Key to New England Myrmica

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This key is modified from the 2012 book A Field Guide to the Ants of New England
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Related pages:

1

  • Antennal scape viewed in full profile is evenly curved near its base . . . . . 2
  • Antennal scape viewed in full profile is bent abruptly near its base at a nearly 90° (right) angle; there is often a thick lamina or other outgrowth on the dorsal surface of the bend . . . . . 11

2

return to couplet #1

  • Anterior margin of clypeus distinctly notched; if notch is shallow, propodeal spines are short (lobifrons group) . . . . . 3
  • Anterior margin of clypeus usually without a notch; if a very shallow notch is present, the clypeus bulges outward in the middle and the propodeal spines are long . . . . . 4

3

return to couplet #2

  • Clypeus deeply and distinctly notched; propodeal spines long and pointed rearward at an ~45° angle and with tips that curve gently downward; a bog specialist . . . . . Myrmica lobifrons
Myrmica lobifrons casent0105638 head 1.jpg
Myrmica lobifrons casent0105638 profile 1.jpg
  • Clypeus shallowly notched; propodeal spines short and pointing straight upward; a boreal species known in New England only from White Mountains of New Hampshire . . . . . Myrmica brevispinosa
Myrmica brevispinosa casent0104831 head 1.jpg
Myrmica brevispinosa casent0104831 profile 1.jpg

4

return to couplet #2

  • Coarse, large punctures (pits) at the base of the erect hairs on the top of the gaster; level of propodeum noticeably lower than the level of the promesonotum (punctiventris group) . . . . . 5
  • No, or at best fine, inconspicuous punctures at the base of the erect hairs on the top of the gaster; level of propodeum more or less even with the level of the promesonotum . . . . . 7

5

return to couplet #4

  • Propodeal spines short with thickened base; large triangular process visible below the petiole; a temporary social parasite of Myrmica punctiventris
Myrmica-punctiventris-MCZ001H.jpg
Myrmica-punctiventris-MCZ001L.jpg

. . . . . Myrmica semiparasitica

Myrmica semiparasitica holotype MCZ head.jpg
Myrmica semiparasitica holotype MCZ side.jpg
  • Propodeal spines long with narrow base; triangular process below the petiole inconspicuous . . . . . 6

6

return to couplet #5

  • Propodeal spines longer than the distance separating their tips and often wavy; frontal lobes extend upward at a shallow angle, exposing the insertion of the antennae; rugae thick, but flattened on top . . . . . Myrmica punctiventris
Myrmica-punctiventris-MCZ001H.jpg
Myrmica-punctiventris-MCZ001L.jpg
  • Propodeal spines shorter than the distance separating their tips and usually straight; frontal lobes flat to the head, often with a distinct downward deflection at their edges, and covering the insertion of the antennae; rugae thick and rounded on top . . . . . Myrmica pinetorum
Myrmica-pinetorum-MCZ001H.jpg
Myrmica-pinetorum-MCZ001L.jpg

7

return to couplet #4

  • Viewed from above, frontal lobes thin, and pointed upwards, exposing the insertion of the antennae; clypeal margin with small indentations; an introduced Palearctic species common along coasts and rivers, as well as in urban disturbed areas . . . . . Myrmica rubra
Myrmica-rubra-MCZ001H.jpg
Myrmica-rubra-MCZ001L.jpg
  • Viewed from above, frontal lobes thick and laterally extended, at least partially covering the insertion of the antennae; clypeal margin entire, without small indentations (incompleta group) . . . . . 8

8

return to couplet #7

  • Head, clypeus, mesosoma, and petiole heavily sculptured and striated; lower surface of petiole with at most a small outgrowth or process; top of post-petiole in side view evenly (straight) sloped . . . . . 9
  • Ant weakly sculptured, if at all; lower surface of petiole with a large, process; top of post-petiole hump-shaped in profile; inquiline social parasites; if workers are present, they lack the process under the petiole and instead are workers of the host species . . . . . 10

9

return to couplet #8

  • Ant of deciduous forests; clypeus bulges in the middle and straight or modestly concave on the margin; rugae on top of the head anastomosing and net-like . . . . . Myrmica incompleta
Myrmica incompleta casent0005703 head 1.jpg
Myrmica incompleta casent0005703 profile 1.jpg
  • Ant of boreal forests; clypeus evenly convex in the middle and distinctly convex on the margin; rugae on top of the head parallel . . . . . Myrmica alaskensis
Myrmica alaskensis casent0104830 head 1.jpg
Myrmica alaskensis casent0104830 profile 1.jpg

10

return to couplet #8

  • Process below the petiole conical and angular; ant shiny, with virtually no sculpturing; an inquiline social parasite of Myrmica alaskensis . . . . . Myrmica lampra
Francoeur 1968 M lampra.jpg

