Key to Lasius-Nearctic workers of Acanthomyops short key

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This worker key is based on: Wing, M. W. 1968. Taxonomic revision of the Nearctic genus Acanthomyops (Hymenoptera: Formicidae). Cornell University, New York State College of Agriculture, Agricultural Experiment Station, Ithaca, NY, Memoir No. 405. 173 pages.

Wing 1968 Acanthomyops

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Wing's preface: This key was constructed for typical and near-typical specimens of 7 species in the worker and queen castes only. Males were excluded because they rarely need to be keyed out, and, furthermore, the limits of their variation are poorly known. The 7 included species are sporadic to very common, and are widespread in their distribution. In most areas, over 90 percent of the samples collected can be identified, correctly by using the shorter key. However, there is a danger that the use of this key may occasionally result in the misidentification of a sample. Reference to the sets of illustrations, included in the treatment of each taxon, and to the 15 tables presenting frequency distributions of metric data, located at the end of the systematic section, will greatly reduce this risk. Should difficulty arise, it will probably be either because the species at hand is not 1 of the 7 included in the shorter key or because the specimens are atypical. In case of doubt, use the general key for the appropriate caste, always selecting the queen key rather than the one for workers whenever possible.

1

2

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  • Standing hairs on dorsum of gaster confined to posterior edges of tergites beyond first. Pubescence on gaster dilute, that on head moderately dense. Crest of petiolar scale sharp in side view, emarginate in anterior view. A large species . . . . . Lasius interjectus
  • Standing hairs more or less uniformly distributed over dorsum of gaster, not confined to posterior edges of tergites. Pubescence, petiolar scale and size varying . . . . . 3

3

return to couplet #2

  • In side view, crest of petiolar scale blunt; entire surface of gula covered by many standing hairs . . . . . 4
  • In side view, crest of petiolar scale sharp to moderate; gula either without hairs on with fewer standing hairs over the posterior 3/4 to 1/2 of its surface . . . . . 5

4

return to couplet #3

  • Standing hairs short, about twice as numerous on propodeum as elsewhere on dorsum of alitrunk . . . . . Lasius murphyi
  • Standing hairs longer, more or less evenly distributed over dorsum of alitrunk . . . . . Lasius latipes ( = beta-latipes of authors)

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return to couplet #3

6

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  • In side view, crest of petiolar scale blunt and covered with 65 or • more standing, or appressed and matted hairs . . . . . 7
  • In side view, crest of petiolar scale sharp or moderate and covered with fewer standing hairs, none matted . . . . . 8

7

return to couplet #6

  • Principal body hairs all standing, more or less evenly distributed, Fore femur very wide (FI 58 or more), with large, conspicuous genual plates. Antenna} scape and funiculus short (SI 68 or less), very strongly clavate . . . . . Lasius latipes ( = beta-latipes of authors)
  • Principal body hairs mostly appressed and matted to surface, unevenly distributed. Fore femur not as wide (FI 40 or less), with small and inconspicuous genual plates. Antennal scape and funiculus longer (SI 78 or more), more or less slender . . . . . Lasius murphyi

8

return to couplet #6

  • A smaller species with posterior border of head distinctly emarginate in perfect full-face view. Eyes large, eye length about equal to width of fore femur. Antennal scape short and slender, its apex reaching to about half way between eye and posterior corner of head . . . . . Lasius occidentalis
  • Species size varying, but posterior border of head not emarginate as seen in perfect full-face view. Eyes not appearing unusually large, eye length less than width of fore femur in at least the smaller species. Antenna} scape and funiculus varying . . . . . 9

9

return to couplet #8

  • A small species with standing body hairs very short and delicate. Pubescence on gaster dense in all specimens except those from East Coast below New England, where it is dilute . . . . . Lasius subglaber
  • Larger species with standing body hairs long and not delicate. Pubescence on gaster dilute . . . . . 10

10

return to couplet #9

  • CI 103 or more. Pubescence on most of head moderately dense. Basal margin of mandible with 1 or more denticles. Antennae long and slender. Body color variable, but mostly light brownish yellow to yellowish brown . . . . . Lasius interjectus
  • CI 102 or less. Pubescence on most of head dilute. Basal margin of mandible without denticles. Antennae shorter, stout or slender. Body color medium to very dark brown . . . . . 11

11

return to couplet #10

  • SI 66 or less. Antennal scape and funiculus moderately to fairly strongly clavate. Body color medium to dark brown, not appearing black to naked eye . . . . . Lasius claviger
  • SI 67 or more. Antenna! scape and funiculus at most very weakly clavate. Body color very dark brown, often appearing black or nearly black to naked eye . . . . . Lasius coloradensis