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.

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.

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.

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.

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.

Afrobaetodes lenae n. sp. is described at the larval stage. It represents the first report of Afrobaetodes in Madagascar and outsidecontinental Africa. The species presents all the very peculiar apomorphies of Afrobaetodes. It is distinguished from theAfrican species by the absence of tracheation on the abdominal gills and the absence of compact tufts of stout setae on the pronotum.Affinities and ecology are discussed.

Papuanatula, n. gen. (Ephemeroptera : Baetidae), is described from New Guinea and New Britain and based on both larvae and adults. Larvae of Papuanatula are distinguished by having basally narrow and distally broad antennal scapes ; glossae shorter than paraglossae ; segment 3 of labial palps more convex laterally than medially ; ventral long, somewhat robust, simple seta subdistally on tarsi ; gills on abdominal segments 2-7 ; reduced medial caudal filament ; and absence of hindwingpads. Adults have double marginal intercalaries in the forewings, lack hindwings, and males possess a sclerotized process between the genital forceps. Five new species are described from New Guinea [P. bessa n. sp., P. copis n. sp., P. lenos n. sp., P. plana n. sp., and P. tuber, n. sp. (type species)] and one new species named from New Britain (P. vaisisi n. sp.). An identification key to the larvae of the six new species is included.

Two new species of Herbrossus (Ephemeroptera: Baetidae) are described at the larval stage and for the first time the imagoesof this genus are also described. New information on larval and imaginal stages of the type species H. edmundsorum is presented.Affinities and ecology are discussed.

The description of new taxa of small minnow mayflies (Insecta : Ephemeroptera : Baetidae) includes the following. Cryptonymphacopiosa n. gen. and n.sp., from Brazil, is distinguished by long, robust, pilose setae on the medial margin of the prosthecae; apically narrow glossae and paraglossae ; absence of hindwingpads ; and long, basally narrow gill 1. Rivudiva n. gen., includingR. minantenna n.sp., from Brazil, and R. trichobasis n.sp., from Brazil and Paraguay, is distinguished by a broad linguaand relatively narrow superlinguae ; broad glossae with a distomedial row of long, robust, falcate, simple setae ; and tarsal clawswith minute denticles arranged in an ellipse. Spiritiops silvudus n.gen. and n. sp., from Brazil and French Guyana, is distinguishedby a long, robust, pilose seta arising from the medial margin of the right prostheca and tarsal claws with two rows of denticlesand lateral long, fine, simple seta. Varipes lasiobrachius n. gen. and n. sp., from Colombia and Ecuador, is distinguished bythe reduced right prostheca and U-shape arrangement of denticles on the tarsal claws. Zelusia principalis n. gen. and n. sp., fromBrazil and Colombia, is distinguished by a medially raised labrum, bifid right prostheca, and long, slender maxillary palps.

Edmulmeatus grandis, n. gen. and sp. (Ephemeroptera : Baetidae) is described from larvae collected from eastern Madagascar.The genus is distinguished primarily by having a relatively very large head capsule, large and robust mandibles with specializedarmature, and gills on abdominal segments 2-7 only. The relatively massive mandibles suggest that larvae have unusual feedinghabits compared to other baetids, being probably a macrovore-herbivore adapted for cutting and crushing plant food items. Edmulmeatusis possibly related to other Afrotropical genera having two rows of denticles on the tarsal claws.

The African genus Acanthiops Waltz and McCafferty (Ephemeroptera : Baetidae) is reviewed, redescribed, and figured. The genus is a monophyletic group, easily identified in the larval stage by its distinctive labium, dorsal abdominal armature, claw armature, and two-tailed condition. A previous synonymy of Afroptilum (subgenus Afroptiloides) Gillies with Acanthiops is corroborated. Nominal species included in Acanthiops are A. marlieri (Demoulin) from Zaire, A. tsitsa n. sp. from South Africa, A. variegatus (Gillies) n. comb, from Tanzania, and A. varius (Crass) from South Africa. There are other undescribed species more widespread in sub-Saharan Africa. Species vary considerably and express relative apotypy in development of dorsal armature. Acanthiops tsitsa is described from larvae taken in the North East Cape; it is related to A. varius, but differs in dorsal armature and mouthpart characterization.

