Habitat and conservation of the enigmatic damselfly <Emphasis Type="Italic">Ischnura pumilio</Emphasis>

Ischnura pumilio is threatened in the UK and its habitat requirements are not well understood. This study tests previously held notions of the habitat requirements of I. pumilio, investigates the features of a habitat influencing odonate species composition and provides recommendations for habitat creation and management for I. pumilio persistence. Thirty-one sites across south west England with past I. pumilio records were surveyed in 2006. Environmental variables and odonate abundance were recorded. Odonate species composition and I. pumilio abundance were related to environmental variables using multivariate techniques and GLM. Ischnura pumilio was found at a wide variety of habitat types; key habitat features were a muddy substrate with some open ground, turbid water, and low levels of shade. It was associated with increased structural diversity of vegetation away from water but low maximum height; characteristic of early-successional sites. The variables predicting odonate composition were location, shade, level of disturbance, water depth, and cover of terrestrial dwarf shrubs and Sphagnum species. Vegetation height and structure were also highly influential to at least 20 m from water. This study indicates that odonate habitat management should include adjacent hinterland. Management for I. pumilio may be complicated by the species’ use of two habitat types, each with associated problems. Furthermore, odonate species diversity was negatively associated with I. pumilio abundance, which may cause conflict of interest when managing habitats.     

Interspecific crossing between blue‐tailed damselflies Ischnura elegans and I. senegalensis in the laboratory

Ischnura species (Odonata) are among the most common damselflies in the world, which often exhibit female color polymorphisms. One morph, called androchrome, is similar to males in its color pattern, whereas the other morphs, generally referred to as gynochromes, exhibit female‐specific colors. In several Ischnura species, the female polymorphism is heritable, although molecular and genetic mechanisms remain largely unknown. The dominant‐recessive patterns of the female color morphs may differ between species. For example, androchromic females are dominant to gynochromic females in Ischnura elegans, whereas androchromic females are recessive in Ischnura senegalensis. Here we report a case of interspecific hybridization between a gynochrome female of I. elegans and a male of I. senegalensis in the laboratory. We obtained 61 hybrid adult offspring, of which all 31 females were of gynochrome morph. DNA analyses of the hybrids confirmed that nuclear DNA sequences were derived from both parent species, whereas mitochondrial DNA sequences were maternally inherited. In the hybrids, the postocular spots of female heads, the shape of male appendages, and the color of female's cerci resembled those of I. elegans, whereas the size of abdominal blue spots was similar to that of I. senegalensis. The shape of prothorax and basal abdominal markings were intermediate in females. The larval developmental traits and the morphological changes in the final larval instar of the hybrids were similar to those of I. senegalensis. To our knowledge, this is the first report of hybrids between two damselfly species with different dominant‐recessive patterns of female color morphs.     

Isolation and characterization of microsatellite loci to study parthenogenesis in the citrine forktail,Ischnura hastata (Odonata: Coenagrionidae)

The citrine forktail, Ischnura hastata, is an American damselfly species, widely distributed, with only‐female populations also found at the Azores islands. Here we report the development of nine microsatellite loci for this species. The number of alleles per locus ranged from six to 11, with an observed heterozygosity ranging from 0.245 to 0.737. Eight of the nine loci successfully amplified in a sample of parthenogenetic females from the Azores. The developed microsatellite system will be a useful tool to investigate population structure, as well as the number of clones, the type of parthenogenesis and the origin of the parthenogenetic populations of this species.     

Molecular and ecological signatures of an expanding hybrid zone

Many species are currently changing their distributions and subsequently form sympatric zones with hybridization between formerly allopatric species as one possible consequence. The damselfly Ischnura elegans has recently expanded south into the range of its ecologically and morphologically similar sister species Ischnura graellsii. Molecular work shows ongoing introgression between these species, but the extent to which this species mixing is modulated by ecological niche use is not known. Here, we (1) conduct a detailed population genetic analysis based on molecular markers and (2) model the ecological niche use of both species in allopatric and sympatric regions. Population genetic analyses showed chronic introgression between I. elegans and I. graellsii across a wide part of Spain, and admixture analysis corroborated this, showing that the majority of I. elegans from the sympatric zone could not be assigned to either the I. elegans or I. graellsii species cluster. Niche modeling demonstrated that I. elegans has modified its environmental niche following hybridization and genetic introgression with I. graellsii, making niche space of introgressed I. elegans populations more similar to I. graellsii. Taken together, this corroborates the view that adaptive introgression has moved genes from I. graellsii into I. elegans and that this process is enabling Spanish I. elegans to occupy a novel niche, further facilitating its expansion. Our results add to the growing evidence that hybridization can play an important and creative role in the adaptive evolution of animals.     

