Key to Palaearctic Lasius subgenus Lasius s. st.

This key to workers is based on a key from: [[Media:Seifert, B. 2020. A taxonomic revision of the Palaearctic members of the subgenus Lasius.pdf|Seifert, B. 2020. A taxonomic revision of the Palaearctic members of the subgenus Lasius s.str. (Hymenoptera, Formicidae). Soil Organisms 92(1):15-86.]].

The publication provides more details about the methods and measurements associated with the use of this key.

Siefert states: Truly cryptic species constitute more than 50% of the 56 species and some members of one species group may share some characters typical for other species groups. This makes the writing of a dichotomous key a frustrating business. Regrettably, the only way to classify all species recognized here is using adequate microscopic equipment, recording the full set of NUMOBAT characters under meticulous consideration of character definitions and running discriminant functions using the morphometric data provided in supplementary information SI2. Candidate species for LDA runs can be selected beforehand by combined consideration of morphometric tables, pictures and geographic distribution. Here I present a dichotomous key which should work for a good number of species with acceptable error rates but in the end using this key is probably more time consuming than running discriminant functions on the basis of SI2. All absolute measurements used in the key as input in discriminant functions are given in mm. All setae counts are arithmetic means of the data from the left and right body half. Note that the morphometric tables Tabs. 1–11 show RAV-corrected values in order to show interspecific differences more clearly. The key, in contrast, always uses primary data.

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Lasius genus page

1

 * Europe, Mediterranean islands, Caucasus and Asia Minor . . . . . 6

2

 * Canaries, North Africa, Middle East, Iran . . . . . 26

3

 * Afghanistan, Tadzhikistan, Uzbekistan, Kyrgyzstan, Kazakhstan, Russian Siberia, Mongolia . . . . . 39

4

 * Himalaya, Meghalaya and Tibet . . . . . 47

5

 * China, Korea, Russian Far East, Japan . . . . . 54

6
return to couplet #1
 * Eyes and torulo-clypeal distance very small, scape shorter; nest means: EYE/CS 0.209 ± 0.010, dClAn/CS 0.0257 ± 0.0034, SL/CS 0.928 ± 0.023. Discriminant 110.85 x EYE –18.91 x SL +45.21 x dClAn –5.91 < 0 [error 0% in 40 individuals]. Subterranean species. S Moravia and E Austria, Asia Minor . . . . . Lasius austriacus


 * Eyes and torulo-clypeal distance larger, scape with exception of L. brunneus longer. Discriminant >0 [error 0% in 2445 individuals] . . . . . 7

7
return to couplet #6
 * Nest sample means. Scape short, SL/CS 0.865 ± 0.016. Pronotal setae short, PnHL/CS 0.097 ± 0.007. Mediumsized and larger workers bicolored: head dark yellowish brown, mesosoma lighter yellowish brown, gaster dark brown. Setae numbers on whole body strongly reduced, nOcc 2.1 ± 0.8. Dorsal and posterior profile of propodeum linear and forming a distinct, obtuse angle. Frontal line long and well marked. Pubescence on whole body and appendages very smooth, appressed and short. Mean number of mandibular dents only 7.06. Nest means of discriminant 19.4 x SL –26.63 x CW +0.001 x nOcc +0.33 x nSt +42.13 x PnHL –15.09 x GuHL + 3.929 < 0 [error 0% in 32 nest samples]. Arboricolous . . . . . Lasius brunneus


 * Nest sample means given. Scape longer, SL/CS >0.904. PnHL/CS in most species > 0.110; if similarly short, then SL/CS and /or nOcc much higher. Nest means of discriminant > 0 [error 0% in 1161 nest samples] . . . . . 8

8
return to couplet #7
 * Mesosoma, petiole, gaster and appendages yellow; head and gaster sometimes a littler darker with a brownish tinge. Scape and maxillary palp long (nest sample means SL/CS 1.020± 0.021, MP6/CS 0.206 ± 0.009). Pubescence on clypeus and sides of head extremely dilute, nest sample mean sqPDCL 6.49 ± 0.73. Setae on hind margin of head long and numerous but absent from scape; nOcc 14.4 ± 3.2, nSc 0.2 ± 0.3. Asia Minor only . . . . . Lasius schulzi


 * Character combination in at least two characters strongly deviating . . . . . 9

9
return to couplet #8
 * Nest means given. Standing setae on area below propodeal spiracle usually absent (nSt 0.34 ± 0.45). Pronotal setae rather long PnHL/CS 0.152 ± 0.007. Clypeal pubescence moderately dense (sqPDCL 4.16 ± 0.26). Scape rather short SL/CS 0.962 ± 0.036. Discriminant 9.098 x SL/CS –32.38 x PnHL/CS +0.453 x sqPDCL +0.678 x nSt –6.643 < 0 [error 4.2% in 48 nest samples]. . . . . . Lasius alienus


 * Nest means given. At least few standing setae on area below propodeal spiracle present; if absent, then scape longer (lasioides), pronotal setae shorter (lasioides) or clypeal pubescence denser (paralienus and Cretan kritikos) Discriminant > 0 [error 1.0% in 794 nest samples] . . . . . 10

