Zigrasimecia tonsora
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Zigrasimecia Temporal range: Late Aptian to Early Cenomanian |
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| Z. tonsora holotype | |
| Scientific classification | |
| Kingdom: | Animalia |
| Clade: | Euarthropoda |
| Class: | Insecta |
| Order: | Hymenoptera |
| Family: | Formicidae |
| Subfamily: | †Sphecomyrminae |
| Tribe: | †Sphecomyrmini |
| Genus: |
†Zigrasimecia Barden & Grimaldi, 2013 |
| Type species | |
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Zigrasimecia tonsora |
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| Species | |
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Zigrasimecia is an extinct genus of ants which existed in the Cretaceous period approximately 98 million years ago. The first specimens were collected from Burmese amber in Kachin State, 100 kilometres (62 mi) west of Myitkyina town in Myanmar. In 2013, palaeoentomologists Phillip Barden and David Grimaldi published a paper describing and naming Zigrasimecia tonsora. They described a dealate female with unusual features, notably the highly specialized mandibles. Other features include large ocelli, short scapes, 12 antennomeres, small eyes, and a clypeal margin that has a row of peg-like denticles. The genus Zigrasimecia was originally incertae sedis (uncertain placement) within Formicidae until a second species, Zigrasimecia ferox, was described in 2014, confirming its placement in the subfamily Sphecomyrminae.
Due to the highly specialized mandibles, scientists believe that the ants exhibited habits no longer seen in extant ants. The highly movable head suggests that mobility was an important factor for them (probably for feeding behavior), and the rugose projections may have played a major role in nest excavation because the mandibles would have prevented such activity. Zigrasimecia most likely interacted with the extinct ant genus Gerontoformica through conflict and probably shared some of their ecological niches. The mandibles of these ants were probably used for mechanical interactions with food, and they may also have served as traps for potential arthropod prey such as mites and small flies. Zigrasimecia was possibly a generalist predator.
Zigrasimecia tonsora is only known from a single specimen, the holotype, specimen number JZC Bu-159. At the time of description, the specimen was residing in the private collection of James Zigras and only available for study through the American Museum of Natural History. The solitary adult fossil is composed of a mostly-complete dealate adult female which has been preserved as an inclusion in transparent chunks of deep yellow and relatively clear Burmese amber. The amber specimen was recovered from deposits in Kachin State, 100 kilometres (62 mi) west of Myitkyina town in Myanmar. Burmese amber has been radiometrically dated using U-Pb isotopes, yielding an age of approximately 99 million years old, close to the Aptian – Cenomanian boundary. The fossil was first studied by palaeoentomologists Phillip Barden and David Grimaldi, both of the AMNH. Barden and Grimaldi's 2013 type description of the new genus and species was published in the online journal Zootaxa. The genus name Zigrasimecia is a patronym which was coined as a combination of James Zigras' last name and -mecia which is a commonly used suffix in ant generic names. The specific epithet tonsora was derived from a combination of the Latin words tonsor meaning "barber" or "hairdresser" and oris meaning "mouth", in reference to the ants' mouthparts bearing combs and brushes.Zigrasimecia is one of seven ant species described from Burmese amber and one of the five Burmese amber species placed in Sphecomyrminae or incertae sedis. The other sphecomyrmin species are: Haidomyrmex cerberus, Haidomyrmex scimitarus, Haidomyrmex zigrasi, and Gerontoformica orientalis.
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