Rapid evolution of prezygotic barriers in non‐territorial damselflies

A central question in evolutionary biology concerns the accumulation of reproductive barriers during speciation. However, separating the reproductive barriers that have led to speciation from those that have secondarily accumulated (i.e. after initial divergence) is a widely recognized problem. Ideal candidate species for overcoming this problem are young species, where time for additional barriers to accrue has been limited. In the present study, we add to previous studies investigating the strength of reproductive barriers between the parapatric damselflies Ischnura elegans and Ischnura graellsii by quantifying seven prezygotic barriers between the allopatric pairs of I. elegans and Ischnura genei, as well as I. graellsii and I. genei. Specifically, we measured four premating (temporal, sexual, mechanical _I, and mechanical _II) and three postmating (oviposition success, fecundity, and fertility) barriers using experimental approaches and, for first time, we investigated the mechanisms causing mechanical isolation, which is the strongest reproductive barrier in ischnurans. The findings of the present study support the notion that premating barriers are generally strong and contribute significantly to total reproductive isolation in young lineages (65–98%), although they never solely lead to complete isolation. Asymmetry was generally stronger in premating than in postmating barriers, and was driven mostly through asymmetry in mechanical isolation, which is caused by morphological divergence of secondary sexual appendages. We found that barriers act multiplicatively in all species combinations tested, with the exception of sexual isolation, which was not detected. Our results are consistent with a recent allopatric speciation scenario driven by differences in male anal appendages, either impeding copulation or affecting female preferences. Taken together, the results from this and previous studies in diverse odonate genera suggest that premating barriers have evolved rapidly in ischnuran damselflies and, although reproductive isolation in ischnurans is more commonly the result of several barriers acting together, morphological divergence of secondary sexual appendages appears to be a common factor facilitating premating isolation in this group. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 485–496.     

Co-existence of larval zygoptera (Odonata) common to the Norfolk Broads (U.K.)

Summary The temporal and spatial components of resource partitioning were investigated in an assemblage of zygopterans. Spatial separation appeared to be relatively more important to their co-existence than temporal separation. Spatial differences separated Coenagrion pulchellum from the other species, Enallagma cyathigerum from both Ischnura elegans and Erythromma najas, and to a small extent I. elegans from E. najas. Difference in size (temporal separation) was important to the co-existence of I. elegans and E. najas (through a difference in final instar size), and may have been important in assisting the spatial separation of E. cyathigerum (through displacement of life cycles). This arrangement appears to differ from that of other aquatic insects for whom temporal separation through life cycle displacement is a very important component of community structure.     

Tolerance of low pH exposure by the eggs of Odonata (dragonflies and damselflies)

The development times and hatching success of the eggs of four species of Odonata (Ischnura verticalis, Lestes congener, Libellula lydia, and Sympetrum vicinum) were unaffected by exposure to soft water at pH 5.1 and 3.5. Tolerance of low pH, soft water conditions by Odonata eggs may in part account for the widespread distribution of Odonata in potentially acid-stressed regions.     

Morphological specializations of dorsal rim ommatidia in the compound eye of dragonflies and damselfies (Odonata)

We have examined the fine structure of dorsal rim ommatidia in the compound eye of the three odonate species Sympetrum striolatum, Aeshna cyanea and Ischnura elegans. These ommatidia exhibit several specializations: (1) the rhabdoms are very short, (2) there is no rhabdomeric twist, and (3) the rhabdoms contain only two, orthogonally-arranged microvillar orientations. The dorsal rim ommatidia of several other insect species are known to be anatomically specialized in a similar way and to be responsible for polarization vision. We suggest that the dorsal rim area of the odonate compound eye plays a similar role in polarization vision. Since the Odonata are a primitive group of insects, the use of polarized skylight for navigation may have developed early in insect phylogeny.     