10
return to couplet #9
 * All workers in a nest very small, CL 0.66–0.75 mm. Metanotal groove very shallow; as result dorsal profile of mesosoma more or less approaching linearity. Pubescence on head sides ventral of the eye extremely reduced. Pronotal setae rather long, PnHL/CS 0.154 ± 0.007. Number of standing setae on surface below propodeal spiracle comparatively large, nSt 3.3 ± 0.3. Cretan endemic living in moist, closed canopy forests . . . . . Lasius tapinomoides


 * Larger, dorsal mesosomal profile not approaching linearity, whole character combination different . . . . . 11

11
return to couplet #10
 * Due to appressed pubescence all body surfaces completely smooth. Dorsal plane of scape, tibiae and genae without standing setae. Nest means of nOcc+nGu+nHT < 5.5. Dorsal and posterior profile of propodeum linear and forming a distinct, obtuse angle. Nest means of SL/CS 0.992 ± 0.030, number of mandibular dents only 6–8. Holomediterranean, Middle East, Iran . . . . . Lasius lasioides


 * Pubescence on all body surfaces not completely smooth. Nest mean of nOcc+nGu+nHT > 5.5. Dorsal and posterior profile lines of propodeum not distinctly linear . . . . . 12

12
return to couplet #11
 * 12a Mean number of mandibular dents <8. Pubescence distance on clypeus very large, sqPDCL 5.4 ± 0.4. Setae on scape and hind tibiae usually absent, nSc+nHT 0.4 ± 0.5. Pronotal setae short, barely longer than gular setae, PnHL/CS 0.127 ±0.007, GuHL/CS 0.124 ± 0.012. Petiole scale in lateral view thin, with sharp dorsal crest . . . . . 13


 * Character combination in at least one character strongly deviating . . . . . 15

13
return to couplet #12
 * Discriminant of nest sample means: 17.41 x SL/CS+0.584 x nOcc–0.50 x nGu–45.1 x GuHL/CS +88.9 x dClAn/CS +67.884 x EYE/CS –34.60 >0 [error 0% in 67 nest sample means]. Supercolonial invasive species, widely distributed but not reaching subboreal and boreal regions . . . . . Lasius neglectus


 * Discriminant of nest sample means <0 [error 0% in 128 nest sample means] . . . . . 14

14
return to couplet #13
 * Nest sample means given. On average smaller, CS 0.768 ± 0.038 mm. Postocular distance larger, PoOc/CL 0.241 ±0.006. Eye larger, EYE/CS 0.245 ± 0.004, torulo-clypeal distance smaller dClAn/CS 3.75 ± 0.22 %. Discriminant 17.32 x CS +20.79 x CL/CW + 32.86 x SL/CS +0.625 x nGen +0.599 x sqPDCL +126.0 x dClAn/CS –50.71 x PoOc/CL – 93.03 x EYE/CS – 43.41 < 0 [error 0% in 51 nest samples]. Western Anatolia and its coastal Islands. Often polydomous. . . . . Lasius precursor


 * Nest sample means given. On average larger, CS 0.858 ± 0.047 mm. Postocular distance smaller, PoOc/CL 0.229 ±0.006. Eye smaller, EYE/CS 0.237 ± 0.006, torulo-clypeal distance larger dClAn/CS 4.00 ± 0.35 %. Discriminant > 0 [error 1.3% in 77 nest samples]. Western Aegean, Asia Minor, N Syria, N Iran. Often monodomous . . . . . Lasius turcicus

15
return to couplet #12
 * Nest sample means. Medium-sized, CS 0.912 mm. Head broad CL/CW 1.034. Scape long, SL/CS 1.022. Pronotal hairs short, only slightly longer than gular setae, PnHL/CS 0.108, GuHL/CS 0.094. Torulo-clypeal distance small, dClAn/CS 4.25%. Terminal segment of maxillary palp short, MP6/CS 0.177. Genae almost without standing setae, nGen 0.4. Only one sample known from Pindos Mountains / Greece . . . . . Lasius karpinisi


 * Character combination in at least one character strongly deviating. Rather similar to L. karpinisi is L. illyricus but nest sample means here PnHL/CS 0.124–0.152, GuHL/CS 0.104–0.140, dClAn/CS 4.54–6.34%, MP6/CS 0.196–0.244, nGen 3.0–9.2 . . . . . 16

16
return to couplet #15
 * Head and gaster yellowish brown, remaining body parts yellowish. Nest sample means: Scape long, SL/CS 0.994–1.021; eye small, EYE/CS 0.228–0.233; clypeal pubescence distance very large, sqPDCL 5.43–5.66 but frontal pubescence in contrast rather dense and long. All surfaces of head and mesosoma with numerous standing setae of medium to large length (PnHL/CS 0.158–0.161, GuHL/CS 0.125–0.132, nGu 8.5–11.8, nOcc 18.3–19.2, nGen 9.5–10.0). Only known from Asia Minor . . . . . Lasius flavoniger


 * Character combination strongly deviating . . . . . 17

17
return to couplet #16
 * Scape without or only single standing setae, nSc 0.6 ± 0.8; pubescence distance on clypeus very low, sqPDCL 3.49 ± 0.16; torulo-clypeal distance rather small, dClAn/CS 4.21 ± 0.38%. . . . . . Lasius paralienus, Lasius bombycina, Lasius casevitzi, Lasius kritikos


