The aquarium trade has been shown to be a source for introductions of nonnative aquatic macrophyte species. Improvements are needed in identification, labeling, and retailer awareness of banned aquatic plants. In the state of Connecticut, United States, 20 nonnative macrophytes are banned from sale by state statute. At least 13 of these species are already established in the state's lakes, while the remainder are either present in near-shore wetlands or absent but thought to be capable of naturalizing. We documented the sale of banned plants in the Connecticut aquarium trade by visiting 23 retailers in 2008 and 47 retailers in 2010. Plants that resembled Connecticut's banned species were purchased and identified using standard morphological techniques. In 2010, we also employed DNA sequencing to aid in plant identification. We found that nearly 30% of stores sold banned aquatic plants including Cabomba caroliniana, Egeria densa, Myriophyllum aquaticum, and Myriophyllum heterophyllum. Cabomba caroliniana represented more than half of the banned species being sold; it was found in 17% of the stores in 2008 and 19% of the stores in 2010. Egeria densa was mislabeled 50% of the time as Egeria najas or Anacharis najas; it was sold in 11% of the stores in 2008 and 17% of the stores in 2010. In 2010, Myriophyllum specimens from 6 stores were unidentifiable using morphological characteristics. Using these techniques, one of the specimens was identified as Myriophyllum heterophyllum. Of the 29 chain stores surveyed, 7% sold banned species compared to 56% of the 27 independent stores.

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Although the phylogenetic relationships of the major groups of fishes have been extensively studied with morphological characters, not all have been convincingly resolved. Analyses of molecular sequences from these groups may provide additional insights into problematical relationships, but are only just beginning to appear. We compare our own results from analyses of 18s ribosomal RNA sequences with those of other studies using globins, parvalbumins, insulin, 28s ribosomal RNA, and portions of two mitochondria1 genes (12s ribosomal RNA and cytochrome b). Our evaluation of these studies reveals some of the difficulties encountered in reconstructing ancient divergences within the fishes, including unequal rates of evolution (among regions of a molecule as well as among lineages), gene duplication, extinction of lineages, and a possible rapid radiation of gnathostome higher taxa. The importance of evaluating the robustness of particular phylogenetic hypotheses is stressed. Some molecules appear to be inappropriate for investigating higher level divergences within the fishes; others are more promising, but must be examined in more taxa to allow an adequate evaluation of their utility. Convincing support for particular hypotheses of relationship will ultimately require congruence of trees generated from independent molecular data sets.