Zigrasimecia

A genus of iron maiden ants, a Formicidae stem lineage with bizarre mouthpart morphology.

Distribution
This taxon is known from.

Discussion
Cao et al. (2020) - Zigrasimecia was erected based on a single piece of Burmese (Myanmar) amber which contains a dealate gyne, designated as Zigrasimecia tonsora. The unique type specimen was only partially preserved, missing part of petiole and gaster, and details of the mouthparts were difficult to ascertain. The second species of this genus, Zigrasimecia ferox, was described based on the worker caste. Numerous features are shared between Z. ferox and Z. tonsora, although Perrichot (2014: p. 168) adduced a list of specific features which distinguish the two species. The unique morphology of Zigrasimecia is nowhere fully paralleled in the extant Formicidae, and is thought to represent habits that became extinct with the lineage (Barden & Grimaldi 2013).

Conclusion: Our study of Zigrasimecia hoelldobleri and Protozigrasimecia chauli reveals both morphological and functional diversity in stem Formicidae. The holotype of Z. hoelldobleri is shockingly well-preserved for light microscopy, and has yielded insights into mandibular, labral, and clypeal function of the Burmese Zigrasimeciini. Based on the interpreted mouthpart function, we colloquially recognize Zigrasimecia and Protozigrasimecia as the iron maiden ants. Among the Zigrasimeciini, we severely doubt that the monotypic genus Boltonimecia from Canadian amber is correct to include, and recommend revised study. In summary, there are ample opportunities for discovery, characterization, and evolutionary analyses of the Zigrasimeciini, which we have attempted to facilitate through the present work.

Castes
There is a diagnosis of this alate but it has not been assigned to a species.

Nomenclature
Taxonomic history
 * † ZIGRASIMECIA [†Zigrasimeciinae]
 * †Zigrasimecia Barden & Grimaldi, 2013: 407. Type-species: †Zigrasimecia tonsora, by original designation.
 * †Zigrasimecia in †Sphecomyrminae: Barden & Grimaldi, 2013: 410.
 * †Zigrasimecia in †Sphecomyrminae, †Sphecomyrmini: Perrichot, 2014: 166.
 * †Zigrasimecia in †Sphecomyrminae, †Zigrasimeciini: Borysenko, 2017: 18.
 * †Zigrasimecia as genus: all authors.

Cao et al. (2020) - Emended diagnosis (female): Distinguished from both Boltonimecia and Protozigrasimecia as outlined in the key above. Sharing uniquely with Protozigrasimecia the large, dome-shaped head with deep and broadly concave occiput in posterior view, and evenly and broadly concave, arcuate clypeus. Additional definition provided by the following characters: antenna of worker and alate gyne 12-merous (see Note 5); worker body length 1.8 - 4.6 mm, gyne body length 2.7 - 4.0 mm; head massive, nearly as large as mesosoma; frontal carinae present; clypeus in form of an evenly arched transverse bar; anterior margin concave with dozens of denticulate traction setae; labrum with dense spiniform traction setae; inner surface of mandibles with traction setae distributed along their length; worker eyes small and rounded; scape at least twice length of pedicel; labrum covered with erect and strong spiniform traction setae; labrum apicomedially bilobate; mesosoma strongly convex and anteroposteriorly compact, without external indication of segmental articulation; helcium (= articulatory sclerites of abdominal segment III) axial (situated at segment midheight). Gyne: most of characters similar with workers, except for the following: eyes reniform; mesoscutum and mesoscutellum demarcated by sulcus; mesosoma musculated for flight; forewing with seven closed cells: the costal, two submarginal, one marginal, the basal, subbasal, and first discal.

Note 6: The antennomere counts of alate Boltonimecia and Protozigrasimecia are unknown.

Note 7: The coronal rugosities described on the vertexal area of the holotype of Z. tonsora are almost certainly artefacts derived from the taphonomic process (BEB, pers. obs., ). The rugosities are asymmetrical, and similar apparent bubble streaks can be observed on other, distantly related taxa.