Key to the Lasius of the Indian Himalayas

This worker key is based on Bharti, H.; Gul, I. 2013. Lasius elevatus, a new ant species of the subgenus Cautolasius (Hymenoptera: Formicidae) from the Indian Himalayas. Asian Myrmecology 5:53-58.

1

 * Eyes small, eye length one-sixth or less the length of lateral cephalic margin; colour yellow to yellowish brown . . . . . 2
 * Eyes larger, eye length more than one-fifth the length of lateral cephalic margin; colour pale brown to black . . . . . 7

2
return to couplet #1
 * Gena curving inwards below eyes to close-set mandibular insertions; petiole low and thick, subconical in side view with rounded dorsal crest; queen exceedingly small (HW 760-790 μm) . . . . . Lasius carniolicus
 * Genal margins straight or curving gently to wide-set mandibular insertions; petiole tapering dorsally in side view; queen larger in size (HW > 790 μm) . . . . . 3

3
return to couplet #2
 * Petiole, in frontal view, with deeply emarginate dorsal crest . . . . . Lasius bicornis
 * Petiole, in frontal view, with unbroken dorsal crest or with shallow emargination . . . . . 4

4
return to couplet #3
 * Large species; head width 950-1250 μm . . . . . 5
 * smaller species; head width 670-860 μm . . . . . 6

5
return to couplet #4
 * Petiole in front view high, conical, tapering to narrow rounded dorsal crest . . . . . Lasius mikir
 * Petiole in front view, with broadly rounded sides, dorsal crest convex, occasionally with slight median incision; petiole and basal face of gaster with very long curved hairs; tibiae without projecting hairs; occipital hairs restricted to median area . . . . . Lasius crinitus

6
return to couplet #4
 * Petiole node in frontal view with feebly convex sides, narrowing towards the crest and somewhat rounded dorsal crest; eye smaller (EL <90 μm) . . . . . Lasius elevatus
 * Petiole in frontal view with sides not narrowing towards the crest and a straight dorsal crest; eye larger (EL>120 μm) . . . . . Lasius alienoflavus

7
return to couplet #1
 * Combined total number of hairs on hind tibia plus hairs on scape not exceeding 8 . . . . . 8
 * Combined total number of hairs on hind tibia plus hairs on scape always greater than 8 . . . . . 11

8
return to couplet #7
 * Dorsum of scape with perfectly appressed pubescence; masticatory margin of mandibles usually with 7 or fewer teeth; pubescence on all surfaces of body perfectly appressed or decumbent, giving smooth appearance . . . . . 9
 * Dorsum of scape with pubescence hairs projecting ≤ 5 μm from cuticular surface; masticatory margin of mandibles usually with 8 or more teeth; pubescence on surface of body not perfectly appressed or decumbent, therefore rough in appearance . . . . . 10

9
return to couplet #8
 * Size smaller; head and mesosoma yellowish brown to pale brown, gaster dark brown; SL/HL <0.86; CI<104 . . . . . Lasius brunneus
 * Size larger; head, mesosoma and gaster brown to dark brown; SL/HL >0.87; CI>104 . . . . . Lasius himalayanus

10
return to couplet #8
 * Scape shorter, SL/HL < 0.890; mesopropodeal depression deep, mesonotum high and vaulted; mesosoma yellowish brown . . . . . Lasius breviscapus
 * Scape longer, SL/HL > 0.890; mesopropodeal depression shallow; the propodeal dome is more conical; the species is relatively concolorous, with the mesosoma dirty brown . . . . . Lasius alienus

11
return to couplet #7
 * Paramedian pubescence hairs on posterior dorsum of gastral tergites directed caudomedially or medially; clypeal pubescence extremely sparse (PDCL > 30); broad and massive petiolar scale . . . . . Lasius magnus
 * Pubescence hairs on whole surface of gastral tergites directed strictly longitudinally; clypeal pubescence much denser (PDCL < 30); petiolar scale comparatively smaller . . . . . 12

12
return to couplet #11
 * PDCL < 18; propodeal dome high and hemispheric to conic-hemispheric; posteroventral sides of pronotum more-or-less pubescent, somewhat dull; colour of head and gaster blackish brown, mesosoma dark brown to medium brown . . . . . Lasius niger
 * PDCL > 18; propodeal dome flatter; posteroventral sides of pronotum without pubescence, brilliantly shining; whole body concolorous yellowish to reddish brown . . . . . Lasius wittmeri