Key to Lasius-Nearctic Acanthomyops queens

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. You may also be interested in


 * Lasius
 * Key to Nearctic workers of Acanthomyops - the short key
 * Key to Nearctic Acanthomyops workers
 * Key to Nearctic Acanthomyops males

Wing's preface: This key is the most reliable of the three. A large number of distinctive characters, representing several lines of specialization, are present in this caste. Also a fairly sizable collection of specimens was available for study. The key is thus relatively uncomplicated, even though some extreme. variants were included.

The number of outcomes in the key is 18. This includes 14 species and 5 hybrid taxa, 2 of which are lumped together. Only colei remains unknown in the queen caste. In general the queen key should lead to correct identification of specimens about 99 percent of the time, often with only single specimens available.

1

 * Principal body hairs standing, distally plumose (fig. 4), numerous, more or less evenly distributed over body . . . . . Lasius plumopilosus


 * Principal body hairs either standing or appressed and matted to surface; simple or weakly to strongly barbulate (figs. 5-7), never distally plumose; varying in number and distribution . . . . . 2

2
return to couplet #1
 * Body hairs either standing or appressed and matted to surface; numerous and unevenly distributed, especially numerous in frons, clypeus, genae, gula, pronotum, coxae meso- and metapleura, propodeum, and •petiolar scale. Crest and sides of petiolar scale with 125 or more standing or matted hairs. Head noticeably distorted (fig. 111) . SI 71 to 84, FI 35 to 51 . . . . . 3


 * Body hairs standing, sparse to numerous, but if numerous then more or less evenly distributed over body. Crest and sides of petiolar scale with fewer than 125 standing hairs. Head not noticeably distorted (fig. 26) . SI and FI varying. However, if petiolar scale has 125 or more standing hairs, then head is clearly distorted (fig. 93) and SI ranges from 59 to 68 and FI from 58 to 70 . . . . . 4

3
return to couplet #2
 * Hairs coarse, whitish-yellow, mostly blunt-ended, tightly appressed and matted to body. Petiolar livery so dense that it completely hides the underlying scale even when viewed from the side with lighting from behind. SI 78 to 84, FI 35 to 40 . . . . . Lasius murphyi


 * Hairs finer, dirty yellow to reddish-brown, mostly with pointed tips, tangled and twisted, but not tightly appressed and matted to body. Petiolar livery dense above, but outline of scale is more or less visible when viewed from the side with lighting from behind. SI 71 to 74, FI 46 to 51 . . . . . Lasius murphyi X latipes hybrid

4
return to couplet #2
 * In side view, standing hairs more or less evenly distributed over entire surface of gula, ranging in number from 16 to 80, and 0.20 to 0.40 mm long. SI 56 to 68, FI usually 35 to 70 . . . . . 5


 * In side view, gula either without any standing hairs, or with up to 36, these confined to posterior 3/4 to 1/2 of its surface and ranging from 0.03 to 0.35 mm in length SI and FI varying. However, in the rare cases where hair distribution on gula is entire as described in the couplet above, than either (1) length of longer standing hairs on gula does not exceed 0.10 mm, or (2) SI greater than 70, FI less than 35, and antennal scapes often covered with prominent, delicate, suberect pubescence hairs . . . . . 7

5
return to couplet #4
 * Fore femora with large conspicuous laminate genual plates, FW measuring 0.80 mm or greater, FI 58 or more. Crest of petiolar scale very blunt in side view; convex or straight in anterior view, without median emargination, or with an occasional small notch-like impression. Standing hairs on crest and sides of scale numbering 65 to 180. Antennal scape and funiculus extremely clavate, antepenultimate segment of funiculus at least 2.30 times wider than long. Length of standing hairs on gula 0.30 to 0.40 mm, ranging in number from 35 to 80 . . . . . Lasius latipes ( = beta-latipes of authors)


 * Fore femora without or with only moderate genual plates, FW measuring 0.75 mm or less, FI 54 or less. Crest of petiolar scale sharp to very blunt in side view; convex, straight, or broadly emarginate in anterior view. Standing hairs on crest and sides of scale numbering 20 to 75. Antennal scape and funiculus weakly to quite clavate, antepenultimate segment of funiculus less than 2.30 times wider than long. Length of standing hairs on gula usually 0.30 mm or less, usually 35 or fewer in number . . . . . 6

6
return to couplet #5
 * Fore femora without genual plates, FI 33 to 42. Crest of petiolar scale moderately sharp to sharp in side view; broadly emarginate, often distinctly so, in anterior view; not over 45 standing hairs on crest and sides of scale. Antennal scape and funiculus from weakly clavate to clavate, antepenultimate segment of funiculus not over 1.55 times wider than long . . . . . Lasius claviger


