Short term toxicity of iron (Fe) and lead (Pb) to the mayfly Leptophlebia marginata (L.) (Insecta) in relation to freshwater acidification

The mayfly Leptophlebia marginata was exposed to different concentrations of Fe²⁺ or Pb²⁺ at pH 4.5 and pH 7.0. The effects of the metals on escape behavior and survival of the mayflies were investigated during an exposure of 120 hours.

1. Whole-body metal loads (Fe; Pb) of the mayflies increased in a dose-dependent way at both pH levels. A significant effect of pH on metal concentration in the mayflies was only found for Pb (p < 0.001).
2. In terms of mortality, both metals were more toxic at pH 4.5 than at pH 7. The 96 h-LC₅₀ values for Fe were 106.3 mg Fe l^-1 at pH 7 and 89.5 mg Fe l^-1 at pH 4.5. Those for Pb were > 5 mg Pb l^-1 at pH 7 and 1.09 mg Pb l^-1 at pH 4.5.
3. The mayflies lost their escape behavior, when exposed to the metals, the effects being more pronounced at low than at circumneutral pH for both metals (p < 0.05). The 96 h-EC₅₀ values for Fe were 70.0 mg Fe l^-1 at pH 7 and 63.9 mg Fe l^-1 at pH 4.5.

     

Joint and single toxicity of Cd and Fe related to metal uptake in the mayfly Leptophlebia marginata (L.) (Insecta)

The toxic effects of Cd and Fe on the mayfly Leptophlebia marginata were tested during single and joint exposure to the metals. Data on uptake and localization of the metals were related to the following biological parameters: survival, food consumption (% gut contents) and activity (escape from prodding).The uptake of Cd by L. marginata was significantly reduced by the presence of Fe (p<0.0005).Fe²⁺- and Fe³⁺-crusts on the gills, body surface and on the gut membrane precipitated when the mayflies were exposed to either Fe alone or to Fe and Cd. This caused decreased food consumption by the mayflies.In the pigments of the eyes and the cuticle Fe²⁺ was found.Exposure to Cd led to disturbances in Cl^– and K⁺ ion balance, which were ameliorated by additional Fe-exposure due to co-precipitation processes.Exposure to Cd caused an increase in the concentrations of S and P in the mayflies.Whereas Fe caused sublethal effects (food consumption) without being taken up into the organism. Cd caused lethal effects (inactivity, death) due to disturbances of the ion balance at the membranes.     

Experimental studies on nymphal growth in Leptophlebia vespertina (L.) (Ephemeroptera)

The mayfly, Leptophlebia vespertina (L.) was reared at field temperatures in the laboratory. The egg incubation period was 21–26 days. There were seventeen to nineteen nymphal instars. Growth was generally rapid during the first 3½ months and slow thereafter. This change occurred at the same time in both the laboratory and the field population. Temperature is considered to be the major factor regulating this and other changes in growth rate.     

Migrations of Leptophlebia vespertina L. and L. marginata L. (Ins.: Ephemeroptera) in the estuary of a coastal stream

Investigations carried out in a coastal stream flowing to the Northern Bothnian Sea (Ängerån, 63°35'N, 19°50'E) have shown a high drift rate of mayfly nymphs towards the coastal areas. The nymphal development takes place in the estuaries with low salinity (conductivity between 47 and 9800 μS; salinity between 0 and 4–5%₀). After the emergence (May/June) the adults fly from the coastal areas to lay their eggs in the stream biotope in the Ängerån. There thus appears to be a colonization cycle between the coastal stream and adjacent coastal areas. The migration movements of downstream drift and the compensatory upstream directed flight are interpreted as asurvival strategy of the species concerned.     

The life cycles of Leptophlebia vespertina (L.) and L. marginata (L.) (Ephemeroptera) in Llyn Dinas, North Wales

Data is presented on the life cycles of Leptopblehia vespertina (L.) and L. marginata (L.) in Llyn Dinas, an oligotrophic North Wales lake. Both species are univoltine and growth continues throughout the winter although somewhat retarded. Except during July and August there is a clear size separation of the two species, L. marginata being larger and emerging earlier. The egg incubation period was determined directly from laboratory studies. The results are discussed in relation to previous research in the English Lake District.     

