page_title: Sphecomyrma
section_title: S. mesaki
hierarchical_section_title: Sphecomyrma / Description / S. mesaki
caption_attribution_description: English: Closeup view of the specimen Sphecomyrma mesaki
context_page_description: Sphecomyrma is an extinct genus of ants which existed in the Cretaceous approximately 79 to 92 million years ago. The first specimens were collected in 1966, found embedded in amber which had been exposed in the cliffs of Cliffwood, New Jersey, by Edmund Frey and his wife. In 1967, zoologists E. O. Wilson, Frank Carpenter and William L. Brown, Jr. published a paper describing and naming Sphecomyrma freyi. They described an ant with a mosaic of features—a mix of characteristics from modern ants and aculeate wasps. It possessed a metapleural gland, a feature unique to ants. Furthermore, it was wingless and had a petiole which was ant-like in form. The mandibles were short and wasp-like with only two teeth, the gaster was constricted, and the middle and hind legs had double tibial spurs. The antennae were, in form, midway between the wasps and ants, having a short first segment but a long flexible funiculus. Two additional species, S. canadensis and S. mesaki, were described in 1985 and 2005, respectively.
  The genus is among the earliest known ants to roam the earth and at the time was considered to be the evolutionary link between ants and wasps.
context_section_description: S. mesaki was found in a small piece of amber barely larger than the ant itself. The incomplete specimen numbered AMNH NJ-1023 is currently preserved at the American Museum of Natural History in New York City. The appendages breach the surface of the amber while the petiole and gaster are completely absent. Engel and Grimaldi coined the specific epithet after Bob Mesak, the original collector who donated the specimen to the museum. The species is discernible from the other species by a portion of the clypeus having an elongated ventral lobe. The broad but shallow scrobes of the antennae, the size of the head and oval-shaped eyes can further distinguish S. mesaki from other Sphecomyrma ants. The only body parts of the ant that are preserved are the legs, mesosoma and head. The head is notably large, but it is shorter than its mesosoma. The head is 2.2 mm (0.087 in) long and 1.95 millimetres (0.077 in) wide, with the eyes alone measuring 0.66 millimetres (0.026 in). The vertex is covered in sparse pilosity with 0.2 millimetres (0.0079 in) setae. Ocelli are present on top of the ants' head, precisely located just above the dorsal tangent. The base of the antennae emerges from the scrobes, which are equally as long as the scape. The eyes are well developed and located above the bottom of the antennae. The clypeus is setose, meaning that it bears bristles or setae, except on the middle part. The mandibles are small and only contain two teeth. The antennae are moderately long, the scapes are very short but the pedicel is even shorter. The mesosoma measures 2.66 millimetres (0.105 in) and is setose. Several setae are seen around the metanotum (the dorsal sclerite) and propodeum. The coxae, the proximal segment and functional base of the leg, are setose (bearing bristle or setae), inflated and large. The metapleural gland opening is small and noticeable, located away from the propodeum and above the metacoxa (the hind of the coxa). The legs are moderately long. The forelegs first tarsomere (subsegments of the tarsus) is longer than the combined length of other tarsomeres more distant than the first subsegment. The number of stiff setae varies on each tarsomere: for example, the first tarsomere has seven pairs while the fourth tarsomere has only two pairs. The pretarsal claw has a single subapical tooth and the metasoma is absent.
caption: Closeup view of S. mesaki
exif: {"Image DocumentName": "amnh-nj1023", "Image Software": "EXIFutils V3.1.4", "Image DateTime": "2015:02:13 06:28:29", "Image Artist": "David Grimaldi/AMNH - Vincent Perrichot", "Image Copyright": "California Academy of Sciences&#44; 2002-2012", "Image ExifOffset": "220", "EXIF ExifVersion": "0221"}