Protozigrasimecia

Distribution
This taxon is known from.

Discussion
Cao et al. (2020) - 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.

Nomenclature

 * † PROTOZIGRASIMECIA [†Zigrasimeciinae]
 * †Protozigrasimecia Cao, Boudinot & Gao, 2020: 166. Type-species: †Protozigrasimecia chauli, by original designation.

Uniquely identified among all Formicidae by the diagnostic features listed for Zigrasimeciini and in the Key to the genera of Zigrasimeciini. The new genus is defined by the following combination of character states (see Note 8): (1) head massive, omega-shaped (Ω); (2) anterior clypeal margin broadly concave and arcuate; (3) traction setae present on the anterior clypeal margin and labrum; (4) clypeal traction setae not restricted to single row on anterior margin, but doubling and tripling on clypeus toward cranial midlength; (5) basal mandibular margin evenly convex, ending apically at base of basal tooth; (6) masticatory margin bidentate, comprising well-developed, acute basal and apical teeth; (7) flagellomeres elongate, length > 2 × width; (8) diagonal antennal scrobes present (extending from toruli to anteromedian eye margins); (9) ocelli present; (10) mesosoma diagonal, with domed promesonotum; (11) promesonotal articulation clearly defined and probably mobile; (12) mesonotum well-developed, comprising only mesoscutum; (13) mesoscutellum and metanotum not expressed; (14) propodeum rectangular and box-shaped; (15) propodeal spiracle situated low and laterally on segment; (16) propodeal spiracle slit-shaped; (17) tibial spur formula 2b,2(1b,1s) (b = barbirulate, i.e., with fringed margin, but spur not pectinate); (18) pretarsal claws with denticle situated in basal half; (19) helcium apparently infraaxial (anterior articulatory sclerites of abdominal segment III situated below segment midheight); (20) prora of abdominal sternum III in form of longitudinal keel; (21) abdominal tergum III constricted posteriorly, almost nodiform, albeit segment large; (22) abdominal segment IV with cinctus (tergum and sternum IV divided into pre- and postsclerites by transverse sulcus); and (23) sting robust (Fig. 5D).

Note 8: Because the uniqueness of these characters in comparison to other Zigrasimeciini has already been addressed in the Zigrasimeciini definition, the Zigrasimecia diagnosis, and the key, we simply provide these characters in sequence from anterior to posterior along the body axis. The taxon definition provided here includes characters which encompass meaningful variation among all described and many undescribed stem Formicidae, as well as with relevant comparisons with crown groups. See, for example, Fisher & Bolton (2016) for a comparable approach.

Etymology
The generic name refers to the set of retained plesiomorphic features which distinguish the new taxon from Zigrasimecia (namely, the mandibular dentition and mesosomal form).