Explanation of Names
Formica lasioides Emery, 1893
Identification
Formica neogagates, and F. lasioides, are the only two species in the neogagates group in New England (ref. 2). Both species are very similar, described as "uniformly brown, shiny" (p. 129, ref. 2) and "brown-to-black concolorous ants" in the key (p. 140, ref. 2). Part of the major key character: "an ant of open fields = lasioides" vs. "an ant of forests = neogagates" (p.140,ref. 2) is unreliable. Antweb (ref. 1) lists meadows and short grass prairie as well as woodlands as common habitats for neogagates; and woodland and forest habitats for lasioides as well as meadows.
These two species are best separated by the absence/presence of erect white hairs on the scape: none (rarely 1-2) in neogagates, 3 or more in lasioides (ref. 2). Also, neogagates dorsally has fewer hairs than lasiodes and is often black (The New World Black Ant); lasiodes is often dark brown with many hairs dorsally (The Fuzzy Formica).
I doubt these species can be separated (in New England) other than by high-quality close up images.
lasioides
Print References
Emery, C. 1893. Beiträge zur Kenntnis der nordamerikanischen Ameisenfauna. Zoologische Jahrbücher Abteilung für Systematik Ökologie und Geographie der Tiere 7: 633-682. [original description; PDF
here]
Ref. 2 Ellison et al. 2012. A Field Guide to the Ants of New England. Yale University Press.
