Key to Haidomyrmecinae genera and species

This worker key is based on: [[Media:Perrichot, V., Wang, B. et al. 2020. New remarkable hell ants (10.1016@j.cretres.2020.104381).pdf|Perrichot, V., Wang, B., Barden, P. 2020. New remarkable hell ants (Formicidae: Haidomyrmecinae stat. nov.) from mid-Cretaceous amber of northern Myanmar. Cretaceous Research 109, 104381]].

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Haidomyrmecinae

1

 * Clypeus posteriorly with a slightly elevated setose lobe positioned just ventrad or between antennal insertion . . . . . 2
 * Clypeus posteriorly projecting forward into a cephalic horn arising ventrad, between, or dorsad antennal insertion . . . . . 5

2
return to couplet #1
 * Antenna compact, with flagellomeres short (<2 x as long as broad); first flagellomere as long as longer than second one . . . . . 3
 * Antenna elongate, with flagellomeres long (>2 x as long as broad); first flagellomere shorter than second one . . . . . 4

3
return to couplet #2
 * All flagellomeres nearly of same length; clypeal setose pad positioned anterior to antennal insertion; ocelli present; two metatibial spurs . . . . . Haidomyrmodes mammuthus
 * Flagellomere I longest of basal four flagellar articles; clypeal setose pad positioned slightly posterior to antennal insertion; ocelli absent; one metatibial spur . . . . . Haidoterminus cippus

4
return to couplet #2
 * Flagellomere II longest of basal three flagellar articles; frontal triangle moderately elevated; vertex, ventral margin of mandibles, and antennomeres densely setose; mandibles with medioventral blade bearing at least one large apical tooth, with tip of apical portion tapered to acute point, smooth; ocelli reduced to pit-like traces; subpetiolar process present. . . . . Haidomyrmex cerberus
 * Flagellomere II longest; frontal triangle strongly elevated; vertex, ventral margin of mandibles, and antennomeres mostly glabrous; mandibles with medioventral blades asymmetrical, left one bearing three small teeth, right one bearing two larger teeth; tip of apical portion tapered to sharp point, smooth; ocelli and subpetiolar process absent . . . . . Haidomyrmex scimitarus
 * Apical flagellomere longest; frontal triangle feebly elevated; vertex, ventral margin of mandibles, and antennomeres mostly glabrous; mandibles with medioventral blade bearing a single apical tooth, with tip of apical portion tapered to blunt point and minutely serrate; ocelli absent; subpetiolar process a minute tooth . . . . . Haidomyrmex zigrasi

5
return to couplet #1
 * Posterior clypeal projection not furrowed ventrally (¼ without lateral ridges), forming a pointed or paddle-shaped horn; long, paired trigger setae present, arising from base of clypeal process or ventral surface of apical setose pad; peg-like denticles absent or present only on ventral setose pad; labrum not obviously exposed . . . . . 6
 * Posterior clypeal projection distinctly furrowed ventrally, with lateral ridges originating above mandible insertions, and converging posteriorly to form the lateral margins of a horn; paired trigger setae absent; peg-like denticles present along lateral clypeal ridges, or on labrum, or both; labrum exposed ventrally of horn . . . . . 9

6
return to couplet #5
 * Clypeal horn a small triangulate cuticular elevation; one pair of trigger setae positioned at base of horn; compound eyes small (OI 24); ocelli absent; flagellomeres IIeX compact, barely longer than wide . . . . . Protoceratomyrmex revelatus
 * Clypeal horn paddle-shaped, comprising basal stalk and apical setose pad; compound eyes small to large (OI 26e39); ocelli present; flagellomeres IIeX elongate, distinctly longer than wide . . . . . 7

7
return to couplet #6
 * Clypeal horn and curved apical portion of mandibles extremely long, reaching high above vertex (HoI 140; MDI 130); peg-like denticles present on ventral setose pad; 2 pairs of trigger setae positioned at base of horn's stalk; frontal triangle fused with horn, not distinguishable; gastral constriction between AIII and AIV at most faintly impressed . . . . . Ceratomyrmex ellenbergeri
 * Clypeal horn and curved apical portion of mandibles distinctly shorter, not reaching above vertex (MDI 70); peg-like denticles absent; 1 pair of trigger setae positioned on ventral surface of apical setose pad; frontal triangle connecting with horn by cleared cuticular membrane; gastral constriction between AIII and AIV deeply impressed . . . . . 8

8
return to couplet #7
 * Clypeal horn reduced (HoI 25e35), with stalk almost indistinct and apical setose pad hexagonal, as broad as (worker) or smaller than (gyne) compound eye's length (EL); mandibles with medioventral blade bearing two teeth and, in worker, surpassing midlength of apical curved portion; compound eyes small in worker (OI 25); propodeum higher than long . . . . . Linguamyrmex brevicornis
 * Clypeal horn conspicuous (HoI 56), with stalk short, not surpassing frontal triangle in dorsal view, and apical setose pad circular, broader than EL in worker; mandibles with medioventral blade smooth and not reaching to midlength of apical curved portion; compound eyes large in worker (OI 39); propodeum longer than high . . . . . Linguamyrmex vladi
 * Clypeal horn enormous (HoI 95e105), with apical setose pad circular, nearly as broad as head in dorsal view, and stalk about as long as pad; mandibles with medioventral blade smooth and, in worker, not reaching to midlength of apical curved portion; compound eyes large in worker (OI 44); propodeum longer than high . . . . . Linguamyrmex rhinocerus

9
return to couplet #5
 * Body and legs robust; mandibles scythe-shaped, with medioventral triangular blade present; in frontal view, the outline of apical portion of mandibles aligned with clypeal lateral ridges; clypeal horn gradually tapering to rounded tip; genae elongate, the mandibles inserted far from compound eyes . . . . . 10
 * Body and legs gracile; mandibles sickle-shaped, with medioventral triangular blade absent; clypeal horn and labrum protruding horizontally, their tip with a deep median notch; apical lateral margins of horn bilobed; genae strongly reduced, the mandibles inserted close to compound eyes . . . . . Aquilomyrmex huangi

10
return to couplet #9
 * Mandibles with apical curved portion much longer than basal portion and entirely serrate along dorsal margin; with medioventral blade an isosceles tooth not projecting beyond mandibular elbow (labrum and clypeal surface below horn entirely exposed when mandibles closed); ocelli large, antennomeres and compound eyes distinctly elongate . . . . . Dhagnathos autokrator
 * Mandibles with apical curved portion not distinctly longer than basal portion; with medioventral blade a large triangle gradually tapering to tip of apical portion (labrum and clypeal surface below horn entirely concealed when mandibles closed); dorsal margin of mandibles serrate along distal half of medioventral projection, bidentate apically; ocelli, antennomeres, and compound eyes more reduced . . . . . Chonidris insolita