Key to genera of Zigrasimeciinae

Based on: [[Media:Cao, H., Boudinot, B.E. et al. 2020. Cretaceous ants shed new light on the origins of worker polymorphism (10.1007@s11427-019-1617-4).pdf|Cao, H., Boudinot, B.E., Shih, C., Ren, D., Gao, T. 2020. Cretaceous ants shed new light on the origins of worker polymorphism. Science China Life Science 63, 1-4]].

This key is for determining worker fossil-specimens of Zigrasimeciinae to genus.

1

 * Head wedge-shaped, not omega-shaped (Ω), and not massive relative to mesosoma. Anterior clypeal margin evenly convex across its length between the anterolateral clypeal lobes. Face with shield-like dorsal thickening posterior to antennal scrobes. Face between antennae with several long, erect setae. Abdominal segment III (= metasomal II, gastral I) apparently without massive, longitudinal, keel-like prora . . . . . †''Boltonimecia


 * Head omega-shaped (Ω), not wedge-shaped, and massive relative to mesosoma Anterior clypeal margin evenly concave across its length between the anterolateral clypeal lobes. Face without shield-like dorsal thickening posterior to antennal scrobes. Face between antennae without several long, erect setae. Abdominal segment III with massive, longitudinal, keel-like prora. . . . . . 2

2

 * Body small, total length < 5mm. Mesosoma compact, with dorsal surface forming a single hump in profile view (a lumpy or even convexity). Promesonotal articulation completely fused. Flagellum relatively compact; fifth through terminal antennomeres with length < 3 × width. Masticatory margin of mandible with two very small denticles, or unidentate. Basal mandibular margin curving broadly to apical tooth, hence basal and masticatory margins indistinct. Median portion of clypeus, between lateral lobes, without traction setae except for even row along anterior clypeal margin. Labral traction setae aggressive and nail-shaped, longer than those of the anterior clypeal margin. Maxillary palps relatively short, palp length less than length of scape. Ocelli absent. Petiolar node high and squamiform, with short, poorly defined anterior peduncle. Abdominal segment IV without transverse sulcus defining pre- and postsclerites of tergum and sternum . . . . . †''Zigrasimecia


 * Body large, total length > 10mm. Mesosoma comparatively elongate, with dorsal surface forming, approximately, a pair of humps in profile view (with convex mesonotum distinctly offset from propodeum). Promesonotal articulation well-developed, mobile. Flagellum relatively elongate; fifth through terminal antennomeres with length ≥ 4 × width. Masticatory margin of mandible clearly bidentate, with two long, acute teeth. Basal mandibular margin obliquely meeting base of basal / subapical tooth, hence basal and masticatory margins clearly distinct. Median portion of clypeus, between lateral lobes, with traction setae in irregular rows in addition to even row along anterior margin. Labral traction setae relatively fine, approximately equal in size to those of the anterior clypeal margin. Maxillary palps relatively long, palp length greater than length of scape. Ocelli present. Petiolar node low and convex, with an apparently elongate anterior peduncle. Abdominal segment IV with transverse sulci (= cinctus) defining pre- and postsclerites of tergum and sternum . . . . . †''Protozigrasimecia