 * Scape without or only single standing setae, nSc 0.6 ± 1.3; pubescence distance on clypeus larger, sqPDCL 4.61 ± 0.41; torulo-clypeal distance rather small, dClAn/CS 4.00 ± 0.39%. . . . . . Lasius obscuratus, Lasius psammophilus, Lasius piliferus, Lasius creticus
 * Scape usually with more standing setae; if not (illyricus), then torulo-clypeal distance and clypeal pubescence distance large: dClAn/CS 5.5 ±0.4%, sqPDCL 5.38 ±0.58 . . . . . 18

18
return to couplet #17
 * Clypeal pubescence distance low (sqPDCL 3.58 ± 0.29), scape rather short (SL/CS 0.979 ± 0.018), pronotal and gular setae rather short (PnHL/CS 0.124 ± 0.008, GuHL/CS 0.092 ± 0.009). Discriminant 21.967 x SL/CS +51.739 x GuHL/CS +52.02 x PnHL/CS +0.731 x sqPDCL –37.01 < 0 [error 0% in 68 nest samples]. Widely distributed from 10°W to 108°E . . . . . Lasius niger


 * Clypeal pubescence distance higher; scape, pronotal and gular setae often longer. Discriminant > 0 [error 0.4% in 230 nest samples] . . . . . 19

19
return to couplet #18
 * Postocular distance large (PoOc/CL 0.247 ± 0.006 ), head and scape short (CL/CW 1.037 ± 0.020, SL/CS 0.965 ± 0.018),pronotal setae long (PnHL/CS 0.164 ±0.008). Discriminant 10.953 x CS +48.26 x CL/CW +15.306 x SL/CS –115.44 x PoOc/CL –29.18 x PnHL/CS –45.905 < 0 [error 0% in 52 nest samples] . . . . . 20
 * Postocular distance smaller, head and scape longer, pronotal setae shorter. Discriminant > 0 [error 0% in 178 nest samples] . . . . . 21

20
return to couplet #19
 * Widely distributed from 10°W to 105°E. Discriminant 1.034 x sqPDCL–0.175 x nSc + 0.511 x nSt + 0.127 x nHT –9.351 < 0 [error 0% in 111 worker individuals] . . . . . Lasius platythorax


 * Endemic of Cyprus. Differing from the former by more dilute pubescence on petiole scale and clypeus (sqPDCL 5.91), smaller postocular distance (0.234), shorter and fewer scape setae (nSc 12.1) combined with extremely long setae on posterior margin of vertex, and the yellowish component of body color. Discriminant > 0 [error 0% in 5 worker individuals] . . . . . Lasius cyperus

21
return to couplet #19
 * Top summits of Mallorca island between 800 and 1400 m. Small (CS 0.69–0.93 mm), number of standing setae on basically all body parts very high (nOcc 21.8, nGen 7.8, nGu 6.4, nSc 29.4, nHT 11.3, nSt 6.2). Terminal segment of maxillary palp rather short and postocular distance rather large (MP6/CS 0.186, PoOc/CL 0.234) . . . . . Lasius balearicus


 * Character combination deviating . . . . . 22

22
return to couplet #21
 * Maltese Islands. Terminal segment of maxillary palp very long (MP6/CS 0.236 ± 0.012), head longer and postocular distance large (CL/CW 1.095 ±0.023, PoOc/CL 0.227 ±0.009), all body parts with very numerous standing setae (nGen 13.9 ± 2.3). Discriminant 45.42 x PoOc/CL –0.183 x CL/CW+55.63 x MP6/CL +0.312 x nGen –25.59 > 0 [error 0% in 4 nest samples] . . . . . Lasius maltaeus
 * Character combination differing. Discriminant < 0 [error 0% in 112 nest samples] . . . . . 23

23
return to couplet #22
 * Cuticular surface of dorsal head and mesosoma completely matt, caused by fine punctures within the meshes of the microreticulum or in interspaces of microrugae. Discriminant 12.08 x CS +38.08 x MP6/CS +15.289 x SL/CS –0.21 x nGu +33.36 x GuHL/CS +0.530 x nSt –38.48 < 0 [error 0% in 20 nest samples]. Iberia and S France . . . . . Lasius cinereus
 * Cuticular surface of dorsal head and mesosoma not completely matt. Discriminant > 0 [error 4.4% in 91 nest samples] . . . . . 24

24
return to couplet #23
 * Eye and clypeal pubescence distance smaller (EYE/CS 0.234 ± 0.006, sqPDCL 4.37 ± 0.39), terminal segment of maxillary palps shorter (MP6/CS 0.208 ± 0.009), scape setae usually more numerous and more erect (nSc 19.5 ±5.7). Discriminant 23.02 x CS +26.17 x SL/CS +175.34 x EYE/CS +0.88 x sqPDCL –0.121 x nSc –0.225 x nGu +0.332 x nGen –94.23 < 0 [error 0% in 47 nest samples]. Iberia, S France, Corsica, Sardinia . . . . . Lasius grandis


 * Eye and clypeal pubescence distance usually larger, terminal segment of maxillary palps longer, scape setae usually less numerous and less erect. Discriminant > 0 [error 0 % in 44 nest samples] . . . . . 25

