A nonoccluded virus in nymphs of the dragonfly Leucorrhinia dubia (Odonata,Anisoptera)

This work establishes the sequence of events as the water mold, Coelomomyces psorophorae, develops and enters mosquito larvae through the cuticles of these insects. The fungal cyst shows a number of adaptations for a parasitic function. A bulb-shaped appressorium is produced at germination which is initiated and/or maintained by a microtubular skeleton. The tip of the appressorium secretes a dense amorphous substance, then produces a narrow penetration tube which grows through the larval cuticle. The penetration tube maintains its narrow diameter as it grows inside the host epidermal cell. The parasite protoplasm is injected into a host epidermal cell. The protoplast is squeezed through the narrow tube by the (probably rapid) expansion of a vacuole in the cyst body at the end distal to the penetration point. There is a correlation of cuticular texture with adhesion patterns of cysts. A cuticular collar is always seen in successful penetrations. The sequence of development after attachment of the fungal zygotes is: germination between 1 and 2 hr; penetration between 3 and 4 hr; and injection between 6.5 and 8 hr.     

Genetic diversity,sexual condition,and microhabitat preference determine mating patterns in Sphagnum (Sphagnaceae) peat‐mosses

In bryophytes, the possibility of intragametophytic selfing creates complex mating patterns that are not possible in seed plants, although relatively little is known about patterns of inbreeding in natural populations. In the peat‐moss genus Sphagnum, taxa are generally bisexual (gametophytes produce both sperm and egg) or unisexual (gametes produced by separate male and female plants). We sampled populations of 14 species, aiming to assess inbreeding variation and inbreeding depression in sporophytes, and to evaluate correlations between sexual expression, mating systems, and microhabitat preferences. We sampled maternal gametophytes and their attached sporophytes at 12–19 microsatellite loci. Bisexual species exhibited higher levels of inbreeding than unisexual species but did generally engage in some outcrossing. Inbreeding depression did not appear to be common in either unisexual or bisexual species. Genetic diversity was higher in populations of unisexual species compared to populations of bisexual species. We found a significant association between species microhabitat preference and population genetic diversity: species preferring hummocks (high above water table) had populations with lower diversity than species inhabiting hollows (at the water table). We also found a significant interaction between sexual condition, microhabitat preference, and inbreeding coefficients, suggesting a vital role for species ecology in determining mating patterns in Sphagnum populations. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 115 , 96–113.     

Predator‐induced spine length and exocuticle thickness in Leucorrhinia dubia (Insecta: Odonata): a simple physiological trade‐off?

1. Morphological defence structures evolve against predators but are costly to the individual, and are induced only when required. A well‐studied example is the development of longer abdominal spines in dragonfly larvae in the presence of fish. Numerous attempts to discover trade‐offs between spine size and behaviour, development time or body size have, however, produced little evidence. 2. We considered a physiological trade‐off. Spines consist of cuticle and using material to build longer structures may result in less material remaining elsewhere. We therefore measured exocuticle thickness at nine locations on Leucorrhinia dubia larvae from habitats with and without fish. 3. Our results show a significant effect of the interaction between fish presence and spine length on head and fore leg exocuticle thickness. Relative thickness increased with relative length of lateral spine 9 in the absence of fish, whereas no such relationship existed with fish. Hence, synthesis and secretion of cuticle material occur as a trade‐off when larvae react to fish presence. 4. We assume the mechanism to be a selective synthesis of material with different responses in different parts of the larval body. These findings offer a new angle to the fish/spine trade off debate.     

