| Summary: | 17 p. : ill., maps 26 cm. Includes bibliographical references (p. 16-17). A survey of the Microcoryphia of New York, New Jersey, and Pennsylvania as well as the New England states and the Canadian provinces of New Brunswick, Nova Scotia, and Newfoundland showed four species present. Petrobius brevistylis and Trigoniophthalmus alternatus were probably introduced from Europe on ballast; Pedetontus saltator, new species, and Machiloides petauristes, new species, are native. Petrobius canadensis Paclt, 1969, is synonymized with Petrobius brevistylis Carpenter, 1913. The presence of Petrobius maritimus (Leach) in North America is not confirmed. Machilis variabilis Say, described from 'North America,' is not identifiable. Males were not found among the hundreds of specimens of North American Trigoniophthalmus alternatus examined, making a parthenogenetic mode of reproduction highly likely. Males were rare in Petrobius brevistylis (approximately 3 percent of all specimens examined), and were not discovered among the limited material of the new species of Pedetontus and Machiloides"--P. [1].
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