25
return to couplet #24
 * Dorsum of scape, tibiae and metapleuron with rather many setae (nSc 11.5 ± 7.0, nHT 20.3 ±6.0, nSt 4.2 ± 1.1). Discriminant 0.072 x nSc –0.173 x nHT +0.386 x nSt –32.94 x PoOc –11.20 x CS + 14.05 > 0 [error 2.0% in 152 specimens]. Temperate and submediterranean zone of Europe. Sympatric with L. illyricus in Balkans and Ukraine . . . . . Lasius emarginatus


 * Setae numbers on scape, tibiae and metapleuron lower (nSc 2.5 ± 3.4, nHT 8.7 ±3.3, nSt 2.7 ± 1.1). Discriminant < 0 [error 1.0% in 94 specimens]. Submediterranean and mediterranean zone of the Balkans, Ukraine, southern Caucasus, Asia Minor, north Iran . . . . . Lasius illyricus

26
return to couplet #2
 * Nest sample means. Scape short, SL/CS 0.899 ± 0.013. Torulo-clypeal distance very small, dClAn/CS 3.37 ± 0.33%. Medium-sized and larger workers bicolored: head dark yellowish brown, mesosoma lighter yellowish brown, gaster dark brown. Setae numbers on whole body strongly reduced, setae numbers on gula as large or larger than on postocular head margin (nOcc 3.3 ± 0.8, nGu 3.8 ±0.8. Dorsal and posterior profile of propodeum linear and forming a distinct, obtuse angle. Pubescence on whole body and appendages very smooth, appressed and short. Mean number of mandibular dents only 7.3. Nest means of discriminant 33.83 x CW –30.38 x SL–129.0 x dClAn –0.073 x nOcc +0.138 x nHT +0.103 > 0 [error 0% in 9 nest sample means]. Arboricolous. N Iran. . . . . . Lasius silvaticus


 * Character combination deviating. Discriminant < 0 [error 0% in 479 nest sample means] . . . . . 27

27
return to couplet #26
 * Pubescence on scapes and tibiae (and on whole body) appressed and surfaces as a consequence ideally smooth. Dorsal and posterior profile of propodeum linear and forming a distinct, obtuse angle. Petiole scale in lateral view thin with a sharp dorsal crest. Seta numbers on scape, hind tibia, head and mesosoma very low (nOcc 3.0 ± 1.0, nGen 0.2 ± 0.5, nGu 0.5 ± 0.7, nSc 0.0 ± 0.1, nHT 0.0 ± 0.1, nSt 1.8 ± 1.1). Frontal pubescence short (PLF 23.6 ± 3.0 µm) . . . . . 28


 * Character combination deviating . . . . . 29

28
return to couplet #27
 * Less xerothermous sites with some trees in the highland desert of Iran. Head short (CL/CW 1.028 ± 0.017). Posterior margin of head at least suggested excavated and postocular distance small (PoOc/CL 0.222 ±0.003). Medium-sized (CS 900 ± 31 µm). Scape of medium length (SL/CS 0.974 ± 0.015). Mesosoma usually lighter than head and gaster. . . . . . Lasius excavatus


 * In the reference area widely distributed. Head longer (CL/CW 1.073 ± 0.023). Posterior margin of head not suggested excavated and postocular distance larger (PoOc/CL 0.240 ±0.009). Often smaller (CS 813 ± 67 µm). Scape often longer (SL/CS 0.991 ± 0.032). Head, mesosoma and gaster usually concolorous. . . . . . Lasius lasioides

29
return to couplet #27
 * Setae number on head and hind tibia low (nOcc 6.8 ±3.0, nGen 1.2 ± 1.1, nHT 1.2 ± 1.6), Scape and terminal segment of maxillary palp shorter (SL/CS 0.969 ± 0.028, MP6/CS 0.187 ± 0.016). Discriminant 14.67 x SL–17.85 x CL+26.36 x MP6+0.292 x nHT–0.051 x nOcc+0.062 x nGen–3.273<0 [error 0% in 594 worker individuals] . . . . . 30


 * Setae number on head and hind tibia large (nOcc 17.3 ± 6.1, nGen 9.4 ± 3.9, nHT 21.9 ± 6.6), Scape and terminal segment of maxillary palp longer (SL/CS 1.022 ± 0.025, MP6/CS 0.207 ± 0.016). Discriminant <0 [error 0% in 231 worker individuals] . . . . . 35

30
return to couplet #29
 * Standing setae on area below propodeal spiracle usually absent and setae on postocular head margin only few (nSt 0.34 ± 0,45, nOcc 4.5 ± 1.3). Pronotal setae rather long (PnHL/CS 0.152 ± 0.007). Nest means of individual values of discriminant 0.403 x nSt+0.169 x nHT +0.165 x nOcc+0.056 x nGu–52.07 x PnHL+11.89 x GuHL+4.938 < 0 [error 1.1% in 87 nest samples] . . . . . Lasius alienus


 * At least single standing setae on area below propodeal spiracle present and setae numbers on postocular head margin higher (nSt 3.2 ± 1.4, nOcc 8.0 ± 2.9). Nest means of individual values of discriminant > 0 [error 0.9% in 214 nest samples] . . . . . 31