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 Larvae of the Mesozoic family Aeschnidiidae and their Phylogenetic Implications (Insecta, Odonata, Anisoptera)

Four giant dragonfly larvae are described from the Lower Cretaceous of China. Owing to the preservation of wing tracheal venation on the larval wing sheaths, they can be identified as the first undoubted larvae of the extinct Mesozoic family Aeschnidiidae. They are ultimate or penultimate male and female specimens, and a younger larva. The female larva has a very long ovipositor sheath. These larvae have an anisopteran anal pyramid and a very particular spoon-shaped labial mask, with a very narrow prementum and large palps with numerous teeth, suggesting possible affinities of the Aeschnidiidae with the Anisoptera Cavilabiata. The positions of other larvae formally attributed to the Aeschnidiidae are discussed, i.e. Nothomacromia sensibilis (Carle and Wighton, 1990), Sona nectes Pritykina, 1986, and the alleged larvae of Hemeroscopus baissicus Pritykina, 1977. They differ greatly from the true Chinese larval Aeschnidiidae, in the labial mask and female ovipositor, even if they show some similarities in the anal pyramid.     

Ventilatory movements of the abdomen and branchial apparatus in dragonfly larvae (Odonata: Anisoptera)

Use of cine-photography in the analysis of ventilatory movements has necessitated a reappraisal of the ventilatory patterns previously described in dragonfly larvae. Movements of the abdominal exoskeleton, monitored by cine-photography, phototransistor and strain gauge, are discussed in relation to known muscular activity. Internal movements of the branchial apparatus, which consists of two chambers and three valves, are also illustrated in the intact animal. The mechanism of "gulping" ventilation ( V _a) in dragonfly larvae is discussed.     

Relationship between morphology,dispersal and habitat distribution in three species of Libellula (Odonata: Anisoptera)

Morphology is an important determinant of flight performance and can shape species’ dispersal behaviour. This study contrasted the morphology of flight-related structures in dragonfly species with different dispersal behaviours to gain insights into the relationship between morphology and dispersal behaviour. Specifically, wing size, wing shape and thorax size were compared in three co-occurring species from different clades within the genus Libellula (Odonata: Anisoptera: Libellulidae) to assess how these morphological traits are related to differences in dispersal behaviour and to how broadly their larvae occur across a habitat gradient. Two species had broad larval habitat distributions as well as high rates and distances of dispersal. These two species had relatively larger wings and thoraces than the third species, which was found only in permanent lakes and had limited dispersal. The hind-wings of more dispersive species also had lower aspect ratios and a relatively wider basal portion of the wing than the less dispersive species. Broad hind-wings may facilitate the use of gliding flight and reduce the energetic costs of dispersal. Determining the morphological traits associated with alternative dispersal behaviours may be a useful tool to assess the differential dispersal capacities of species or populations.     

Spatial distribution, life history and estimates of survivorship in a fourteen-species assemblage of larval dragonflies (Odonata: Anisoptera)

SUMMARY. 1. Spatial and temporal changes in larval densities were used to infer patterns of habitat use and survivorship in a fourteen-species assemblage of dragonflies (Odonata: Anisoptera) in a small fishless pond. The density of all species combined peaked at >1000 m⁻² in late summer, Most species (e.g. Libellula spp.) were restricted to shallow, nearshore habitats (<1.0m in depth), but a few (e.g. Epitheca spp.) also used deeper areas of the pond. Only Perithemis tenera was most abundant in deep habitats.
2. Because many species exhibited temporal shifts in their use of habitats, it was necessary to estimate survival from changes in population size, calculated as the product of density and habitat area, summed across habitats. In most species, periods of high mortality in autumn and spring were separated by 3–4 months of negligible mortality in winter. Survivorship was linear only in the two species that completed all of larval development in summer ( Sympetrum vicinum and Pantala flavescens) . Average survival rates for these two species (−0.0049 and −0.0079 log density d⁻¹) were similar to those in previous studies (Lawton, 1970; Benke & Benke, 1975).
3. Survivorship in many species was confounded by other life history phenomena such as (i) mixed voltinism, (ii) overlapping migrant and resident cohorts, and (iii) asynchronous development within species. Asynchrony made it difficult to estimate initial and final population sizes, hence total larval survivorship. However, based on emergence data, only 0.4–3% of larvae survived after peak abundance. None of this mortality can be ascribed to vertebrate predation, and only a little to overwintering stress and starvation. Thus, predation by invertebrates might play a major role in the regulation of these populations.     

