J. M. Webb

A DNA Barcode Library for North American Ephemeroptera: Progress and Prospects

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.

Adult and larval associations of the alpine stonefly genus Riekoperla McLellan (Plecoptera : Gripopterygidae) using mitochondrial DNA

The current taxonomic understanding of the genus Riekoperla McLellan, 1971 (Gripopterygidae) is poor, with 15 of the 28 species and subspecies having unknown or uncertain larval associations. Sequences of a 657 bp fragment from the mitochondrial gene cytochrome c oxidase subunit 1 (CO1) were obtained from 122 specimens of 13 species collected throughout the alpine areas of New South Wales and Victoria, Australia. Of these, sequence data associated adults and larvae for the following 10 species: R. alpina McLellan, 1971, R. cf. intermedia, R. compressa Theischinger, 1985, R. hynesorum Theischinger, 1985, R. karki McLellan, 1971, R. montana Theischinger, 1985, R. reticulata (Kimmins, 1951), R. rugosa (Kimmins, 1951), R. trapeza Theischinger, 1985, and R. tuberculata McLellan, 1971. Adults of R. intermedia Theischinger, 1985, R. triloba triloba McLellan, 1971 and R. williamsi McLellan, 1971 were sequenced but no larvae were associated with them. The 13 species were reciprocally monophyletic and had minimum interspecific sequence divergences ranging from 7.2–19.5%, higher than the maximum intraspecific sequence divergences (0.6–5.8%). The combination of morphology and molecular data enabled rapid life stage association for alpine Riekoperla species and this method should be used more frequently for other environmentally significant aquatic insects.

The state of systematics of North American Baetis Leach, 1815 (Ephemeroptera: Baetidae), with recommendations for identification of larvae

The North American species of Baetis Leach (Ephemeroptera: Baetidae) are reviewed. Nearly one-third of species are either unknown or inadequately described in the larval stage, a fact not reflected in most keys or standard taxonomic efforts for bioassessment, which typically recommend species-level identifications of larvae. Furthermore, our new observations indicate that some previously published stage associations should be viewed as only tentative, and molecular evidence suggests that current species taxonomy does not reflect biological species. In order to acknowledge these deficiencies, but at the same time provide a degree of higher taxonomic resolution beyond the genus level, we recommend a scheme for identifications incorporating previously established species groups and the species complexes and species included within them. Species complexes are proposed for instances when there are either multiple species that cannot be differentiated in the larval stage or when multiple lines of evidence indicate more than one actual species is included in a single species concept. Complexes include B. flavistriga complex (B. flavistriga McDunnough + B. phoebus McDunnough + B. rusticans McDunnough), B. intercalaris complex (B. intercalaris McDunnough), B. vernus complex (B. brunneicolor McDunnough + B. vernus Curtis), B. bicaudatus complex (B. bicaudatus Dodds), B. tricaudatus complex (B. tricaudatus Dodds), and B. piscatoris complex (B. piscatoris Traver + B. palisadi Mayo + B. persecutus McDunnough [=B. persecutor McCafferty n. obj. syn]). A new larval identification key incorporating the B. piscatoris complex is provided.