Interpreting dragonfly diversity to aid in conservation assessment: lessons from the Odonata assemblage at Middle Creek, north-eastern Victoria, Australia

In order to evaluate single-occasion sampling in compiling inventories for Odonata, larvae were sampled on 20 occasions from 1987–1990 at a site on Middle Creek, north-eastern Victoria, and adults sought also on each visit to more fully evaluate the diversity of the asemblage, and limitations of depending on a single life stage for this purpose. A total of 18 species (7 Zygoptera, 11 Anisoptera) included 15 species collected as larvae and 16 as adults. Few species were common as larvae, and about half the 2806 specimens identified were Austrogomphus cornutus Watson. Orthetrum caledonicum (Brauer) and Ischnura heterosticta (Burmeister) were also abundant, and these three species were also the most common as adults. The number of species obtained ranged from 2–9 on different occasions, and represent different 'habitat groups' within the local fauna. The Middle Creek odonate fauna appears to be much richer than that of a nearby site on the Kiewa River (12 species), and reasons for this are discussed. Seasonal variation in species representation and relative abundances are noted. Any single sample occasion provided insufficient knowledge of the total assemblage to interpret odonate diversity reliably.     

On the species-pool hypothesis and on the quasi-neutral concept of plant community diversity

5.1. According to the results from studying a broad variety of Estonian herbaceous communities (4.11) the question in 1.14 should be answered as:selection from a regional species pool into an actual species pool and selection from actual species pool into a microsite are mostly random and neutral processes and they are not directed significantly by interspecific competition. 5.2. Yet, the formation of a diversity pattern should be called aquasi-neutral process,mainly because the exclusion of species from communities due to asymmetric light competition is common during succession (when taller species outcompete shorter ones).     

Identifying adult dragonfly prey items using DNA barcoding and stable isotope analysis

Using DNA barcoding and stable isotope analysis, we identified adult dragonfly prey items from the fecal pellets of five dragonfly species—Nannophya pygmaea, Ischnura asiatica, Sympetrum eroticum, Orthetrum albistylum, and Anax parthenope—collected from a mountain bog located in south‐eastern South Korea. Twelve operational taxonomic units (OTUs) belonging to four orders, Coleoptera, Diptera, Hemiptera, and Lepidoptera, were identified as prey items of adult dragonflies using DNA barcoding. Among prey items, Dipterans were the most common, comprising seven of the 10 OTUs. Based on stable isotope analysis, adult dragonflies and their nymphs were among the most numerous predators in both aquatic and terrestrial habitats. Additionally, dragonfly species with smaller adult sizes had different isotopic compositions to those reaching larger adult sizes. Both δ¹⁵N and δ¹³C values were significantly lower in smaller species than in larger species, indicating differences in their trophic levels and carbon sources.     

Review of the neotropical endemics Burmeistera, Centropogon, and Siphocampylus (Campanulaceae: Lobelioideae), with description of 18 new species and a new section

Burmeistera, Centropogon, and Siphocampylus together comprise more than 500 species endemic to the Neotropics, Current knowledge of these genera is unsatisfactory, with much diversity yet to be described. Over the past seven years, one out of every 28 specimens received for identification has represented a new species, many characterized by unique or unusual character states. Siphocampylus smilax (Bolivia) is unique in the genus in its parallelodromous leaf venation and extra-floral nectaries. Centropogon dianae (Peru) cannot be accommodated in any recognized infrageneric taxon, and a new section, Centropogon sect. Niveopsis, is proposed for it. The flowers of C. steinii (Ecuador) are the smallest known in the genus, while C. connatilobatus (Venezuela) is the first species to combine arbusculiform pubescence and connate calyx lobes. Burmeistera venezuelensis is only the second species of the genus known to occur in Venezuela and the first to be endemic; similarly, Centropogon wilburii is only the third species of Centropogon known from Mexico and the first to be endemic to that country. Additional novelties are also described.     

Zur Parasitologie und postparasitischen Entwicklung der neotropischen Wassermilbe Arrenurus valencius (Hydrachnellae,Acari), nebst einigen faunistischen Angaben zum See “Laguna Chichoj”; in Guatemala

During two visits to Guatemala in 1974 and 1975 observations were made on the fauna in Eichhomia growth of the small lake “Laguna Chichoj”;. Chemical and physical data and faunistic finds are reported. Particular attention was paid to the water mite Arrenurus (Arrenurus) valencius MARSHALL, 1919. Adults of this species occur commonly in the Eichhornia growth. The larvae parasitize adult Ischnura ramburi crédula (Zygoptera, Odonata). This fits the known pattern according to which nearly all species of the subgenus Arrenurus are parasites of dragonflies belonging to both the Zygoptera as well as Anisoptera (Münchberg 1935, Mitchell 1959, Böttger 1965, Cassagne‐Méjean 1966, Cook 1974, Stechmann 1977). Also the first mentions in the literature on tropical species of the subgenus Arrenurus pointed to Odonata as specific hosts (Münchberg 1958, 1959, 1960).

