Key to Dacetini 2007

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This worker key is based on: Baroni Urbani, C. & De Andrade, M.L. 2007. The ant tribe Dacetini: limits and constituent genera, with descriptions of new species. Annali del Museo Civico di Storia Naturale “G. Doria”. 99:1-191.

They note about their key: The key to the Dacetini genera by Bolton (2000), in spite of the facilitation due to the exclusion of Basiceros and some small genera, contains a number of invalid statements if one broadens the number of taxa examined. For instance, presence or absence of the limbus as used in the first couplet to separate his “strumigenyte genera” from the other dacetines does not hold if Phalacromyrmex and Basiceros are also considered. Several elements of Bolton's (2000) key cannot be used in our context. On the other hand, uncertainties are implicitly recognized also by Bolton while qualifying characters as “extremely rare” or “extremely rarely absent”. Several other characters were already shown during the present study to hold for a majority of species only.

The following key should be of broader validity due to the more rigorous and operational generic definitions adopted for the present study. Although imprecise, the key still contains also some probabilistic statements similar to those employed by Bolton since they may facilitate identification in a number of cases.


This key was constructed when Dacetini was considered to be a valid tribe within the subfamily Myrmicinae. Our understanding of the higher level relationships within Myrmicinae have changed (Ward et al. 2015) and all of the genera in this key are now considered to belong to the large tribe Attini. A group of genera within this tribe, the Daceton genus-group, contains most of the genera of the former Dacetini. One exceptions collectively includes a large number of species. The species rich Strumigenys is no longer considered to be part of the Daceton genus-group. This genus is included in the key below. The genus Lenomyrmex is also now added to the Daceton genus-group. This genus is not included in this key (see the introduction to the Bolton (2000) Dacetini key for further discussion).

1

  • Eyes present and posterior to the antennal scrobe. Petiolar tergum and sternum differently shaped. No specialized large mechanoreceptors on the mouthparts. Neotropical . . . . . Tatuidris
  • Eyes generally present and never posterior to the antennal scrobe, or, very rarely (Strumigenys inopinata) absent. Petiolar tergum and sternum equally convex. Mouthparts nearly always with some large, specialized mechanoreceptors (exceptions a few Strumigenys and Epopostruma species) . . . . . 2

2

return to couplet #1

  • Pretergite of first gastral segment sub sessile to sessile. Base of scape bent at right angle near the base. First gastral segment nearly always sculptured. Neotropical, Indomalayan, Australian . . . . . Basiceros
  • Pretergite of first gastral segment neck like. Base of scape straight or at least complanar with the basal condyle, rarely bent at right angle. First gastral segment almost never sculptured (exceptions, a few Strumigenys species) . . . . . 3

3

return to couplet #2

  • Mandibles with alternating small and large teeth. Scape clavate. Basimandibular process absent. . . . . . 4
  • Mandibular dentition different, or, if alternating large and small teeth present, the scape is never clavate. Basimandibular process nearly always present . . . . . 6

4

return to couplet #3

  • Katepisternal oblique groove deeply impressed. Vertexal angles pointed backwards, mesosoma dorsally marginate. Malaysia . . . . . Ishakidris

5

return to couplet #4

  • Mesosternal hair beds hypertrophied. Long and flexuous pilosity on the whole body. Head sculpture deeply reticulate. Antennae eight jointed. Madagascar . . . . . Pilotrochus
  • Mesopleurae obliquely costulate. Pilosity rare and short. Frontal lobes strongly developed. Antennae eleven jointed. Brazil . . . . . Phalacromyrmex

6

return to couplet #3

  • Eyes ventral or, very rarely, absent. Labial palps one jointed. Basal process of the mandibles never hypertrophied. World tropics and temperate areas . . . . . Strumigenys
  • Eyes always present, dorsal or lateral. Labial palps generally two or three jointed, if one jointed, the basal process of the mandibles is hypertrophied . . . . . 7

7

return to couplet #6

  • Basimandibular process hypertrophic and bifurcated at the apex, situated below the labrum with closed mandibles. Maxillary palps absent. Neotropical . . . . . Acanthognathus
  • Basimandibular process normally developed, situated above the labrum with closed mandibles. Maxillary palps present . . . . . 8

8

return to couplet #7

  • Second funicular joint hypertrophic, longer than the last segment. Indomalayan and Australian . . . . . Orectognathus
  • Second funicular joint normally developed, shorter than the last segment . . . . . 9

9

return to couplet #8

  • Antennae eleven jointed. Eyes dorsal. Occipital foramen dorsal. Neotropical . . . . . Daceton
  • Antennae four to eight jointed. Eyes dorsolateral. Occipital foramen posterior . . . . . 10

10

return to couplet #9

  • Large pre-genal cavity visible in profile behind the base of the mandibles. Palp formula 3,2. Labrum not capable of full reflexion over the buccal cavity. Antennal scrobes absent. Ethiopian . . . . . Microdaceton
  • Gap between mandibles and head capsule reduced in profile. Palp formula 5,3. Labrum capable of full reflexion over the buccal cavity. Antennal scrobes below the eyes. Australian . . . . . Epopostruma

References

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