NE US Myrmica

rubra group
Myrmica rubra - small, thin frontal lobes that point upwards so that the base of the antennae are clearly visible. The edges of the frontal lobes are evenly convex, and the triangle between the two frontal lobes is smooth, often shiny, and lacks the prominent ridges (rugae) that are visible on the rest of the head and mesosoma.

Specimen Label

punctiventris group 3 species - a large, coarse pit or puncture at the base of each erect hair on their gasters. Also, the edges of their frontal lobes are rounded or somewhat convex, and the margin of the clypeus is more or less angular. The propodeum of ants in the punctiventris group is noticeably lower than the promesonotum, giving the mesosoma a stepped-down appearance.

incompleta group 4 species - more triangular frontal lobes, a smoothly convex or modestly concave clypeal margin, and only small, generally inconspicuous pits at the base of the hairs on their gasters. The propodeum of ants in the incompleta group is at the same level as the pronotum, as it is in all other New England Myrmica species.

lobifrons group 2 species - have a shallow- to deeply-notched clypeus.

Bent Antennal Bend

sculptilis group 2 (undescribed) species - characterized by thick, rounded, parallel rugae (ridges) on the head, mesosoma, petiole, and post-petiole, and by extended wings on the side of the clypeus that create a ridge that encloses the antennal socket. The sculpturing at the bend of the antennal scape is relatively inconspicuous on top but more pronounced along the inner descending side. The remaining groups have thinner rugae on their heads, mesosomas, petioles, and post-petioles, and their rugae are wavy and net-like (anastomosing).

scabrinodis group M. scabrinodis - prominently flattened scape that gives it a tapered (not round) appearance in cross-section (to use this character, imagine cutting the scape like a salami and looking at the shape of the slice). Known only on three islands in Boston Harbor, and in a single backyard in Porter Square in Cambridge, Massachusetts.

nearctica group 3 species - clypeus that is concave or shallowly notched, a flat lower surface of their post-petiole, and antennal scapes that are uniformly wide for their entire length. The projection at the bend of the antennal scape looks like a soup spoon.

latifrons group M. latifrons – has characters that are intermediate between the sculptilis and nearctica groups. It has only a shallow concavity (barely a notch) on the margin of its clypeus and a lobed lower surface of its post-petiole.

detritinodis group 4 species - antennal scapes that are not uniformly wide for their entire length. Rather, their scapes taper and are narrower at the base (closer to the head). The projection at the bend of the antennal scape is less conspicuous on top, but more conspicuous along the inner side of the base, facing the head. One of the species in the detritinodis group has no propodeal spines and is thought to workerless social parasite. It is known from only a single specimen collected in 2006 in a pitfall trap in a blueberry barren in Maine; it is not yet formally named.