Key to South American species of Pogonomyrmex based on the queen caste; names

in apostrophes (“ ”) are unpublished manuscript names (new species and change

of status) that are invalid names that are not to be used.  This key includes

only species in which queens lack striae on their first gastral tergum; those

with striae on their first gastral tergum will be treated separately.  Also

note intraspecific variation in this character as queens of some species have

striae while others lack these striae: these species are keyed out here with

an annotation, and they will also be keyed out in a separate treatment.

 

 1 Ergatoid --------------------------------------------------------------- 2

-- Winged (occasionally brachypterous) ------------------------------------ 8

 

 2 Small species (HW < 1.30 mm); mesoscutum, mesoscutellum, and posterior

   surface of petiole rugoreticulate; in profile, mesosoma discontinuous

   between the metanotum and propodeum ---------------------- naegelii (part)

-- Larger species (HW > 1.40 mm); mesoscutum, mesoscutellum, and posterior

   surface of petiole usually rugose, rarely rugoreticulate; in profile,  

   mesosoma continuous or nearly so between metanotum and propodeum ------- 3

 

 3 Larger species (HW > 2.40 mm); in dorsal view, petiole only slightly

   longer than wide, anterior margin broadly rounded; in dorsal view,

   postpetiole wider than long ----------------------------------- bispinosus

-- Smaller species (HW < 2.35 mm); in dorsal view, petiole notably longer

   than wide, anterior margin spatulate to angulate; in dorsal view,

   postpetiole longer than wide ------------------------------------------- 4

 

 4 Eyes large (OI > 27.5); posterior surface of petiole and dorsum of  

   postpetiole weakly coriarious, petiole sometimes with few longitudinal

   rugae; in profile, petiolar node usually angulate with a small crest along

   anterior margin; propodeal spiracles circular or nearly so (brevibarbis-

   group [part]) -------------------------------------------- *** (see below)

-- Eyes small (OI < 26.0); posterior surface of petiole and/or dorsum of

   postpetiole with transverse rugae; in profile, petiolar node usually

   rounded to subangulate and lacking a small crest along anterior margin;

   propodeal spiracles narrowly ovate ------------------------------------- 5

 

 5 Anterior margin of clypeus concave; gaster blackish to black; psammophore

   well-developed, consisting of long hairs along basolateral margin of

   head  ---------------------------------------------------- laticeps (part)

-- Anterior margin of clypeus flat to weakly convex; gaster tannish-brown,

   reddish-brown, or brown; poorly-developed psammophore that consists

   of short to medium-length hairs scattered across ventral side of

   head (cunicularius-group) ---------------------------------------------- 6

 

 6 In profile, petiolar node rounded; inferior propodeal spines wider than

   high, broadly rounded; dorsum of first gastral tergum smooth and polished,

   strongly shining -------------------------------------------- cunicularius

-- In profile, petiolar node angulate; inferior propodeal spines about

   as wide as high, acuminate; dorsum of first gastral tergum moderately to

   strongly coriarious, dull to weakly shining ---------------------------- 7

 

 7 Sculpturing on dorsum of mesosoma and posterior surface of petiole coarse,

   rugoreticulate to vermiculate; bicolored, mesosoma and petiole medium to

   dark orangish-brown to reddish-brown, rest of body lighter ---- “serpens

-- Sculpturing on dorsum of mesosoma and posterior surface of petiole weak

   to moderately strong, irregularly rugose to moderately rugoreticulate;

   body concolorous tannish-red ------------------------------ “pencosensis

 8 Small species (HW < 1.35 mm); psammophore poorly-developed, consisting

   of scattered short hairs on ventral side of head ----------------------- 9

-- Larger species (HW > 1.40 mm); psammophore well-developed, consisting

   of numerous long hairs along basolateral margin of head --------------- 10

 

 9 Cephalic dorsum, mesoscutum, mesoscutellum, and posterior surface of

   petiole at least partly rugoreticulate to vermiculate ---- naegelii (part)

-- Cephalic dorsum, mesoscutum, and mesoscutellum with regular to weakly

   irregular longitudinal rugae, posterior surface of petiole granulate-

   punctate ----------------------------------------------------- abdominalis

 

10 Large species (HW > 2.90 mm); head with scattered foveae; in full-face

   view, part to all of cephalic dorsum with longitudinal striae; antennal

   scapes short, extending less than one-third the distance from posterior

   margin of eye to posterior corner of head (coarctatus-group) ---------- 11 

-- Smaller species (HW < 2.70 mm); head lacking scattered foveae; in

   full-face view, cephalic dorsum with prominent longitudinal rugae; scapes

   longer, extending more than one-half the distance from posterior margin

   of eye to posterior corner of head ------------------------------------ 14

 

11 Fine striae cover part to most of cephalic dorsum, areas lacking striae

   and interstriae shining to strongly shining --------------------------- 12

-- Fine striae cover entire cephalic dorsum, entire dorsum weakly

   shining --------------------------------------------------------------- 13

 

