Zigrasimecia goldingot Zhuang, Ran, Li, Feng & Liu, 2022

Abstract, Júlio Cezar Mário Chaul, 2023, A revision of the Cretaceous ant genus Zigrasimecia Barden & Grimaldi, 2013 (Hymenoptera: Formicidae: † Zigrasimeciinae), Zootaxa 5325 (3), pp. 301-341 : 319-320

Zigrasimecia goldingot Zhuang, Ran, Li, Feng & Liu, 2022

Diagnosis (worker). Head roughly subquadrate in full-face view. Pilosity on body composed of inconspicuous, decumbent, small setae; on the dorsum of head setae curving towards the midline. Compound eyes subcircular (in relation to Z. tonsora ). Reduced number of clypeal chaetae (less than 25). Dorsal propodeal surface relatively short (in relation to Z. tonsora ). Petiolar node apex sharp, not forming a proper dorsal surface; transversally the apex is mildly bilobed.

Comments. Zigrasimecia goldingot and Z. tonsora are species known only by queens. Below is summarized why the species described from workers are unlikely conspecific to them.

Zigrasimecia goldingot differs strikingly in pilosity from the species Z. boudinoti , Z. chuyangsui , Z. ferox , and Z. hoelldobleri as it has small and decumbent setae while those four species have conspicuous standing setae on the body. It differs from Z. thate and Z. perrichoti in the low number of clypeal chaetae (less than 25, rather than more than 30); from Z. thate alone, for not having the flagellate, hook-shaped setae on the frons and vertex; and from Z. perrichoti alone in the subquadrate, rather than subrectangular, head (although different shape of the head is common between queens and workers in many ant species), and for having many small, recurved, decumbent setae on the head, rather than a mostly glabrous head (or maybe with very thin and inconspicuous setae, see description of Z. perrichoti ). Finally, Z. goldingot is unlikely conspecific to Z. caohuijiae for its petiole with a short and bilobed apex, rather than having the broad and round dorsal surface of the node seen in Z. caohuijiae .

Zigrasimecia tonsora can be differentiated from Z. boudinoti , Z. chuyangsui , and Z. hoelldobleri for the type of its standing pilosity, which is shorter, thinner and not as homogeneously distributed on the dorsal surfaces of the head, mesosoma and metasoma as in those species. Also due to pilosity, Z. tonsora is unlikely conspecific to Z. caohuijiae , Z. perrichoti , and Z. thate , as the three are mostly glabrous, except that Z. thate has a patch of hook-shaped, flagellate standing setae on the head (setae on the head of Z. tonsora being simple, thin, and suberect). The type of the pilosity in Z. ferox is similar to Z. tonsora for being short and suberect to erect, however, in Z. ferox the setae appears more sparse and evenly distributed, while it is patchy and denser in Z. tonsora . Z. tonsora differs from most species by having the apical tooth strongly offset (outer margin sinuous distally, Fig. 2 , D). Finally, there are two unique traits that isolate Z. tonsora , a V-shaped groove on the frons, and a pair of vertexal ridges (see comment on that last character under Z. tonsora ).

Figures

FIGURE 2. Masticatory margin of mandible in Gerontoformica and Zigrasimecia. A, Gerontoformica sp. (ANTWEB1032629); B, Z. ferox (ANTWEB1008126); C, Z. chuyangsui (ANTWEB1032660); D, Z. tonsora (ANTWEB11008098). Black triangles indicate incision between apical and basal teeth (or basal lamella). Image of Z. tonsora by Philip Barden and image of Z. ferox by Vincent Perrichot, courtesy of Antweb.org.