Phylogeny and zoogeography of salmoniform fishes and relationships of Lepidogalaxias salamandroides. Bulletin of the AMNH ; v. 153, article 2

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New York : [American Museum of Natural History]
"The affinities of the tiny, freshwater Australian fish Lepidogalaxias salamandroides have remained uncertain since its original description in 1961. Comparisons of Lepidogalaxias with various salmoniforms, which it superficially resembles, uncovered a number of major problems in salmoniform taxonomy. A review of the anatomy of salmoniform gill arches, caudal skeletons, and secondary sexual characters suggests that Lepidogalaxias is an esocoid, that galaxiids and aplochitonids are related to salmonids (as salmonoids), and that retropinnids and prototroctids are related to osmerids, salangids, and plecoglossids (as osmeroids). A comparison of possible salmoniform phylogenies based on various anatomical features indicates that the phylogeny derived from gill arch evidence leads to the most economical hypothesis involving the fewest assumptions of independent origin of similar character states. The proposed phylogeny recognizes salmonoids and osmeroids (each as redefined to include parts of the former galaxioid assemblage) as sister groups. Argentinoids are considered a plesiomorph sister group of these two, and esocoids plus Lepidogalaxias the plesiomorph sister group of all other salmoniforms. Salmoniforms are amphitropical, panboreal, and panaustral in distribution and their worldwide and southern hemisphere distributions correspond partly or wholly with those of chironomid midges, southern beech trees (Nothofagus), and other plant groups. Alternative biogeographic interpretations of these distributions are considered: chance dispersal over uninhabitable gaps in relation to the present continental landscape versus an original and ancient Pangaean distribution followed by continental drift. Waif dispersal hypotheses are found to be aprioristic, wanting in evidence, highly imaginative, and untestable, whereas the continental drift model simply and directly accounts for the present distributions of varied organisms with different mobilities and other biological properties. Acceptability of the continental drift model would place the minimum age of the main groups of salmoniforms at 180 million years and of some of the southern assemblages at 90 million years. Reasons for rejecting the concepts of primary and secondary division freshwater fishes as applied to the solution to zoogeographic problems are given. A return to the concepts of continental and oceanic fish groups is advocated, the zoogeographic interpretations of which are determined not by what we imagine to be the habits of the fishes and their possible dispersal mechanisms but by their distributions in relation to phylogeny and in relation to the distributions of other organisms"--P. 269.
p. 267-325 : ill., maps ; 27 cm.
Includes bibliographical references (p. 323-325).