Formica

Genus Formica Linne, 1758

Formica Linne, 1758: 579.

Type-species: Formica rufa Linne, 1758 (Yarrow, 1954).

Antennae 12 segmented in worker and female, 13 segmented in male; antennal insertions contiguous with clypeal border. Funiculus segments 2 to 5 longer than 6 to 10. Maxillary palps 6 segmented, occasionally 5; labial palps 4 segmented. Ocelli distinct in all castes; frontal ridges diverging posteriorly; frontal triangle always very distinctly defined. Propodeal spiracle elliptical placed at some distance from propodeal border. Wings with cubital and one discoidal cell. Male external genitalia large and conspicuous. The species of this genus are relatively robust and active.

Holarctic genus with over 150 species. There are at least 20 species known to occur in Fennoscandia; in some groups, notably F. rufa and its allies, species distinctions are not always clearcut necessitating the comparison of a number of specimens preferably with males and females as well as workers.

Keys to species of Formica

Workers

1 Bicoloured species: alitrunk red with varying amounts of dark brown to blackish patches........................................................................................ 2

Body colour evenly greyish or brownish black........................................... 18

2(1) Anterior margin of clypeus emarginate or with distinct median notch (Fig. 222)........................................................................... 56. sanguinea Latreille

Anterior margin of clypeus broadly rounded and entire................................ 3

3 (2) Head flattened posteriorly, with deeply concave occipital border.................. 4

Head evenly rounded posteriorly, occipital margin straight, convex or very weakly concave......................................................................................... 8

4 (3) Eyes with distinct microscopic hairs; maxillary palps longer than half head length (Figs. 201,212)................................................... 50. exsecta Nylander

Eyes bare; maxillary palps half head length or shorter................................. 5

5(4) Occipital corners smoothly rounded; posterior emargination shallow, head not longer than maximum width across eyes; maxillary palps 6 segmented, as long as half head length (Fig. 213)...................................... 54. suecica Adlerz

Occipital corners sharp; back of head deeply emarginate; maxillary palps often 5 segmented, shorter than half head length; head longer than broad 6

6 (5) Dorsal hairs on gaster few but present on all tergites; middle of clypeus as well as its anterior border with projecting hairs (Figs. 204,205) 52. forsslundi Lohmander

Dorsal hairs on gaster restricted to posterior margin of third tergite to apex; clypeal hairs restricted to anterior border (Fig. 207)............................ 7

7 (6) Gaster moderately shining, with dilute sculpture and pubescent hairs shorter than their interspaces. Clypeus transversely impressed below midline (Figs. 206,215)................................................................. 53. pressilabris Nylander

Basal tergite of gaster with upper surface sculptured and dull; pubescent hairs slightly longer than their interspaces. Clypeus with or without shallow impression below midline (Fig. 216)...................................... 51. foreli Emery

8(3) Frontal triangle dull; terminal segment of maxillary palp as long as fifth segment.................................................................................................... 9

Frontal triangle reflecting light; terminal segment of maxillary palp shorter than fifth segment.................................................................................... 12

9 (8) Head and frontal triangle coarsely sculptured, opaque black. Head as broad as long; antennal scape short, not over-reaching occipital margin by more than 1/4 its length (Fig. 219)............................................ 55. uralensis Ruzsky

At least genal margins and clypeus reddish, sculpture weaker but pubescense strongly developed and moderately thick especially on gaster. Head distinctly longer than broad; antennal scape slender, over-reaching occipital margin by 1/3 its length or more............................................................................... 10

10 (9) Whole body including gula and posterior margin of head with numerous projecting hairs (Figs. 162,188)............................................ 47. cinerea Mayr

Gula and posterior margin ofhead entirely without hairs............................ II

11 (10) Dorsum of promesonotum and upper margin of petiole scale with projecting hairs (Fig. 197)........................................................... 49. rufibarbis Fabricius

Promesonotum and scale without projecting hairs, occasionally one or two short hairs present on promesonotum (Fig. 193)........... 48. cunicularia Latreille

12 (8) Antennae long with scapes longer than head width; second and third funiculus segments in larger workers twice as long as broad (Fig. 225) 57. truncorum Fabricius

Antennal scape shorter than head width; funiculus segments always less than twice as long as broad.............................................................................. 13

13 (12) Gaster thickly pubescent and dull; frons closely sculptured and dull: dark patch on promesonotum normally clearly defined and opaque.................... 14

Gaster and frons moderately shining; dark patch on promesonotum very variable, not normally clearly defined and sometimes absent...................... 15

14 (13) Head and body profusely hairy with longest hairs on alitrunk x 0.1 or more head width. Antennal scapes usually with two or three short projecting subde- cumbent hairs (Fig. 266).................................................. 63. nigricans Emery

Pilosity variable, alitrunk hairs usually less than x 0.1 head width. Antennal scapes with adpressed pubescence only (Figs. 256, 261).... 62. pratensis Retzius

Figs. 159-162. Head of Formica-workers in dorsal view. - 159: fusca (L.); 160: rufibarbis Fabr.; 161: cunicularia Latr.; 162: cinerea Mayr. Scale: 1 mm.