Crassabwa Lugo-Ortiz & McCafferty (Ephemeroptera : Baetidae), n. gen., is erected for a small monophyletic group of distinctive Afrotropical species previously assigned to Afroptilum Gillies and Centroptilum Eaton, including C. badia (Kopelke), n. comb., C. flava (Crass), n. comb. (type species), C. loweae (Kimmins), n. comb., and C. vitrea (Navás), n. comb. Larvae of Crassabwa are distinguished by possessing a thumb-like distomedial process on labial palp segment 2, a proximal arc of setae on the tibiae, two enlarged subapical denticles in the tarsal claws, and seven gill pairs with posteriorly oriented tracheae and anterodistal marginal serration. Adults are distinguished by possessing hindwings with two longitudinal veins and an elongate, acute costal process, and a robust segment 3 of the male genital forceps. The larval stage of C. flava is redescribed, and new figures are provided to illustrate previously overlooked characters.

The genus Paracloeodes (Insecta : Ephemeroptera : Baetidae) is newly reported from South America. Because of the discovery of species with hindwings and other characteristics not previously associated with Paracloeodes, a redescription of the genus is provided. Cladistic data suggest a South American center of origin for this Panamerican genus. Paracloeodes binodulus,n. sp., is described from larvae from northern Brazil, and is distinguished by the lack of hindwingpads and presence of small mesonotal tubercles. Paracloeodes eurybranchus n. sp., is described from larvae and female adults from north-central Argentina and southeastern Brazil; it is distinguished as larvae by the relatively large size, hindwingpads, and medially broad gills. Paracloeodes ibicui, n. sp., is described from a mature larva collected from Paraguay, and is distinguished by hindwingpads andabdominal coloration. Paracloeodes leptobranchus, n. sp., is described from larvae from Paraguay and southeastern Brazil, and is distinguished by relatively large size, hindwingpads, and slender gills.

Three new genera of Baetidae (Ephemeroptera) are described from larvae from South America. Adebrotus Lugo-Ortiz & McCafferty, n.gen., and its type species, A. amazonicus Lugo-Ortiz & McCafferty, n.sp., were taken from Amazonas, Brazil. The genus possesses numerous unique mouthpart characteristics, including a labrum with distinct anteromarginal protrusions, a left mandible with the inner incisors rotated to a right angle with the flat plane of the mandible, a right mandible with a large denticle in the midregion of the mola, unusually shaped galealaciniae with distally pectinate setae, and an unusually shaped labium. Tomedontus Lugo-Ortiz & McCafferty, n.gen., and its type species, T. primus Lugo-Ortiz & McCafferty, n.sp., were taken from Amazonas and Pará, Brazil. The genus possesses a trapezoidal labrum lacking an anteromedial emargination, a distomedial process on the hypopharyngeal superlinguae, laterally denticulate mandibles, and unusually shaped maxillae and labium. Waltzoyphius McCafferty & Lugo-Ortiz, n.gen., and its type species, W. fasciatus McCafferty & Lugo-Ortiz, n.sp., were taken from Amazonas and Pará, Brazil, and Paraguarí, Paraguay. The genus is distinct in that the maxillae have only falcate denticles on the galealaciniae,the labium is unusually shaped, and the midsternum has an acute medial spur.

Une espèce nouvelle, Baetis albinatii nov. sp., est décrite (imago mâle et larve au dernier stade) à partir de matériel récolté en Corse. Elle appartient au groupe muticus et est très voisine de B. navasi Müller-Liebenau, 1974.

Description illustrée de la larve au dernier stade de Baetis cleopatrae n. sp., rencontrée dans le delta du Nil (Egypte). Cette espèce appartient au groupe atrebatinus et présente des affinités morphologiques avec B. balcanicus Müller-Liebenau & Soldán. 1981.

Description illustrée de la larve au dernier stade de Baetis ingridae n. sp., rencontrée en Corse. Cette espèce appartientau groupe rhodani.

Description illustrée de la larve au dernier stade de Baetis spei n.sp. Cette espèce, rencontrée dans le Sud du Liban,présente quelques affinités morphologiques avec B. buceratus Eaton.

Description illustrée de la larve au dernier stade de Baetis cyrneus n.sp. Cette espèce, rencontrée en Corse, appartient au groupe alpinus : elle est comparée à cette dernière espèce et à B. punicus Thomas, Boumaiza et Soldán.