Two new genera of Baetidae are described from East Kalimantan (Borneo): Asiobaetodes n.gen. and Acerobiella n.gen. Both genera are monospecific and only known from a very restricted area. They are highly adapted to fast flow and are closely related to Oriental genera Liebebiella Waltz & McCafferty, 1987 and Platybaetis Müller-Liebenau, 1980. Asiobaetodes is characterized by five pairs of ventrally orientated gills and tubular accessory gills at the bases of mouthparts and forelegs; these characters are also present in the Panamerican genus Baetodes Needham and Murphy, 1924 and the African genus Afrobaetodes Demoulin, 1970. The study of the mouthparts clearly indicates that the similarities must be considered as homoplasies. Acerobiella is characterised by its dorsal armature, especially the spike tubercles turned upwards on tergum II, which constitutes a unique character among the Baetidae.

Four new species of Thraulodes Ulmer (Ephemeroptera: Leptophlebiidae), Thraulodes amanda sp. n., Thraulodes pelicanus sp. n., Thraulodes xavantinensis sp. n. and Thraulodes sinuosus sp. n are described based on imagos. A new synonymy (Thraulodes lepidus [Ulmer]=Thraulodes cryptodrilus Nieto & Domínguez) is proposed and the distribution of Thraulodes schlingeri is expanded based on a new record from western Brazil.

Many species of Ephemeroptera have been described based on either nymphs or adults. Only 10% of Ephemeroptera species in South America are known in both life stages. The current research was carried out in order to molecularly associate nymphs and adults of Ephemeroptera, using the amplified fragment length polymorphism (AFLP) technique. We obtained molecular fingerprints by the AFLP of five species: Leptohyphes albipennis, Leptohyphes coconuco, Leptohyphes ecuador, Baetodes levis and Prebaetodes sitesi. The association between nymphs and adults of L. albipennis and L. coconuco by this analysis confirmed the effectiveness of the technique. The molecular fingerprints of B. levis and P. sitesi were generated with the hope that future collections of unknown adults would match the fingerprint and solve an identification problem. We describe here for the first time the adult of L. ecuador by matching an adult trapped in the field with the DNA fingerprint of nymphs obtained by means of AFLP.

The aim of the study was to test the hypothesis that patterns of cross-Eurasian longitudinal distribution of lotic mayflies are determined by species' ecological requirements and the presence of the West Siberian Lowland. In particular, the objective was to test whether this great lowland is an environmental barrier preventing longitudinal dispersal of the rheophilic (i.e., preferring fast-running highland waters), but not the potamophilic (i.e., preferring slow-current lowland waters) mayflies, as its entire territory contains no rapidly-flowing streams suitable for rheophilic species. This hypothesis was tested indirectly by comparison of altitudinal ranges of species characterised by different cross-Eurasian distribution patterns (mainly East Palaearctic and Transpalaearctic species distributed over the Asian part of Palaearctica and entire Palaearctica respectively). The material used for the analyses was collected in the centre of Eurasia, south-western Siberia, Russia. The region covered both lowland and mountain territories. The studied biogeographical groups of mayflies have distinctly different altitudinal distribution: the Transpalaearctic species inhabit lowland watercourses only, while the East Palaearctic species inhabit the entire altitudinal range with most of the species preferring high elevations (on average 700 m a.s.l.). These results confirmed the stated hypothesis and showed that for most of the East Palaearctic (but not Transpalaearctic) species the West Siberian Lowland can be an environmental barrier preventing their westward dispersal and therefore precluding mixing of the East and West Palaearctic rheophilic faunas. However, possible alternative hypotheses cannot be ruled out, as altitudinal ranges of some of these species do not fall out of the elevation range of the West Siberian Lowland. Remarkably, the East Palaearctic species, which by definition have narrower distribution than the Transpalaearctic species, have broader altitudinal ranges than the Transpalaearctic species. This pattern is related to the altitudinal Rapoport effect recently detected for mayfly distribution over the river systems.