15 (13) Eyes, gula, alitrunk and posterior margin of head conspicuously hairy, with hairs extending forward laterally as far as eyes (Figs. 249. 254) 61. lugubris Zetterstedt

Eyes with very short hairs or bare. Fringe of hairs at back of head when present not extending forward beyond occipital corners............................. 16

16(15) First tergite of gaster evenly and closely set with micropunctures; eyes always with distinct short hairs; frons closely sculptured and rather dull; extensor surface of hind femora and tibiae always with some projecting hairs; posterior ofhead with projecting hairs, sometimes very few or absent (Figs. 242, 247) 60. aquilonia YarrowFirst tergite of gaster with punctures widely spaced on upper medial area; eyes bare or with very few microscopic hairs; frons moderately shining with shallow sculpture and easily seen scattered coarse punctures. Back of head without projecting hairs........................................................................... 17

17 (16) Gula, dorsum of head and alitrunk with conspicuous projecting hairs; occasional or few projecting hairs normally present on extensor surface of hind femora and tibiae. Mesopleurae from above with evenly distributed long hairs (Fig. 229)........................................................................ 58. rufa Linne

Gula bare or with one or two weak hairs, dorsum of head and alitrunk with occasional short hairs. Hind femora and tibiae normally bare. From above projecting hairs on mesopleurae restricted to a few only at posterior end (Fig. 236)...................................................................... 59. polyctena Forster

18(1) Back and underside of head with copious erect hairs (Fig. 188) 47. cinerea Mayr

Back of head bare................................................................................... 19

19(18) Dorsum of promesonotum with erect hairs................................................ 20

Dorsum of promesonotum bare or with occasional one or two hairs only.... 21 20(19) Whole body brilliantly shining; premesonotal hairs pointed, long and curving forward; one or two gula hairs often present (Fig. 184) 46. transkaucasica Nasonov Body with subdued shine; premesonotal bristles short and blunt; gula hairs never present (Fig. 182)................................................... 45. lemani Bondroit

21 (19) Gaster shining, with very dilute pubescence and absence of sculpture medially; petiole scale emarginate dorsally.......................... 44. gagatoides Ruzsky

Gaster with close pubescence and microsculpture; petiole scale with rounded or flat dorsal crest.................................................................. 43. fusca Linne

Females

1 Anterior margin of clypeus impressed or notched......... 56. sanguinea Latreille

Anterior margin of clypeus entire, broadly convex....................................... 2

2 (I) Occipital margin of head deeply excised or broadly emarginate.................... 3

Occipital margin of head convex................................................................. 7

3 (2) Eyes with copious hairs; size larger, length: 7.5-9.0 mm... 50. exsecta Nylander

Eyes bare; size smaller, length: 5.5-7.2 mm.................................................. 4

4 (3) Occipital corners smoothly rounded, emargination of head shallow; petiole scale with angular lobes; maxillary palps 6 segmented......... 54. suecica Adlerz

Occipital corners sharp, enclosing deep emargination: petiole scale with rounded lobes; maxillary palps short, normally 5 segmented......................... 5

5 (4) Erect hairs present on dorsum of second gaster tergite to apex; middle of clypeus with long hairs........................................... 52. forsslundi Lohmander

Erect hairs on dorsum of gaster restricted to posterior border of third tergite to apex; clypeal hairs restricted to anterior border only...................... 6

6 (5) Body uniformly shining dark brown.......................... 53. pressilabris Nylander

Gaster somewhat matt appearance, propodeum and petiole yellowish red 51. foreli Emery

7 (2) Body colour uniformly brownish black or black........................................... 8

Body bicoloured with portions of alitrunk at least distinctly reddish............ 12

8 (7) Back of head and gula with copious erect hairs (Fig. 190)...... 47. cinerea Mayr

Back ofhead always bare........................................................................... 9

9 (8) Underside of mid femora bare; in dorsal view hairs on pronotum restricted to anterior portion only............................................................................ 10