Heptageniidae (Insecta,Ephemeroptera) of Thailand

Nine genera and twenty-two species of heptageniid mayflies from Thailand are defined in this present work as well as one suggested further subgenus, Compsoneuria (Siamoneuria) kovaci (species “incertae sedis”) including some particular characters. Taxonomic remarks, diagnoses, line drawings of key characters, distribution, habitat and biological data, and a larval key to the genera and species are provided. The chorionic eggs of eight genera and eight species were observed and shown using a scanning electron microscope.     

Mayflies of the Northern Levant (Insecta: Ephemeroptera)

Abstract

For 31 species of mayflies, new records on their distribution are presented. Most of them are new to the Middle East or to the northern Levant (Turkey, Syria, Lebanon). The fauna is composed for the most part of species widespread in Europe (63%), a relatively high number (26%) of endemic species, and a few Caucasian (8%) and South European (3%) species. Using the genus Prosopistoma as an example, it is shown that the mayfly fauna of the northern Levantine has been isolated from the faunas of Africa and Asia for a very long period.     

The complete mitochondrial genome of Parafronurus youi (Insecta: Ephemeroptera) and phylogenetic position of the Ephemeroptera

The first complete mitochondrial genome of a mayfly, Parafronurus youi (Arthropoda: Insecta: Pterygota: Ephemeroptera: Heptageniidae), was sequenced using a long PCR-based approach. The genome is a circular molecule of 15,481 bp in length, and encodes the set of 38 genes. Among them, 37 genes are found in other conservative insect mitochondrial genomes, and the 38(th) unique gene is trnM-like (trnM2). The duplication-random loss model can be used to explain one of the translocations at least. The A+T content of the control region is 57%, the lowest proportion detected so far in Hexapoda. Based on the nucleotide dataset and the corresponding amino acid dataset of 12 protein-coding genes, Bayesian inference and maximum likelihood analyses yielded stable support for the relationship of the three basal clades of winged insects as Ephemeroptera+(Odonata+Neoptera).     

Global diversity of mayflies (Ephemeroptera, Insecta) in freshwater

The extant global Ephemeroptera fauna is represented by over 3,000 described species in 42 families and more than 400 genera. The highest generic diversity occurs in the Neotropics, with a correspondingly high species diversity, while the Palaearctic has the lowest generic diversity, but a high species diversity. Such distribution patterns may relate to how long evolutionary processes have been carrying on in isolation in a bioregion. Over an extended period, there may be extinction of species, but evolution of more genera. Dramatic extinction events such as the K-T mass extinction have affected current mayfly diversity and distribution. Climatic history plays an important role in the rate of speciation in an area, with regions which have been climatically stable over long periods having fewer species per genus, when compared to regions subjected to climatic stresses, such as glaciation. A total of 13 families are endemic to specific bioregions, with eight among them being monospecific. Most of these have restricted distributions which may be the result of them being the relict of a previously more diverse, but presently almost completely extinct family, or may be the consequence of vicariance events, resulting from evolution due to long-term isolation. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment     

Croatian mayflies (Insecta,Ephemeroptera): species diversity and distribution patterns

Knowledge of the mayfly biodiversity in the Balkan Peninsula is still far from complete. Compared to the neighbouring countries, the mayfly fauna in Croatia is very poorly known. Situated at the crossroads of central and Mediterranean Europe and the Balkan Peninsula, Croatia is divided into two ecoregions: Dinaric western Balkan and Pannonian lowland. Mayflies were sampled between 2003 and 2013 at 171 sites, and a total of 66 species was recorded. Combined with the literature data, the Croatian mayfly fauna reached a total of 79 taxa. Of these, 29 species were recorded for the first time in Croatia while 15 species were not previously recorded in Dinaric western Balkan ecoregion. Based on the mayfly assemblage, sampling sites were first structured by ecoregion and then by habitat type. In comparison with the surrounding countries, the Croatian mayfly fauna is the most similar to the Hungarian and Bosnian fauna. Some morphologically interesting taxa such as Baetis cf. nubecularis Eaton, 1898 and Rhithrogena from the diaphana group were recorded. Ephemera cf. parnassiana Demoulin, 1958, the species previously recorded only from Greece, was also recorded.     