 * Fore femora with moderate genual plates, FI 43 to 54. Crest of petiolar scale blunt to very blunt in side view; convex, straight, or more rarely with a slight median notch in anterior view; 50 to 7 5 standing hairs on crest and sides of scale. Antennal scape and funiculus quite clavate, antepenultimate segment of funiculus greater than 1.55 and less than 2.30 times wider than long . . . . . Lasius latipes X claviger hybrid ( = alpha-latipes of authors) . . and . . Lasius latipes X coloradensis hybrid

7
return to couplet #4
 * Length of longer standing hairs on gula usually 0.20 mm or more, and posterior border of head not broadly and deeply emarginate as seen in perfect full-face view. In side view, number of standing hairs on gula usually 15 or more, but not less than 10. Longer standing hairs on posterior edge of first tergite of gaster usually more than 0.20 mm. Abundance of body pilosity and pubescence varying, but both never extremely sparse. Standing body hairs simple to weakly barbulate . . . . . 8


 * Length of longer standing hairs on gula less than 0.20 mm (except for an occasional specimen of occidentalis, which has posterior border of head broadly and deeply emarginate as seen in perfect full-face view). In side view, standing hairs on gula 0 to 16, usually less than 10. Longer standing hairs on posterior edge of first tergite of gaster 0.20 mm or less, with 1 exception (arizonicus, southern Arizona, with pilosity on gaster about 0.4 mm; both body pilosity and pubescence extremely sparse) . Standing body hairs simple to strongly barbulate . . . . . 14

8
return to couplet #7
 * Longer standing hairs on dorsum of alitrunk 0.40 to 0.45 mm. SI usually 67 or greater, FI 34 or less . . . . . 9


 * Longer standing hairs on dorsum of alitrunk less than 0.40 mm, usually 0.20 to 0.35 mm. SI and FI varying. However, if standing hairs on dorsum of alitrunk measure as much as 0.40 mm (a very few large claviger queens), then SI is 66 or less and FI 35 or greater . . . . . 10

9
return to couplet #8
 * In anterior view, crest of petiolar scale usually narrowly but distinctly emarginate, or more rarely straight or convex; sides distinctly convex. Basal margin of mandible usually with 1 or more denticles. Penultimate and antepenultimate segments of funiculus at least as long as wide, usually longer than wide. In side view, gula with 10 to 18 standing hairs 0.25 to 0.35 mm long covering the posterior ¾ of its surface . . . . . Lasius interjectus


 * In anterior view, crest of petiolar scale broadly emarginate, usually deeply so; sides more or less straight and converging dorsally. Basal margin of mandible less commonly with a denticle. Penultimate and antepenultimate segments of funiculus a little wider than long. In side view, gula with about 14 to 16 standing hairs about 0.25 mm long located more or less centrally on its surface . . . . . Lasius californicus

10
return to couplet #8
 * Crest of petiolar scale blunt as viewed from the side; as viewed anteriorly, crest straight and without emargination, or, at most, with a narrow median notch. Crest and sides of scale covered with 40 or more very coarse standing hairs . . . . . Lasius murphyi X subglaber hybrid


 * Crest of petiolar scale sharp to moderately sharp as viewed from the side; as viewed anteriorly, crest emarginate, either deeply or shallowly so. Crest and sides of scale usually with fewer than 40 delicate to moderately coarse standing hairs . . . . . 11

11
return to couplet #10
 * Antennal scapes uniformly and heavily covered with prominent, delicate, decumbent to suberect pubescence hairs about 0.07 mm long. In side view, entire surface of gula covered with 20 or more standing hairs, 0.20 mm or a little more in length. Pubescence hairs on gula numerous, decumbent, long (0.10 to 0.15 mm) and conspicuous. Entire dorsum of gaster evenly covered by standing hairs measuring 0.30 to 0.35 mm, and with pubescence moderate to dilute, long (many pubescence hairs measuring over 0.10 mm), and mostly inclined at angles of about 15 degrees with the surface. Crest of petiolar scale with longer standing hairs 0.12 mm or less. Sides of scale nearly straight and converging dorsally. Body color light brownish yellow . . . . . Lasius creightoni


 * Pubescence hairs on antennal scapes coarser, less numerous, and usually entirely appressed to surface, but some specimens have hairs decumbent to suberect, varying in length. In side view, only posterior ¾ to ½ of surface of gula covered with 10 to 20 standing hairs, and measuring 0.20 to 0.28 mm. Pubescence on gula shorter, usually appressed and not conspicuous. Distribution and length of standing hairs on dorsum of  gaster varying. Pubescence on dorsum of gaster dilute to dense, but more or less appressed to its surface and shorter (most hairs well under 0.10 mm). Crest of petiolar scale with longer standing hairs 0.18 mm or more. Sides of scale varying, but often convex or straight and usually parallel to diverging dorsally. Body color of unfaded specimens darker, usually medium to piceous brown . . . . . 12