In the present paper, based on the rearing of nymphs in the field, we present for the first time the description of the adult stage of Rivudiva Lugo-Ortiz and McCafferty and of its type species, R. minnatena Lugo-Ortiz and McCafferty. Adults of Rivudiva can be distinguished from the other genera of Baetidae by the following combination of characters: (1) hindwings present or absent, when present with two longitudinal veins and with costal projection pointed, placed in the basal fourth of anterior margin; (2) forceps three-segmented, segment III long, about 2× as long as wide; (3) distal margin of subgenital plate with small pointed projection. Besides that, R. coveloae (Traver, 1971 [Proc. Entomol. Soc. Washington, 73, 58–63]), new combination, and R. venezuelensis (Traver, 1943 [Bol. Entomol. Venezolana, 2, 79–98]), new combination, are proposed based on the characteristics listed above, specially the distal margin of subgenital plate with a small pointed projection. Comments on the biology of the nymphs are also provided.

A new species of Tricorythodes Ulmer (Ephemeroptera: Leptohyphidae) is described based on nymphs from the Northern Region of Brazil. Tricorythodes rondoniensis sp. n. can be distinguished from other species in the genus by the following characters: wide femora, nearly circular, with the margins covered with very long setae; tarsal claws with 5–6 marginal denticles; terga III–VII with an acute median tubercle; operculate gill ovoid and abdominal colour pattern.

The habitat preferences, temporal dynamics in density and the life history of two species of mayflies, Metamonius anceps andMeridialaris chiloeensis, were investigated in a Patagonian mountain stream over a period of one year. Benthic samples weretaken in a low order Nothofagus forested stream. M. anceps was univoltine with small nymphs predominating in winter andemergence occurring in summer. M. chiloeensis showed a bivoltine life cycle with a winter and summer generation, andemergence period in spring and summer. Both species were significantly more abundant in the low water period than in the highdischarge season. Gravels supported significantly more individuals of M. chiloeensis than sand in pools and leaf packs. Temporaloverlap of abundance between species was low. The existence of different life history strategies and the temporal shift of maingenerations and density peaks were critical to allow species coexistence.

Apobaetis insolitus n. sp., Apobaetis kallawaya n. sp. and Apobaetis niger n. sp. (Ephemeroptera: Baetidae) are described fromnymphs collected in Argentina and Bolivia. Apobaetis insolitus can be distinguished by the labrum with anterior margin with aU-shaped emargination, segment II of labial palpi with triangular apically rounded distomedial projection. Apobaetis kallawayacan be distinguished by segment II of labial palpi with triangular, slender and apically pointed distomedial projection, the posteriormargins of the abdominal terga with blunt spines and paraprocts with blunt spines apically. Apobaetis niger can be distinguishedby the anterior margin of labrum with medial lobe and segment II of labial palpi with triangular apically rounded distomedialprojection. The three new species possess tarsal claws with two rows of denticles. A key to all species known fromnymphs is presented.

In order to assign 18 mayfly taxa found in streams in the Macaé River basin into Functional Feeding Groups, the anatomy of their feedingapparatus was examined through scanning electron microscopy. Also, habitat preference and field observations of feeding behaviour were madeto assure FFG assignment. Ephemeropteran taxa were classified into five FFGs: Passive Filterers - Hylister plaumanni; Active Filterer -Lachlania boanovae and Campylocia sp.; Brushers - Askola froehlichi, Farrodes carioca, Hagenulopsis spp., Massartela brieni, Miroculis froehlich,Miroculis sp., and Thraulodes spp; Grazers - Cloeodes spp., Americabaetis spp., Camelobaetidius spp.and Baetodes spp.; Scrapers -Leptohyphes pereirae, Leptohyphes spp., Tricorythodes spp. and Tricorythopsis spp. Species of the three best represented mayfly families insouth-east Brazil were assigned to different FFGs (Leptophlebiidae - Brushers; Baetidae - Grazers and Leptohyphidae - Scrapers), with oneexception, Hylister plaumanni (Leptophlebiidae; Active filterers). This information is useful to understand the role of mayflies in stream ecosystems,and to help the development of ecological theories for tropical streams.