New mayfly nymphs (Insecta: Ephemeroptera) from Yixian Formation,China

Three new species of mayfly nymphs, Clavineta excavata sp. nov., Clavineta brevinodia sp. nov., and Siberiogenites branchicillus sp. nov., from the Yixian Formation (Late Jurassic-Early Cretaceous) in western Liaoning Province, China, are described. These mature nymphs are small-sized, with the body less than 16.0 mm long. The systematic position of the genera Clavineta and Siberiogenites, which are recorded for the first time in the Yixian Formation, is briefly discussed.     

A new record of monogeneric family Vietnamellidae (Insecta: Ephemeroptera) from India

A new record of monogeneric family Vietnamellidae (Insecta: Ephemeroptera) is established for India with Vietnamella sp. A described based on the larvae from Arunachal Pradesh, India. This species can be distinguished from other known species of this genus in the larval stage by the following combination of characters: (i) outer pair of projections in head large and stout, triangular, cone-shaped with serrated spines; (ii) posterolateral angles of abdominal terga 2–9 extended into sharp projections; (iii) caudal filaments pale yellowish brown with dense lateral setae on inner and outer margins of middle part; (iv) femora of mid- and hind-legs broader; and (v) second segment of the maxillary palpi shorter than first segment.     

Phylogeny of the mayfly family Leptohyphidae (Insecta: Ephemeroptera) in South America

Abstract.  A cladistic analysis of the South American members of the Ephemeropteran family Leptohyphidae is presented. A matrix of 73 taxa and 124 morphological characters was analysed under two distinct weighting criteria (implied weighting, which weights characters as a whole, and self-weighted optimization, which differentially weights character state transformations). To assess the monophyly of the Leptohyphidae, representatives of Ephemerellidae, Ephemerythidae, Machadorythidae, Teloganodidae, Tricorythidae, Coryphoridae and Melanemerellidae were also included. Trees were rooted in Ephemerellidae. Conspicuous differences in consensus topology occur when transformation costs among character states are weighted (including asymmetries). The differences in the assessments of character reliability in the two weighting criteria used are discussed. In many cases, self-weighting, in allowing for asymmetries in transformation costs, considered many of the character state transformations as more reliable (= informative) than implied weights (which needlessly down-weighted the whole character). The results confirm the monophyly of Leptohyphidae and support its sister-group relationship with Coryphoridae. The shortest trees do not support the recently proposed division of Leptohyphidae into two subfamilies. Ephemerelloidea higher classification is discussed briefly.     

Cladistic analysis of the family Baetidae (Insecta: Ephemeroptera) in South America

The family Baetidae, which belongs to the order Ephemeroptera, was first described by Leach in 1815 . Since then, almost 100 genera and 900 species have been described. Although diverse, this family is relatively homogeneous. The adults are extremely similar to one another, the wings vary little and the penes are membranous, features that significantly reduce differentiation among taxa. In contrast, the larvae have more conspicuous differences. Most are collector–gatherers, but a few are carnivorous or filter feeders. In South America, although knowledge concerning the 27 genera and 132 species of Baetidae described for this region has improved in the last three decades, phylogenetic relationships remain unknown. The present study, the first cladistic analysis of Baetidae in South America, included 70 species (55 are Neotropical) and 126 morphological characters. The matrix was analysed using tnt , under implied weights. Although the monophyly of the family Baetidae was obtained with good support, the subfamilies proposed originally (Baetinae, Cloeoninae and Callibaetinae) were recovered as paraphyletic. The Baetodes complex, as well as the relationships between genera, is discussed. The validity of some structures or characters as support of different groupings is also discussed.     