12
return to couplet #11
 * SI 66 or less. Scape and funiculus weakly to strongly clavate. Distribution of standing hairs on dorsum of gaster varying in the following manner: (1) confined to posterior edges of tergites except first, (2) more or less uniformly covering entire dorsum, or (3) intermediate between (1) and (2). Body color of unfaded specimens medium to dark brown, often with a slight reddish cast, rarely dark enough to appear black to the naked eye . . . . . Lasius claviger


 * SI 67 or greater. At most, scape very weakly clavate. Standing hairs on dorsum of gaster confined to posterior edges of tergites beyond first. Body color of unfaded specimens dark to piceous brown, often appearing black or nearly black to the naked eye . . . . . 13

13
return to couplet #12
 * Dorsum of gaster densely pubescent. In side view, crest of erect petiolar scale approximately on level with propodeal spiracle. In anterior view, sides of petiolar scale straight and diverging dorsally, usually with 4 or fewer standing hairs per side, 0.10 mm or less in length. CI 100 or more, FI 31 or less . . . . . Lasius bureni.


 * Dorsum of gaster with dilute to very dilute pubescence. In side view, crest of erect petiolar scale above to well above level of propodeal spiracle. In anterior view, sides of scale moderately to strongly convex, usually with 10 or more standing hairs per side, 0 . .14 mm or more in length. CI usually 99 or less, FI usually 32 or more . . . . . Lasius coloradensis

14
return to couplet #7
 * Longer standing hairs on dorsum of alitrunk 0.35 mm or more; body pilosity sparse, posterior edge of first tergite of gaster with 0 to 6 standing hairs. Gula without standing hairs, or rarely with 1 or 2. Pubescence extremely dilute over whole body. SI 72 or more, FI 32 or less . . . . . Lasius arizonicus


 * Longer standing hairs on dorsum of alitrunk 0.30 mm or less; body pilosity denser, posterior edge of first tergite of gaster with 10 to 24 standing hairs. Gula usually with standing hairs. Pubescence varying from dilute to very dense. SI and FI varying . . . . . 15

15
return to couplet #14
 * Dorsum of gaster very densely pubescent. In side view, crest of erect petiolar scale below level of propodeal spiracle, blunt to very blunt; crest with 2 or 3, and sides each with 0 to 2, standing hairs from 0.08 to 0.12 mm long. SI 75 or more, FI 30 or less . . . . . Lasius pubescens


 * Dorsum of gaster with pubescence varying from very dilute to moderately dense. In side view, crest of erect petiolar scale usually at, above, or well above level of propodeal spiracle, sharp to moderately blunt; crest with 4 or more, and sides each with 3 or more standing hairs, from 0.10 to 0.17 mm long. SI 70 or less, Fl 32 or more . . . . . 16

16
return to couplet #15
 * In anterior view, crest of petiolar scale with a distinct emargination, usually broad and fairly deep; sides more or less straight and usually diverging dorsally, but sometimes parallel. In side view, crest of scale sharp to moderately sharp. Mesoscutum moderately to densely pubescent. Body color light brown to light yellowish brown . . . . . 17


 * In anterior view, crest of petiolar scale convex or straight; sides more or less straight and parallel. In side view, crest of scale moderately blunt. Mesoscutum with dilute pubescence. Body color, except in badly faded specimens, darker brown, often with a reddish or piceous component . . . . . 18

17
return to couplet #16
 * In perfect full-face view, head with posterior border broadly and distinctly emarginate, sides nearly straight and more or less parallel. In side view, standing hairs on gula numbering 8 or more, usually 0.15 mm or more in length. Width of scale at crest about equal to height above petiolar spiracle. Standing hairs on crest and sides of scale usually numbering 28 or more, often with as many as 60. CI 98 or less . . . . . Lasius occidentalis


 * In perfect full-face view, head with posterior border straight or nearly so, sides slightly convex. In side view, standing hairs on gula usually numbering 0 to 6, usually under 0.15 mm long. Width of scale at crest 1.2 to 1.4 times greater than height above petiolar spiracle. Standing hairs on crest and sides of scale usually numbering 26 or fewer. CI 100 or more . . . . . Lasius mexicanus

18
return to couplet #16
 * Standing body hairs simple, delicate; those on dorsum of alitrunk and gaster not more than 0.15 mm long; those on dorsum of gaster almost alwa ys confined to posterior edges of tergites beyond first. Crest of erect petiolar scale above level of propodeal spiracle . . . . . Lasius subglaber


 * Standing body hairs, especially those on occiput, dorsum of alitrunk, and crest of petiolar scale, strongly barbulate; many hairs on dorsum of alitrunk and gaster measuring up to 0.20 mm; those on dorsum of gaster unevenly distributed. Crest of erect petiolar scale at or just below level of propodeal spiracle . . . . . Lasius subglaber X plumopilosus hybrid