The type specimen numbers are UC no.
15174 and USNM no.
69617 for the part and counterpart; females of the type species A. rostratus have a body length estimated to be between 13.2–15.8 mm (0.52–0.62 in), with a small gaster that is shorter than the mesosoma and sporting a short thick sting.
The length of the head when excluding the mandibles is 4 mm (0.16 in), the mesosoma is 5.3 mm (0.21 in) and the middle femur is around 3.7 mm (0.15 in).
The preserved specimens from the Green River Formation are brown and the upper area of the head and gaster is black, which is similar to Myrmecia nigriceps.
The head capsules have antennae borne on a scape which is long and passes the edge of the occipital margin of the head.
The short, thickened mandibles have several larger teeth interspersed with small denticles, and are about 50% of the length of the head capsule.
The scape is believed to be long and thin, and its mesosoma is narrow and long.
The width of the scutum is greater than its length, the legs are noticeably elongated and thin, and the podeum (a narrow stalk that connects the mesosoma with the abdomen) is slightly convex.
The type specimen numbers are UC no. 15174 and USNM no. 69617 for the part and counterpart; females of the type species A. rostratus have a body length estimated to be between 13.2–15.8 mm (0.52–0.62 in), with a small gaster that is shorter than the mesosoma and sporting a short thick sting. The length of the head when excluding the mandibles is 4 mm (0.16 in), the mesosoma is 5.3 mm (0.21 in) and the middle femur is around 3.7 mm (0.15 in). The preserved specimens from the Green River Formation are brown and the upper area of the head and gaster is black, which is similar to Myrmecia nigriceps. The head capsules have antennae borne on a scape which is long and passes the edge of the occipital margin of the head. The short, thickened mandibles have several larger teeth interspersed with small denticles, and are about 50% of the length of the head capsule. The scape is believed to be long and thin, and its mesosoma is narrow and long. The width of the scutum is greater than its length, the legs are noticeably elongated and thin, and the podeum (a narrow stalk that connects the mesosoma with the abdomen) is slightly convex.
Archimyrmex