Formica dirksi

Known from a single queen collected in Daigle, Maine. She is a social parasite and was found in a colony of her host, Formica subaenescens. This colony was located at the edge of a small clearing in mixed woods, which were predominantly coniferous forest, and was located under loose bark in the wood of a large, erect, partially decayed, dry stump. The galleries of the nest were partially filled with a the detritus, which was also banked around the base of the stump. The colony was very large, consisting of several hundred workers, and a large number to pupae.

Identification
Wing (1949) states that this species is related to Formica microgyna. He notes several differences between the two, including 1) its larger size (total length 5.1 mm); 2) the antepenultimate segment of the maxillary palp is longer (0.23 mm) then the penultimate joint (0.11 mm), as compared to the situation in F. microgyna, in which the two segments are approximately equal in length; 3) the mandible is 7-toothed in-stead of 8-toothed as in the typical F. microgyna; 4) the apex of the petiole is lower and more blunt than in F. microgyna; 5) the petiole has small, posterior lateral the he directed lobes on the ventral surface, where the petiole joins the gaster, which are absent in the typical F. microgyna; 6) hairs are more numerous and slightly shorter, the hairs on the gaster of F. microgyna are fewer in number dorsally and nearly absent ventrally; 7) the pubescence on the gaster is longer, more dense, whiter, and with a silvery tinge, the similar pubescence in F. microgyna has a yellowish tinge; 8) this species is distinctly darker in color, and the areas of infuscation are deeper and more extensive, the gaster of F. microgyna is lighter. This species should be easily separated from F. microgyna, which is known primarily from western United States, and does not occur in Maine.

Distribution based on Regional Taxon Lists
Nearctic Region: United States.

Nomenclature

 *  dirksi. Formica dirksi Wing, 1949: 13 (q.) U.S.A.