31
return to couplet #30
 * Terminal segment of maxillary palp and scape shorter, eye smaller. Frontal pubescence longer (PLF> 26 µm. Discriminant 59.35 x MP6+35.04 x SL–44.09 x CL+76.324 x EYE–19.41 < 0 [error 0% in 484 individuals] . . . . . 32


 * Terminal segment of maxillary palp and scape long, eye larger. Frontal pubescence very short (PLF < 23 µm). Discriminant > 0 [error 0% in 6 individuals]. Large (CS >900 µm). In contrast to poorly developed pilosity on other body parts, frontal clypeal margin with a conspicuous row of setae, only moderately decreasing their length laterad. Tunisia. . . . . . Lasius tunisius

32
return to couplet #31
 * Clypeal pubescence distance low and terminal segment of maxillary palps short (sqPDCL 4.10 ± 0.57, MP6/ CS 0.172 ± 0.013). Pronotal setae usually significantly longer than gular setae (PnHL/CS 0.146 ± 0.017, GuHL/CS 0.098 ± 0.017). Number of mandibular dents larger (MaDe 8.33 ± 0.34). Discriminant 0.93 x sqPDCL +24.96 x MP6– 55.28 x PnHL+66.71 x GuHL–0.359 x nHT – 7.77 < 0 [error 1.1% in 181 individuals] . . . . . 33
 * Clypeal pubescence distance higher and terminal segment of maxillary palps longer (sqPDCL 5.45 ± 0.57, MP6/CS 0.198 ± 0.011). Pronotal setae not much longer than gular setae (PnHL/CS, 0.127 ± 0.012, GuHL/CS 0.122 ± 0.018). Number of mandibular dents lower (MaDe 7.50 ± 0.55). Discriminant > 0 [error 0.7% in 298 individuals] . . . . . 34

33
return to couplet #32
 * Clypeal pubescence distance larger (sqPDCL 4.40 ±0.43), terminal segment of maxillary palp longer (MP6/CS 0.177 ±0.011). Discriminant 1.934 x sqPDCL–58.58 x GuHL+51.21 x MP6–0.126 x nOcc–8.288 > 0 [error 3.8% in 132 individuals] N Iran. . . . . . Lasius obscuratus


 * Clypeal pubescence distance small (sqPDCL 3.43 ±0.23), terminal segment of maxillary palp shorter (MP6/CS 0.160 ±0.009). Discriminant <0 [error 0% in 50 individuals]. Potentially occurring in the northeast of the reference area. . . . . . Lasius bombycina

34
return to couplet #32
 * Usually supercolonial. Absolute size small (CS 773 ± 47 µm), number of mandibular dents small (MaDe 7.27 ±0.49), gular setae slightly shorter and less numerous (GuHL/CS 0.117 ± 0.021, nGu 2.5 ± 0.5). Discriminant 17.512 x CL+11.91 x SL+35.919 x GuHL–17.52 x PoOc–93.04 x EYE +0.353 x nGu –0.356 x nOcc+0.004 x nGen–4.599 <0 [error 0% in 56 nest sample means]. . . . . . Lasius neglectus


 * Supercoloniality unknown so far, usually monodomous. Absolute size larger (CS 855 ± 64 µm), number of mandibular dents larger (MaDe 7.68 ±0.54), gular setae slightly longer and more numerous (GuHL/CS 0.125 ±0.014, nGu 3.52 ±1.4). Discriminant >0 [error 1.3% in 77 nest sample means]. . . . . . Lasius turcicus

35
return to couplet #29
 * Israel and Jordan. Scape without or very few standing setae (nSc 1.1 ± 1.2). Number of mandibular dents lower (MaDe 7.67 ± 0.49). Torulo-clypeal distance smaller (dClAn/CS 4.16 ± 0.37%, dClAn 35.9 ± 2.6 µm ). . . . . . Lasius israelicus


 * Scape with numerous standing setae (nSc 19.6 ± 7.7). Number of mandibular dents higher .(MaDe 8.57 ± 0.46). Torulo-clypeal distance larger (dClAn/CS 5.16 ± 0.52%, dClAn 49.5 ± 6.5 µm) . . . . . 36

36
return to couplet #35
 * Humid broad-leafed forest of northern Iran. Clypeal pubescence distance and postocular distance larger, terminal segment of maxillary palps shorter (sqPDCL 5.10 ±0.45, PoOc/CS 0.239 ±0.009, MP6/CS 0.191 ±0.012). Discriminant 1.266 x sqPDCL+38.697 x CW–62.393 x CL+73.402 x PoOc–19.803 x MP6+31.648 x PnHL+1.690 >0 [error 0% in 25 individuals]. . . . . . Lasius persicus
 * Unknown from Iran and Middle East. Clypeal pubescence distance and postocular distance smaller, terminal segment of maxillary palps longer (sqPDCL 4.29 ±0.51, PoOc/CS 0.220 ±0.008, MP6/CS 0.208 ±0.016). Discriminant <0 [error 0% in 198 individuals] . . . . . 37

37
return to couplet #36
 * Introduced to the Canary Islands. Discriminant 82.736 x MP6–52.319 x EYE–28.836 x CL + 38.406 x dClAn+16.587 x GuHL–0.046 x nSc–0.107 x nHT+0.161 x nGen+0.391nSt–0.704 x sqPDCL–1.335 <0 [error 0.8% in 124 individuals]. . . . . . Lasius grandis


