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in apostrophes (“ ”) are unpublished manuscript names (new species and change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