12 species are mentioned for the first time as components of the Mongolian fauna. Comparisons of several morphometrical characters (body length, relative length of the abdomen, absolute and relative body weight) between anisopteran species and between the population groups from north, west and south‐west Mongolia as well as from central Europe have led to some remarkable results: (1) According to the proportions of the body and the differences between males and females in relative length of the abdomen the species can be grouped into separate constitutional types (Aeshna type, Libellula type, Sympetrum type and others). These types seem to represent special evolutionary strategies to perfect the dragonfly body as a “flying machine”. (2) In the different parts of western Mongolia (northern mountain steppes and woodlands, western desert plains, Dzungarian deserts), the majority of the species is represented by populations differing from each other in measurements and/or body proportions. These differences may be as large as or even larger than the distinction rate between each of the Mongolian and the Central European populations. (3) The differences in body length and proportions between the population groups are expressions of different genotypes; it seems impossible to interprete them as results of diverse conditions for larval growth. (4) Some species of dragonflies in western Mongolia occur as geographically isolated populations; the Altai and other mountain ridges lying to the north and southwest separate them from populations in eastern Kazakhstan (Lestes macrostigma, Libellula quadrimaculata and, may be, some more).