 * Canary Islands and N Africa. Discriminant > 0 [error 1.4% in 74 individuals] . . . . . 38

38
return to couplet #37
 * Discriminant 0.148 x nSc+0.113 x nOcc+0.237 x nSt–21.293 x SL+52.263 x PoOc–35.858 x GuHL +8.448 <0 [error 0% in 21 individuals]. . . . . . . Lasius tebessae


 * Discriminant >0 [error 0% in 54 individuals]. . . . . . . Lasius mauretanicus

39
return to couplet #3
 * Gular setae very long (GuHL/CS 0.133 ± 0.011 ). Hind tibia with a moderate number of standing setae (nHT 4.2 ± 4.1). Eye very large (EYE/CS 0.267 ±0.008).West Tianshan between 1400 and 2400 m. . . . . . Lasius uzbeki


 * Character combination strongly deviating. If gular setae are long, then number of setae on hind tibia much larger (nHT 23.2 ± 5.0, flavescens and platythorax) or much smaller (nHT 0.5 ± 0.9, neglectus and obscuratus) . . . . . 40

40
return to couplet #39
 * Less hirsute, nest means of nGen+nGu+nSc+nHT +nSt 25 [error 0% in 195 nest samples ) . . . . . 41


 * More hirsute, nest means of nGen+nGu+nSc+nHT +nSt >25 [error 0% in 260 nest samples) . . . . . 44

41
return to couplet #40
 * Use nest means. Clypeal pubescence distance large (sqPDCL 5.54 ± 0.34). Pronotal setae not much longer than gular setae (PnHL/CS 0.127 ±0.010, GuHL/CS 0.117 ± 0.016). Number of mandibular dents low (MaDe 7.26 ± 0.37). Body size small (CS 773 ± 40 µm). Supercolonial invasive species. . . . . Lasius neglectus


 * Use nest means. Clypeal pubescence distance smaller (sqPDCL 4.37 ± 0.36). Pronotal setae significantly longer than gular setae (PnHL/CS 0.145 ±0.013, GuHL/CS 0.071 ± 0.034). Number of mandibular dents higher (MaDe 8.29 ± 0.37). Body size often larger . . . . . 42

42
return to couplet #41
 * Scape long but terminal segment of maxillary palps short (SL/CS 1.022 ± 0.013, MP6/CS 0.158 ±0.009). Clypeal pubescence more dilute (sqPDCL 5.08 ± 0.47). A number of setae on dorsal plane of scape present but these rather short, many of these protruding close to counting threshold of 20 µm (nSc 4.2 ± 3.7). Discriminant 25.991 x SL–26.223 CW+49.767 x PoOc–61.95 x MP6+0.711 x sqPDCL +0.519 x nSc–7.106 >0 [error 0% in 12 individuals]. Hot steppe of E Kazakhstan. . . . . Lasius brevipalpus


 * Scape shorter and terminal segment of maxillary palps usually longer (SL/CS 0.962 ± 0.021, MP6/CS 0.181±0.012). Clypeal pubescence more dense (sqPDCL 4.22 ± 0.40). Number of setae on dorsal plane of scape lower (nSc 0.34 ± 0.88). Discriminant <0 [error 0.4% in 238 individuals] . . . . . 43

43
return to couplet #42
 * Setae numbers very low, pronotal setae a little longer. Discriminant 0.26 x nOcc+0.35 x nGu+0.662 x nSt–32.945 x PnHL–0.237 GuHL–1.019 < 0 [error 1.1% in 87 nest sample means]. . . . . . Lasius alienus


 * Setae numbers higher but pronotal setae a little shorter. Discriminant > 0 [error 5.2% in 58 nest sample means]. . . . . . Lasius obscuratus

44
return to couplet #40
 * At least mesosoma pale yellowish brown. Discriminant 0.646 x sqPDCL+0.133 x nHT+0.325 x nSt–121.26 x d ClAn– 30.76 x MP6–30.82 x PnHL+4.943 > 0 [error 0% in 42 specimens]. NE Afghanistan, Tian Shan. . . . . . Lasius flavescens


 * Concolorous dark brown, mesosoma occasionally a little lighter with a yellowish color component. Discriminant < 0 [error 0.8% in 263 individuals] . . . . . 45

45
return to couplet #44
 * Nest means of pronotal and gular setae length and clypeal pubescence distance large (PnHL/CS 0.163 ±0.009, GuHL/CS 0.134 ± 0.010, sqPDCL 4.96 ±0.53). Discriminant 5.029 x PnHL+47.808 x GuHL+1.498 x sqPDCL–58.86 EYE –5.818 > 0 [error 0% in 111 individuals] . . . . . Lasius platythorax


 * Nest means of pronotal and gular setae length and clypeal pubescence distance smaller (PnHL/CS 0.124 ±0.008, GuHL/CS 0.092 ± 0.009, sqPDCL 3.54 ±0.30). Discriminant <0 [error 0% in 152 individuals] . . . . . 46

46
return to couplet #45
 * Southern parts of East Siberia between 106 and 134°E (Ussuri). Differs from niger by a combination of more numerous metapleural setae, less numerous scape setae and less dense clypeal pubescence. Discriminant 4.378 x CW –1.640 x sqPDCL+0.164 x nSc –0.349 x nSt+3.458 < 0 [error 0% in 7 workers]. . . . . . Lasius vostochni


