The species currently included in Telagrion Selys are found to belong to three different genera: Telagrion sensu stricto, monotypic, including only the type species T. longum Selys, Schistolobos gen. nov., also monotypic, including Telagrion boliviense Daigle, and Aceratobasis Kennedy, resurrected to include Metaleptobasis cornicauda Calvert (type species), Agrion macilentum Rambur, Telagrion mourei Santos and T. nathaliae Lencioni. Synonymic lists, diagnoses, illustrations and distribution maps for the three genera and a key for species of Aceratobasis are provided.

Atychodea Reitter is re-described, and descriptions of the eight species included are given. Three of these were known and have been included in this genus earlier, two, from other genera, newly included in Atychodea, and three are new (A. portentosa sp. n. from Myanmar, and A. fedorenkoi sp. n. and A. vicina sp. n. from southern Vietnam). One species, A. lenticornis Reitter, is excluded from this genus and a new monotypic genus Amorphodea gen. n. is described to include this species. A key to the species of Atychodea is given. On the basis of a large set of morphological data, the relationships of all genera of the Tychini are considered, and Hesperotychus Schuster and Marsh and Tychomorphus Jeannel are synonymized with the genus Tychus Leach. A key to genera of Tychini is given. A complete catalogue of the tribe, with 20 new combinations and 12 revised combinations, with data on species distribution, is also provided.

The following nine new species of Pseudomethoca are described and illustrated: P. hansoni n. sp., P. roubiki n. sp. and P. ugaldei n. sp. from Costa Rica and Panama; P. bicarinata n. sp. and P. masneri n. sp. from El Salvador, Honduras, Nicaragua and Costa Rica; P. sermenoi n. sp. from El Salvador, Nicaragua and Costa Rica; P. bimaculata n. sp. from Panama and Ecuador; P. cartaginense n. sp. from Costa Rica; and Pseudomethoca jica n. sp. from Panama. New distribution records are presented for: Pseudomethoca expansa (André, 1906), Costa Rica and Panama, previously known from Guatemala, and Pseudomethoca tetraspilota (Gerstaecker, 1874), New Combination from Mutilla, Panama, previously known from the type specimen from Colombia. Pseudomethoca cleonica (Cameron, 1894), from Mexico, is an additional New Combination from Sphaerophthalma. We have prepared two identification keys for the females of 20 species of Pseudomethoca, including the nine new species.

The following species are recorded by first time in Mexico: Lepidiella albipeda (Rapp, 1945b), L. matagalpensis (Collantes and Martínez-Ortega, 1998), Australopericoma caudata (Satchell, 1955), Balbagathis sylvatica Quate, 1994, Paramormia furcata (Kincaid, 1899), Psychoda cinerea Banks, 1894, P. lativentris Berdén, 1952, P. savaiiensis Edwards, 1928, and P. tothastica Quate, 1955. Aditionally, some state records of Clogmia albipunctata (Williston, 1893), Psychoda alternata Say, 1824, and P. alternicula Quate, 1955, are provided. The female of Lepidiella albipeda (Rapp), the male of Balbagathis sylvatica Quate, 1994, and the male and female of one previously unknown species of the genus Psychoda Latreille, 1796, are described and illustrated by first time. Additionally, Telmatoscopus sobrinus Quate, 1955 and Duckhousiella corniculata Vaillant, 1973 of North America are transferred to the genus Paramormia Enderlein.

