446 bulletin: museum of comparative zoology. 



F. rufa subsp. ohscuriventris Emery, Zool. jahrb. Syst., 1893, 7, p. 649; 



Wheeler, Ants, 1910, p. 570. 

 F. dryas Wheeler, Bull. Amer. mus. nat. hist., 1905, 21, p. 268, ^ 9 . 



Worker. Length 3.5-7.5 mm. 



Averaging smaller than the preceding .subspecies. Base of epino- 

 tum usually convex and rounded. Petiole moderately broad, strongly 

 compressed anteroposteriorly, its dorsal border thin and sharp, entire 

 and produced upward in the middle. 



Opaque; mandibles and clypeus slightly shining, longitudinally 

 striate, frontal area very smooth and shining. Gaster subopaque or 

 slightly shining, finely shagreened and punctate. 



Hairs and pubescence yellowish, the former short, erect, as abundant 

 as in the typical truncicola, covering all parts of the body except the 

 antennae; scapes sometimes with a few scattered hairs on their pos- 

 terior surfaces. Eyes hairy. Pubescence distinct and rather dense 

 on the head and thorax, sparser and finer on the gaster so that the 

 surface is clearly visible. 



Deep red, when mature; mandibles and corners of clypeus darker; 

 gaster black, with the anal region and sometimes also a small spot at 

 the base of the first segment reddish. Large workers very rarely, 

 smallest workers somewhat more frequently, with a brownish cloud 

 in the region of the ocelli and on the pro- and mesonotum. 



Female. Length 7-8 mm. 



Surface of body more shining than in the worker, especially' the 

 gaster, which is as glabrous and shining as in the female of the typical 

 rufa. Mandibles coarsely striatopunctate, head and thorax very 

 finely and densely punctate; clypeus, front, and anterior portion of 

 mesonotum with several large, elongate punctures. 



Hairs longer and more flexuous than in the worker, especially on the 

 top of the head, gula, thoracic dorsum, and tibiae, varying greatly 

 in length, sparse on the pleurae and absent on the gaster, except on 

 the ventral surface and tip. Antennal scapes often with a row of 

 long, flexuous, erect hairs along their posterior surfaces. Eyes hairy. 

 Pubescence yellowish, abundant and rather dense on the thorax and 

 legs; sparse on the gaster. 



Deep red, three elongate spots on the mesonotum, the posterior 

 portion of the scutellum, the metanotum, and the gaster black. 

 Tibiae, tarsi, and funiculi dark brown. Anal region sometimes red- 

 dish ; first segment often with a yellowish red spot at the base. Wings 

 strongly infuscated, with paler tips, brown veins and stigma. 



Male. Length 8 mm. 



Mandibles edentate, rather narrow. Eyes large. Petiole more com- 

 pressed anteroposteriorly than in the other subspecies, its border rather 

 sharp and not excised. 