Underside of mid femora with several long hairs; erect hairs on pronotum extend round the sides to the tegulae......................................................... 11

10 (9) Gaster and scutellum brilliant; middle of gaster dorsum impunctate, pubes- cence very sparse and dilute; petiole scale broadly heart-shaped; gula hairs occasionally present (Fig. 181)..................................... 44. gagatoides Ruzsky

Gaster and scutellum with subdued shine, with distinct microsculpture an pubescence; petiole scale normally with dorsal crest flat or convex; gula hairs never present (Fig. 178).................................................. 43. fusca Linne

11 (9) Whole body shining; pubescence on gaster long but sparse; 2 or 3 gula hairs

normally present (Fig. 187)................................... 46. transkaucasica Nasonov Gaster dull with close pubescence and distinct microsculpture; underside of head always bare (Fig. 183).............................................. 45. lemani Bondroit

12(7) Frontal triangle densely sculptured or dull. Eyes completely hairless. Terminal segment of maxillary palp as long as fifth.......................................... 13

Frontal triangle reflecting light. Eyes with conspicuous hairs or with occasional microscopic hairs. Terminal segment of maxillary palp shorter than preceding segments................................................................................. 16

13 (12) Whole body including gula and posterior margin of head with, profuse hairs; body colour mainly brownish black, but occasionally genae and mesopleural articulations reddish (Fig. 190)............................................. 47. cinerea Mayr

Hairs entirely absent on posterior margin of head...................................... 14

14 (13) Head entirely black, coarsely sculptured; antennal scape short and thick; femora black; underside of head usually with a few coarse hairs 55. uralensis Ruzsky

Genae and clypeus distinctly reddish; antennal scapes slender: femora yellowish red; underside of head always bare...................................................... 15

15 (14) Propodeum with a few erect hairs; mesoscutum in part reddish (Fig. 199) 49. rufibarbis Fabricius

Propodeum without erect hairs; mesoscutum normally entirely dark (Fig. 195).......................................................................... 48. cunicularia Latreille

16(12) Gaster and whole of scutum matt with more or less dense pubescence........ 17

Gaster and scutellum distinctly shining; pubescence dilute, not obscuring cuticular shine......................................................................................... 19

17 (16) Second funiculus segment twice as long as broad. Whole body including meso-

notum with large shallow punctures. Head normally with red colour predominating(Fig. 226)............................................... 57. truncorum Fabricius

Second funiculus segment always less than twice as long as broad. Larger punctures deep and normally concealed by pubescence............................. 18

18 (17) Whole body including propodeum, scale and basal face of gaster with conspi- cuous long bent hairs. Antennal scape often with two or three projecting

hairs (Figs. 263, 264)........................................................ 63. nigricans Emery

Projecting hairs on posterior margin of head and basal face of gaster normally short, absent on dorsum of propodeum and scale. Scapes without projecting hairs (Figs. 258,259)................................................. 62. pratensis Retzius

19 (16) Back of head, basal face of gaster scale and propodeum with long hairs (Figs.

251,252).................................................................... 61. lugubris Zetterstedt

Dorsum of scale and propodeum without hairs, back of head and basal face of gaster either bare or with short sparse hairs............................................ 20

20 (19) Gaster including medial dorsal area of first tergite very finely and closely set with micropunctures. Eyes with distinct short erect hairs (Figs. 174, 244, 245)............................................................................. 60. aquilonia Yarrow

Micropunctures on gaster sparse and widely set, larger punctures well spaced and clearly visible. Eyes with a few microscopic hairs or bare (Figs. 171,172,232,239).................................................................................... 21

21 (20) Middle of scutellum normally brilliant, without punctures or striae. 58. rufa Linne

Middle of scutellum with longitudinal striae and punctures rather dull 59. polyctena Forster

Males

1 Back ofhead broadly excavate with pronounced occipital angles................. 2

Back of head convex................................................................................. 6

2(1) Occipital margins and eyes conspicuously hairy (Fig. 208) 50. exsecta Nylander

Occipital margins and eyes bare or with very sparse short hairs..................... 3

3 (2) Mesonotum with scattered hairs; maxillary palps 6 segmented; occipital corners smoothly rounded (Fig. 209)....................................... 54. suecica Adlerz

Mesonotum bare; maxillary palps short, normally 5 segmented; occipital corners sharp............................................................................................ 4

4 (3) Outstanding hairs on dorsum of gaster present on second tergite to apex 52. forsslundi Lohmander

Outstanding hairs on gaster restricted to fifth tergite to apex......................... 5