11

return to couplet #1

  • Antennal scape tapered on both sides, giving it a ridge on top and a triangular appearance in cross-section; a Palearctic, non-native species . . . . . Myrmica scabrinodis
Myrmica-scabrinodis-MCZ001H.jpg
Myrmica-scabrinodis-MCZ001L.jpg
  • Antennal scape not tapered, giving it a rounded shape in cross-section; Nearctic, native species . . . . . 12

12

return to couplet #11

  • Mesosoma, petiole, and post-petiole with thick, parallel, rugae that would appear round in cross-section; in full-face view, lateral wings of clypeus extended and raised anteriorly into a ridge that encloses the antennal socket; in dorsal view, lamella on the antennal bend are most apparent on the interior side, not on top, of the bend (sculptilis group) . . . . . 13
  • Mesosoma, petiole, and post-petiole with thinner, net-like, anastomosing rugae that would appear sharply-angled in cross-section; in full-face view, lateral wings of the clypeus usually not raised anteriorly into a ridge that encloses the antennal socket; but if the clypeal wings are raised and enclose the antennal socket, then the lamella on the top of the antennal bend, in dorsal view, is apparent and well developed . . . . . 14

13

return to couplet #12

  • In full-face view, frontal lobes large and rounded, covering the antennal socket; in dorsal view, antennal scape with a small outgrowth/lamella that is not wider than the base itself and with a ridge running along the inside of the base (towards the head). . . . . Myrmica sp. AF-scu - an undescribed species
  • Frontal lobes smaller and with a convex margin, not covering the antennal socket; margin of the frontal lobes may have two separate ridges; in dorsal view, the lamella on the base of the scape is wider than the base itself . . . . . Myrmica sp. AF-smi - an undescribed species

14

return to couplet #12

  • In dorsal view, the shaft of the antennal scape is distinctly narrower at the bend than it is at its apex; the lamina on the dorsal part of the antennal bend may extend downwards towards the head, but never extends along the scape itself (detritinodis group) . . . . . 15
  • In dorsal view, the shaft of the antennal scape is more or less uniformly wide across its entire length; the lamina on the dorsal part of the scape does not extend downwards towards the head, but may extend anteriorly along the scape itself . . . . . 18

15

return to couplet #14

  • Propodeum without spines; rugae create a spider-web pattern on the head, and anastomosing rugae on the sides . . . . . Myrmica sp. AF-ine - an undescribed species

16

return to couplet #15

  • In dorsal view, the bend of the antennal scape has a curved or transverse lamina that continues downwards along the inner side of the base (towards the head). Forested habitats . . . . . Myrmica detritinodis
Mcz-ent00668928 Myrmica detritinodis hef.jpg
Mcz-ent00668928 Myrmica detritinodis hal.jpg
  • In dorsal view, the lamina at the bend of the antennal scape is restricted to the top of the scape and does not run downwards along the base of the antenna; open and forest-edge habitats . . . . . 17

17

return to couplet #16

  • In dorsal view, the lamina at the bend of the scape is small and barely visible; a widespread ant of open habitats in northern New England . . . . . Myrmica fracticornis
Myrmica-fracticornis-MCZ001H.jpg
Myrmica-fracticornis-MCZ001L.jpg
  • In dorsal view, the lamina at the bend of the scape is large and conspicuous; an uncommon, boreal species . . . . . Myrmica cf. AF-sub - an undescribed species

18

return to couplet #14

  • Lower surface of post-petiole is lobed and projecting forward when viewed in profile . . . . . Myrmica latifrons
Myrmica latifrons casent0104815 head 1.jpg
Myrmica latifrons casent0104815 profile 1.jpg
  • Lower surface of post-petiole is flat; in profile, post-petiole is slightly convex, but not lobed (nearctica group) . . . . . 19

19

return to couplet #18

  • In full-face view, lateral wings of clypeus are raised into a ridge that encloses the antennal socket; margin of frontal lobes are evenly rounded over most of their length; in dorsal view, lamella at antennal bend is spoon-shaped, not extending along the inner (posterior) side of the scape towards its apex . . . . . 20
  • In full-face view, lateral wings of clypeus flattened and not enclosing the antennal socket; margin of frontal lobes rounded towards the front but straight or convex posteriorly; in dorsal view, lamella at antennal bend large, and the lamina extends along the inner margin of the scape anteriorally towards its apex . . . . . Myrmica nearctica
Myrmica nearctica casent0104839 head 1.jpg
Myrmica nearctica casent0104839 profile 1.jpg

20

return to couplet #19

  • In dorsal view, the bend of the antennal scape has a large, circular, spoon-like lamella that projects sharply upward . . . . . Myrmica americana
Myrmica-americana-MCZ001H.jpg
Myrmica-americana-MCZ001L.jpg
  • In dorsal view, the bend of antennal scape with a smaller lamella that is barely deflected inwardly, giving it a shallow spoon-shape . . . . . Myrmica sp. AF-eva - an undescribed species