The Ephemeroptera fauna of Nicaragua is inventoried based on the study of recent collections and includes eight families, 28 genera, and 56 species. Forty-seven species are reported from Nicaragua for the first time. Genera found in Nicaragua for the first time include Allenhyphes Hofmann and Sartori, Baetodes Needham and Murphy, Camelobaetidius Demoulin, Choroterpes Eaton, Epiphrades Wiersema and McCafferty, Fallceon Waltz and McCafferty, Farrodes Peters, Guajirolus Flowers, Hagenulopsis Ulmer, Haplohyphes Allen, Lachlania Hagen, Leptohyphes Eaton, Maccaffertium Bednarik, Paracloeodes Day, Terpides Demoulin, Thraulodes Ulmer, Traverella Edmunds, Tricoryhyphes Allen and Murvosh, Ulmeritoides Traver, and Vacupernius Wiersema and McCafferty. Americabaetis alphus Lugo-Ortiz and McCafferty, Baetodes bibranchius McCafferty and Provonsha, Campsurus notatus Needham and Murphy, Fallceon planifrons (Kluge), Farrodes pakitza Domínguez, Molineri and Peters, F. savagei Domínguez, Traverella albertana (McDunnough), Tricoryhyphes condylus (Allen), and the genus Tricoryhyphes are reported from Central America for the first time.

The faunal inventory of the Great Plains state of South Dakota includes 15 families, 40 genera, and 77 species of Ephemeroptera, including the first published state records for 37 species, and 187 new county records for 64 of the species. The mayfly fauna of South Dakota includes transcontinental species, widespread species, many species that typify the central lowlands of North America, and some 18 species that find their eastern range limits in South Dakota, five species that find their northern range limits in South Dakota, and 16 species that find their western range limits in South Dakota and often additional states directly north or south of South Dakota.

The nymphs of three nemourid stonefly species, Malenka bifurcata (Claassen), Ostrocerca dimicki (Frison) and Soyedina producta (Claassen), are described and illustrated from field correlated and reared specimens collected from Oregon summer-dry headwater streams from 1992-2007. Their characters affirm the nymphal diagnostic generic characters proposed by Stewart & Stark (2002). Variation in specific characters from the few described congeners is discussed; these traits may be useful in eventual construction of species-level keys.

The generic classification of Ephemerellidae Klapálek (Ephemeroptera) is reviewed and revised. Taxonomic status quo is maintained for the subfamily Timpanoginae Allen, except that Melanameleus Tiensuu (Ameletidae McCafferty) is not synonymous with Eurylophella Tiensuu. Data from the external morphology of eggs, larvae and adults of Ephemerellinae, s.s., species are coded into a data matrix and analyzed via the parsimony criterion of PAUP^* to construct phylogenetic trees. A higher classification of Ephemerellinae is proposed based on the naming of groups from these trees. Two tribes are recognized and redefined: Ephemerellini, s.s., and Hyrtanellini Allen. Ephemerellini contains eleven genera: Drunella Needham [= Eatonella Needham, new synonym; = Myllonella Allen, new synonym; = Tribrochella Allen, new synonym; = Unirhachella Allen, new synonym], Caurinella Allen, Ephemerella Walsh, Matriella, new genus, Tsalia, new genus, Caudatella Edmunds, Notacanthella, new genus, Spinorea, new genus, Adoranexa, new genus, Ephacerella Paclt and Cincticostella Allen [= Rhionella Allen, new synonym]. The genus Notacanthella contains two subgenera: Notacanthella, s.s., and Samiocca, new subgenus. The genus Ephemerella contains six subgenera: Zonadia, new subgenus, Hosoba, new subgenus, Draeconia, new subgenus, Scholitza, new subgenus, Vittapallia, new subgenus, and Ephemerella, s.s. [= Chitonophora Bengtsson]. Hyrtanellini contains six genera: Penelomax, new genus, Teloganopsis Ulmer [= Amurella Kluge, new synonym; = Kangella Sartori, new synonym; = Uracanthella Belov, new synonym], Serratella Edmunds, Quatica, new genus, Hyrtanella Allen and Edmunds and Torleya Lestage [= Crinitella Allen and Edmunds, new synonym]. Four replacement names are established for species: Drunella fuso, new name [=Ephemerella fusongensis Su and Gui nec Ephemerella fusongensis Su and You], Serratella occiprens, new name [= Ephemerella imanishii Gose nec Ephemerella imanishii Allen], Serratella tsuno, new name [= Ephemerella cornuta Gose nec Ephemerella cornuta Morgan] and Cincticostella braaschi, new name [= Ephemerella serrata Braasch nec Ephemerella serrata Morgan]. New gener