5 (4) Body shining; pubescent hairs on gaster shorter than interspace; eyes with 1 or 2 microscopic hairs at most.................................. 53. pressilabris Nylander

Body somewhat dull; pubescent hairs on gaster longer than interspaces; eyes with scattered microscopic hairs.................................... 51. foreli Emery

6 (1) Front border of clypeus emarginate or notched in middle (Fig. 221) 56. sanguinea Latreille

Front border of clypeus not impressed, with straight or convex front border...................................................................................................... 7

7 (6) Eyes with conspicuous hairs....................................................................... 8

Eyes bare................................................................................................ 14

8 (7) Whole body thickly haired, in side view suberect hairs on dorsum of gaster numerous and uninterrupted from base to apex. Frontal triangle without punctures or coarse sculpture. Legs and external genitalia mainly yellow. Antennae long and slender, second and third funiculus segment more than x 2.5 as long as broad (Fig. 227).................................... 57. truncorum Fabricius

In side view hairs on dorsum of gaster sparse and not appearing as an uninterrupted fringe. Frontal triangle shining but normally micropunctures and/ or some pubescence present. Genitalia and legs with at least femora partly infuscated. Funiculus segments less than x 2.5 as long as broad..................... 9

9 (8) Scutellum and gaster pubescent and dull (eyes and genae always with profuse hairs)...................................................................................................... 10

Scutellum and gaster at least moderately shining........................................ 11

10 (9) Tibial hairs numerous, with occasional long erect hairs on hind tibiae at least x 0.5 maximum tibial width............................................. 63. nigricans Emery

Tibial hairs short often sparse, none exceeding x 0.3 hind tibial width (Fig. 257).............................................................................. 62. pratensis Retzius

11 (9) Genal hairs profuse. Tibial hairs long and profuse (Figs. 250,253) 61. lugubris Zetterstedt

Genal margins below eyes either with a few projecting hairs or none. Tibial hairs short and sparse or absent................................................................ 12

12 (11) Frons and gaster very finely punctured. Fringe of short hairs always present on upper surface of hind femora. In normal populations projecting hairs are present on the genae below eyes (Fig. 246)..................... 60. aquilonia Yarrow

Frons and gaster widely and coarsely punctured. Upper surface of hind femora with occasional hairs or none........................................................ 13

13 (12) Metanotum bare or with sparse hairs. Longer hairs on mesonotum sparse. Genae never with projecting hairs below eyes (Fig. 237) 59. polyctena Forster Metanotum with long hairs which are also numerous over mesonotum. Genal projecting hairs occasionally present in some populations, normally absent (Fig. 230)................................................................................ 58. rufa Linne

14(7) Scutellum dull or opaque......................................................................... 15

Scutellum moderately shining or brilliant.................................................. 18

15 (14) Antennal scapes thick - width equal to more than half narrowest eye width; head broad and not conspicuously narrowed anteriorly; femora and whole body opaque black, coarsely sculptured, petiole scale broadly convex (Fig. 220).............................................................................. 55. uralensis Ruzsky

Antennal scapes slender - maximum width less than x 0.3 minimum eye width; head narrowing conspicuously towards clypeal border; sculpture fine but obscured by more or less thick pubescence on dorsal surfaces; legs yellowish or yellowish red with only femora sometimes infuscate, petiole scale emarginate..................................................................................................... 16

16 (15) Underside ofhead with erect hairs (Fig. 192)........................ 47. cinerea Mayr

Underside of head always bare................................................................. 17

17 (16) Femora dark at least in part. Dorsal border of petiole scale sharply angulate at sides (Fig. 168)....................................................... 49. rufibarbis Fabricius

Femora unicolorous with tibiae reddish or pale reddish yellow, sides of petiole scale rounded................................................. 48. cunicularia Latreille

18 (14) Petiole scale with very short fine hairs only; normally with rounded or flat dorsal border (Fig. 165).......................................................... 43, fusca Linne

Petiole scale with long hairs; dorsal border more or less deeply emarginate (Figs. 163, 164,166).................................................................................. 19

19 (18) Underside of mid and hind femora bare; erect hairs on promesonotum sparse, short and weak................................................ 44. gagatoides Ruzsky

Underside of mid femora with one or more scattered hairs, semi-erect hairs on promesonotum numerous and strong........................................... 20

20 (19) Gaster brilliant almost without sculpture medially, with long fine scattered pubescence; underside of head normally with one or two long hairs; frontal triangle shining.................................................... 46. transkaucasica Nasonov

Gaster moderately shining with short close pubescence and distinct microsculpture. Underside of head never with hairs; frontal triangle dull 45. lemani Bondroit