Two New Genera of Baetidae (Ephemeroptera; Insecta) from Madagascar

Two new genera of Baetidae (Ephemeroptera), Scutoptilum gen. n. and Echinopus gen. n., are described to accommodate three new species from Madagascar: Scutoptilum verrucosum sp. n., Echinopus giboni sp. n., Echinopus minutus sp. n.. They all share a unique apomorphy; they possess a subapico-transverse arc of long setae on the outer margin of femora. Scutoptilum presents important adaptations to fast flowing waters and mouthparts modified for scraping. Moreover, Scutoptilum shows an unusual general habitus with a prothorax broadly expanded laterally, forewing pads extremely developed and shape of the head subrectangular. Echinopus appears less derived and possesses more plesiomorphic features. Both genera are closely related to the Afrotropical genus Afroptilum and belong to the Centroptiloides complex.     

Two new genera of Caenidae (Insecta: Ephemeroptera) from Guinea,West Africa

Larvae of two new genera of Caenidae are described from the River Niandan, Guinea. Their position in the phylogenetic system of Caenidae is discussed. Niandancus alienus gen. n., sp. n. is the first known representative of the Brachycercinae in the Ethiopic region. Aenigmocaenis morgensterni gen. n., sp. n. could represent the sister group to all other Caenidae, as the most important larval synapomorphy of the family, a band or row of microtrichia on the ventral side of the operculate gill, is lacking.     

The distribution,life cycle and production of Leptophlebia vespertina (L.) (Ephemeroptera) in a lowland lake

Oak Mere, the water body studied, is a moderately productive base-poor lowland lake. It has zones of submerged marginal vegetation growing on sand at the south-west end and on peat at the north-east end. The distributions of L. vespertina and other macroinvertebrates are described in relation to these two distinct areas. Laboratory experiments on behaviour and survival are described in an attempt to explain the patterns of distribution. The seasonal distribution, variations in population density, spatial distribution variance in relation to mean density, life cycle, length-weight relationship, growth and biomass of L. vespertina are then described during two years at the sandy south-west end. The data are used to estimate annual production. Distribution, life cycle, growth and production are compared with populations in water bodies of lower conductivity in the British Isles and Scandinavia.     

Seasonal dynamics of a mayfly (Insecta: Ephemeroptera) community in a Laurentian stream

The purpose of our study was to compare on a seasonal basis the emergence, the drift and the benthos on a short and uniform section (18.5 m)of a stream in the Laurentian Hills of Québec. Nineteen species occurred on this stretch, but only six were abundant: Leptophlebia cupida (Say), Habrophlebia vibrans Needham, Baetis pygmaeus (Hagen), Eurylophella verisimilis (McDunnough), Stenonema modestum (Banks), and Stenonema vicarium (Walker). Emergence was monitored for 5 years; densities differed from one trap to the next, as did species dominance, but total densities were similar. These data conform to Illies' rules of constancy and harmony. Nymphal densities were high (mean of 16000 m⁻²). The dominant species were univoltine, except H. vibrans (semivoltine), and B. pygmaeus (polyvoltine). Larger species contributed relatively more to the production of the reach despite their low densities than did the more abundant smaller species, especially those with long life cycles. Drift was low during most of the year, except during spring and species composition varied considerably. A comparison of the three data sets (emergence, drift and benthos) shows a general agreement for the less abundant species, but for three of the dominants, H. vibrans, L. cupida and E. verisimilis , movements of individuals to and from the reach at various times in the life cycle (adult flight, nymphal drift and migration) must be taken into account in order to correlate the data. None of the methods alone gives a satisfactory picture of the community structure, each is to some extent misleading and needs to be used in conjunction with the others; the conflicting results obtained from the data sets often reveal interesting life history traits which otherwise would not have been detected.