Key to Malagasy Erromyrma, Monomorium, Syllophopsis and Trichomyrmex species

This worker key is based on:

After the publication of this key Monomorium species have been reorganized into the genera: Monomorium, Syllophopsis and Trichomyrmex. This key reflects this new nomenclature.

You may also be interested in


 * Monomorium
 * Syllophopsis
 * Trichomyrmex

1

 * Antenna 11-segmented (M. monomorium species group) . . . . . 2


 * Antenna 12-segmented (various species groups) . . . . . 3

2
return to couplet #1
 * Metanotal groove weakly impressed; in profile, propodeum rather elongate and petiolar node always conical, its dorsum tapered (depigmented yellow to brown) . . . . . Monomorium exiguum


 * Metanotal groove strongly impressed; in profile, propodeum evenly rounded and petiolar node may be thick, broadly rounded (dark reddish-brown to black) . . . . . Monomorium nigricans

3
return to couplet #1
 * Palps long (PF 5,3); propodeum usually lacking standing setae, where present these short and fine; occipital carina strongly defined and conspicuous along rear margin of head when head viewed in profile; mandible armed with five distinct teeth (M. shuckardi species group) . . . . . 4


 * Palps shorter (PF 3,3 or less); propodeum usually with standing setae, but if these lacking, then mandible armed with four teeth, or with three distinct teeth and a small to minute denticle or angle; occipital carina vestigial or short, not conspicuous along rear margin of head when head viewed in profile . . . . . 7

4
return to couplet #3
 * Head and mesosoma finely striolate; in profile, propodeum without a distinct angle between its dorsal and declivitous faces . . . . . Royidris robertsoni


 * Head and mesosoma finely striolate-microreticulate, microreticulate-punctate with or without unsculptured areas, or head and dorsum of mesosoma smooth and shining; propodeum in profile with blunt to sharply defined propodeal angle . . . . . 5

5
return to couplet #4
 * Antennal scape very long, extending beyond vertex of head capsule (SI 113–132) larger (HW 0.62–0.72 mm), depigmented yellow ants . . . . . Royidris notorthotenes


 * Antennal scape shorter, barely or not attaining vertex (SI 90–108); if yellowish, then much smaller (HW 0.35–0.47 mm compared with 0.62–0.72 mm) . . . . . 6

6
return to couplet #5
 * In full-face view, frons of head capsule densely microreticulate-punctate; generally larger species (HW 0.46–0.72 mm, usually 0.55 mm<) . . . . . Royidris shuckardi


 * In full-face view, frons of head capsule finely striolate-microreticulate or smooth and shining; generally smaller species (HW 0.35–0.47 mm compared with 0.46–0.72 mm, usually 0.55 mm ≥) . . . . . Royidris clarinodis

7
return to couplet #3
 * Mandible distinctly longitudinally striate, maximum number of teeth four . . . . . 8


 * Mandible smooth and shining, except for piliferous pits, with three to five teeth . . . . . 12

8
return to couplet #7
 * In full-face view, frons of head capsule smooth, with exception of piliferous punctures, fine rugulae on vertex (M. destructor) and fine, circular striolae around antennal insertions (M. destructor species group) . . . . . 9


 * In full-face view, frons of head capsule sculptured, sculpture varying from superficial reticulation to shagreenate-punctate (M. salomonis species group) . . . . . 10

9
return to couplet #8
 * Head and mesosoma brown to dark brown . . . . . Trichomyrmex robustior


 * Head and mesosoma yellow to light brownish-yellow . . . . . Trichomyrmex destructor

10
return to couplet #8
 * Mesosoma possessing one or more pairs of erect and/or sub-erect setae . . . . . Monomorium pharaonis


 * Mesosoma without standing setae . . . . . 11

11
return to couplet #10
 * In full-face view, frons of head capsule shining, with surface sculpture confined to faint reticulation, the vertex more noticeably shagreenate; scape shorter (SI < 100) . . . . . Monomorium willowmorense


 * In full-face view, frons of head capsule opaque, reticulate to shagreenate-punctate; scape longer (SI 100 >) . . . . . Monomorium subopacum

12
return to couplet #7
 * Either frontal lobes separated by a strip of posterior sector of clypeus that is clearly wider than either of them, or, if frontal lobes closely approximated, metanotal groove strongly indented and propodeum smooth; propodeal dorsum rounding into declivitous face without distinct angle; propodeal denticles always absent; fine, transverse ridges always absent from underside of petiolar peduncle and node; anteroventral postpetiolar process commonly vestigial or absent, rarely an inconspicuous lip and prominent only in M. latinode . . . . . 13


 * Frontal lobes usually closely approximated, and separated by a strip of posterior sector of clypeus that is narrower than either of them, or, if frontal lobes well separated, and metanotal groove deeply impressed, then propodeal dorsum meeting declivitous face at a distinct angle; propodeum often armed with flanges or denticles; several to many fine, transverse ridges present on underside of petiolar peduncle and node; anteroventral postpetiolar process usually distinct as sharp angle, conspicuous lip or spur (M. hanneli and M. hildebrandti species groups.) . . . . . 26