Key to Myrmica of Romania

This worker key is based on Czekes, Z.; Radchenko, A. G.; Csősz, S.; Szász-Len, A.; Tăuşan, I.; Benedek, K.; Markó, B. 2013. The genus Myrmica Latreille, 1804 (Hymenoptera: Formicidae) in Romania: distribution of species and key for their identification. Entomologica Romanica 17:29-50.

Myrmica karavajevi is a workerless species. Its queens well differ from any other Romanian Myrmica by the presence of wide lamella on the ventral surfaces of both petiole and postpetiole. Its males have 12-segmented antennae (instead of 13-segmented in other species), long scape that surpasses occipital margin, and forewing with completely fused closed cells 1r+2r+rm (forewing in other species with closed cells 1r+2r and rm partly separated by short vein.

1

Frontal carinae curved outwards to merge with the rugae that surround antennal socket. Scape very smoothly curved at the base, never angled and without any trace of a lobe or carina . . . . . 2

Frontal carinae merging with the rugae that extend to the occipital margin, they do not curve outwards and do not merge with rugae that surround antennal sockets. Scape more strongly curved, often angled at the base, usually with, but sometimes without a lobe, ridge or carina . . . . . 3

2

Petiolar node with rounded dorsum, without flattened dorsal plate, node of petiole and postpetiole smooth, at most very finely striated; propodeal spines short, mean ESL/HW 0.26). Males: scape and tibiae with rather long standing hairs . . . . . Myrmica rubra

Head of Myrmica rubra worker

Profile of Myrmica rubra worker

Petiolar node with flattened dorsal plate, node of petiole and postpetiole with quite coarse, short sinuous longitudinal rugae; propodeal spines longer, mean ESL/HW 0.41. Males: scape and tibiae with short standing hairs . . . . . Myrmica ruginodis

Head of Myrmica ruginodis worker

Profile of Myrmica ruginodis worker

3

Scape with a vertical lobe or dent and sharply angled at the base . . . . . 4

Scape never with a vertical lobe or dent, angled at the base, often with horizontal lobe, ridge or carina of various shape . . . . . 7

4

Frontal carinae very strongly curved, frons extremely narrow (the narrowest among all known Myrmica species), FW/HW < 0.19, FLW/FW > 1.95. Scape at the base with an extremely massive, subvertical, plate-like lobe . . . . . Myrmica ravasinii

Head of Myrmica ravasinii worker

Profile of Myrmica ravasinii worker

Frontal carinae less curved, frons wider, FW/HW > 0.20, FLW/FW < 1.90. Scape at the base with vertical lobe ranging from moderately sized plate-like structure to a small dent . . . . . 5

5

Petiole with short peduncle, its anterior surface steep, only slightly concave, meeting the dorsal one at an acute or right angle, petiolar node with a distinct, declined posteriorly, flattened dorsal plate (seen in profile). Base of scape (seen anteriorly) without extended shield-like plate, scape at the base usually with a distinct lobe (its size may vary, but it is never dentiform). Males: scape long, SL/HL < 0.70 . . . . . Myrmica lobicornis

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Profile of Myrmica lobicornis worker

Petiole with well developed peduncle, its anterior surface not steep, distinctly concave, meeting the dorsal one to form a blunt, rounded angle, petiolar node without a distinct dorsal plate, its dorsum convex or at most slightly flattened (seen in profile). Base of scape (seen anteriorly) with extended, shield-like plate. Scape at the base either with big or small, often dentiform lobe. Males: scape short, SL/HL < 0.50 . . . . . 6

6

Frons narrower, mean FW/HW 0.23. Scape at the base with big lobe. Males: scape strongly curved at the base, relatively long, subequal to the length of three basal funicular segments together, mean SL/HW 0.43 . . . . . Myrmica schencki

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Profile of Myrmica schencki worker

Frons wider, mean FW/HW 0.31. Scape at the base with small dent. Males: scape very feebly curved at the base, very short, subequal to the length of first and second funicular segments together, mean SL/HW 0.34 . . . . . Myrmica deplanata

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Profile of Myrmica deplanata worker

7

Mesosoma and waist with very coarse, straight (not sinuous) longitudinal rugae; petiole with a very short peduncle, and steep anterior surface that meets the dorsal one at an almost right angle, dorsal plate well developed and flattened. Scape strongly but gradually curved at the base, at most slightly angled, sometimes with a weak longitudinal. Large and robust species, usually bicoloured, with reddish alitrunk and blackish head dorsum and gaster. Males: scape long SL/HL > 0.80 . . . . . Myrmica sulcinodis

