Key to Acanthostichus workers

This worker key is based on: [[Media:MacKay 1996.pdf|MacKay, W.P. 1996. A revision of the ant genus Acanthostichus. Sociobiology 27:129-179. PDF]]

This key does not include Acanthostichus emmae and Acanthostichus longinodis.

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 * Acanthostichus
 * Key to US Acanthostichus species
 * Key to Acanthostichus males

1

 * Subpetiolar process large. well developed (Fig. 3), apex usually sharply angulate (occasionally truncate - see Fig. 26) (specimens of A. texanus from Texas and Mexico and a fossil taxon from Dominican Republic often have large, rounded lobes which are not angulate, have relatively large eyes in A. texanus - go to couplet 11) top of petiole usually sculptured; anterior edge of scape usually concave (Fig. 7); femur never notably incrassate (Fig. 49); relatively common species . . . . . 2


 * Subpetiolar process consisting of a small, rounded lobe (Fig. 1), usually not sharply angulate or truncate, (occasionally angulate posteriorly), dorsum of petiole usually smooth and glossy; anterior edge of scape usually convex (Fig. 6) (slightly concave in A. quiroziand and probably A. skwarrae); hind femur often incrassate (Fig. 44); rarely collected species (brevicornis species complex) . . . . . 13

2
return to couplet #1
 * Anterior edge of scape concave, with angle near apex (Fig. 7); relatively common; South America (serratulus species complex) . . . . . 3


 * Anterior edge of scape convex (or straight), without well defined angle at apex (Fig. 16); North America (including Mexico) or fossil from Dominican Republic; rarely collected . . . . . 11

3
return to couplet #2
 * SL/SW < 2.40 (mean = 2.19); angle on anterior edge of scape very large (Fig. 4) . . . . . Acanthostichus laticornis


 * SL/SW > 2.25 (usually > 2.5); angle on scape moderately well developed (Figs. 7) . . . . . 4

4
return to couplet #3
 * Dorsum of petiole completely glossy and strongly shining, occasionally with small, elongate depressions; scape relatively long (mean SL/SW = 2.94, range = 2.80 - 3.08); Venezuela . . . . . Acanthostichus laevigatus


 * Dorsum of petiole roughened and sculptured, if somewhat shining, then long, longitudinal troughs or depressions are located near lateral edges, sides parallel (Fig. 37) or posterior half wider than anterior half (Fig. 24); scapes usually shorter; widely distributed in South America . . . . . 5

5
return to couplet #4
 * Petiole elongate, PI> 110 (PL/PW * 100), if less, lateral clypeal teeth poorly developed; posterior half of petiole usually wider than anterior half (Fig. 24) . . . . . 6


 * Petiole quadrate or subquadrate (Fig. 32), PI < 110; sides of petiole usually parallel (or only slightly narrowed anteriorly) . . . . . 9

6
return to couplet #5
 * Subpetiolar process strongly truncate (Fig. 26); Colombia . . . . . Acanthostichus truncatus


 * Subpetiolar process not truncate, usually with posteriorly directed tooth-like process (Fig. 25); widely distributed, including Colombia . . . . . 7

7
return to couplet #6
 * Carinae on sides of petiole well developed, or at least sides of petiole meet at right angle; lateral clypeal teeth usually poorly developed (Fig. 13); dorsum of petiole lightly punctate and usually with well developed, longitudinal troughs; rarely collected . . . . . 8


 * Lateral edges of petiole rounded, with little or no evidence of carinae; lateral clypeal teeth well developed (Fig. 10), especially in larger workers; dorsum of petiole moderately punctate, longitudinal troughs poorly developed or absent; widely distributed, common species . . . . . Acanthostichus kirbyi

8
return to couplet #7
 * Anterior face of petiole strongly concave (Fig. 21), dorsum of petiole mostly smooth and shining . . . . . Acanthostichus concavinodis


 * Anterior face of petiole not strongly concave (Fig. 37), although may be somewhat concave, dorsum of petiole roughened . . . . . Acanthostichus serratulus

9
return to couplet #5
 * Carinae on sides of petiole usually developed; dorsum of petiole lightly punctate with well developed lateral longitudinal troughs; medial lobe of clypeus excised (Fig. 13), often with blunt tooth; scape usually short (SL/SW range = 2.45 - 3.07); relatively common (Ecuador to Argentina) (and rarely collected A. flexuosus MacKay from southern Brazil) . . . . . Acanthostichus quadratus


 * Lateral edges of petiole broadly rounded, if well developed carinae present, medial lobe of clypeus excised and usually without a tooth (Fig. 13); dorsum of petiole longitudinally striate, without longitudinal troughs; scape normally longer (SL/SW range = 2.53 - 3.29); rarely collected . . . . . 10

10
return to couplet #9
 * Anterior medial border of clypeus with blunt tooth (Fig. 11); Venezuela . . . . . Acanthostichus lattkei


 * Anterior medial border of clypeus strongly concave, without tooth (Fig. 7); Brazil . . . . . Acanthostichus bentoni

11
return to couplet #2
 * Maximum eye diameter often nearly as long as length of second and third funicular segments combined (Fig. 16) (usually more than V2 length); subpetiolar lobe of petiole with a posterior angle or is a large, broadly rounded lobe (Fig. 42); dorsum of petiole smooth and glossy; extreme southern Texas and eastern Mexico (texanus species complex) . . . . . Acanthostichus texanus


 * Maximum eye diameter equal to or smaller than length of second funicular segment (Fig. 6) . . . . . 12

12
return to couplet #11
 * Subpetiolar process with a ventrally directed. sharp tooth (Fig. 31); dorsum of petiole and scape heavily punctate; New Mexico (brevicornis species complex. in part) . . . . . Acanthostichus punctiscapus


 * Subpetiolar process without ventrally directed tooth; fossil taxon from Dominican Republic . . . . . species A

13
return to couplet #1
 * Dorsum of petiole densely punctate; subpetiolar process poorly developed (Fig. 18); Arizona . . . . . Acanthostichus arizonensis


 * Dorsum of petiole smooth and shining; subpetiolar process consisting of a broadly rounded lobe which may be angulate anteriorly (Fig. 40) . . . . . 14

14
return to couplet #13
 * Petiole somewhat wider posteriorly than anteriorly (Fig. 39) much longer than broad (PI = 129); Mexico (Vera Cruz) . . . . . 15


 * Sides of petiole parallel or slightly wider posteriorly (Fig. 36); petiole usually only slightly longer than broad (103 > PI > 135); South America . . . . . 16

15
return to couplet #14
 * Pronotum with less than five erect hairs; petiole with less than six erect hairs; gaster essentially without erect hairs . . . . . Acanthostichus skwarrae


 * Pronotum with six or more long. pOinted. erect hairs (0.1-0.2 mm); petiole with more than ten erect hairs; gaster abundantly hairy . . . . . Acanthostichus quirozi

16
return to couplet #14
 * Propodeal spiracle located on upper half (Fig. 1); petiole usually only slightly longer than broad (103 < PI < 112) . . . . . 17


 * Propodeal spiracle located at midline or below; petiole usually somewhat longer than broad (108 < PI < 135) . . . . . Acanthostichus brevicornis

17
return to couplet #16
 * Outer surface of scape completely convex; dorsum of petiole very glossy and strongly shining; Argentina and Brazil . . . . . Acanthostichus femoralis


 * Outer surface of scape angulate near apex (Fig. 14); dorsum of petiole smooth, but not strongly shining; Colombia . . . . . Acanthostichus sanchezorum