Three new species of Camelobaetidius Demoulin (Ephemeroptera : Baetidae), C. hamadae sp. n., C. lassance sp. n., and C.maranhensis sp. n., are described based on nymphs from Brazil. Some of the diagnostic characters of the new taxa are : C. hamadaesp. n., two thoracic gills at base of forelegs and claws with 36-37 denticles ; C. lassance sp. n., claws with approximately60 denticles and posterior margin of terga with few, large and elevated spines ; C. maranhensis sp. n., pronotum with medialpair of tubercles and terminal filament shorter than 10th abdominal segment. Camelobaetidius cayumba (Traver & Edmunds),C. matilei Thomas &Perú, and C. tuberosus Lugo-Ortiz &McCafferty, are recorded for the first time from Brazil. A key to thespecies of Camelobaetidius recorded from Brazil based on nymphs is presented.

Emergence traps were operated over three years in a stream near Lunz in southwestern Lower Austria, to find out the differences between eight types of traps. Trichoptera, Plecoptera, Ephemeroptera, Simuliidae, Limoniidae and Empididae were compared quantitatively as whole groups. Trichoptera, Limoniidae and aquatic Empididae were compared at species level. Except for the expected statistical variation, there was wide variation in the number of specimens between groups and species, and also between the trap types, to such a degree that the emergence method appears to be of limited value for productivity or other quantitativestudies. The total catch of insects caught in the traps, consisted of freshly emerged adults, aged ovipositing females and many other insects (including terrestrial ones) which entered the traps in unknown ways. The variation may depend on the biology and behaviour of the insects, on the design of the traps and on an unknown number of other factors.

The genus Labiobaetis recently has been reported from Madagascar by Lugo-Ortiz and McCafferty (1997). The two described species were only known from the nymphal stage. Examination of material from more than 800 samples in Madagascar allows descriptions of six new species: Labiobaetis longicercus, L. dambrensis, L. nigrocercus, L. vulgaris, L. punctatus and L. gilliesi. They can be distinguished easily by the shape of the second segment of the labial palp, the shape of the second segment of the maxillary palp, the setation of the labrum, the number of gills, the presence or absence of hindwings and coloration of the abdomen. At present, the imagoes of only five of the eight species are known. They can be identified by the presence or absence of hindwings, coloration of the wings, shape of the sclerotized process between gonopods and shape of the third segment of the gonopods. As all the species assigned to Labiobaetis were recently reassigned to Pseudocloeon, the status and validity of the genera Labiobaetis and Pseudocloeon are discussed.

A strictly phylogenetic classification of the supergeneric taxa within the subfamily Timpanoginae includes the Attenellini, n.tribe, consisting of Attenella Edmunds ; the Eurylophellini, n. tribe, consisting of Dentatella Allen, n. stat., and EurylophellaTiensuu ; and the Timpanogini, n. tribe, consisting of Timpanoga Needham and Dannella Edmunds, n. stat. Dentatella danutae McCafferty, n. sp., is described from larvae taken from a stream in southern Québec, Canada. The new species differs from the obviously closely related D. bartoni (Allen) by possibly striking coloration differences as well as numerous slight structural differences.

Nous avons analysé la distribution régionale de 147 espèces appartenant aux 4 ordres d'insectes aquatiques les mieux connusdans le Sud-Ouest de la France - Ephéméroptères, Plécoptères, Trichoptères, Coléoptères Elmidae et Hydraeniidae -, afin d'établirune classification des cours d'eau basée sur des associations spécifiques au sein du réseau hydrographique Adour-Garonne(116 000 km2). La distribution spatiale des espèces a été précisée par des Analyses Factorielles des Correspondances (AFC), etles noyaux d'affinité entre espèces et/ou stations ont été recherchés par la Méthode des Nuées Dynamiques. Six zones ont étédéfinies, ainsi que leurs peuplements théoriques. Un intérêt majeur de telles classifications est que la stabilité spatio-temporelledes associations spécifiques peut être utilisée pour définir des sites ou des stations de référence, pour une surveillance biologiquedes rivières au sein d'une région ou d'une section longitudinale identifiée par un peuplement référentiel.