Maternal transmission of cytoplasmic DNA in interspecific hybrids of peat mosses, Sphagnum (Bryophyta)

The progeny of spontaneous interspecific hybrid sporophytes of Sphagnum were used to analyse the inheritance of cytoplasmic DNA. The analysis showed that only the female parent donated chloroplasts and mitochondria in Sphagnum hybrids. Thus, this is the first study demonstrating maternal cytoplasmic inheritance in a nonvascular land plant. This finding has important implications for phylogenetic reconstructions utilizing chloroplast and mitochondrial DNA sequences as well as for the evolution of cytoplasmic inheritance in relation to the life cycle of land plants.     

The development of dragonfly larvae (Odonata: Anisoptera) from two streams in north-eastern Victoria, Australia

Developmental stages of larvae of eight species of Anisoptera from the Kiewa River and Middle Creek, Victoria, were determined and their phenology investigated. The last six to nine instars of each species were distinguished by size frequency and scatter plots, using labium width, metafemur and wing-pad measurements, and the early instars were estimated from Dyar's Law. This suggested between 11 to 14 instars. Four species appeared to be univoltine and four species semivoltine.     

Larval ecomorphology of 13 Libellulidae (Anisoptera, Odonata) of the Middle Rio Doce Valley, Minas Gerais, Brazil.

In the lakes of the Middle Rio Doce, Minas Gerais (MG), two groups of larval Libellulidae are distinguished by preferences of habitat use: one uses mainly aquatic macrophytes and the other uses the bottom substrate. The goal of this work was to verify if there is a morphological distinction between the two groups of species. Thirteen body measures were taken from the larvae and analyzed. No difference was found between the two groups of species regarding the body size, but shape differences were observed for two morphological variables. The species that use mainly macrophytes tend to have larger relative measures of the labium and smaller measures of the abdomen width. Advantages in resource obtainment and in vulnerability to predation are probably the explanations for the morphological divergence among these larval groups.     

Hybridization between the peat mosses, Sphagnum capillifolium and S. quinquefarium (Sphagnaceae, Bryophyta) as inferred by morphological characters and isozyme markers

 Isozyme markers and morphological characters were studied in four populations of Sphagnum capillifolium and S. quinquefarium. Recombinant plants were found in three populations, where the two species occur sympatrically. All recombinants possessed different haplotypes and combinations of morphological characters, which show that they are results of independent hybridization events. Strongly male-biased sex ratios were found for Sphagnum capillifolium in all populations where it grew sympatrically with S. quinquefarium. Most of the recombinants were also male fertile. These observations suggest that S. quinquefarium is the female parent in the primary crosses and in subsequent backcrosses. Received September 3, 2001; accepted March 16, 2002 Published online: November 7, 2002 Addresses of the authors: Nils Cronberg (e-mail: Nils.Cronberg@sysbot.lu.se), Department of Systematic Botany, Lund University, S?lvegatan 37, SE-223 62 Lund, Sweden. Rayna Natcheva (e-mail: renimoss@iph.bio.bas.bg), Institute of Botany, Bulgarian Academy of Sciences, 23 Acad. G. Bonchev Str., 1113 Sofia, Bulgaria.     

Identification of dragonflies (Odonata) as indicators of general species richness in boreal forest lakes

We argue the need to select indicator species on empirical data to avoid influence of personal opinions. To test an empirical selection process based on a nested subset matrix, we sampled partivoltine dragonfly larvae from 74 small lakes in central Sweden. A nestedness matrix was set up using the 'nestedness temperature calculator' program, selecting 11 species as potential indicators of species richness. These were tested against a known indicator species for water quality (the pool frog) and plant diversity through inventories and comparison to existing surveys of biological values ('rich' lakes vs. 'ordinary' lakes). We could only see a trend towards the pool frog occurring in dragonfly-rich lakes, but found a significant connection between the number of aquatic plants along the shore line and the number of dragonfly species present. A significantly higher number of indicators were encountered in lakes previously surveyed as 'rich' in plants than in lakes classified as 'ordinary'. Dragonfly species richness therefore appears to be positively associated with species richness of vascular plants. We propose nestedness matrices to be a good selecting tool for indicator species, particularly in groups where the biology of the species is not well known. However, it is important to define what such indicators really indicate.     