12 Larger species (HW > 3.6 mm); cephalic dorsum mostly lacking fine striae;

   inferior propodeal spines poorly-developed, wider than tall, broadly

   rounded ------------------------------------------------------- coarctatus

-- Smaller species (HW < 3.1 mm); moderately dense striae cover most of

   head; inferior propodeal spines well-developed, triangular, apex bluntly

   angulate to acuminate -------------------------------------------- marcusi

 

13 In profile, lateral lobe of clypeus massively enlarged with narrow

   gap (much less than width of antennal scape) between clypeal lobe and

   frontal carina; concolorous ferruginous orange to orange-red ----- lobatus

-- In profile, lateral lobe of clypeus not enlarged with broad gap

   (similar to the width of antennal scape) between clypeal lobe and

   frontal carina; bicolored, head dark red to reddish-black, gaster

   blackish ---------------------------------------------------------- micans

 

14 Fine, dense incised striae (usually longitudinal) cover anterior

   one-third or more of first gastral tergum ---------------- *** (see below)

-- First gastral tergum smooth and shining to moderately coriarious,

   weakly shining, lacking striae except occasionally at base ------------ 15

  

15 Superior propodeal spines absent or consisting of denticles, tubercles,

   or minute teeth ------------------------------------------------------- 16

-- Superior propodeal spines present, moderately to well-developed ------– 17

 

16 Larger species (HW > 1.75 mm); inferior propodeal spines lacking; in

   dorsal view, dorsum of postpetiole lacking transverse rugae or with few

   incomplete rugae; body usually bicolored with gaster notably darker

   than rest of body ------------------------------------------------ inermis

-- Smaller species (HW < 1.60 mm); inferior propodeal spines moderately

   Wo8ell-developed, consisting of a broadly rounded, thin process; in dorsal

   view, dorsum of postpetiole covered with weak transverse rugae; body

   concolorous ferruginous orange ----------------------------- “semistriata

17 Brachypterous; in dorsal view, pronotum large and well-developed,

   mesoscutum poorly-developed, anterior margin barely surpassing humeral

   shoulders; in profile, pronotum meeting mesoscutum at an obtuse angle - 18

-- Wings fully-developed; in dorsal view, pronotum small, poorly-developed,

   mesoscutum well-developed, anterior margin extending to or near pronotal

   collar; in profile, pronotum meeting mesoscutum at or near a straight

   line  ----------------------------------------------------------------- 20

 

18 Gaster dark ferruginous orange -------------------------------- mendozanus

-- Gaster black ---------------------------------------------------------– 19

 

19 Head and mesosoma dark reddish-black, gaster black –------ laticeps (part)

-- Concolorous black except for reddish area encircling eye ----- “tinogasta

 

20 Head blackish to black –--------------------------------------- pronotalis

-- Head ferruginous orange, dark reddish-brown, or reddish-black --------- 21

 

21 Posterior surface of petiole and dorsum of postpetiole smooth and shining

   to moderately coriarious, weakly shining, rarely with few longitudinal or

   transverse rugae; head, mesosoma, and gaster concolorous dark brown to

   black; inferior propodeal spines well-developed, acuminate; propodeal    

   spiracles circular or nearly so (brevibarbis-group [part]) ---------------

   ---------------------------------------------------------- *** (see below)

-- Posterior surface of petiole and usually dorsum of postpetiole with

   numerous transverse rugae; color variable, usually orangish or orange and

   black but never concolorous dark brown to black; inferior propodeal spines

   poorly-developed, tip usually subangulate to broadly rounded; propodeal

   spiracles narrowly ovate –--------------------------------------------- 22  

 

22 Mesosoma and gaster black ---------------------------------- vermiculatus++

-- Color of mesosoma and gaster variable but not concolorous black ------- 23

 

23 Rugae on dorsum of postpetiole lacking or present laterally, faint

   to absent medially; body concolorous tannish-brown to reddish-brown;

   lateral margins of propodeal declivity with numerous fine, delicate

   hairs ------------------------------------------------------- uruguayensis

-- Transverse rugae cover dorsum of postpetiole; body usually bicolored;

   lateral margins of propodeal declivity lacking numerous fine, delicate

   hairs ----------------------------------------------------------------  24

 

24 Mesopleura, propodeum, and petiole black, not concolorous with

   mesoscutum -------------------------------------------------- “intermedia

-- Mesopleura, propodeum, and petiole dark ferruginous orange to orangish-

   brown, concolorous with mesoscutum --------------------------- “spinolae++

 

*** these species will be treated in separate manuscripts.

 

++ queens of araucania and maulensis are described in this paper, but they have

  striae on their first gastral tergum; queens of spinolae and vermiculatus

  are variable as some queen have striae and some queens lack these striae.

  Species that have striae are excluded from this key, and will be keyed out

  in a separate manuscript.