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Profile of Myrmica sulcinodis worker

Mesosoma, and especially waist, with less coarse, usually sinuous longitudinal rugosity; petiole of different shape. Scape of various shape. Males: scape shorter, SL/HL < 0.70 . . . . . 8

8

Scape at the base bent in an “ideal” curve, with no trace of an angle, carina or ridge . . . . . 9

Scape either strongly angled at the base, with horizontal lobe, carina or a weak ridge, or at least slightly angled, but never bent in an “ideal” curve . . . . . 10

9

Propodeal spines short, mean ESL/HW 0.28, petiole low, mean PL/PH 1.24. Generally bigger, mean HW 1.12, mean AL 1.80 mm, more robust and darker coloured species . . . . . Myrmica bergi

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Profile of Myrmica bergi worker

Propodeal spines longer, mean ESL/HW 0.36, petiole higher, mean PL/PH 1.14. Generally smaller, mean HW 1.04, mean AL 1.62 mm, more slender and lighter coloured species . . . . . Myrmica gallienii

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Profile of Myrmica gallienii worker

10

Scape slightly angled at the base, without horizontal lobe, at most with very weak short horizontal ridge . . . . . 11

Scape strongly angled at the base, with horizontal lobe, carina or well developed ridge . . . . . 12

11

Scape at the base with no trace of a ridge. Frontal lobes less extended, FLW/FW < 1.10 . . . . . Myrmica rugulosa

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Profile of Myrmica rugulosa worker

Scape at the base with weak ridge. Frontal lobes more extended, FLW/FW ≥ 1.15 . . . . . Myrmica constricta

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Profile of Myrmica constricta worker

12

Frons very narrow, FW/HW < 0.30, mean 0.27. Lobe at the base of scape quite large, but not extended to form a longitudinal carina on the dorsal surface of scape . . . . . Myrmica curvithorax

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Profile of Myrmica curvithorax worker

Frons wider, FW/HW ≥ 0.30, species’ means ≥ 0.33. Base of the scape with ornamentation ranging from a ridge or a distinct carina to a large, well developed lobe, but if the lobe is large, it extends to form a longitudinal carina on the dorsal surface of scape . . . . . 13

13

Postpetiole very wide, PPW/HW > 0.55. Body with very abundant, long standing hairs. Males: scape relatively long, as long as four basal funicular segments together, SL/HL > 0.50. Head margins and waist with numerous long hairs . . . . . Myrmica hirsuta

Postpetiole narrower, PPW/HW < 0.45. Body with less abundant and shorter hairs. Males: scape of various length, head pilosity various . . . . . 14

14

Relatively hairy species, petiole with more than 10 (usually with 12-20) long, thin and often curved hairs; mesosomal dorsum with longitudinal, slightly sinuous rugae, without reticulation; postpetiolar dorsum with partly reduced sculpture. Anterior clypeal margin shallowly but distinctly notched medially. Spurs on middle and hind tibiae at least partly reduced and usually not pectinate. Queens: petiolar node with coarse, regular longitudinally-concentric rugosity, without reticulation. Males: scape relatively long, as long as four basal funicular segments together, SL/HL > 0.50; head margins with numerous long hairs . . . . . Myrmica vandeli

Head of Myrmica vandeli worker

Profile of Myrmica vandeli worker

Less hairy species, petiole with less than 10 (usually not more than 8) long, straight, thick standing hairs; mesosomal dorsum with strongly sinuous longitudinal rugae and often also with reticulation; postpetiolar dorsum with coarser sculpture. Anterior clypeal margin not notched medially. Spurs on middle and hind tibiae as a rule well developed and pectinate. Queens: petiolar node with various sculpture, but never with coarse, regular longitudinally-concentric rugosity. Males: scape shorter, if the same length then head margins with very short and sparse standing hairs . . . . . 15

15

Scape at the base with very large, massive lobe, which is clearly raised over the dorsal plane of scape (seen in profile). Frons narrow, mean FW/HW 0.32. Males: scape relatively long, as long as 4-4.5 basal funicular segments together, SL/HL > 0.50 . . . . . Myrmica lonae

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Profile of Myrmica lonae worker

Scape at the base with smaller, not very massive lobe, which is never raised over the dorsal plane of the scape (seen in profile), or with narrow carina or ridge. Males: scape of various lengths . . . . . 16