 * From 10°W to 108°E. Discriminant > 0 [error 0% in 155 workers] . . . . . Lasius niger

47
return to couplet #4
 * Whole body very hirsute (nGen 20.5 ± 3.3, nGu 19.8 ±5.3, nHT 32.1 ±3.6). Gular setae very long (GuHL/CS 0.154 ± 0.010). Scape long (SL/CS 1.018 ±0.022). SW flank of Himalayas above 2000 m. . . . . . Lasius hirsutus


 * Much less hirsute (nGen < 12.5, nGu < 14). Gular setae usually shorter . . . . . 48

48
return to couplet #47
 * Very large body size (CS 1153 ± 108 µm). Clypeal pubescence distance very large (sqPDCL 6.85 ± 0.88). Paramedian pubescence hairs on posterior dorsum of gaster tergites directed caudomediad or even mediad. Pronotal setae short (PnHL/CS 0.119 ±0.011). Number of mandibular dents low (MaDe 7.22 +0.67M). Southern flank of Himalayas between 1700 and 3100 m. . . . . . Lasius magnus
 * Character combination strongly deviating . . . . . 49

49
return to couplet #48
 * Setae numbers on whole body strongly reduced (nOcc + nGen = 1.2 ± 0.9). Pubescence on whole body and appendages very smooth, appressed and short. Dorsal and posterior profile of propodeum linear and forming a distinct, obtuse angle. Number of mandibular dents low (7.25 ± 0.49). Rather large (CS 1003 ± 82 µm). Scape short (SL/CS 0.900 ± 0.024). Pronotal setae short, PnHL/CS 0.108 ± 0.011. SW flank of the Himalayas at elevations between 2300 and 2800 m . . . . . Lasius himalayanus


 * Character combination strongly deviating . . . . . 50

50
return to couplet #49
 * Terminal segment of maxillary palp and scape long (MP6/CS 0.201 ±0.014, SL/CS 1.021 ±0.025). Clypeal pubescence distance large (sqPDCL 5.05 ± 0.47). Discriminant 41.753 x MP6+13.0 x SL +1.481 x sqPD CL–0.244 x nSt–45.071 x PnHL– 19.61 >0 [ error 2.9% in 68 individuals]. Eastern margin of Tibetan Plateau. . . . . . Lasius longipalpus


 * Terminal segment of maxillary palp and scape shorter. Clypeal pubescence distance often smaller. Discriminant < 0 [ error 1.9% in 159 individuals] . . . . . 51

51
return to couplet #50
 * Southern flank of Himalayas . . . . . 52
 * Tibetan Plateau . . . . . 53

52
return to couplet #51
 * Eye small (EYE/CS 0.221 ±0.008). Number of genal and gular setae lower (nGen 2.3 ± 1.4, nGu 3.1 ± 1.4). Discriminant 199.63 x EYE–56.58 x CL+108.61 x PnHL–4.236 < 0 [error 0% in 13 individuals]. . . . . . Lasius lawarai


 * Eye larger (EYE/CS 0.245 ±0.006). Number of genal and gular setae larger (nGen 6.2 ± 2.6, nGu 7.9 ± 3.3). Discriminant > 0 [error 0% in 12 individuals]. . . . . . Lasius wittmeri

53
return to couplet #51
 * Standing setae on extensor profile of hind tibia more numerous and extending over the whole profile (nHT 10.8 ± 0.9). . . . . . Lasius schaeferi


 * Setae on extensor profile of hind tibia much fewer and concentrated to the proximal half of profile (nHT 2.5 ± 2.0). . . . . . Lasius obscuratus

54
return to couplet #5
 * Terminal segment of maxillary palp and scape extremely long (MP6/CS 0.267 ± 0.008, SL/CS 1.131 ± 0.031). Discriminant 34.93 x SL–23.33 x CW–15.45 > 0 [error 0% in 17 specimens]. Japan. . . . . . Lasius productus


 * Terminal segment of maxillary palp and scape much shorter. Discriminant < 0 [error 0% in 375 specimens] . . . . . 55

55
return to couplet #54
 * Mesosoma with very flat propodeal dome and convex to angulate-convex posterior propodeal slope that is transversally carinulate. Petiole scale in lateral view thick, low and with a blunt apex; in anterior view rather narrow, with convex to nearly straight subparallel sides. Whole body very hirsute (nSt 12.2 ±2.2). Discriminant 0.464 x nSt–15.38 x CL+20.00 x SL–23.77 x PoOc–23.98 x GuHL–0.727 > 0 [error 0% in 12 individuals]. May form supercolonies. Japan. . . . . . Lasius sakagamii
 * Mesosoma and petiole of differing morphology. Number of standing setae on area below propodeal spiracle lower (nSt 3.3 ± 2.5). Discriminant < 0 [error 0.7% in 269 individuals] . . . . . 56

56
return to couplet #55
 * Microsculpture between the frontal carinae rather deep, with the margins of meshes developed as elevated ridges and their inner part developed as a rather deep foveola which centrally carries the base of a pubescence hair; short fragments of microcarinulae are irregularly dispersed over the surface. Frontal pubescence short (PLF 25.4 ± 1.9 µm). Body size small (CS 819 ± 41 µm). Head elongated (CL/CW 1.104 ± 0.015). Scape short (SL/CS 0.973 ± 0.023). North Korea. . . . . . Lasius koreanus


