THE AMERICAN ORB-WEAVER GENERA DOLICHOGNATHA AND TETRAGNATHA NORTH OF MEXICO (ARANEAE: ARANEIDAE, TETRAGNATHINAE) HERBERT W. LEVI* Abstract. One species of Dolichognatha and fif-teen species of Tetragnatha are found in North America north of Mexico. Of these, three are new: T. earmra from the Everglades; T. shoshone, wide-spread in south central Canadian provinces and north central states; and T. branda, found from Connecticut to Mississippi. Tetragnatha harrodi is a synonym of T. dear-mata, described from northern Eurasia. Tetragna-tha antillana is a synonym of the cosmotropical T. nitens. Males of Tetragnatha are readily separated by the shape and structure of the palpal conductor and paracxnibium; they cannot be separated by the structure of the chelicerae. Females can be sepa-rated by the configuration and placement of seminal receptacles, as revealed by simple dissection; they cannot be separated by the structure of the chelic-erae. Several Tetragnatha species are distributed from Canada to the tropics. Several uncommon species probably have specialized habitats: T. viridis in pines; T. vermiformis on reeds; and T. branda in salt marsh grass. INTRODUCTION One of the aims of a generic revision is to find diagnostic characters that sep-arate the species. Reliable identification is essential for any work by ecologists and physiologists. Another aim, of course, is to reveal the relationships among the species, and, more important, the rela-tionship of the genus to other genera. Tetragnatha species are among the most abundant spiders worldwide. North American species can be determined only with difficulty using Chickering's papers (1957a, b, c, 1959). Chickering (with one exception) detemiined species ' Museum of Comparative Zoology, Harvard Uni-versity, Cambridge, Massachusetts 02138. correctly, but could determine only males; his drawings are awkward, often failing to tell what position is illustrated or whether the structure illustrated is from the left or right palpus. Also, his Tetragnatha reports are limited geo-graphically to Michigan and to some trop-ical American regions. Tetragnatha is the second largest araneid genus north of Mexico, after Araneus. Despite a conscious effort not to change names, two synonymies had to be resolved. To avoid further name changes, neotypes were designated for several old names, the use of which has been based mainly on tradition rather than on the type method. The neotypes were desig-nated in accordance with Article 75 (1961) of the International Code of Zoo-logical Nomenclature. ACKNOWLEDGMENTS I would like to thank the following per-sons for the loan of specimens: J. Beatty; D. Boe; G. Byers and M. Rothschild (Snow Entomological Museum, Univer-sity of Kansas); J. Carico; C. Dondale (Biosystematics Research Institute, Agri-culture Canada, CNC); M. Grasshoff (Senckenberg Museum); M. Hubert (Mu-seum National d'Histoire Naturelle, Paris); J. Kaspar; B. J. Kaston; C. Okuma; B. Opell; W. Peck (Exline-Peck collec-tion); N. I. Platnick (American Museum of Natural History, AMNH, and Cornell University Collection, CUC); J. Proszyri-ski; W. F. Rapp; A. Riedel (Polish Acad-emy of Science); W. T. Sedgwick; W. Shear; W. Star^ga; F. Wanless (British Bull. Mus. Comp. Zool., 149(5): 271^18, July, 1981 271
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