Ischnura ramburi credula is quite abundant in Eichhornia growth. Both sexes are infested by water mites, the males carrying a maximum of 111, the females of 66 parasites. The average were 24 parasites per male and 16 per female. For both sexes the extensity of infestation was an equal 90%.

The parasites are located predominantly at the ventral side of the thorax and the first abdominal segments. During the parasitic phase the volume of the larvae increases considerably: body length and width double. Separation from the host ‐ notwithstanding a few exceptions ‐ does not take place when after a few days of parasitic existence the amount of food necessary for further development has been ingested but only at the moment of death of the host. This raises the chances of the parasites of returning to the water: the host dragonflies live near the shore and regularly dying individuals fall on the surface of the water or among the Eichhornia plants.

Larvae which had left their dead host in the laboratory have been reared through the Postlarval Resting Stage I, the deutonymph stage and the Postlarval Resting Stage II up to the adult. The deutonymphs are carnivorous like the adults; they prey on ostracods with predilection.     

A revision of the Chinese Catops Paykull 1798 of the Catops fuscus species group (Coleoptera: Leiodidae: Cholevinae)

Five species of the Catops fuscus species group are reported from China. Three species are newly described: C. hlisnikovskyi n. sp. from the Beijing municipality and Jiangsu province, C. schuelkei n. sp. from Sichuan and Yunnan provinces, and C. smetanai n. sp. from Sichuan and Yunnan provinces. Female of C. sasajii Nishikawa 2007 is described and the species is reported from Hubei, Sichuan and Yunnan provinces for the first time. Catops nigricans (Spence 1813) is reported for the first time from China (Xinjiang Uygur autonomous region). Important morphological characters are illustrated and the distribution of all species in China is mapped. Preliminar phylogenetic analysis separates (C. hlisnikovskyi n. sp.+C. fuscus fuscus Panzer 1794) as a sister clade to C. nigricans+(C. sasajii+(C. schuelkei n. sp.+C. smetanai n. sp.)), with C. paramericanus Peck & Cook 2002 as outgroup.     

Factors influencing age related dispersal of the nymphal OdonatesIschnura barberi (Currie),Pachydiplax longipennis (Burm.) andErythemis simplicicollis (Say)

Size related spatial patterns were observed in naiads of the three dominant odonate taxa in a man-made marsh. These patterns were correlated with various physical and chemical parameters, the vegetation gradient, and prey availability using linear and curvilinear regressions.Ischnura barberi andPachydiplax longipennis naiads increased linearly in head capsule widths from the marsh center to the marsh edge. Increasing naiad size correlated with changes in vegetation. Additionally, the spatial patterning ofPachydiplax longipennis was correlated with decreasing submerged plant surface area as naiad size increased. The head capsule width ofErythemis simplicicollis increased from the marsh center to the marsh edge and then continued to increase towards the marsh center. This complex dispersal pattern did not correlate with any of the measured physical or chemical parameters or the vegetation gradient. However, the dispersal pattern ofErythemis simplicicollis correlated with increased in consumable prey densities along the migratory path. No correlation existed between consumable prey and the dispersal pattern ofIschnura barberi orPachydiplax longipennis.     

New Hypogastrura species and new distributional data for Hypogastrura distincta (Axelson 1902) from China (Collembola: Poduromorpha: Hypogastruridae)

Two new species, Hypogastrura analpapillata n. sp., on mushrooms from Yunnan Province, and Hypogastrura microspinata n. sp., on moss from Hunan Province, are described. Hypogastrura analpapillata n. sp. is the sixth species with highly modified mouthparts in the trybomi group. Hypogastrura microspinata n. sp. is close to H. yosii Stach 1964, but can be differentiated from the latter by body granules, tenent hair and lateral teeth on tibiotarsus. A key to Chinese species of Hypogastrura is provided and a list of Chinese Hypogastrura species and their distributional data are given.     