The 138 species and subspecies of Ephemeroptera now known to occur in Mexico, of which 35, approximately 25 %, areendemic, are listed along with distributional annotations. New Mexican records are included for Americabaetis lugoi Waltz &McCafferty, Baetodes velmae Cohen & Allen, Drunella coloradensis (Dodds), Farrodes otiesa Lugo-Ortiz & McCafferty,Plauditus virilis (McDunnough), Tricorythodes fictus Traver, T. texanus Traver, and Varipes lasiobrachius Lugo-Ortiz &McCafferty, the latter of which also constitutes a new continental record for the genus Varipes Lugo-Ortiz & McCafferty inNorth America. Traverella sallei (Navás), n. comb., is transferred from the genus Thraulus.

The seventh in a series on the Leptophlebiidae (Ephemeroptera) of New Caledonia, this papers treats three new genera(Paraluma, Oumas, and Amoa) and 12 new species. For Paraluma gen.n., the type species P. cancellata sp.n., P. triangularissp.n., P. gilva sp.n. and P. minuta sp.n. are described from male and female imagos and nymphs, P. pulla sp.n. from male imagosand nymphs, and P. maculata sp.n. from male and female imagos. For Amoa gen.n., the type species A. fronini sp.n., A. subsolanosp.n. and A. orthogonia sp.n. are described from male and female imagos and nymphs, A. cressonensis sp.n. from nymphsonly and A. hebes sp.n. from the male imago only. Oumas orbis gen.n. sp.n. is described from male and female imagos andnymphs.

The use of available morphological characters in the interpretation of the flight of insects known only as fossils is reviewed, and the principles are then applied to elucidating the flight performance and techniques of Palaeozoic palaeopterous insects. Wing-loadings and pterothorax mass/total mass ratios are estimated and aspect ratios and shape-descriptors are derived for a selection of species, and the functional significance of wing characters discussed. Carboniferous and Permian ephemeropteroids (‘mayflies’) show major differences from modern forms in morphology and presumed flight ability, whereas Palaeozoic odonatoids (‘dragonflies’) show early adaptation to aerial predation on a wide size-range of prey, closely paralleling modern dragonflies and damselflies in shape and wing design but lacking some performance-related structural refinements. The extensive adaptive radiation in form and flight technique in the haustellate orders Palaeodictyoptera, Megasecoptera, Diaphanopterodea and Permothemistida is examined and discussed in the context of Palaeozoic ecology.

South American species of small minnow mayflies (Insecta : Ephemeroptera : Baetidae) that have been previously placed in Baetis Leach or Pseudocloeon Klapálek are revised. Species that resided in Baetis are shown to include Camelobaetidius alcyoneus, n. comb., C. coveloae, n. comb., C. dryops, n. comb., C. tantillus, n. comb., Cloeodes nocturnus, n. comb., C. stelzneri, n. comb., Fallceon inops, n. comb., F. murphyae, n. comb., F. yaro, n. comb., Moribaetis aneto, n. comb., M. comes, n. comb., and M. socius, n. comb. Species that resided in Pseudocloeon are shown to include Americabaetis albinervis, n. comb., A. bridarolli, n. comb., A. bruchi, n. comb., A. jorgenseni, n. comb., A. oldendorffi, n. comb., A. peterseni, n. comb., A. weiseri, n. comb., Cloeodes turbinops, n. comb., and C. venezuelensis, n. comb. The bases of the revisions are discussed under each species. The presence of Fallceon and Moribaetis in South America is confirmed for the first time.

Electrogena affinis (Eaton, 1883) is redescribed in all developmental stages. Larvae were analysed, in comparison with other congeneric european species, by a standard set of diagnostic characters which, in previous works, proved to be very useful in the taxonomy of Electrogena. The status of E. fascioculata (Sowa, 1974) is discussed and the synonymy E. fascioculata = E. affinis is stated. Finally, phenetic relationships between E. affinis and some other related european species are represented by cluster analysis, on the basis of quantitative characters of larvae.