 * Character combination different . . . . . 57

57
return to couplet #56
 * Small (CS 826 ± 49 µm). Number of setae on surface below propodeal spiracle larger than number of genal setae (nSt 6.8 ± 1.7, nGen 4.7 ± 2.7). Clypeal pubescence distance low (sqPDCL 3.97 ±0.42). Scape and pronotal setae rather short (SL/CS 0.976 ±0.008, PnHL/CS 0.128 ± 0.005). Reddish color components absent. Ussuri region. . . . . . Lasius vostochni


 * Character combination strongly different . . . . . 58

58
return to couplet #57
 * Clypeal pubescence distance large (sqPDCL 5.78 ±0.27). Terminal segment of maxillary palp short (MP6/CS 0.176 ±0.007). Pronotal setae long (PnHL/CS 0.160 ±0.008). High mountain range of Sichuan 3000–3500 m. Discriminant 1.614 x sqPDCL+0.229 x nSt–43.39 x MP6+23.468 x PnHL –5.68> 0 [error 0% in 12 individuals] . . . . . Lasius kabaki


 * Clypeal pubescence distance frequently smaller, terminal segment of maxillary palp frequently longer. Discriminant < 0 [error 0% in 243 individuals] . . . . . 59

59
return to couplet #58
 * Setae number on whole body low (nHT 4.2 ±4.1, nSt 0.4 ±0.5). Eye large (EYE/CS 0.251 ±0.007). Clypeal pubescence distance large (sqPDCL 5.05 ±0.47). Torulo-clypeal distance low (dClAn/CS 4.47 ±0.37%). Discriminant 0.089 x nHT–1.095 x sqPDCL–82.69 x EYE+70.50 x dClAn+17.58 x PnHL+5.123 x CW +10.933 < 0 [error 0% in 68 individuals]. . . . . . Lasius longipalpus


 * Setae numbers and torulo-clypeal distance larger, clypeal pubescence distance lower and eye larger. Discriminant > 0 [error 3.4% in 175 individuals] . . . . . 60

60
return to couplet #59
 * Sculpture on metapleuron and lower propodeum with regular, slightly curved and dense longitudinal carinulae and very delicate linear microstructures within the meshes of the microreticulum. This produces a matt overall surface appearance at lower magnifications. Chinese regions Yunnan, Sichuan, Shaanxi and Taiwan . . . . . 61
 * Metapleuron and lower propodeum without or only very few suggested carinulae; usually only with a very delicate microreticulum and overall more shining . . . . . 62

61
return to couplet #60
 * Scape longer (SL/CS 1.010 ±0.027). Clypeal pubescence distance and torulo-clypeal distance larger (sqPDCL 4.61 ±0.49, dClAn 5.26 ± 0.52). Setae longer and more numerous (PnHL/CS 0.156 ± 0.019, GuHL/CS 0.101 ± 0.014, nSc 27.6 ± 7.2, nGu 6.9 ± 1.5). Discriminant 0.353 x nGu–64.932 x EYE+0.138 x nSc+9.961 >0 [error 0% in 34 individuals]. . . . . . Lasius coloratus


 * Scape shorter (SL/CS 0.976 ±0.030). Clypeal pubescence distance and torulo-clypeal distance smaller (sqPDCL 4.14 ± 0.54, dClAn 4.94 ± 0.54). Setae shorter and less numerous (PnHL/CS 0.135 ± 0.010, GuHL/CS 0.083 ± 0.018, nSc 11.2 ± 6.9, nGu 3.4 ± 1.8). Discriminant < 0 [error 0% in 29 individuals]. . . . . . Lasius sichuense

62
return to couplet #60
 * Head capsule homogenously yellowish brown. Head short (CL/CW 1.028 ± 0.013) and usually with concave posterior margin. Scape rather short (SL/CS 0.958 ± 0.016). Eye rather small (EYE/CS 0.224 ± 0.007). Petiole sides more convex. Shady deciduous woodland in Japan, Korea, Kuriles. . . . . Lasius hayashi


 * Head capsule not homogenously yellowish brown; vertex dark or blackish brown; if reddish or yellowish pigmentation is present then restricted to clypeus. Head longer (CL/CW 1.062 ± 0.026) and without concave posterior margin. Scape longer (SL/CS 1.002 ± 0.028). Eye larger (EYE/CS 0.238 ± 0.009). Petiole sides less convex . . . . . 63

63
return to couplet #62
 * Number of setae on whole body less large (nGu 9.0 ±3.0, nSt 3.1 ±1.2). Discriminant 0.21 x nGu+0.739 x sqPDCL+ 0.528 x nSt–37.83 x EYE+0.133 < 0 [error 0% in 59 individuals]. NE China, Korea, Russian Far East, Japan . . . . . Lasius japonicus


 * Number of setae twice as large (nGu 18.7 ±4.6, nSt 6.2 ±1.5). Discriminant > 0 [error 4.9% in 41 individuals, 0% in 13 sample means]. E Tibet to NE China. . . . . . Lasius chinensis