16

Frons relatively narrow, species’ means FW/HW ≤ 0.35. Scape at the base with relatively large posteriorly bulging lobe. Males: scape of various length . . . . . 17

Frons relatively wide, species’ means FW/HW ≥ 0.36. Scape at the base with smaller lobe, carina or ridge. Males: scape short, SL/HL < 0.45 . . . . . 19

17

Frons somewhat wider, mean FW/HW 0.35, frontal lobes less extended, mean FLW/FW 1.50. Males: scape somewhat shorter than first to third basal funicular segments together, mean SL/HL 0.42. Standing hairs on tibiae ant tarsi shorter, longest hairs on tibiae not longer than tibial width, same on tarsi less than twice longer than tarsal width . . . . . Myrmica kozakorum (=Myrmica specioides)

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Profile of Myrmica specioides worker

Frons somewhat narrower, species’ means FW/HW 0.33-034, frontal lobes more extended, species’ means FLW/FW 1.53-1.57. Males: scape either short (SL/HL < 0.40) or long (SL/HL > 0.50). Standing hairs on tibiae and tarsi very long, longest hairs on tibiae distinctly longer than tibial width, same on tarsi more than twice longer than tarsal width . . . . . 18

18

Spur of hind and middle tibiae well developed, pectinate. Males: scape relatively long, as long as length of 4-4.5 basal funicular segments together, SL/HL > 0.50 . . . . . Myrmica sabuleti

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Profile of Myrmica sabuleti worker

Spur of hind and middle tibiae often reduced to some extent. Males: scape short, shorter than length of first to third basal funicular segments together, SL/HL < 0.40 . . . . . Myrmica tulinae

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Profile of Myrmica tulinae worker

19

Frons very wide, mean FW/HW 0.43, frontal lobes weakly extended, mean FLW/FW 1.15. Scape at the base with a narrow horizontal lobe, carina or even distinct ridge (size of this structure is quite variable) . . . . . Myrmica hellenica

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Profile of Myrmica hellenica worker

Frons narrower, species’ means FW/HW ≤ 0.40, frontal lobes distinctly more extended, species’ means FLW/FW ≥ 1.30. Scape at the base with a much more pronounced, larger horizontal lobe or carina . . . . . 20

20

Frons somewhat wider, mean FW/HW 0.38, frontal lobes less extended, mean FLW/FW 1.32. Petiolar node without a distinct horizontal dorsal plate, its posterior surface declines gradually to postpetiole (seen in profile); propodeal spines relatively short, mean ESL/HW 0.36. Scape at the base with a rather small lobe or only narrow carina. Males: middle and hind tibiae and basitarsi with shorter standing hairs, longest hairs not longer than maximum width of tibia . . . . . Myrmica specioides

Head of Myrmica specioides worker

Profile of Myrmica specioides worker

Frons narrower, species’ mean FW/HW 0.36, shape of frontal lobes, petiole and propodeum various. Males: pilosity on middle and hind tibiae and basitarsi various . . . . . 21

21

Frontal lobes less extended, mean FLW/FW 1.31. Scape at the base with narrow horizontal ridge or at most very small carina. Propodeal spines short, mean ESL/HW 0.31, not widened at the base, thin, often needle-like; metanotal groove weak or completely absent; petiolar node without dorsal plate, usually only rounded, its posterior surface gradually declines to postpetiole; sides of alitrunk with relatively coarse, regular, almost straight longitudinal rugae. Body colour rather dark, brownish-red. Males: scape very short, mean SL/HL < 0.33. Middle and hind tibiae and basitarsi with short subdecumbent hairs . . . . . Myrmica stangeana

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Profile of Myrmica stangeana worker

Frontal lobes more extended, mean FLW/FW ≥ 1.40. Scape at the base with more developed, but never massive, horizontal carina or lobe. Propodeal spines longer, mean ESL/HW > 0.40, usually widened at the base (more thorn-like) never needle-like; metanotal groove well developed, often deep; petiolar node with a distinct horizontal or slightly declined posteriorly dorsal plate; sides of alitrunk with less coarse sinuous longitudinal rugae. Body colour lighter, usually ochreous- or yellowish-red. Males: scape somewhat longer, mean SL/HL > 0.37. Middle and hind tibiae and basitarsi with very long standing hairs, longest hairs longer than maximum width of tibia . . . . . Myrmica scabrinodis

Head of Myrmica scabrinodis worker

Profile of Myrmica scabrinodis worker