Chlorophyll-phosphorus relationship in acidified lakes of the High Tatra Mountains (Slovakia)

Concentrations of total phosphorus (TP) and chlorophyll a (CHLA) were measured in 28 lakes in the High Tatra Mountains (Slovakia) from 1983 to 1990. The relationship between log CHLA and log TP in the Tatra lakes is similar to relationships developed for lakes in other regions, but variation is higher. A part of this variation is caused by acidification of the lakes. In the lakes with pH between 4.9 and 6.3 the CHLA concentrations are often extremely low while TP concentrations decreased, but not as drastically.     

Cytology of ten South American Libellulidae,with cytophylogenetic considerations on the genera Orthemis Hagen and Erythrodiplax Brauer (Odonata,Anisoptera)

Notes on karyotypic morphology are given for ten South American species of the dragonfly family Libellulidae that were either cytologically little known or not studied previously, viz. Dasythemis venosa (Burm.) (Brasil, n=13), Orthemis ferruginea (Fab.) (Peru, n=12), Micrathyria laevigata Calv. (Brasil, n=13), Erythrodiplax cleopatra Ris (Peru, n=13), E. connata connata (Burm.) (Chile, n=12). E. media Borror (Brasil, n=11), E. melanorubra Borror (Venezuela, n=13), Dythemis velox Hag. (Peru, n=13), Macrothemis declivata Calv. (Brasil, n=12) and M. imitans imitans Karsch (Brasil, n=13). A pair (bivalent) of m-chromosomes is present in all species. Orthemis is the only genus in the family with n=12 or a derivative of it, met with in all species. This number is considered primary rather than secondary. As seen from pronounced variations in cytogenetic structure of its members, the genus appears genetically unstable, while the low recombination indices in all species may serve a need for biological stability.The cytophylogenetic history of the connata group of Erythrodiplax is discussed.     

Evidence for crypsis in coho salmon, Oncorhynchus kisutch (Walbaum), parr: substrate colour preference and achromatic reflectance

The crypsis hypothesis of salmonid parr coloration and behaviour is evaluated in light of the criteria for protective resemblance. A review of the literature indicates that salmonid parr coloration and behaviour correspond to a cryptic interpretation. Experiments on coho salmon, Oncorhynchus kisutch , parr substrate colour preference indicate that the behavioural correlate of appropriate background choice is satisfied. Absorption spectrophotometry of diapositives of fish and experimental substrates suggests that background matching is achieved through achromatic reflectance and absorption of wavelengths by the silvery sides and parr marks, respectively.     

Ontogenic colour change,survival, and mating in the damselfly Agriocnemis pygmaea Rambur (Insecta: Odonata)

1. Damselflies often show intra-specific colour variation, which may represent genetic polymorphism or age-related (ontogenic) colour changes. 2. Such variation has distinct implications for the species' ecology and evolution. Colour variation in females of the damselfly Agriocnemis pygmaea was studied, which range from blue male-like individuals (andromorphs) to those with a distinct red colour (heteromorphs). From preliminary observations, it was hypothesised that this species exhibits ontogenic colour change from heteromorph to andromorph coloration. 3. Mark–recapture experiments and egg counts of dissected females suggested that immature females are heteromorphic and gradually begin to resemble males as they attain sexual maturity. 4. Reflectance spectra of field-caught individuals indicated that, although males are indistinguishable from andromorphs, they could be easily differentiated from heteromorphs. 5. Finally, field observations and mate choice experiments showed that males rarely attempt to mate with heteromorphic females and prefer andromorphs. Together, this study's results suggest that the observed colour variation in A. pygmaea females is ontogenic and is associated with sexual maturity.