SynopsisEcomorphological analyses that search for patterns of association between morphological and prey-use data sets will have a greater chance of understanding the causal relationships between form and diet if the morphological variables used have known consequences for feeding performance. We explore the utility offish body size, mouth gape and jaw-lever mechanics in predicting patterns of prey use in two very different communities of fishes, Caribbean coral reef fishes, and species of the Centrarchidae that live in Lake Opinicon, Ontario. In spite of major differences in the spectrum of potential prey available, the centrarchids of Lake Opinicon show dietary transitions during ontogeny that are very similar to those seen among and within species of Caribbean groupers (Serranidae ). The transition from small zooplankton to intermediate sized invertebrates and ultimately to fishes appears to be very general in ram-suction feeding fishes and is probably driven largely by the constraints of mouth size on prey capture ability. The jaw-lever systems for mouth opening and closing represent direct trade-offs for speed and force of jaw movement. The ratio of in-lever to out-lever in the opening system changes during ontogeny in bluegill, indicating that the mechanics and kinematics of jaw movement may change as well. Among 34 species of Caribbean reef fishes, biting species had jaw-closing ratios that favored force translation, while species that employ rapid-strike ram-suction had closing ratios that enhanced speed of closing and mouth opening ratios that favored a more rapid expansion of the mouth during the strike. We suggest that when prey are categorized into functional groups, reflecting the specific performance features that are important in capturing and handling them, and the differences among habitats in the available prey resource are taken into account, general patterns can be found in morphology-diet relations that cross phylogenetic boundaries.

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DNA barcoding of aquatic macroinvertebrates holds much promise as a tool for taxonomic research and for providing the reliable identifications needed for water quality assessment programs. A prerequisite for identification using barcodes is a reliable reference library. We gathered 4165 sequences from the barcode region of the mitochondrial cytochrome c oxidase subunit I gene representing 264 nominal and 90 provisional species of mayflies (Insecta: Ephemeroptera) from Canada, Mexico, and the United States. No species shared barcode sequences and all can be identified with barcodes with the possible exception of some Caenis. Minimum interspecific distances ranged from 0.3–24.7% (mean: 12.5%), while the average intraspecific divergence was 1.97%. The latter value was inflated by the presence of very high divergences in some taxa. In fact, nearly 20% of the species included two or three haplotype clusters showing greater than 5.0% sequence divergence and some values are as high as 26.7%. Many of the species with high divergences are polyphyletic and likely represent species complexes. Indeed, many of these polyphyletic species have numerous synonyms and individuals in some barcode clusters show morphological attributes characteristic of the synonymized species. In light of our findings, it is imperative that type or topotype specimens be sequenced to correctly associate barcode clusters with morphological species concepts and to determine the status of currently synonymized species.

Three new species of Cloeodes are described from Argentina (C. barituensis, C. espinillo and C. opacus), based on nymphs and from adults for the first two species. Two species, C. stelzneri and C. nocturnus, are proposed as nomen dubia. The only other species from Argentina, C. penai, is revised. The validity of the monotypic genus Bernerius is analyzed. A cladistic analysis including five species of the genus Cloeodes and Bernerius is presented and the synonymy of the latter is confirmed. A key for South American species of Cloeodes is presented.

Recent discovery and description of fossil Baetiscidae has dramatically changed the biogeographical and evolutionary perspective of the family. Since the mideighteenth century until recently, the family has been known only from the Nearctic realm and all extant species of the family still remain geographically limited to this region. Here, we present the first parsimony algorithm generated cladistic analysis of the phylogeny of Baetisca based on external morphological characters of both larvae and adults. The results are compared with the previously published phylogeny of the genus and differences between the two studies are discussed. The southeastern United States is the centre of biodiversity of the genus where 11 of the 12 currently known nominal species have been reported. Biogeographical and evolutionary implications of the current geographic range of extant Baetisca and fossil species are discussed.