Key to Myrmoteras

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This worker and queen key is based on: Moffett, M.W. 1985b. Revision of the genus Myrmoteras (Hymenoptera: Formicidae). Bulletin of the Museum of Comparative Zoology. 151:1-53. PDF. This key is dated. Many new species have been described after this key was published.

Moffett partitioned what was, at the time of his publication, the known species into subgenera and species groups. Many new species have been described since then, and the genus has more than doubled in the number of species. Authors describing new species after 1985 have mostly ignored assigning species to these subgenera and groups.

Noted with the key: The workers and queens of those Myrmoteras species in which both castes have been described are very similar except for characters on the trunk. In the key that follows I make the assumption that this holds true for species in which one or the other caste remains undescribed.

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1

  • A pair of long trigger hairs originates from middle of labrum; surface of labrum visible in full face view conspicuously projecting, more or less triangular; frontal sulcus very feeble or absent (subgenus Myrmoteras) . . . . . 2
  • Without trigger hairs; surface of labrum visible in full face view rounded or truncated, not strongly projecting; frontal sulcus on head usually prominent (subgenus Myagroteras) . . . . . 8

2

return to couplet #1

  • Mandibles longer than head (MI > 110); cephalic index < 105; from Southeast Asia (binghami group) . . . . . 3
  • Mandibles as long as head or shorter (MI < 105); head wider (cephalic index > 105); from India (ceylonicum group) . . . . . 6

3

return to couplet #2

  • In addition to scattered long hairs, pronotum and dorsum of head with numerous very short, fine hairs, and smooth with minute shallow punctures; mandibles lacking denticles except for apical pair . . . . . Myrmoteras binghamii
  • Without short fine pilosity on head and pronotum; sculpture not as described; with one or more denticles on mandible in addition to apical pair . . . . . 4

4

return to couplet #3

  • Head and pronotum smooth or virtually smooth, with at most traces of granulate sculpture . . . . . 5

5

return to couplet #4

  • Head and trunk shining and smooth except for very poorly defined longitudinal rugae on mesothorax in worker, and with very sparse long hairs . . . . . Myrmoteras mjoebergi
  • Head and trunk much less strongly shining, virtually smooth except for mesothorax of workers, which is more lustrous and has conspicuous narrow irregular rugae; long hairs moderately numerous . . . . . Myrmoteras iriodum

6

return to couplet #2

7

return to couplet #6

  • Dorsum of head strongly granulo-rugose scabrum Dorsum of head evenly granulate . . . . . Myrmoteras ceylonicum

8

return to couplet #1 Dorsum of head and pronotum granulate or rugose . . . . . 9

  • Dorsum of head and disc of pronotum smooth (except for very feeble rugae on frons of some species) . . . . . 15

9

return to couplet #8

  • Head feebly sculptured; petiole strongly convex beneath node; with a relatively conspicuous ruga which originates anterior to base of each metathoracic tubercle and extends forward across mesothorax; maxillary palps with five segments or fewer (donisthorpei group) . . . . . 13
  • Head strongly sculptured; petiole feebly convex or concave beneath node; lacking conspicuous narrow ruga described above; maxillary palps with six segments (williamsi group) . . . . . 10

10

return to couplet #9

  • Evenly granulate all over dorsal and lateral surfaces of head and trunk; in workers mesonotum greatly depressed relative to the pronotum and propodeum, which are very high and rounded; from the Philippines . . . . . Myrmoteras williamsi
  • Sculpture different from above; occiput, surface of head beneath eyes, and mesothorax without regular granulate sculpture. In workers pronotum and propodeum not strongly convex, mesonotum depressed, but not strongly so; from Sulawesi . . . . . 11

11

return to couplet #10 Propodeum of worker moderately convex; head and pronotum with narrow longitudinal rugae, without granulate sculpture on clypeus . . . . . Myrmoteras toro

  • Propodeum of worker conspicuously flattened dorsally; clypeus granulate . . . . . 12

12

return to couplet #11

  • Head longitudinally rugose, except for clypeus and frontal area, which are evenly granulate . . . . . Myrmoteras wolasi
  • Head entirely granulate dorsally, except for frontal area, which is smooth and shining . . . . . Myrmoteras morowali

13

return to couplet #9

14

return to couplet #13

  • In worker, propodeum and pronotum high, convex; mesonotum relatively depressed (queen not known) . . . . . Myrmoteras karnyi
  • Worker with propodeum and pronotum not high and strongly convex, so that summit of propodeum is about level with mesonotum . . . . . Myrmoteras donisthorpei

15

return to couplet #8

16

return to couplet #15

  • Wide sulcus between clypeus and head capsule; shallow grooves proceed longitudinally dorsad on mandibles for most of the length of the shafts . . . . . Myrmoteras diastematum
  • Very narrow gap between clypeus and head capsule; grooves on mandibles usually absent or poorly developed . . . . . 17

17

return to couplet #16

  • Mandible with two apical denticles, smallest tiny but readily visible; middle tibiae moderately dilated, 16 to 20% as wide as long; propodeum dorsally flattened; from the Malay Archipelago . . . . . Myrmoteras bakeri
  • Mandible with single apical denticle; middle tibiae thick (26 to 27% as wide as long); propodeum evenly convex; from southern India . . . . . Myrmoteras indicum