Three new species of Philocorydoras Suriano, 1986 (Monogenoidea: Dactylogyridae) infecting the gills of callichthyids (Actinopterygii: Callichthyidae) from the Peruvian Amazonia

During a research on gill ectoparasites of callichthyids fishes from the Peruvian Amazonia, the following monogenoideans were found: Philocorydoras peruensis n. sp. from Corydoras splendens (Castelnau); Philocorydoras multiradiatus n. sp. and Philocorydoras jumboi n. sp. from Brochis multiradiatus (Orcés, V.). All new species described herein are mainly differentiated from their congeners based on the morphology of the copulatory complex. In P. peruensis n. sp. the cirrus is “J”-like shaped tube slightly tilted to one side, while in P. jumboi n. sp. is “J”-like shaped tube in a straight position and in P. multiradiatus n. sp. the cirrus is an arced tube with inflated base and distally narrow. Brochis (Orcés, V.) represents a new genus hosting species of Philocorydoras. All new species presented in this work represent the first species of Philocorydoras reported for Peru.

     

Six new species of Rhamnocercus Monaco,Wood & Mizelle, 1954 (Monogenea: Diplectanidae) infecting the gills from South American sciaenid fishes

A parasitological survey searching diplectanids (Monogenea: Diplecatnidae) infesting the gills of marine fishes from South America was carried out during the 2019–2020 period. The gills of four sciaenid species, 2 Cheilotrema fasciatum Tschudi, 1 smalleye croaker Nebris microps Cuvier, 2 royal highhat Pareques lanfeari (Barton), and 1 minor stardrum Stellifer minor (Tschudi), were sampled. Six new species of Rhamnocercus Monaco, Wood & Mizelle, 1954 were described: Rhamnocercus chacllae n. sp. and Rhamnocercus chaskae n. sp. from P. lanfeari, Rhamnocercus fasciatus n. sp. from C. fasciatum, Rhamnocercus microps n. sp. from N. microps, and Rhamnocercus rimaci n. sp. and Rhamnocercus tantaleani n. sp. from S. minor. Rhamnocercus chacllae n. sp. can be differentiated from its congeners by its L-shaped male copulatory organ (MCO) and by having an anteromedial slight notch at ventral bar. Rhamnocercus chaskae n. sp. differs from the other species of the genus by its long and straight MCO with bifid distal end and by having haptoral accessory spines at level of ventral bar with quadrifid distal portion. Rhamnocercus fasciatus n. sp. is characterized by possessing a straight and long MCO with truncated distal end, haptoral accessory spines at level of ventral bar with bifid distal portion, dorsal bars with a knob at lateral extremity, and a large vagina with bell-shaped. Rhamnocercus microps n. sp. differs from all congeners mainly by having a short and straight MCO with the distal end of internal tube spatulate and uncovered by external tube. Rhamnocercus rimaci n. sp. is can be distinguished from all other species of Rhamnocercus by having an almost J-shaped MCO with the distal end of external tube slight expanded and the distal end of internal tube narrow and uncovered by external tube. Rhamnocercus tantaleani n. sp. is mainly characterized by its MCO, which is tubular and straight, having the distal end of external tube bifurcated (right branch well-expanded and left branch narrow) and the distal end of internal tube enveloped by left branch of the external tube. This is the first data on the parasites of P. lanfeari, a little known, but popular fish in local markets from Peru. Rhamnocercus microps n. sp. is the first described species of Rhamnocercus in Brazil. The present finding brings to 12, the number of known species of Rhamnocercus. A key to Rhamnocercus species is provided.

     

Larval Ischnura verticalis (Odonata: Coenagrionidae) Respond to Visual Cues of Predator Presence

Larvae of some species of damselflies respond to chemical cues of fish predators but, while larvae of many species are thought to detect prey through vision, there is little evidence that larvae respond to visual cues of predator presence. This laboratory study indicated larval Ischnura verticalis behaviours are affected by visual cues and, to a much lesser extent, chemical cues of fish; there was no significant interaction between the effects of visual and chemical cues. Responses to chemical cues of fish did not depend on whether fish were fed I. verticalis larvae versus commercial fish food. Larvae were more active in the spring than the fall when they were likely in diapause. Results suggest larvae can use vision to detect large, active predators but can also detect predators through olfaction when visual cues are unreliable.